AU667587B2 - Method of inserting rigid plastic lining tube through pipe - Google Patents

Description

AUSTRAL IA Patenta Act 1990 COMPL-ETE SPECIFICATION STANTDARD PATENT Applicant: OSAKA BOUSUI CONSTRUCTION CO., LTD.

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Invention Title:-

METHOD

LINING

OF INSERTING RIGID PLASTIC TUBE THROUGH PIPE S. 0

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The following statement is a full description of this invention, including the best method of performing it known to me/us: -1B METHOD OF INSERTING RIGID PLASTIC LINING TUBE THROUGH PIPE TECHNICAL FIELD The present invention relates to a method of inserting a rigid plastic lining tube through pipes, and more particularly to a method of inserting a rigid plastic tube through a pipe to line the pipe with the rigid plastic tube.

BACKGROUND ART Methods of lining pipes with a rigid plastic tube have already been proposed wherein the plastic tube is inserted through the' pipe and thereafter inflated radially of the pipe by applying heat and pressure to the tube from inside to cover the inner surface of the pipe 15 with the tube. The lining formed by the proposed method is made of the inflated rigid plastic tube and therefore has shape retentivity, high strength and a high quality.

**Although the pipe lining work differs with the type of pipe, the work is performed for a length of pipe 20 which is usually about 10 to about 200 m as single span.

o: .ii °"iThe rigid plastic tube serving as the lining material has a considerably large length longer than one span of pipe, so that the tube can be transpirted to the work site conveniently when it is wound on a drum. The rigid plastic tube can be wound on the drum when collapsed s Y rt -2radially thereof from the form having a circular cross section to a flat form and made flexible by being softened with heating.

To pay out the plastic tube from the drum, there arises a need to heat and soften the tube at the work site as when it was wound on the drum. However, since the plastic tube wound on the drum is in the form of layers of a flat tube, it is difficult to directly heat the layers. Further because plastic materials generally have low heat conductivity, the layers of tube can not be heated effectively through heat conduction.

Accordingly, even if the tube winding on the drum is heated, the outermost layer may be softened but the 0 underlying layers remain unsoftened, with the result that 15 the plastic tube can not be smoothly paid out from the

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drum and inserted into the contemplated pipe and thereby entails a low work efficiency.

When steam is passed through the plastic tube in this case, the entire inner peripheral surface of the 20 plastic tube can be heated with the steam flowing through 0oe• :the tube, whereas we have found that as the tube is continuously heated with the steam from inside, drain 0*e collects inside the tube, impeding the flow of steam through the tube by the drain remaining therein and resulting in insufficient and uneven heating and 3softening of the plastic tube.

DISCLOSURE OF THE INVEN!TON The main object of the present invention is to provide a method of inserting into a pipe a rigid plastic tube wound up on a drum and heated with steam passed through the tube, the method being adapted to heat and soften every portion of the plastic tube uniformly over the entire length thereof although drain remains inside the tube so as to permit the tube to be paid out from the drum and inserted into the pipe smoothly and efficiently.

Other features of the present invention will become apparent from the following description.

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The present invention provides a method of 550055 inserting a rigid plastic lining tube into a pipe, comprising the steps of: winding the rigid plastic tube as deformed to a flat tubular form around a take-up spool of a drum into a spiral plane roll; S S installing the drum having the plastic tube wound thereon in a horizontal position at a work site; S. S 20 supplying steam to the plastic tube in the horizontal position to pass the steam from one end of the tube which is located at an innermost layer of said roll toward the other end thereof which is located at an outermost layer of said roll and to thereby heat and soften the plastic tube over the entire length thereof; inclining the drum from the horizontal position and rotating the drum in the tube winding direction whereby i 3A drain produced inside the tube is forcibly discharged from said other tube end to outside the tube while being forcibly moved toward said other tube end and thereafter inserting the plastic tube into the pipe while paying out the tube from the drum.

