CA1084224A - Process for lining high pressure pipeline - Google Patents
Process for lining high pressure pipelineInfo
- Publication number
- CA1084224A CA1084224A CA334,208A CA334208A CA1084224A CA 1084224 A CA1084224 A CA 1084224A CA 334208 A CA334208 A CA 334208A CA 1084224 A CA1084224 A CA 1084224A
- Authority
- CA
- Canada
- Prior art keywords
- liner
- pipeline
- section
- inside diameter
- pipeline section
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C63/00—Lining or sheathing, i.e. applying preformed layers or sheathings of plastics; Apparatus therefor
- B29C63/26—Lining or sheathing of internal surfaces
- B29C63/34—Lining or sheathing of internal surfaces using tubular layers or sheathings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
- B29C49/00—Blow-moulding, i.e. blowing a preform or parison to a desired shape within a mould; Apparatus therefor
- B29C49/24—Lining or labelling
- B29C49/26—Lining or labelling inner lining of tubes
Abstract
PROCESS FOR LINING HIGH PRESSURE PIPELINE
A B S T R A C T
A method for lining a high pressure pipeline with a tubular plastic liner. After de-pressurizing, purging and cleaning, the pipeline is broken into discrete sections. A
close-fitting liner segment is pulled into each pipeline section. Advantageously, the liner segments are fixed inside the pipeline sections to prevent longitudinal movement of the liner segments. Bleeder holes are provided through the pipeline walls at opposed ends of each pipeline section. The lined pipeline sections are reconnected to reform the pipeline, and then a relatively warm, pressurized fluid is pumped through the pipeline to radially expand each liner segment against the inner walls of the pipeline, thus evacuating the spaces between liner segments and pipeline sections by forcing air, water and other impurities through the bleeder holes.
A B S T R A C T
A method for lining a high pressure pipeline with a tubular plastic liner. After de-pressurizing, purging and cleaning, the pipeline is broken into discrete sections. A
close-fitting liner segment is pulled into each pipeline section. Advantageously, the liner segments are fixed inside the pipeline sections to prevent longitudinal movement of the liner segments. Bleeder holes are provided through the pipeline walls at opposed ends of each pipeline section. The lined pipeline sections are reconnected to reform the pipeline, and then a relatively warm, pressurized fluid is pumped through the pipeline to radially expand each liner segment against the inner walls of the pipeline, thus evacuating the spaces between liner segments and pipeline sections by forcing air, water and other impurities through the bleeder holes.
Description
` -FIELD OF THE INVENTION
This invention relates to methods for lining pipelines, and, in particular, to a method for lining a buried high pressure pipeline.
BACKGROUND OF THE INVENTION
. . . . .
It is known to provide a loose-fitting plastic liner to extend the life of an existing low pressure pipeline. (By "low pressure" it is meant that pressures inside the pipeline do not exceed about 150 pounds per square inch ("psi") when the pipeline is in service.) However, plastic liners are not used in high pressure pipelines such as water injection lines where pressures of 5,000 psi or more may be encountered inside the pipeline.
The reason for this is that in conventional "relining" applications, the existing pipeline is used simply as a "guide" to receive a loose-fitting tubular plastic insert. The loose-fitting insert once lnstalled in the pipeline, serves as a new "pipeline" - the insert conveys the material : ~
formerly conveyed by the pipeline, but, in doing so, must be capable of withstanding whatever pressures ., .
may be required to transport the material there-through. Such loose-fitting plastic inserts are unsuitable for use in high pressure pipelines because they are not capable of withstanding the strain encountered when the interior region of ,~
the liner is pressuri2ed, forcing the liner~ to expand radially toward-the internal walls of the pipellne. ~ `
This invention relates to methods for lining pipelines, and, in particular, to a method for lining a buried high pressure pipeline.
BACKGROUND OF THE INVENTION
. . . . .
It is known to provide a loose-fitting plastic liner to extend the life of an existing low pressure pipeline. (By "low pressure" it is meant that pressures inside the pipeline do not exceed about 150 pounds per square inch ("psi") when the pipeline is in service.) However, plastic liners are not used in high pressure pipelines such as water injection lines where pressures of 5,000 psi or more may be encountered inside the pipeline.
The reason for this is that in conventional "relining" applications, the existing pipeline is used simply as a "guide" to receive a loose-fitting tubular plastic insert. The loose-fitting insert once lnstalled in the pipeline, serves as a new "pipeline" - the insert conveys the material : ~
formerly conveyed by the pipeline, but, in doing so, must be capable of withstanding whatever pressures ., .
may be required to transport the material there-through. Such loose-fitting plastic inserts are unsuitable for use in high pressure pipelines because they are not capable of withstanding the strain encountered when the interior region of ,~
the liner is pressuri2ed, forcing the liner~ to expand radially toward-the internal walls of the pipellne. ~ `
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. ~, `
:L~8~2Z4 Viewed in this light, it becomes apparent that, strictly speaking, the use of a loose-fitt.ing insert is not properly described as "pipeline relininy"
~; because the insert does not serve as A 1l liner" but serves instead as a new pipeline having a somewhat smaller external diameter than the internal diameter ~ -of the existing pipeline, there being an annular gap between the outer wall of the plastic insert and the inner wall of the existing pipeline. The present invention, by contrast, provides a close-fitting liner - after completion of the procedure :
described below, the liner is disposed inside the pipeline with no annular gap between the liner and ~ .
` the pipeline. Because the liner contacts the inner walls of the pipeline the liner itself need not be capable of withstanding the pressures encountered :. .
inside the pipeline.
Loose-fitting plastic in.serts are conven- ;
tionally installed in pipelines in an effort to extend the piping system life at a cost `somewhat .: :
lower than that of instalIing a new pipeline. Loose-fitting plastic inserts are somet`imes also intended to protec~ an existing pipeline~against internal corrosion~or abrasion. The installation of a loose-fitting plastic insert into a pipeline may also imprbve the flow characteristics of the ~ ~
pipeline beyond those obse~rved in a similar ~ -pipeline which is not equipped with a loose~
fitting plastic insert. Loose-fitting plastic inserts may aIso eliminate~, or at least reduce
. ~, `
:L~8~2Z4 Viewed in this light, it becomes apparent that, strictly speaking, the use of a loose-fitt.ing insert is not properly described as "pipeline relininy"
~; because the insert does not serve as A 1l liner" but serves instead as a new pipeline having a somewhat smaller external diameter than the internal diameter ~ -of the existing pipeline, there being an annular gap between the outer wall of the plastic insert and the inner wall of the existing pipeline. The present invention, by contrast, provides a close-fitting liner - after completion of the procedure :
described below, the liner is disposed inside the pipeline with no annular gap between the liner and ~ .
` the pipeline. Because the liner contacts the inner walls of the pipeline the liner itself need not be capable of withstanding the pressures encountered :. .
inside the pipeline.
Loose-fitting plastic in.serts are conven- ;
tionally installed in pipelines in an effort to extend the piping system life at a cost `somewhat .: :
lower than that of instalIing a new pipeline. Loose-fitting plastic inserts are somet`imes also intended to protec~ an existing pipeline~against internal corrosion~or abrasion. The installation of a loose-fitting plastic insert into a pipeline may also imprbve the flow characteristics of the ~ ~
pipeline beyond those obse~rved in a similar ~ -pipeline which is not equipped with a loose~
fitting plastic insert. Loose-fitting plastic inserts may aIso eliminate~, or at least reduce
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the oeec~ to use oYy~en scavengers, rus-t inhibitors or other chemicals -to maintain the pipeline.
The present invention, while providing these advantages, provides the further advantage that it is not restricted to use in low pressure applications but may be used in applications where internal pipeline pressures of several thousand psi are encountered.
Accordingly, it is an object of the pre-sent invention to provide a method of lining a pipeline with a plastic liner such that the lined pipeline is capable of withstanding internal pressures in excess of those which the llner alone could withstand.
A further object is to provide such a method which is relatively inexpensive, when compared with the cost of installing a new pipeline, and which is relatively easy to implement.
SUMMARY OF THE INVENTION
The invention provides a method of lining a section of a pipeline comprising drawing ~ -a selected plastic liner into the section until the liner is substantially longitudinally co-extensive with the section, the liner having an outside diameter sufficiently less than the inside diameter ;~
of the pipeline to enable such drawing, but sufficiently large so that the liner can be non-destructively radially expanded against the inside wall of the pipeline section; stretching the liner within the section; fixing the llner against longitudinal movement within the section; radially expanding the liner against
the oeec~ to use oYy~en scavengers, rus-t inhibitors or other chemicals -to maintain the pipeline.
The present invention, while providing these advantages, provides the further advantage that it is not restricted to use in low pressure applications but may be used in applications where internal pipeline pressures of several thousand psi are encountered.
Accordingly, it is an object of the pre-sent invention to provide a method of lining a pipeline with a plastic liner such that the lined pipeline is capable of withstanding internal pressures in excess of those which the llner alone could withstand.
A further object is to provide such a method which is relatively inexpensive, when compared with the cost of installing a new pipeline, and which is relatively easy to implement.
SUMMARY OF THE INVENTION
The invention provides a method of lining a section of a pipeline comprising drawing ~ -a selected plastic liner into the section until the liner is substantially longitudinally co-extensive with the section, the liner having an outside diameter sufficiently less than the inside diameter ;~
of the pipeline to enable such drawing, but sufficiently large so that the liner can be non-destructively radially expanded against the inside wall of the pipeline section; stretching the liner within the section; fixing the llner against longitudinal movement within the section; radially expanding the liner against
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the inside wall of the pipeline by means of application of fluid to the inside wall of the liner; and bleedi~g -the space between the liner and -the pipeline during the expanding step.
Preferably, the fluid used in the expanding step is under relatively low pressure and is relatively warm.
Before -the expanding step, at least one bleeding port is opened in the pipeline section for bleeding the space between the liner and the pipeline. After the expanding and bleeding steps, the bleeding port is closed.
In one embodiment, the invention is .. . .
directed to a method of lining a section of a high pressure pipeline with a tubular plastic liner which utilizes the structural strength of the pipeIine to enable the lined plpeline section to ; be operated at high pressure, the section including first and second flanges disposed at opposite !: 20 ends of the section, the method compri~ing drawing `
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a seleated plastic liner into the section until the liner is substantially~longitudinally co-extensive with the section, the liner having an outside diameter sufficiently less than the inside diameter of the pipeline to enable such drawlng, but suff~iciently~large~so that the liner can be non-destructively radially expanded against the inside wall of the pipeline section stretching the liner within the section; fixing the ~ -~
liner against longitudinal movement within the section;
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2~
opening at least one bleeding port in the section;
radially expanding the liner against the inside wall of the pipeline by means of application of relatlvely warm fluid under relatively low pressure to the inside wall of the liner while bleeding the space between the liner and the pipeline through the bleeding port; and, thereafter, closing the bleeding port.