With the method of the invention, the drum is el 4 0 B B

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IL4~1 -4installe~ in a horizontal position at the work site, so that the rigid plastic tube wound up on the drum has a steam flow channel formed inside thereof and continuously extending spirally in a plane. This assures that the steam flow channel is provided at least in the inside upper portion of the tube even if drain collects under the flow channel, enabling steam to smoothly flow through the channel in the inside upper tube portion over the entire length of the tube. Consequently, the plas .ic tube is softened uniformly at every portion thereof by being internally heated with the steam over the entire length so as to be paid out from the drum and inserted into the pipe smoothly and efficiently.

Since the steam is supplied into the rigid e09 15 plastic tube from its one end toward the other end thereof, the steam can be so supplied continuously also during the insertion of the tube through the pipe, :thereby holding the plastic tube softened with good stability properly until the tube is completely inserted through the pipe. Accordingly, the plastic tube can be Seasily passed through an intermediate bent pipe portion, if any.

.L b According to -thzmthod of the invention, the rigid plastic tube may be heated with a heating fluid, such as hot air, from outside thereof in addition to the I- '3 e heating with the steam from inside. Heating the tube with the fluid from both inside and outside is useful especially when the tube has a relatively large wall thickness.

The rigid plastic tube to be inserted by the method of the invention is one made of a thermoplastic synthetic resin, such as polyvinyl chloride, polyethylene or polypropylene, which has a softening point of up to 1000C and which can be softened by heating with steam.

The rigid plastic tube is circular in cross section, has an outside diameter corresponding to about 50 to about 100% of the inside diameter of the pipe, and is collapsed radially thereof to a flat tubular form when wound onto a drum.

9* 15 The steam is supplied to the plastic tube 6 usually from one tube end which is positioned at the innermost layer of the roll toward the other tube end which is positioned at the outermost layer of the roll.

In 1-,e step of heating and softening the plastic tube et i of the invention, the drum in the horiontai positioi is inclined, and is also rotated in the tube winding direction whereby the drain produced inside the tube is forcibly discharged from the outermost tube end to outside the tube. Use of such means for forcibly draining the plastic tube achieves at least I- -6about 20% reduction in the amount of steam and heating time required for softening the tube in the absence of the forcible draining means.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an overall view schematically showing a mode of practicing the method of the invention; FIG. 2 is an overall view schematically showing how a rigid.plastic tube is formed, flattened and wound up on a drum; FIG. 3 is a view in cross section showing the plastic tube as extruded; FIG. 4 is a view in cross section showing the plastic tube as flattened; FIG. 5 is an enlarged side elevation showing e 15 the plastic tube as it is being wound up on the drum; FIG. 6 is an enlarged side elevation showing the drum as installed in a horizontal position; FIG. 7 is a plan view of FIG. 6 with an upper closure omitted; FIG. 8 is a diagram schematically illustrating drain collecting inside the tube in the method of the

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invention; S" FIG. 9 is a diagram of the drum as installed in a vertical position to illustrate drain collecting inside the tube thereon; C- au FIG. 10 is a diagram of the drum installed in the horizontal position to illustrate the tube thereon while it is being drained by giving an inclination and rotation to the drum; and FIGS. 11 and 12 are diagrams for illustrating the principle of forcibly draining the tube.

BEST MODE OF CARRYING OUT THE INVENTION A mode of practicing the method of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 is an overall view schematically showing the mode of practicing the present method. A rigid plastic tube 1 as wound in a flat tubular form around the 0 take-up spool of a drum 2 is delivered to a work site.

15 Installed in the work site is a drum support device 3, on which the drum 2 is horizontally supported.

FIG. 2 schematically shows how the plastic tube o. .1 is formed and wound up on the drum 2. The rigid plastic tube 1 is formed by an extruder 4 to a circular shape in cross section (see FIG. then passed through

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a cooling bath 5, transport device 6 of the caterpillar

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type and steam heater 7, thereafter deformed to the flat e* w tubular form (see FIG. 4) by flattening rolls 8 and wound up on the drum 2 into a roll.

When the plastic tube 1 is to bhe wound on the ,I i drum 2, steam supply means is provided for the end la of the plastic tube 1 at the innermost layer of the roll (see FIG. The steam supply means is necessary for internally heating the tube 1 with steam when the tube 1 is to be inserted into a pipe a (see FIG. 1).

FIG. 5 shows a hose 9 having mouthpieces 9a, 9h at its respective opposite ends and serving as the steam supply means. One of the mouthpieces, 9a, of the hose 9 is attached to the inner end la of the tube I. The other mouthpiece 9b is withdrawn through an aperture 2b in a side plate 2a of the drum 2 to the outside and fixed to the outer side of the side plate 2a with a fastener This mouthpiece 9b is connected to the supply opening of 69 a steam supply system when required. Alternatively, the inner end la of the plastic tube 1 may be inserted in the e Sfollow take-up spool of the drum 2 so as to supply steam through the spool.

As shown in greater detail in FIG. 6, the a support device 3 for supporting the drum 2 in a horizontal position at the work site comprises a heat 9 insulating casing 11 for housing the drum 2, and a hollow rotary shaft 12 for supporting the drum 2 in the horizontal position. The rotary shaft 12 extends upward through an upper closure Ila of the casing 11 and carries a swivel joint 12a at its upper end outside the casing

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The drum 2 is mounted on the rotary shaft 12 with the upper closure lla removed from the casing 11.

The drum 2 is fitted around the shaft 12 at center mount holes 2c (see FIG. 7) formed in its side plates 2a and fixedly bears in this state on a flange 13 secured to the shaft 12 so as to be rotatable with the shaft. The other mouthpiece 9b withdrawn through the side plate 2a of the drum 2 to the outside is attached to the rotary shaft 12 in communication with a connection opening 14 in an upper portion thereof.

After the drum 2 has been installed in the horizontal position, the upper closure lla is attached to *e 9 the casing 11. The hollow portion of the rotary shaft 12 9* S• 15 is further caused to communicate with a steam supply source, such as a boiler 16 (see FIG. through the swivel joint 12a at the shaft upper end and a conduit connected to the joint, whereby the plastic tube 1 is *made ready for softening by heating. The other end Ib of the plastic tube I on the outer side of its roll can be provided with an end member 17 when required. The end member 17 is formed in its upper portion with an outlet *9 17a for the steam flowing through the tube 1 and in its 9 lower portion with a water outlet 17b for the drain remaining inside the tube.

A P I When steam is supplied from the boiler 16 (see FIG. 1) to the plastic tube 1 in the state shown in FIG.

6, the steam flows into the tube 1 via the conduit joint 12a, rotary shaft 12, connection opening 14, mouthpiece 9b. hose 9, mouthpiece 9a (see FIG. 5) and inner tube end la, then flows toward the outer tube end Ib while heating the tube 1 from inside and is finally discharged from the tube 1 through.the steam outlet 17a of the end member 17 attached to the outer tube end lb.

The plastic tube 1 is thus heated with the steam from inside with the drum 2 installed in the horizontal position, with the inside channel 20 of the plastic tube 1 continuously extending spirally in a horizontal plane over the entire length of the tube 1 as 15 shown in FIG. 8. Consequently, the drain 19 produced on condensation of the steam collects in the lower portion of the channel 20 substantial ly uniformly over the entire tube length. This forms a steam flow channel 20a in the upper portion of the channel 20 over the entire length.

Despite the production of the draia, therefore, the plastic tube 1 can be heated with steam from inside uniformly over the entire length. Incidentally, in the case where the drum 2 is installed in a vertical position, the inside channel 20 of the plastic tube 1 continuously extends spirally in a vertical plane as ~IR~C~-~DIP- C- -y i -11schematically shown in FIG. 9 and includes high and low portions, so that the drain 19 collects in the low channel portions 20b, blocking the channel to hamper the flow of steam through the tube. The horizontal installation of the drum 2 can overcome the foregoing problem of the drum 2 installed in a vertical position.

The plastic tube 1 may be heated with steam from inside while holding t internal atmosphere of the casing 11 heated by supplying hot air to the inside of the casing 11 from an air heater 16a (see FIG. 1) via a conduit 15a as shown in FIG. 6. For the casing 11 to retain the hot atmosphere therein with the supply of hot air, it is desired that an outlet duct lib be sealed with a seal member for permitting the plastic tube 1 to be S 15 withdrawn therethrough, such as a rubber sheet 18 having e e i" a slit 18a for the tube 1 to extend therethrough.