The fixing step may comprise heating the ends of the liner which protrude from the pipeline section, and molding the heated liner ends against the first and second flanges of the pipeline section.
Preferably, before the drawing step, a relatively short segment of liner material is passed through the pipeline section to detect any matter protruding into the space to be occupied by the liner. Any matter protruding into the space to be occupied by the liner is preferably removed before the drawing step.
Preferably, the liner is a high-density polyethylene material.
The invention is also directed to a pipeline section having a tubular plastic liner radially expanded against the inside wall of the section and fixed in tension between opposed ends of the ;~
section. The plastic liner is radially supported by the structural strength of the pipeline section so as to enable the lined pipeline section to be operated at high pressure.
Preferably, for a given inside diameter ;
2~ :
of pipeline section, the outside diameter of the liner before radial expansion is at least 94~ ~ -of the inside diameter in the case of an inside diameter be-tween about 2 inches to about 4 inches ~:
and increases to a-t least 96.5~ of the inside diameter in the case of an inside diameter of about 10 inches or greater.
DRAWINGS
_ FIGURE 1 is a perspective view of an end of a pipeline section having a flange affixed thereto;
FIGURE 2 is a perspective view of a cable-carrying pig; ., ; FIGURE 3 is a fragmentary plan view of a pig launching device coupled to a pipe-line section; : FIGURE 4 is a fragmentary perspec~
tive view of a pulling head affixed to a liner segment; ~ :
FIGURE 5 is a fragmentary perspec-tive view of an alternate pulling arrangement affixed to a l~ner segmert;
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FIGURE 6 is a fragmen-tary perspec-tive ~iew of a further alternate pulling . arrangement affixed to a liner segment;
FIGURE 7 is a perspective view of an excavation site showing a partially exposed portion of a pipeline section into which a liner segment is to be pulled;
`: FIGURE 8 is a perspective view show-ing a further alternate arrangement for pulling a liner segment; ~ ;~
FIGURE 9 is a fragmentary perspec~
tive view of a liner segment having a plastic `
flange affixed thereto;
FIGURE 10 is a fragmentary plan view .~ showing an end of a liner segment being molded against a metal flange;
FIGURE 11 is a perspective view showing the clamping against longitudinal move- ~ :
: -:
` ~ ment of a liner segment which has been drawn through a pipeline section;
. FIGURE 12 is~ a perspective view of a retaining ring for use in one aspect of the invention; : ~;
FIGURE 13 is a sectional view showing ~ .
the installation of the:retaining ring of : .~
FIGUÆ 12 according to one aspect of the ~-- invention. ~ :
. DESCRIPTION OF AN ENBODINENT OF THE I-NVENTION
;: The~ following description will make .`~:~
.: : ` :.
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particular reference to the insertion of a plastic liner into a pipeline which is buried in situ. It is to be understood however, that the method is of general application and may be used with pipelines or pipeline sections which are not buried.
SITE PREPARATION
. ~ .
Before commencing installation of a liner into a pipeline, the right of way along the pipeline route should be examined to determine suitable points at which the pipeline may be uncovered and broken to create a plurality of pipeline sections, each of which sections is to receive an individual liner segment. Typically, for the preferred liner material referred to hereinafter, the pipeline ~ . ~
will be broken about every 2,000 feet along its length. It is recommended that pipeline sections not exceed about 2,500 feet in length because the tensile yield point of the liner ;~ material mlght be exceeded and the liner con~
sequently damaged if the liner segment is subjected to the force necessary to pull it through a pipeline section over such a distance. `
Otherwise, the length of particular plpeline sections is not particularly critical and may : :
be varied to accommodate conditions along the `
pipeline right~of way so as to avoid swamp areas, roads, rail crossings, etc. The length of _ 9 - ~ ~
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individual pipeline sections may also be limited by the availability of winch equipmen-t of a capacity sufficient to exert the force necessary to pull a liner segment of a given length through a pipeline section.
Before work commences, the pipeline ~;
should be de~pressurized, purged, and cleaned if necessary.
LINER MATERIRL
The preferred liner material is polyethylene plastic in a tubular configura tion which may be field~assembled into segments up to 2500 feet in length and which can with-stand a radial expansion of at least 6% with-out cracks developing for at least one year.
~he liner material should also have an environ~
mental stress crack resistance (E.S.C.R.) rating in excess of 1000 hours when tested in accordance with conditions A! B and C of ASTM
test D-1693-70. Ultra High Molecular Weight , .
High Density Polyethylene (''UHr~HDPI') which meets Plastic Pipe Institute designation P.E. 3406 is especially preferred for use as the liner material.
LINER MATERIAL EXTERNAL DIAMETr:R
The external diameter of~the liner - ~;
material must be carefully selected as a flmction of the internal diameter of the ;
pipeline. If the external diameter of the - 10 - ~, ~ o~
liner material is too large, then it may not be possible to pull a liner seyment through a pipeline section without subjecting the liner segment to forces so great that it is ruptured. On the other hand, if the external diameter of the liner material is too small, then the lîner may be ruptured when it is radially expanded inside the pipeline as here-inafter described.
`i 10 Tests indicate that UHMWHDP in tubular form may be expanded radially by a factor of about 12~ to 15~ before rupture occurs. As a safety . ~
measure, these factors are halved in an effort to ensure that the liner material is not ruptured when radially expanded to contact the internal pipeline wall. Preferably, the liner material is radially expanded by a factor of no more than 6%. If radial expansion of the liner material is limited in this manner, there will be minimal xisk that factors -; ~:
such as irregularities in the internal diameter of the pipeline, irregularities in the external diameter '! :
of the liner material, or surface damage caused in pulling a liner segment into a particular pipeline section will result in rupture of the liner.
As a practical matter, the following table illustrates external diameters of UHMWHDP liner materials which have proved acceptable in field applications~
, 2~
Liner Material External Diameter as a ~ of Pipeline Inside Diameter Pipeline Inside Diameter 2" to 3" g4% -6" to 8" 96%
10" and above 96.5% to 97~5%
The closer tolerance used with lar~er diameter pipelines represents a decrease in defor-mation of the liner material as it is radiallyexpanded to contact the inside wall of the pipe-liner with an attendant decrease in probability ~ ;
that the liner material will rupture.
LINER WALL THICKNESS
. _ . , . :
The wall thickness of the liner materialwill be governed by a number of considerations.
To some extent, expense will govern the ., liner material wall thickness. Supplièrs of ~ ~
,: . : .:
liner material have reported~that considerable cost~is involved in retoo]ing to produce a liner material of~a given wall thickness. A further -complication faced by suppllers of liner material ;~ is that, as mentioned~above, the outside diameter `~
of the liner material must he carefully selected where it is desired to insert a close-fittinq liner ~ ;
:: .
into a pipeline. Ideally, both the outside~diameter and the wall thickness~of the llner material are individually matched to a given application.
: ~
UsualIy, however, the;~expense involved in inde~
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pendently tailoring ~oth the external diameter and the wall thickness dictates a practical com-promise in which the outside diameter of the liner material is carefully selected with an attendant sacrifice in wall thickness dimension. For example, the supplier may use a die which is capable of producing a tubular plastic material having a standard outside diameter and a standard wall thickness, but adjust his production method to vary the outside diameter of the liner material as required, which may result in an increase or a decrease in the wall thickness of the liner material.
A further factor governing liner material wall thickness arises because the liner material is usually supplied in relatively short lengths which are heat fused together to produce liner segments up to 2500 feet in length for insertion into particular pipeline sections. The wall thick-ness of the liner material will, within limits, :`
affect the quality of the joints at which the lengths of liner material are heat fused. For example, a liner material having an exceptionally thin wall would be difficult to heat fuse because the ends of the material would tend to assume an oval shape when clamped and heated in a conven-tional fusion joining machine. Practical field experience suggests that the liner material wali -thickness should not be less than about 0.15 inches to prevent this problem. Preferably, the ' 13 - ~ ~
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wall thickness of the liner material is grea-ter than abou-t 0.2 inches.
In some applications the fluids to be transported through the lined pipeline may abrade the liner material. Tests may be conducted to determine the rate at which the liner material is abraded by a particular fluid and then a liner wall thickness may be calculated by assuming a given desired lifetime for the liner material.
Each se~ment of liner material must be capable of withstanding the forces imposed on the segment when it is-pulled into a given pipeline section as herelnafter described, without stressing the liner material beyond its tensile yield point.
It has been found that a satisfactory approximation of the pulling force "Lp" (in pounds) imposed on a segment o~ UHMW~DP liner material having an outside diameter "D" (in inches), a wall thickness "t' (in inches), a density 'Idll (in pounds per cuhic inch), a length llZl~ (in inches) and an inertial ~;
friction factor "Fi" (a dimensionless quantity indicative of the frictional resistance which must be overcome to start moving a liner segment which ~ `
is lying on the ground. Field experience indicates that Fi ~ 1.3.) may be obtained from the formula~
Lp = ~ D t d Z Fi (1) ~ -It has also been found that a satisfactory approx-imation of the liner tensile stress ilSzll (in pounds per square inch) for UHMWHDP may be obtained from the ~' ~:
.
.
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formula: -Lp Sz = ~ (2) ~ D t By combining formulae (1) and (2), one obtains:
Sz = d Z Fi ( ) The liner stress "Sz" must be held below the tensile yield point of the liner material (th~e tensile yield point of a given liner material may be obtained from the manufacturer of the liner material). It may be seen from the above formulae that as the length ~'Z" of a liner segment increases, the pulling force "Lp" required to pull the liner segment ~-through a particular pipeline section also increases, with a corresponding increase in liner stress "Sz".
- At some point, "~" may increase such that "Sz"
exceeds the liner material tensile yield point, resulting in damage to the liner.
The wall thickness of the liner material may also be determinative of the ability of the liner to resist collapse if the interior of the liner is ever subjected to vacuum. An approximation of the collapse pressure ~Pc~ (in pounds per square inch) may be obtained from the formula:
2E (t/D)3 1 - u2 (4j where- E = stiffness modulus (in pounds per square inch) of the liner material (available ~' ' zz~ ~
from the manufacturer of the liner material~
t = liner material wall thickness tin inches) D = external diameter of liner material ~in inches) u = Poisson ratio ~about .45 for UHMWHDP
liner material~.