The internal heating of the plastic tube 1 with steam is continued until every portion of the tube 1 is uniformly softened over the entire length of the tube.

The time required for the plastic tube 1 to be uniformly softened by heating over the entire length is usually about 30 to about 60 minutes although varying 9.

depending on the work conditions such as the wall Lhickness and length of the tube 1 and the atmospheric temperature of the work site.

-12- When the tube is thus continuously heated with steam, condensation of steam produces drain, which collects inside the tube. The amount of drain collecting in the tube increases with time.

With reference to FIG. 8, the lower portion of the plastic tube 1 which is in direct contact with the drain 19 is not directly heated with steam and therefore less softened than the tube upper portion which is directly heated with steam, with the result that softening of the tube involves irregularities between the lower portion of the tube and the upper portion thereof.

Such softening irregularities should be eliminated to the Sgreatest possible extent so as to smoothly pay out the plastic tube 1 from the drum 2.

*ed* 15 The difference in the degree of heating between the lower portion of the plastic tube 1 and the upper portion thereof can be almost completely eliminated by forcibly discharging the drain from inside the tube 13.

'while internally heating the tube 1 with steam 20 continuously.

ee e FIG. 10 shows how the drain 19 is forcibly discharged. For the forced discharge, the heat insulating casing 11, that is, the drum 2 housed in the horizontal position in the casing 11, is inclined.

When the drum 2 as inclined is rotated in the I LI~ s~ -13direction in which the tube is wound on the drum 2, the drain remaining within the tube 1 is forcibly moved in a direction opposite to the direction of rotation by the rotation and inclination of the drum every time the drum makes one turn of rotation, and is eventua, ±y forcibly discharged from the tube 1 into the casing 11 through the water outlet 17b of the end member 17 attached to the outer tube end lb. The drain discharged within the casing 11 is discharged to the outside of the casing through a valve 28 which is opened.

The principle of draining the plastic tube 1 will be described below with reference to FIGS. 11 and 12. When the drum 2 is inclined, the drain 19 in each of S the coil portions IA of the plastic tube 1 wound into a S 0* 15 roll moves toward the lower side thereof under gravity by being guided by the inclination and collects at the lower side as schematically shown in the plan view of FIG. 11.

When rotation in the tube winding direction indicated by an arrow 32 is given to the drum 2, namely, to each coil portion 1A, in the state shown in FIG. 11, o the drain portion 191 remaining in the outermost coil portion 1A 1 at the inclined lower side thereof is discharged from the outer tube end lb to the outside by a gravity movement due to the inclination when the tube end lb passes through the lower position as shown in FIG. 12.

s ~LC I -14- The drain portions 191, remaining at the inclined lower side within the coil portions 1A 1 remain in the initial position without following the rotational movement of the coil portions, with the result that the state shown in FIG. 11 is resumed after the coil portions have made one turn of rotation. The tube 1 is drained again by the subsequent rotation.

Consequently, the drain remaining inside.the tube is successively discharged from the tube by every turn of continued rotation of the inclined drum 2 in the direction of arrow 32.

The amount of! steam required for softening the plastic tube by heating and, therefore, the heating time can be at least about 20% smaller when the tube is thus 15 drained concurrently with heating than otherwise.

**too: 0 t The forced discharge of the drain is suitably effected after the start of internal heating of the plastic tube 1 with steam and before the start of paying out of the tube 1 from the drum 2.

FIGS. 6 and 10 show as means for inclining the o drum 2 a jack 27 which is a component of a base 26 for the heat insulating casing 11 and which is operable for pushing up one end of the casing 11.

These drawings also show as rotating means a drive device 21 which is operated to rotate the rotary

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~I shaft 12 through a chain 22 and a sprocket 23.

The drum 2 is inclined at such an angle that the drain can be moved under gravity by virtue of the inclination. The suitable'angle to be determined is usually in the range of about 2 to about 15 degrees.

If the peripheral speed of the drum 2 given by rotation is excessively great, the forced discharge of the drain will be impeded, so that a low peripheral speed of about 5 to about 20 m/min is suitable, for example, when the roll diameter on the drum is 2,000 mm.