The liner will tend to collapse if the collapse pressure is greater than or equal to 1 atmosphere (14.5 pounds per square inch). The wall thickness required to resist such collapse may therefore be calculated for a liner material of a yiven external diameter.
As discussed hereinafter, the preferred installation procedure may produce a vacuum ~n the annular region between the outslde wall of a;liner segment and the inside wal1 of the pipèline section whlch contains~that llner segment. A
vacuum in thls annular region~would tend to~
; offset a vacuum lnside; the~liner~egment~. The wall thickness of the liner~material required to resist collapse due to internal vacuum could thus be decreased somewhat ~to take advantage of the offsetting vacuum surrounding the liner segment.
As a~practical example, the~following table summarizes the wall~thicknes,s of uHr~Dp liners which have~been used~successfully in ~close-fi~tting .'~ pipeline relining applications~
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8~4 U~lr~lwflDP
Pipeline Pipeline Liner Material rJ~r~pp Ex t~rnal Internal External Liner Material Diameter Diameter D1ameter Wall Thickness 12.750" 12.000" 11.60" 0.300"
10.750" 10.062" 9.70" 0.300"
6.625" 6.187" 6.00" 0.258"
4.500" 4.188" 4.00" 0.150"
PREPARATION OF LINER SEGMæNTS AND PIPELINE SECTIONS
_A_ __ _ _ _ ~ . _ _ _ ,, _ ,, .
. 10Liner segments may be assembled on-site using a conventional fusion joining machine to fuse lengths of linar material together. The liner segments should be at least 20 feet longer than the respective pipeline sections into which they are to be inserted. The external bead of polyethylene which is created on the liner segment by the - fusion joining procedure must be removed to leave a smooth surface which will not impede passage - of the liner segment through the pipeline section or interfere with radial expansion of the liner as hereinafter described. An 'iexternal bead trimmer"
satisfactory for this purpose may be obtained from McElroy Equipment of Tulsa, Oklahoma.
If the liner segments are to be fixed in tension inside respective pipeline sections using the procedure hereinafter described, then a plastic flange 86 (FIGURE 9) is fused onto one end of each liner segment as a preparatory step. ~-.
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A Eirst pipeline section is uncovered at opposed ends by excavating a pair of "bell holes"
along the pipeline right of way. A typical bell hole 100 is shown in FIGURE 7. For ease of illustration, only one pipeline section 10 is shown in FIGURE 7. The pipeline, when initially uncovered, would of course extend through bell hole 100 from right to left.
The pipeline is severed in each bell hole, defining a discrete pipeline section between the two bell holes. For smaller diameter pipelines (2 to 4 inches) it will usually be convenient to uncover the pipeline for about 50 to 100 feet on both sides of the bell hole so that opposing ends of the pipeline in the bell hole may be man-oeuvred away from one another for ease of working.
Larger diameter pipelines are usually much more . -.
stiff and less manoeuvrable.
- For a high pressure pipeline (typically :
i~ 20 steel)~flanges 12 (FIGURES 1, 3~ and 11) are we~lded ,- onto opposite ends of pipeline section 10 to facilitate reforming of the pipeline when the pipeline sections have been lined.
, ~
Near each flange 12, a small "bleeder"
hole (typically about 1/32 inch in diameter) is drilled through the wall of the pipeline. The purpose of the bleeder hole is described in more detail below. A threadlet 14 is welded onto the , , .
pipe over the bleeder hole.
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Flange 12 tapers into neck 18 (best seen in FIGURE 3) which 15 butt-welded onto the end of pipeline section 10. Care should be taken when welding flange 12 onto pipeline section :. 10 to avoid excessive penetration of weld bead into the cavity enclosed by pipeline section 10.
Excessive weld bead should be smoothed by grinding or filing to reduce the possibility that the liner will be damaged when it is pulled into pipeline ; 10 section 10. Flange 12 has a raised circular apertured face 20, the inside diameter of the aperture being equal to the inside diameter of :
i pipeline section 10. Flange 12 is conventional . in the art, the only modification being the machin-ing of a 6 radius on internal lip 22 of flange face 20. Lip 22 is machined to eliminate sharp .
edges which might damage the liner segment during insertion into pipeline section 10.
. A cable-carying device 30 (convention- ~ `
alIy called a "pig") is shown in FIGURE 2. This : .
.~ pig comprises a central body member 32, having a pair of curved rubber cups 34 di~posed a~ oppo-site ends. The external diameter of cups 34 is . slightly greater than the internal diameter of the pipeline so that pig 30 may be tightly fitted ~ :
inside pipeline section 10. A pair of eyelets 36 ,: ~ - ..
: are disposed at opposite ends of the pig body : ::
; member. A cable is attached to an eyelet at one -:
end of pig 30 and the opposite end of the pig inserted into pipeline section 10.
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A "pig launching device" 40 (conventional ~.
in the art) is shown in FIGURE 3. Launchin~ device 40 includes flange 42 which is coupled by means ~ -of bolts 44 to flange 12. Plastic gasket 46 is disposed between flanges 12 and 42 to effect a seal. The cable (which has been attached to pig 30, which now rests inside pipeline section 10 near flange 12) passes through aperture 48 at one end of the launching device 40. Water injection port 50 is coupled with a hose or other means to a water truck capable of delivering water under - :
pressure through the hose and into launching device 40. Pressurized water is thus forced :
~ , through water injection port 50 and cavity 52 and thence into pipeline section 10 behind pig 30 to propel pig 30 along pipeline section 10 with the cable trailing behind~ The cable (which may be coiled upon a reel) is drawn through aperture:48 ;: `
as the pig passes through pipeline sec~tion lO. ::
Suitable gasket means should be provided at aperture .
: 48 to prevent excessive loss of water. A water pressure of about loa psi to 150 psi should suffice to propel the pig and cable through about 2,000 feet of pipeline.
In the abs~ence of a source of pressuri~ed water, compressed air could also be used to force the pig and cable through pipeline section 10.
When pig:30 and the attached cable emerge at the opposite end of pipeline section lO, pig 30 ~
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is removed from the cable and replaced by a "pig train" and a test piece of the liner material~
The cable is first attached to a carbide steel headed "sizing" pig, having an external diameter ~;
slightly larger than the external diameter of the liner segmen~ to be inserted into the pipeline section. Preferably, the external diameter of the sizing pig is about one half the sum of the exter~
nal diameter of the liner material and the inter-, 10 nal diameter of the pipeline~ The sizing pig assists in detexmining whether the internal diameter of the pipeline section is too small to receive the liner segment. The second pig in the pig train is a wire brush pig having a plurality of wire bristles for scraping built-up scale off the internal pipeline surface. The third pig in the pig train is a rubber-cupped cleaning pig used -~ to carry out of the pipeline section slag or scale : . .
broken off the pipeline walls by the first two pigs.
The pigs are provided with eye bolts and are con-nected together with steel cable. Finally, a ;
25 to 30 foot test section of the liner material to be used in lining the pipeIine is attached behind the pig train.
A winch is attached to the cable at the , far end of the pipeline~section. The pig train and test section of liner material are then pulled through pipeline section 10 with the winch. Pre-ferably, the winch is equipped with a cable ZZ~ ;
odometer so that the operator may d~termine the location of points at which the pig train may become lodged in pipeline section 10. If the pig train cannot successfully be pulled through pipeline section 10, then it will be necessary to uncover and open the pipeline at the point at which the pig train becomes lodged to efEect repairs.
. .
After the test section of liner material : 10 has passed through pipeline section 10, it is examined for surface damage. If nicks, gouges, sur~ace slits, etc., on the test section do not penetrate into the liner wall to a depth of more ~ -than about 10~ of the liner wall thickness, then the linex segment may be safely inserted into ;~ the pipeline section. If surface nicks, gou~es, i surface slits, etc., penetrate into the liner wall to a depth of more than about 10% of the liner wall thickness, then the pipeIine section must be repigged j ; 20 and cleaned to eliminate such liner surface damage.
(Preferably, the plpeline section is re-pigged and cleaned if the liner material is penetrated to a depth of more than about 0.04 inches, regardless of its wall thickness.) ;~-~
Once the pipeline section has been .
- pigged and cleaned to eliminate unacceptable liner surface damage, launching device 40 is again used to propel pig 30 and the cable back through plpeline section 10 so that the cable may be attached to ,~
.. , .,. , . , - , . . .
liner ~egment 70 which is to be pulled into pipeline section 10. This procedure also gives pipeline section 10 a water flush to remove foreign matter.
PULLING LINER SEGMENT INTO PIPELINE SECTION
Various pulling arrangements which may be used to attach the cable to liner segment 70, are shown in FIGURES 4, 5, 6 and 8.
FIGURE 4 shows a pulling head 60 having a genexally tapered cylindrical confirguration.
Pulling head 60 may be fabricated from a solid piece of polyethylene, and a hole drilled there-through to receive pin 62 to which eyelet 64 is affixed. Pin 62 is anchored against longitudinal movement with respect to pulling head 60 by means of washer 68 and bolt 66 which is threadably i received on the end of pin 62. Pulling head 60 is .
fused onto one end of liner segment 70 and any ~ -protruding fusion bead removed. The cable is then attached to eyelet 64, pulling head 60 is lntro-duced into pipeline section 10, and the winch used to pull the cable, pulling head 60 and liner segment 70 through pipeline section 10. Pulling head 60 is intended ~or use in high pressure appIications where it is~desired to use a close-fitting liner segment having an external diameter of at least 94~ of the internal diameter of pipeline section ~
10. In such close-fitting applications, it is ~-lmportant that pulling head 60 be free of :' - 23 ~
: .
: . - .. .. . .. . .
~8~Z~
protrusions which might impede transit through pipeline section 10.
The pulling arrangement shown in FIGUR~
2Z~
the inside wall of the pipeline by means of application of fluid to the inside wall of the liner; and bleedi~g -the space between the liner and -the pipeline during the expanding step.
Preferably, the fluid used in the expanding step is under relatively low pressure and is relatively warm.
Before -the expanding step, at least one bleeding port is opened in the pipeline section for bleeding the space between the liner and the pipeline. After the expanding and bleeding steps, the bleeding port is closed.
In one embodiment, the invention is .. . .
directed to a method of lining a section of a high pressure pipeline with a tubular plastic liner which utilizes the structural strength of the pipeIine to enable the lined plpeline section to ; be operated at high pressure, the section including first and second flanges disposed at opposite !: 20 ends of the section, the method compri~ing drawing `
`I ~
a seleated plastic liner into the section until the liner is substantially~longitudinally co-extensive with the section, the liner having an outside diameter sufficiently less than the inside diameter of the pipeline to enable such drawlng, but suff~iciently~large~so that the liner can be non-destructively radially expanded against the inside wall of the pipeline section stretching the liner within the section; fixing the ~ -~
liner against longitudinal movement within the section;
Y' ~;
2~
opening at least one bleeding port in the section;
radially expanding the liner against the inside wall of the pipeline by means of application of relatlvely warm fluid under relatively low pressure to the inside wall of the liner while bleeding the space between the liner and the pipeline through the bleeding port; and, thereafter, closing the bleeding port.
The fixing step may comprise heating the ends of the liner which protrude from the pipeline section, and molding the heated liner ends against the first and second flanges of the pipeline section.
Preferably, before the drawing step, a relatively short segment of liner material is passed through the pipeline section to detect any matter protruding into the space to be occupied by the liner. Any matter protruding into the space to be occupied by the liner is preferably removed before the drawing step.
Preferably, the liner is a high-density polyethylene material.
The invention is also directed to a pipeline section having a tubular plastic liner radially expanded against the inside wall of the section and fixed in tension between opposed ends of the ;~
section. The plastic liner is radially supported by the structural strength of the pipeline section so as to enable the lined pipeline section to be operated at high pressure.
Preferably, for a given inside diameter ;
2~ :
of pipeline section, the outside diameter of the liner before radial expansion is at least 94~ ~ -of the inside diameter in the case of an inside diameter be-tween about 2 inches to about 4 inches ~:
and increases to a-t least 96.5~ of the inside diameter in the case of an inside diameter of about 10 inches or greater.
DRAWINGS
_ FIGURE 1 is a perspective view of an end of a pipeline section having a flange affixed thereto;
FIGURE 2 is a perspective view of a cable-carrying pig; ., ; FIGURE 3 is a fragmentary plan view of a pig launching device coupled to a pipe-line section; : FIGURE 4 is a fragmentary perspec~
tive view of a pulling head affixed to a liner segment; ~ :
FIGURE 5 is a fragmentary perspec-tive view of an alternate pulling arrangement affixed to a l~ner segmert;
~'` ' ::
- 7 - .
. , . . ~
. , .
- : . ~. . .. . . . - -.
h(~ ;22~
FIGURE 6 is a fragmen-tary perspec-tive ~iew of a further alternate pulling . arrangement affixed to a liner segment;
FIGURE 7 is a perspective view of an excavation site showing a partially exposed portion of a pipeline section into which a liner segment is to be pulled;
`: FIGURE 8 is a perspective view show-ing a further alternate arrangement for pulling a liner segment; ~ ;~
FIGURE 9 is a fragmentary perspec~
tive view of a liner segment having a plastic `
flange affixed thereto;
FIGURE 10 is a fragmentary plan view .~ showing an end of a liner segment being molded against a metal flange;
FIGURE 11 is a perspective view showing the clamping against longitudinal move- ~ :
: -:
` ~ ment of a liner segment which has been drawn through a pipeline section;
. FIGURE 12 is~ a perspective view of a retaining ring for use in one aspect of the invention; : ~;
FIGURE 13 is a sectional view showing ~ .
the installation of the:retaining ring of : .~
FIGUÆ 12 according to one aspect of the ~-- invention. ~ :
. DESCRIPTION OF AN ENBODINENT OF THE I-NVENTION
;: The~ following description will make .`~:~
.: : ` :.
; : :. . :
, .
; ~
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particular reference to the insertion of a plastic liner into a pipeline which is buried in situ. It is to be understood however, that the method is of general application and may be used with pipelines or pipeline sections which are not buried.
SITE PREPARATION
. ~ .
Before commencing installation of a liner into a pipeline, the right of way along the pipeline route should be examined to determine suitable points at which the pipeline may be uncovered and broken to create a plurality of pipeline sections, each of which sections is to receive an individual liner segment. Typically, for the preferred liner material referred to hereinafter, the pipeline ~ . ~
will be broken about every 2,000 feet along its length. It is recommended that pipeline sections not exceed about 2,500 feet in length because the tensile yield point of the liner ;~ material mlght be exceeded and the liner con~
sequently damaged if the liner segment is subjected to the force necessary to pull it through a pipeline section over such a distance. `
Otherwise, the length of particular plpeline sections is not particularly critical and may : :
be varied to accommodate conditions along the `
pipeline right~of way so as to avoid swamp areas, roads, rail crossings, etc. The length of _ 9 - ~ ~
:
. : .:. ~ . , . j , , :
.: .: . , . -Z~
individual pipeline sections may also be limited by the availability of winch equipmen-t of a capacity sufficient to exert the force necessary to pull a liner segment of a given length through a pipeline section.
Before work commences, the pipeline ~;
should be de~pressurized, purged, and cleaned if necessary.
LINER MATERIRL
The preferred liner material is polyethylene plastic in a tubular configura tion which may be field~assembled into segments up to 2500 feet in length and which can with-stand a radial expansion of at least 6% with-out cracks developing for at least one year.
~he liner material should also have an environ~
mental stress crack resistance (E.S.C.R.) rating in excess of 1000 hours when tested in accordance with conditions A! B and C of ASTM
test D-1693-70. Ultra High Molecular Weight , .
High Density Polyethylene (''UHr~HDPI') which meets Plastic Pipe Institute designation P.E. 3406 is especially preferred for use as the liner material.
LINER MATERIAL EXTERNAL DIAMETr:R
The external diameter of~the liner - ~;
material must be carefully selected as a flmction of the internal diameter of the ;
pipeline. If the external diameter of the - 10 - ~, ~ o~
liner material is too large, then it may not be possible to pull a liner seyment through a pipeline section without subjecting the liner segment to forces so great that it is ruptured. On the other hand, if the external diameter of the liner material is too small, then the lîner may be ruptured when it is radially expanded inside the pipeline as here-inafter described.
`i 10 Tests indicate that UHMWHDP in tubular form may be expanded radially by a factor of about 12~ to 15~ before rupture occurs. As a safety . ~
measure, these factors are halved in an effort to ensure that the liner material is not ruptured when radially expanded to contact the internal pipeline wall. Preferably, the liner material is radially expanded by a factor of no more than 6%. If radial expansion of the liner material is limited in this manner, there will be minimal xisk that factors -; ~:
such as irregularities in the internal diameter of the pipeline, irregularities in the external diameter '! :
of the liner material, or surface damage caused in pulling a liner segment into a particular pipeline section will result in rupture of the liner.
As a practical matter, the following table illustrates external diameters of UHMWHDP liner materials which have proved acceptable in field applications~
, 2~
Liner Material External Diameter as a ~ of Pipeline Inside Diameter Pipeline Inside Diameter 2" to 3" g4% -6" to 8" 96%
10" and above 96.5% to 97~5%
The closer tolerance used with lar~er diameter pipelines represents a decrease in defor-mation of the liner material as it is radiallyexpanded to contact the inside wall of the pipe-liner with an attendant decrease in probability ~ ;
that the liner material will rupture.
LINER WALL THICKNESS
. _ . , . :
The wall thickness of the liner materialwill be governed by a number of considerations.
To some extent, expense will govern the ., liner material wall thickness. Supplièrs of ~ ~
,: . : .:
liner material have reported~that considerable cost~is involved in retoo]ing to produce a liner material of~a given wall thickness. A further -complication faced by suppllers of liner material ;~ is that, as mentioned~above, the outside diameter `~
of the liner material must he carefully selected where it is desired to insert a close-fittinq liner ~ ;
:: .
into a pipeline. Ideally, both the outside~diameter and the wall thickness~of the llner material are individually matched to a given application.
: ~
UsualIy, however, the;~expense involved in inde~
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pendently tailoring ~oth the external diameter and the wall thickness dictates a practical com-promise in which the outside diameter of the liner material is carefully selected with an attendant sacrifice in wall thickness dimension. For example, the supplier may use a die which is capable of producing a tubular plastic material having a standard outside diameter and a standard wall thickness, but adjust his production method to vary the outside diameter of the liner material as required, which may result in an increase or a decrease in the wall thickness of the liner material.
A further factor governing liner material wall thickness arises because the liner material is usually supplied in relatively short lengths which are heat fused together to produce liner segments up to 2500 feet in length for insertion into particular pipeline sections. The wall thick-ness of the liner material will, within limits, :`
affect the quality of the joints at which the lengths of liner material are heat fused. For example, a liner material having an exceptionally thin wall would be difficult to heat fuse because the ends of the material would tend to assume an oval shape when clamped and heated in a conven-tional fusion joining machine. Practical field experience suggests that the liner material wali -thickness should not be less than about 0.15 inches to prevent this problem. Preferably, the ' 13 - ~ ~
.- . . . . . . . .
84~
wall thickness of the liner material is grea-ter than abou-t 0.2 inches.
In some applications the fluids to be transported through the lined pipeline may abrade the liner material. Tests may be conducted to determine the rate at which the liner material is abraded by a particular fluid and then a liner wall thickness may be calculated by assuming a given desired lifetime for the liner material.
Each se~ment of liner material must be capable of withstanding the forces imposed on the segment when it is-pulled into a given pipeline section as herelnafter described, without stressing the liner material beyond its tensile yield point.
It has been found that a satisfactory approximation of the pulling force "Lp" (in pounds) imposed on a segment o~ UHMW~DP liner material having an outside diameter "D" (in inches), a wall thickness "t' (in inches), a density 'Idll (in pounds per cuhic inch), a length llZl~ (in inches) and an inertial ~;
friction factor "Fi" (a dimensionless quantity indicative of the frictional resistance which must be overcome to start moving a liner segment which ~ `
is lying on the ground. Field experience indicates that Fi ~ 1.3.) may be obtained from the formula~
Lp = ~ D t d Z Fi (1) ~ -It has also been found that a satisfactory approx-imation of the liner tensile stress ilSzll (in pounds per square inch) for UHMWHDP may be obtained from the ~' ~:
.
.