When the plastic tube 1 is continuously heated with steam from inside for a predetermined period of time, the tube 1 is softened almost uniformly over the entire length. Because the tube 1 is thus made flexible 15 and further because of the flat tubular form, the tube 0 can be paid off from the drum 2.

When the plastic tube 1 is to be paid out, rollers arranged around the drum 2 (see FIGS. 6 and 7) prevent the tube 1 from slipping off the drum 2.

The tube 1 is guided toward the outlet duct 1lb by a pair 4 0 of guide rollers 25, 25 arranged in the vicinity of the duct lib.

"As shown in FIG. 1, the plastic tube 1 0e withdrawn from the outlet duct llb of the casing 11 in the flat form is initially in a vertical position, is 1 i-i-r- -u I -C -16inclined through 45 degrees by the time it reaches an upper guide roller 34 disposed above a work pit 26 and is further inclined through 45 degrees to a horizontal position by the time it reaches a lower guide roller 33 disposed in the lower portion of the pit 26. In this horizontal position, the tube 1 is attached to a connector 30 at one end of a pulling rope 29 which is inserted through the pipe in advance. The other end of the rope 29 is wound on a winch 31 installed on the ground. The connector 30 is formed with steam ejection bores 30a, through which steam is ejected to ensure the flow of steam through the tube 1.

In the state shown in FIG. 1, the winch 31 is 0 operated to draw the plastic tube 1 into the pipe a, 15 whereby the tube 1 can be inserted through the entire length of the pipe 1.

The plastic tube 1 inserted into the pipe a is inflated by application of heat and pressure from inside *°o°S 0 S' in the usual manner and applied to the inner surface of 20 the pipe a for lining.

iio: With the method of the invention, steam is 9 supplied to a plastic tube wound in a flat form on a drum S*i r as installed in a horizontal position. This provides a steam flow channel inside the plastic tube over the entire length thereof despite the occurrence of drain, ~Be~ I c -17ntaking it possible to insert the plastic tube into a pipe while reliably softening the tube with good stability over the entire length by internal heating with the stea2n.

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Claims (4)

1. A method of inserting a rigid plastic lining tube into a pipe, comprising the steps of: winding the rigid plastic tube as deformed to a flat tubular form around a take-up spool of a drum into a spiral plane roll; installing the drum having the plastic tube wound thereon in a horizontal position at a work site; supplying steam to the plastic tube in the horizontal position to pass the steam from one end of the tube which is located at an innermost layer of said roll toward the other end thereof which is located at an 6 outermost layer of said roll and to thereby heat and soften the plastic tube over the entire length thereof; S. inclining the drum from the horizontal position and rotating the drum in the tube winding direction whereby drain produced inside the tube is forcibly discharged from said other tube end to outside the tube while being 6 forcibly moved toward said other tube end and thereafter i inserting the plastic tube into the pipe while paying out 20 the tube from the drum.

2. A method as defining in claim 1 wherein the drum is inclined at an angle of 2 to 15 degrees to the horizontal position and rotated in the tube winding direction at a lower peripheral speed of up to 20 m/min when the roll has a diameter of 2,000mm. i e 4 19

3. A method as defined in claim 1 or 2 wherein the drum in the horizontal position is housed in a heat insulating casing, and a heated atmosphere is maintained inside the casing by hot air supplied to the casing.

4. A method of inserting a rigid plastic lining tube into a pipe substantially as herein described with reference to and as illustrated in the accompanying drawings. Dated this 21st day of November 1995. 10 OSAKA BOUSUI CONSTRUCTION CO., LTD By its Patent Attorneys: GRIFFITH HACK CO. Fellows Institute of Patent Attorneys of Australia. S. o•ed S* 4 S 4 S o a j I I I ABSTRACT A method characterized by winding a rigid plastic tube as deformed to a flat tubular form around a take-up spool of a drum, installing the drum having the plastic tube wound thereon in a horizontal position at a work site, supplying steam to the plastic tube in the horizontal position to pass the steam from one end of the tube toward the other end thereof and to thereby heat and soften the plastic tube over the entire length thereof, and thereafter inserting the plastic tube into a pipe while paying out the tube from the drum. e o* C eos 6 g *o s a S o* 5 s S *s 41