~8~Z~
formula: -Lp Sz = ~ (2) ~ D t By combining formulae (1) and (2), one obtains:
Sz = d Z Fi ( ) The liner stress "Sz" must be held below the tensile yield point of the liner material (th~e tensile yield point of a given liner material may be obtained from the manufacturer of the liner material). It may be seen from the above formulae that as the length ~'Z" of a liner segment increases, the pulling force "Lp" required to pull the liner segment ~-through a particular pipeline section also increases, with a corresponding increase in liner stress "Sz".
- At some point, "~" may increase such that "Sz"
exceeds the liner material tensile yield point, resulting in damage to the liner.
The wall thickness of the liner material may also be determinative of the ability of the liner to resist collapse if the interior of the liner is ever subjected to vacuum. An approximation of the collapse pressure ~Pc~ (in pounds per square inch) may be obtained from the formula:
2E (t/D)3 1 - u2 (4j where- E = stiffness modulus (in pounds per square inch) of the liner material (available ~' ' zz~ ~
from the manufacturer of the liner material~
t = liner material wall thickness tin inches) D = external diameter of liner material ~in inches) u = Poisson ratio ~about .45 for UHMWHDP
liner material~.
The liner will tend to collapse if the collapse pressure is greater than or equal to 1 atmosphere (14.5 pounds per square inch). The wall thickness required to resist such collapse may therefore be calculated for a liner material of a yiven external diameter.
As discussed hereinafter, the preferred installation procedure may produce a vacuum ~n the annular region between the outslde wall of a;liner segment and the inside wal1 of the pipèline section whlch contains~that llner segment. A
vacuum in thls annular region~would tend to~
; offset a vacuum lnside; the~liner~egment~. The wall thickness of the liner~material required to resist collapse due to internal vacuum could thus be decreased somewhat ~to take advantage of the offsetting vacuum surrounding the liner segment.
As a~practical example, the~following table summarizes the wall~thicknes,s of uHr~Dp liners which have~been used~successfully in ~close-fi~tting .'~ pipeline relining applications~
. - 16 -':.', :.
8~4 U~lr~lwflDP
Pipeline Pipeline Liner Material rJ~r~pp Ex t~rnal Internal External Liner Material Diameter Diameter D1ameter Wall Thickness 12.750" 12.000" 11.60" 0.300"
10.750" 10.062" 9.70" 0.300"
6.625" 6.187" 6.00" 0.258"
4.500" 4.188" 4.00" 0.150"
PREPARATION OF LINER SEGMæNTS AND PIPELINE SECTIONS
_A_ __ _ _ _ ~ . _ _ _ ,, _ ,, .
. 10Liner segments may be assembled on-site using a conventional fusion joining machine to fuse lengths of linar material together. The liner segments should be at least 20 feet longer than the respective pipeline sections into which they are to be inserted. The external bead of polyethylene which is created on the liner segment by the - fusion joining procedure must be removed to leave a smooth surface which will not impede passage - of the liner segment through the pipeline section or interfere with radial expansion of the liner as hereinafter described. An 'iexternal bead trimmer"
satisfactory for this purpose may be obtained from McElroy Equipment of Tulsa, Oklahoma.
If the liner segments are to be fixed in tension inside respective pipeline sections using the procedure hereinafter described, then a plastic flange 86 (FIGURE 9) is fused onto one end of each liner segment as a preparatory step. ~-.
' ~ ' ' ' .
-- 1 7 -- ~ ~
'.'.'.
A Eirst pipeline section is uncovered at opposed ends by excavating a pair of "bell holes"
along the pipeline right of way. A typical bell hole 100 is shown in FIGURE 7. For ease of illustration, only one pipeline section 10 is shown in FIGURE 7. The pipeline, when initially uncovered, would of course extend through bell hole 100 from right to left.
The pipeline is severed in each bell hole, defining a discrete pipeline section between the two bell holes. For smaller diameter pipelines (2 to 4 inches) it will usually be convenient to uncover the pipeline for about 50 to 100 feet on both sides of the bell hole so that opposing ends of the pipeline in the bell hole may be man-oeuvred away from one another for ease of working.
Larger diameter pipelines are usually much more . -.
stiff and less manoeuvrable.
- For a high pressure pipeline (typically :
i~ 20 steel)~flanges 12 (FIGURES 1, 3~ and 11) are we~lded ,- onto opposite ends of pipeline section 10 to facilitate reforming of the pipeline when the pipeline sections have been lined.
, ~
Near each flange 12, a small "bleeder"
hole (typically about 1/32 inch in diameter) is drilled through the wall of the pipeline. The purpose of the bleeder hole is described in more detail below. A threadlet 14 is welded onto the , , .
pipe over the bleeder hole.
, ~, ~
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Flange 12 tapers into neck 18 (best seen in FIGURE 3) which 15 butt-welded onto the end of pipeline section 10. Care should be taken when welding flange 12 onto pipeline section :. 10 to avoid excessive penetration of weld bead into the cavity enclosed by pipeline section 10.
Excessive weld bead should be smoothed by grinding or filing to reduce the possibility that the liner will be damaged when it is pulled into pipeline ; 10 section 10. Flange 12 has a raised circular apertured face 20, the inside diameter of the aperture being equal to the inside diameter of :
i pipeline section 10. Flange 12 is conventional . in the art, the only modification being the machin-ing of a 6 radius on internal lip 22 of flange face 20. Lip 22 is machined to eliminate sharp .
edges which might damage the liner segment during insertion into pipeline section 10.
. A cable-carying device 30 (convention- ~ `
alIy called a "pig") is shown in FIGURE 2. This : .
.~ pig comprises a central body member 32, having a pair of curved rubber cups 34 di~posed a~ oppo-site ends. The external diameter of cups 34 is . slightly greater than the internal diameter of the pipeline so that pig 30 may be tightly fitted ~ :
inside pipeline section 10. A pair of eyelets 36 ,: ~ - ..
: are disposed at opposite ends of the pig body : ::
; member. A cable is attached to an eyelet at one -:
end of pig 30 and the opposite end of the pig inserted into pipeline section 10.
-- 19 -- , .
.: .
.
-` 1084~2Z~
A "pig launching device" 40 (conventional ~.
in the art) is shown in FIGURE 3. Launchin~ device 40 includes flange 42 which is coupled by means ~ -of bolts 44 to flange 12. Plastic gasket 46 is disposed between flanges 12 and 42 to effect a seal. The cable (which has been attached to pig 30, which now rests inside pipeline section 10 near flange 12) passes through aperture 48 at one end of the launching device 40. Water injection port 50 is coupled with a hose or other means to a water truck capable of delivering water under - :
pressure through the hose and into launching device 40. Pressurized water is thus forced :
~ , through water injection port 50 and cavity 52 and thence into pipeline section 10 behind pig 30 to propel pig 30 along pipeline section 10 with the cable trailing behind~ The cable (which may be coiled upon a reel) is drawn through aperture:48 ;: `
as the pig passes through pipeline sec~tion lO. ::
Suitable gasket means should be provided at aperture .
: 48 to prevent excessive loss of water. A water pressure of about loa psi to 150 psi should suffice to propel the pig and cable through about 2,000 feet of pipeline.
In the abs~ence of a source of pressuri~ed water, compressed air could also be used to force the pig and cable through pipeline section 10.
When pig:30 and the attached cable emerge at the opposite end of pipeline section lO, pig 30 ~
: ;', - 20 - ~
: ~' ~` ~L08~Z2~ ~
is removed from the cable and replaced by a "pig train" and a test piece of the liner material~
The cable is first attached to a carbide steel headed "sizing" pig, having an external diameter ~;
slightly larger than the external diameter of the liner segmen~ to be inserted into the pipeline section. Preferably, the external diameter of the sizing pig is about one half the sum of the exter~
nal diameter of the liner material and the inter-, 10 nal diameter of the pipeline~ The sizing pig assists in detexmining whether the internal diameter of the pipeline section is too small to receive the liner segment. The second pig in the pig train is a wire brush pig having a plurality of wire bristles for scraping built-up scale off the internal pipeline surface. The third pig in the pig train is a rubber-cupped cleaning pig used -~ to carry out of the pipeline section slag or scale : . .
broken off the pipeline walls by the first two pigs.
The pigs are provided with eye bolts and are con-nected together with steel cable. Finally, a ;
25 to 30 foot test section of the liner material to be used in lining the pipeIine is attached behind the pig train.
A winch is attached to the cable at the , far end of the pipeline~section. The pig train and test section of liner material are then pulled through pipeline section 10 with the winch. Pre-ferably, the winch is equipped with a cable ZZ~ ;
odometer so that the operator may d~termine the location of points at which the pig train may become lodged in pipeline section 10. If the pig train cannot successfully be pulled through pipeline section 10, then it will be necessary to uncover and open the pipeline at the point at which the pig train becomes lodged to efEect repairs.
. .
After the test section of liner material : 10 has passed through pipeline section 10, it is examined for surface damage. If nicks, gouges, sur~ace slits, etc., on the test section do not penetrate into the liner wall to a depth of more ~ -than about 10~ of the liner wall thickness, then the linex segment may be safely inserted into ;~ the pipeline section. If surface nicks, gou~es, i surface slits, etc., penetrate into the liner wall to a depth of more than about 10% of the liner wall thickness, then the pipeIine section must be repigged j ; 20 and cleaned to eliminate such liner surface damage.
(Preferably, the plpeline section is re-pigged and cleaned if the liner material is penetrated to a depth of more than about 0.04 inches, regardless of its wall thickness.) ;~-~
Once the pipeline section has been .
- pigged and cleaned to eliminate unacceptable liner surface damage, launching device 40 is again used to propel pig 30 and the cable back through plpeline section 10 so that the cable may be attached to ,~
.. , .,. , . , - , . . .
liner ~egment 70 which is to be pulled into pipeline section 10. This procedure also gives pipeline section 10 a water flush to remove foreign matter.
PULLING LINER SEGMENT INTO PIPELINE SECTION
Various pulling arrangements which may be used to attach the cable to liner segment 70, are shown in FIGURES 4, 5, 6 and 8.
FIGURE 4 shows a pulling head 60 having a genexally tapered cylindrical confirguration.
Pulling head 60 may be fabricated from a solid piece of polyethylene, and a hole drilled there-through to receive pin 62 to which eyelet 64 is affixed. Pin 62 is anchored against longitudinal movement with respect to pulling head 60 by means of washer 68 and bolt 66 which is threadably i received on the end of pin 62. Pulling head 60 is .
fused onto one end of liner segment 70 and any ~ -protruding fusion bead removed. The cable is then attached to eyelet 64, pulling head 60 is lntro-duced into pipeline section 10, and the winch used to pull the cable, pulling head 60 and liner segment 70 through pipeline section 10. Pulling head 60 is intended ~or use in high pressure appIications where it is~desired to use a close-fitting liner segment having an external diameter of at least 94~ of the internal diameter of pipeline section ~
10. In such close-fitting applications, it is ~-lmportant that pulling head 60 be free of :' - 23 ~
: .
: . - .. .. . .. . .
~8~Z~
protrusions which might impede transit through pipeline section 10.
The pulling arrangement shown in FIGUR~
5 comprises a plurality of metal straps 72 spaced circumferentially around an end o~ liner segment 70 and bolted directly to the liner segment.
Cable bridle 74 connects straps 72 to the pulling cable. This arrangement may be used in lower pressure applications where the external diameter of liner segment 70 may be considerably less than the internal diameter of pipeline section 10. For example, this arrangement could be used in lining a sewer line having a 20 inch internal diameter ~- with a polyethylene liner having an 18 inch external diameter.
The pulling arrangement shown in FIGU~E
Cable bridle 74 connects straps 72 to the pulling cable. This arrangement may be used in lower pressure applications where the external diameter of liner segment 70 may be considerably less than the internal diameter of pipeline section 10. For example, this arrangement could be used in lining a sewer line having a 20 inch internal diameter ~- with a polyethylene liner having an 18 inch external diameter.
The pulling arrangement shown in FIGU~E
6 may be used in lower pressure applications where misalignment of joints in the pipeline may be encountered, or where foreign matter may have infiltrated into the pipeline section. Pulling head 76 comprises a plurality of metal straps circumferentially spaced around an end of liner segment 70. The straps, which may be bolted to liner segment 70, protrude beyond the end of liner segment 70, and are drawn together to form a cone having an eyelet 78 at its apex. Reinforcing rings 80 add mechanical rigidity. The pulling cable may be a~fixed to~eyelet 78, and pulling ;~
head 76 drawn through pipeline section 10 to ~ ~' ':
:
42~a~
produce a p}oughing action which may permit the -realignment of misaligned joints, and which may clear away debris which has accumulated in the pipeline section.
The pulling arrangement shown in FIGURE
8 should be used only in lower pressure applica~
tions to pull a short length o~ liner into a pipe-liner section. This arrangement is primarily intended for pulling liner segments on the open pipeline right of way. A plurality of apertures 82 are circumferentially spaced around an end of liner segment 70, and a cable pulling bridle 84 passed through the apertures for affixation to the pulling cable.
Referring to FIGURE 7, a trench 102 is - provided to assist in inserting liner segment 70 into pipeline section 10. The floor of the trench should be sloped from ground level down towards , flange 12 at a ratio of about 5 horizontal to 1 `l 20 vertical. Care should be taken to prevent kinking of liner segment 70 as it is pulled into pipeline section 10. `
In addition to the odometer mentioned previously, the winch apparatus (positioned at the end of pipeline section 10 opposite to that shown in FIGURE 7) should be equipped with a cable weight indicator to permit the operator to monitor `
the pulling force being exerted on liner segment -70, and thus ensure that the tensile yield point - 30 of the liner material is not exceededO
.. . . . . . . . . .
2~
FIXING LINER SE:GMENrr INSIDE PIPELINE SECT:I ON
Once liner se~ment 70 has been pulled into pipeline section 10, it should be fixed against longitudinal movement with respect to pipeline section 10. Two separate procedures may be used to achieve this result.
The first procedure will be described with reference to FIGURE 9. Before liner segment 70 is pulled into pipeline section 10, a plast.ic .
flange 86 is fused onto the end of liner segment 70 opposite that to which the pulling head or pulling arrangement has previously been affixed~
The flange collar 88 is sized to have the same internal and external diameter as liner segment 70. The external diameter of flange face 90 is ;
sized to fit inside the bolt circle pattern of flange 12. The winch is then used as described above to pull liner segment 70 into pipeline section ~ :
10 until flange 86 contacts flange 12. Liner seg-ment 70 lS then stretched by continuing to pull :
on liner segment 70 while flange 86 ~ontacts flange 12,~care being taken however, not to exceed the tensile yield point of liner segment 70.
A clamp 92 (FIGURE 11) is then affixed to hold ~ ~ :
liner segment 70 in tension within pipeline :~
section 10 by preventlng liner segment 70 from retracting within pipeIine section 10. The :
pulling head is then cut away from liner segment 70, and a second plastic flange identical to that - 2 6 ~ .
shown .in FIGURE 9 .is fused onto the end of liner segment 70 which protrudes from pipeline section 10 Clamp 32 is then removed and liner segment 70 is allowed to retract inside pipeline section 10 until the second plastic flange contacts the pipe-line flan~e.
An alternate procedure may be used for securing liner segment 70 against longitudinal movement wit.hin pipeline section 10 when the expected internal pipeline pressure is less than about 2500 psi. This procedure is described with reference to FIGURE 10. With this procedure, liner segment 70 is pulled into pipeline section 10 until opposed ~: ;
ends of liner segment 70 protrude from respective ~- ends of pipeline section 10. A special 'iheat moulding" tool 106, available from Phillips Extruded Products Limited, Calgary, Alberta,is then used to heat the protruding ends of liner segment 70 and mold -them back against face 20 of flange l2, after which they 2Q are allowed to~cool~ When this procedure is used, li~er segment 70 wlll not be in tension within pipeline sectlon 10.
When plastic flange 86 is used in hlgh pressure applications, a steel retaining ring 94 ~i (FIGURE 12) should be used to encircle pairs of ~.
adjacent plastic flanges. The inside diameter "A"
of retaining ring 94 is sized to fit the external ~:
diameter of plastic flange face 90. The outside ~
~ :, diameter "D" of retaining ring 94, is sized such that retaining ring 94 wi:11 fit inside ~ ~ :
- 27 - :
, ::
~" ' ' : - , , ,., , .. . , :
....
8'~2~4 the bolt circle pattern of flange 12.
When a pair of adjacent pipeline sections have been lined, those sections are joined together using bolts 96 to couple opposing flanges 12 as shown in FIGURE 13. (Obviously, it is important that the bolt circle patterns of opposing flanges 12 be aligned when the flanges are welded onto adjoining ends of a pair of pipeline sections, so that the bolts 96 will easily pass through both flanges.) Where plastic flanges 86 are fused onto the liner segments inserted into the pipeline sections, opposed plastic flange faces 90 will be in sealing engagement between the steel flange faces 20. The width dimension "B" of retaining ring 94 is sized to permit a tight seal between opposed faces 90 of plastic flanges 86 while preventing contact between ;~
the circumferential ends of retaining ring 94, and opposed flange faces 20.
When the i'heat molding" technique referred to above is used for securing liner segment 70 against ; longitudinal movement within pipeline section 10 in ~ ;
; cases where the expected internal pipeline pressure is less than about 2500 psi, a retaining ring is not required. Opposed pairs of steel flanges 12 may -~
be bolted together and the liner material which has been molded against the flange faces 20 w serve as a gasket.
Work proceeds in the ahove manner over the length of the pipeline. The pipeline i5 uncovered at selected points to create pipeline .~ , 4~24 secti~ns into which liner segments are pulled.
The bell holes which serve as work sites at opposed ends of the various pipeline sections, are left open as the pipeline sec-tions are lined.
RADIALLY EXPANDING LINER SEGMENTS
When liner segments have been inserted into all pipeline sections, and the pipeline sections joined together to reform the pipeline, the liner segments may be radially expandad inside the pipeline sections.
Plugs 16 are first removed from thread-le~s 14 along the entire length of the pipeline.
A hot (typically about 180F) fluid such as water or oil is then injected into one end of the lined pipeline and allowed to flow freely therethrough and emerge from the opposite end thereof. The hot ^~
fluid injection serves to commence radial expansion of the liner segments toward the inside walls of the ~-pipeline sections. The hot fluid injection also - ;
serves to alter some mechanical properties of the -~ liner material in an advantageous manner. For ;~
example, at warmer temperatures, thermoplastic -`~
materials such as UHMWHDP can sustain more defor-mation before rupturing. Such materials also deform more quickly under constant stress as `~
temperature~increases. These two characteristics are prime considerations which suggest the selection of thermoplastic materials such as UHMWHDP as a `~
liner material and which suggest the injectlon of '~
. ~
8~Z2~
hot fluid into the lined pipeline to raise the temperat~lre of the liner material. To take full advantage of these alterations in mechanical ; properties, all liner segments in the pipeline should be at at leas-t 70~ before the pressure expand-ing step discussed below is started. Preferably, hot fluid injection is maintained until the pipe-line itself is at least warm to the touch (70F -100F) at the end from which the injected fluid emerges.
The mere injection of hot fluid is not sufficient to expand the liner segments outward to contact the inside walls of the pipeline sections.
Pressure must be applied to continue the radial ` expansion of the liner segments until they contact the insidewalls of the pipeline sections. When the temperature of all liner segments in the pipe-line has been raised to at least 70F, the end of the pipeline from which the injected fluid emerges is blocked off. The injection of hot fluid at the opposite end of the pipeline is, however, continued. The continued injection of hot fluid will exert pressure inside the liner segments, tend-ing to expand the liner segments radially outward against the inside walls of the pipeline sections, thus evacuating the annular regions between the liner segments and the pipeline sections by forcing entrapped air and fluids out through the bleeder holes. The pressure exerted inside the lined .
: ~`
- 30 - ~
~ . . . .
34:~Z~
pipeline should be monitored and controlled. As this pressu~e increases, a "plateau" will be ob-served at which pressure does not increase as additional hot fluid is injected into the lined pipeline. The pressure inside the lined pipeline should be held relatively constant on the "pla-teau"
to permit the liner se~ments to expand radially outward to contact the inslde walls of the pipeline.
Once the liner segments have contacted the inside walls of the pipeline, there will be observed an increase in pressure above the "plateau" as more hot fluid is injected into the pipeline. Care should be taken to avoid injection of substantial quantities of hot fluid into the lined pipeline before all liner segments have expanded out to contact the insidewalls of the pipPline. Otherwise, .
,, localized stresses may develop on the liner segments, -~
causing rupture of the liner.
.~ .
As pressure inside the pipeline increases, "geysers" about I0 to 15 feet high may be observed at the bleeder holes. This "geyser" effect will usually subside within about 20 to 30 minutes, although the bleeder holes may contine to blow air ~ ;
for some considerable time thereafter. After a ; : .
period of about 2 to 3 hoursi there may be observed a dripping of a milky-white substance (believed to be emulsified air and water) at the bleeder -holes. At this point, the bulk of the air and water entrapped between -the liner segments and the '::
~ 342;~4 inside walls oE the pipeline sections will have been evacuated, and plugs 16 may be inserted into threadle-ts 14 to close the bleeder holes.
The pipeline may then be subjected to the usual tests required to satisfy the appropriate regulatory bodies.
In addition to expanding the liner segments within the pipeline sections, the radial expansion procedure will also indicate whether particular liner segments have been damaged during installation. If the wall of a particular liner segment has been pierced during installation, then the afore-mentioned "geyser" effect will ;~ not diminish at the bleeder holes of the pipeline ; section which contains that liner segment, due to the escape of pressurized fluid through the liner segment into the annular region between the liner ; segment and the insidewall of the pipeline section.
If such damage has occurred, then it will be necessary to remove the defective liner segment, repig and reclean the particular pipeline section, install a new liner segment and then repeat the injection of hot fluid and the pressure expansion step.
Evacuation of the annular region between respective liner segments and pipeline sections may serve a further useful purpose. If the pipeline has to be shut down or depressurized such that a ;
vacuum condition is created inside the liner segments, , . , . . . "
2~
then, lf plu~s 16 have been inserted into threadlets 14 -to close -the bleeder holes, an offsett.ing vacuum condition should be present in the annular xegion surrounding each liner segment which may tend to prevent collapse of the liner segments due to the vacuum inside the liner segments.
:: ~
: ' ,~ .
,~
, .-
head 76 drawn through pipeline section 10 to ~ ~' ':
:
42~a~
produce a p}oughing action which may permit the -realignment of misaligned joints, and which may clear away debris which has accumulated in the pipeline section.
The pulling arrangement shown in FIGURE
8 should be used only in lower pressure applica~
tions to pull a short length o~ liner into a pipe-liner section. This arrangement is primarily intended for pulling liner segments on the open pipeline right of way. A plurality of apertures 82 are circumferentially spaced around an end of liner segment 70, and a cable pulling bridle 84 passed through the apertures for affixation to the pulling cable.
Referring to FIGURE 7, a trench 102 is - provided to assist in inserting liner segment 70 into pipeline section 10. The floor of the trench should be sloped from ground level down towards , flange 12 at a ratio of about 5 horizontal to 1 `l 20 vertical. Care should be taken to prevent kinking of liner segment 70 as it is pulled into pipeline section 10. `
In addition to the odometer mentioned previously, the winch apparatus (positioned at the end of pipeline section 10 opposite to that shown in FIGURE 7) should be equipped with a cable weight indicator to permit the operator to monitor `
the pulling force being exerted on liner segment -70, and thus ensure that the tensile yield point - 30 of the liner material is not exceededO
.. . . . . . . . . .
2~
FIXING LINER SE:GMENrr INSIDE PIPELINE SECT:I ON
Once liner se~ment 70 has been pulled into pipeline section 10, it should be fixed against longitudinal movement with respect to pipeline section 10. Two separate procedures may be used to achieve this result.
The first procedure will be described with reference to FIGURE 9. Before liner segment 70 is pulled into pipeline section 10, a plast.ic .
flange 86 is fused onto the end of liner segment 70 opposite that to which the pulling head or pulling arrangement has previously been affixed~
The flange collar 88 is sized to have the same internal and external diameter as liner segment 70. The external diameter of flange face 90 is ;
sized to fit inside the bolt circle pattern of flange 12. The winch is then used as described above to pull liner segment 70 into pipeline section ~ :
10 until flange 86 contacts flange 12. Liner seg-ment 70 lS then stretched by continuing to pull :
on liner segment 70 while flange 86 ~ontacts flange 12,~care being taken however, not to exceed the tensile yield point of liner segment 70.
A clamp 92 (FIGURE 11) is then affixed to hold ~ ~ :
liner segment 70 in tension within pipeline :~
section 10 by preventlng liner segment 70 from retracting within pipeIine section 10. The :
pulling head is then cut away from liner segment 70, and a second plastic flange identical to that - 2 6 ~ .
shown .in FIGURE 9 .is fused onto the end of liner segment 70 which protrudes from pipeline section 10 Clamp 32 is then removed and liner segment 70 is allowed to retract inside pipeline section 10 until the second plastic flange contacts the pipe-line flan~e.
An alternate procedure may be used for securing liner segment 70 against longitudinal movement wit.hin pipeline section 10 when the expected internal pipeline pressure is less than about 2500 psi. This procedure is described with reference to FIGURE 10. With this procedure, liner segment 70 is pulled into pipeline section 10 until opposed ~: ;
ends of liner segment 70 protrude from respective ~- ends of pipeline section 10. A special 'iheat moulding" tool 106, available from Phillips Extruded Products Limited, Calgary, Alberta,is then used to heat the protruding ends of liner segment 70 and mold -them back against face 20 of flange l2, after which they 2Q are allowed to~cool~ When this procedure is used, li~er segment 70 wlll not be in tension within pipeline sectlon 10.
When plastic flange 86 is used in hlgh pressure applications, a steel retaining ring 94 ~i (FIGURE 12) should be used to encircle pairs of ~.
adjacent plastic flanges. The inside diameter "A"
of retaining ring 94 is sized to fit the external ~:
diameter of plastic flange face 90. The outside ~
~ :, diameter "D" of retaining ring 94, is sized such that retaining ring 94 wi:11 fit inside ~ ~ :
- 27 - :
, ::
~" ' ' : - , , ,., , .. . , :
....
8'~2~4 the bolt circle pattern of flange 12.
When a pair of adjacent pipeline sections have been lined, those sections are joined together using bolts 96 to couple opposing flanges 12 as shown in FIGURE 13. (Obviously, it is important that the bolt circle patterns of opposing flanges 12 be aligned when the flanges are welded onto adjoining ends of a pair of pipeline sections, so that the bolts 96 will easily pass through both flanges.) Where plastic flanges 86 are fused onto the liner segments inserted into the pipeline sections, opposed plastic flange faces 90 will be in sealing engagement between the steel flange faces 20. The width dimension "B" of retaining ring 94 is sized to permit a tight seal between opposed faces 90 of plastic flanges 86 while preventing contact between ;~
the circumferential ends of retaining ring 94, and opposed flange faces 20.
When the i'heat molding" technique referred to above is used for securing liner segment 70 against ; longitudinal movement within pipeline section 10 in ~ ;
; cases where the expected internal pipeline pressure is less than about 2500 psi, a retaining ring is not required. Opposed pairs of steel flanges 12 may -~
be bolted together and the liner material which has been molded against the flange faces 20 w serve as a gasket.
Work proceeds in the ahove manner over the length of the pipeline. The pipeline i5 uncovered at selected points to create pipeline .~ , 4~24 secti~ns into which liner segments are pulled.
The bell holes which serve as work sites at opposed ends of the various pipeline sections, are left open as the pipeline sec-tions are lined.
RADIALLY EXPANDING LINER SEGMENTS
When liner segments have been inserted into all pipeline sections, and the pipeline sections joined together to reform the pipeline, the liner segments may be radially expandad inside the pipeline sections.
Plugs 16 are first removed from thread-le~s 14 along the entire length of the pipeline.
A hot (typically about 180F) fluid such as water or oil is then injected into one end of the lined pipeline and allowed to flow freely therethrough and emerge from the opposite end thereof. The hot ^~
fluid injection serves to commence radial expansion of the liner segments toward the inside walls of the ~-pipeline sections. The hot fluid injection also - ;
serves to alter some mechanical properties of the -~ liner material in an advantageous manner. For ;~
example, at warmer temperatures, thermoplastic -`~
materials such as UHMWHDP can sustain more defor-mation before rupturing. Such materials also deform more quickly under constant stress as `~
temperature~increases. These two characteristics are prime considerations which suggest the selection of thermoplastic materials such as UHMWHDP as a `~
liner material and which suggest the injectlon of '~
. ~
8~Z2~
hot fluid into the lined pipeline to raise the temperat~lre of the liner material. To take full advantage of these alterations in mechanical ; properties, all liner segments in the pipeline should be at at leas-t 70~ before the pressure expand-ing step discussed below is started. Preferably, hot fluid injection is maintained until the pipe-line itself is at least warm to the touch (70F -100F) at the end from which the injected fluid emerges.
The mere injection of hot fluid is not sufficient to expand the liner segments outward to contact the inside walls of the pipeline sections.
Pressure must be applied to continue the radial ` expansion of the liner segments until they contact the insidewalls of the pipeline sections. When the temperature of all liner segments in the pipe-line has been raised to at least 70F, the end of the pipeline from which the injected fluid emerges is blocked off. The injection of hot fluid at the opposite end of the pipeline is, however, continued. The continued injection of hot fluid will exert pressure inside the liner segments, tend-ing to expand the liner segments radially outward against the inside walls of the pipeline sections, thus evacuating the annular regions between the liner segments and the pipeline sections by forcing entrapped air and fluids out through the bleeder holes. The pressure exerted inside the lined .
: ~`
- 30 - ~
~ . . . .
34:~Z~
pipeline should be monitored and controlled. As this pressu~e increases, a "plateau" will be ob-served at which pressure does not increase as additional hot fluid is injected into the lined pipeline. The pressure inside the lined pipeline should be held relatively constant on the "pla-teau"
to permit the liner se~ments to expand radially outward to contact the inslde walls of the pipeline.
Once the liner segments have contacted the inside walls of the pipeline, there will be observed an increase in pressure above the "plateau" as more hot fluid is injected into the pipeline. Care should be taken to avoid injection of substantial quantities of hot fluid into the lined pipeline before all liner segments have expanded out to contact the insidewalls of the pipPline. Otherwise, .
,, localized stresses may develop on the liner segments, -~
causing rupture of the liner.
.~ .
As pressure inside the pipeline increases, "geysers" about I0 to 15 feet high may be observed at the bleeder holes. This "geyser" effect will usually subside within about 20 to 30 minutes, although the bleeder holes may contine to blow air ~ ;
for some considerable time thereafter. After a ; : .
period of about 2 to 3 hoursi there may be observed a dripping of a milky-white substance (believed to be emulsified air and water) at the bleeder -holes. At this point, the bulk of the air and water entrapped between -the liner segments and the '::
~ 342;~4 inside walls oE the pipeline sections will have been evacuated, and plugs 16 may be inserted into threadle-ts 14 to close the bleeder holes.
The pipeline may then be subjected to the usual tests required to satisfy the appropriate regulatory bodies.
In addition to expanding the liner segments within the pipeline sections, the radial expansion procedure will also indicate whether particular liner segments have been damaged during installation. If the wall of a particular liner segment has been pierced during installation, then the afore-mentioned "geyser" effect will ;~ not diminish at the bleeder holes of the pipeline ; section which contains that liner segment, due to the escape of pressurized fluid through the liner segment into the annular region between the liner ; segment and the insidewall of the pipeline section.
If such damage has occurred, then it will be necessary to remove the defective liner segment, repig and reclean the particular pipeline section, install a new liner segment and then repeat the injection of hot fluid and the pressure expansion step.
Evacuation of the annular region between respective liner segments and pipeline sections may serve a further useful purpose. If the pipeline has to be shut down or depressurized such that a ;
vacuum condition is created inside the liner segments, , . , . . . "
2~
then, lf plu~s 16 have been inserted into threadlets 14 -to close -the bleeder holes, an offsett.ing vacuum condition should be present in the annular xegion surrounding each liner segment which may tend to prevent collapse of the liner segments due to the vacuum inside the liner segments.
:: ~
: ' ,~ .
,~
, .-
Claims (17)
EXCLUSIVE PROPERTY OR PRIVILEGE IS CLAIMED ARE
DEFINED AS FOLLOWS:
1. A method of lining a section of a pipeline, comprising:
(a) drawing a selected plastic liner into the section until the liner is substantially longitudinally co-extensive with the section, said liner having an outside diameter sufficiently less than the inside diameter of the pipeline to enable such drawing but sufficiently large so that the liner can be non-destructively radially expanded against the inside wall of the pipeline section;
(b) stretching the liner within the section;
(c) fixing the liner against longitudinal movement within the section;
(d) radially expanding the liner against the inside wall of the pipeline by means of application of fluid to the inside wall of the liner; and (e) bleeding the space between the liner and the pipeline during step (d).
(a) drawing a selected plastic liner into the section until the liner is substantially longitudinally co-extensive with the section, said liner having an outside diameter sufficiently less than the inside diameter of the pipeline to enable such drawing but sufficiently large so that the liner can be non-destructively radially expanded against the inside wall of the pipeline section;
(b) stretching the liner within the section;
(c) fixing the liner against longitudinal movement within the section;
(d) radially expanding the liner against the inside wall of the pipeline by means of application of fluid to the inside wall of the liner; and (e) bleeding the space between the liner and the pipeline during step (d).
2. A method as defined in Claim 1, wherein said fluid is under a relatively low pressure.
3. A method as defined in Claim 2, wherein said fluid is relatively warm.
4. A method as defined in Claim 1, which further comprises before step (d), opening at least one bleeding port in the section for bleeding the space between the liner and the pipeline.
5. A method as defined in Claim 4, which further comprises closing said bleeding port after step (e).
6. A method of lining a section of a high pressure pipeline with a tubular plastic liner which utilizes the structural strength of the pipeline to enable the lined pipeline section to be operated at high pressure, said section including first and second flanges disposed at opposite ends of the section, said method comprising:
(a) drawing a selected plastic liner into the section until the liner is substantially longitudinally co-extensive with the section, said liner having an outside diameter sufficiently less than the inside diameter of the pipeline to enable such drawing but sufficiently large so that the liner can be non-destructively radially expanded against the inside wall of the pipeline section;
(b) stretching the liner within the section;
(c) fixing the liner against longitudinal movement within the section;
(d) opening at least one bleeding port in the section;
(e) radially expanding the liner against the inside wall of the pipeline by means of application of relatively warm fluid under relatively low pressure to the inside wall of the liner;
(f) during step (e), bleeding the space between the liner and the pipeline through the bleeding port; and (g) closing the bleeding port.
(a) drawing a selected plastic liner into the section until the liner is substantially longitudinally co-extensive with the section, said liner having an outside diameter sufficiently less than the inside diameter of the pipeline to enable such drawing but sufficiently large so that the liner can be non-destructively radially expanded against the inside wall of the pipeline section;
(b) stretching the liner within the section;
(c) fixing the liner against longitudinal movement within the section;
(d) opening at least one bleeding port in the section;
(e) radially expanding the liner against the inside wall of the pipeline by means of application of relatively warm fluid under relatively low pressure to the inside wall of the liner;
(f) during step (e), bleeding the space between the liner and the pipeline through the bleeding port; and (g) closing the bleeding port.
7. A method as defined in Claim 6, wherein said stretching step comprises stretching the liner between first and second flanges of the liner disposed at opposite ends of the liner.
8. A method as defined in Claim 6, wherein said fixing step comprises heating the ends of the liner which protrude from the pipeline section and molding the heated liner ends against the first and second flanges of the pipeline section.
9. A method as defined in Claim 7, which further comprises before step (e), encircling adjacent liner flanges disposed between adjacent lined pipeline sections with retaining rings and coupling the adjacent pipeline sections together.
10. A method as defined in Claim 6, which further comprises before step (a), passing a relatively short segment of liner material through the pipeline section to detect any matter protruding into the space to be occupied by the liner.
11. A method as defined in Claim 10, which further comprises before step (a), removing any matter protruding into the space to be occupied by the liner.
12. A method as defined in Claim l or 6, wherein said liner is high density polyethylene.
13. A pipeline section having a tubular plastic liner radially expanded against the inside wall of said section and fixed in tension between opposed ends of said section.
14. A pipeline section as defined in Claim 13, wherein said plastic liner is radially supported by the structural strength of said pipeline section so as to enable the lined pipeline section to be operated at high pressure.
15. A method as defined in Claim 1 or 6, wherein the outside diameter of said liner before radial expansion is at least 94% of the inside diameter of said pipeline section.
16. A method as defined in Claim 1 or 6, wherein, for a given inside diameter of pipeline section, the outside diameter of said liner before radial expansion is at least 94% of said inside diameter in the case of an inside diameter between about 2 inches to about 4 inches, and increasing to at least 96.5% of said inside diameter in the case of an inside diameter of about 10 inches or greater.
17. A method as defined in Claim 1 or 6, wherein, for a given inside diameter of pipeline section, the outside diameter of said liner before radial expansion is at least:
(a) 94% of said inside diameter in the case of an inside diameter between about 2 inches to about 4 inches;
(b) 95% of said inside diameter in the case of an inside diameter of about 4 inches;
(c) 96% of said inside diameter in the case of an inside diameter between about 6 inches to about 8 inches;
(d) 96.5% of said inside diameter in the case of an inside diameter of about 10 inches or greater.
(a) 94% of said inside diameter in the case of an inside diameter between about 2 inches to about 4 inches;
(b) 95% of said inside diameter in the case of an inside diameter of about 4 inches;
(c) 96% of said inside diameter in the case of an inside diameter between about 6 inches to about 8 inches;
(d) 96.5% of said inside diameter in the case of an inside diameter of about 10 inches or greater.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA334,208A CA1084224A (en) | 1979-08-21 | 1979-08-21 | Process for lining high pressure pipeline |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA334,208A CA1084224A (en) | 1979-08-21 | 1979-08-21 | Process for lining high pressure pipeline |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1084224A true CA1084224A (en) | 1980-08-26 |
Family
ID=4114975
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA334,208A Expired CA1084224A (en) | 1979-08-21 | 1979-08-21 | Process for lining high pressure pipeline |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1084224A (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4691740A (en) * | 1983-03-15 | 1987-09-08 | Phillips Petroleum Company | Pipeline lining |
| US4781780A (en) * | 1986-04-11 | 1988-11-01 | Du Pont (U.K.) Limited | Method of producing a thermoplastic polymer-lined pipe |
| US4818314A (en) * | 1980-01-25 | 1989-04-04 | Sentry Piping Systems, Inc. | Process for lining a high pressure pipeline |
| US4985196A (en) * | 1987-10-30 | 1991-01-15 | Pipe Liners, Inc. | Pipe liner process |
| US4986951A (en) * | 1987-07-27 | 1991-01-22 | Pipe Liners, Inc. | Pipe liner process |
| US4998871A (en) * | 1989-01-19 | 1991-03-12 | Pipe Liners, Inc. | Apparatus for deforming plastic tubing for lining pipe |
| US5091137A (en) * | 1989-01-19 | 1992-02-25 | Pipe Liners, Inc. | Pipe lining process |
| US5395472A (en) * | 1992-08-20 | 1995-03-07 | Mandich; Ivan C. | Lining system and methods for installing plastic liners in a pipe |
| CN109262931A (en) * | 2018-09-06 | 2019-01-25 | 陈烈 | A kind of high voltage bearing lining of pipe line molding machine and its forming method |
-
1979
- 1979-08-21 CA CA334,208A patent/CA1084224A/en not_active Expired
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4818314A (en) * | 1980-01-25 | 1989-04-04 | Sentry Piping Systems, Inc. | Process for lining a high pressure pipeline |
| US4691740A (en) * | 1983-03-15 | 1987-09-08 | Phillips Petroleum Company | Pipeline lining |
| US4781780A (en) * | 1986-04-11 | 1988-11-01 | Du Pont (U.K.) Limited | Method of producing a thermoplastic polymer-lined pipe |
| US4986951A (en) * | 1987-07-27 | 1991-01-22 | Pipe Liners, Inc. | Pipe liner process |
| US4985196A (en) * | 1987-10-30 | 1991-01-15 | Pipe Liners, Inc. | Pipe liner process |
| US4998871A (en) * | 1989-01-19 | 1991-03-12 | Pipe Liners, Inc. | Apparatus for deforming plastic tubing for lining pipe |
| US5091137A (en) * | 1989-01-19 | 1992-02-25 | Pipe Liners, Inc. | Pipe lining process |
| US5395472A (en) * | 1992-08-20 | 1995-03-07 | Mandich; Ivan C. | Lining system and methods for installing plastic liners in a pipe |
| CN109262931A (en) * | 2018-09-06 | 2019-01-25 | 陈烈 | A kind of high voltage bearing lining of pipe line molding machine and its forming method |
| CN109262931B (en) * | 2018-09-06 | 2023-06-02 | 陈烈 | High-pressure-resistant pipeline lining forming device and forming method thereof |
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Legal Events
| Date | Code | Title | Description |
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| MKEX | Expiry |