CA1103141A - Pipe wrapping structure - Google Patents
Pipe wrapping structureInfo
- Publication number
- CA1103141A CA1103141A CA353,421A CA353421A CA1103141A CA 1103141 A CA1103141 A CA 1103141A CA 353421 A CA353421 A CA 353421A CA 1103141 A CA1103141 A CA 1103141A
- Authority
- CA
- Canada
- Prior art keywords
- ribs
- pipe
- apertures
- pipe according
- cms
- 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
Landscapes
- Rigid Pipes And Flexible Pipes (AREA)
Abstract
A B S T R A C T
A pipe is protected by wrapping structure that has a plurality of ribs and a plurality of apertures and is flexible. The apertures allow a cathodic protection system to operate. On the side applied to a pipe the surfaces of the ribs lie in a single plane so that when drawn tight there are no projections to cut into wrappings or coatings on the pipe. The wrapping structure is preferably of a resilient polymeric material, preferably air entrained polyethylene.
A pipe is protected by wrapping structure that has a plurality of ribs and a plurality of apertures and is flexible. The apertures allow a cathodic protection system to operate. On the side applied to a pipe the surfaces of the ribs lie in a single plane so that when drawn tight there are no projections to cut into wrappings or coatings on the pipe. The wrapping structure is preferably of a resilient polymeric material, preferably air entrained polyethylene.
Description
~1~3~1 This invention relates to pipes that are protected by a wrapping structure, particularly steel pipelines which may be subjected to impact by hard objects, for example rocks and pebbles. This application is a division of copending application Serial No. 249984 filed April 9, 1976.
It is well known that steel pipelines, whether buried in the ground, or resting on the surface of the sea-bed, can be protected with coating com-positions or wrappings. In order to prevent localised corrosion occurring at holes or tears in these protective coatings or wrappings, cathodic protec-tion is often employed as a second line of defence. This cathodic protection involves placing adjacent to the pipe an anode of a metal which is higher than iron in the electrochemical series, or the impression of electrical current. The cathodic protection is normally only required when the protec-tive coating or wrapping becomes damaged, although, of course, with a buried or submarine pipeline one cannot know whether this has happened.
When a pipeline protected by a coating or wrapping is laid in rocky terrain or a sub-soil containing sharp and abrasive aggregates, it is desir-able to protect the protective coating or wrapping against damage by abrasion or impact with such rock OT sharp aggregate by means of a barrier sufficiently robust to protect the coating or wrapping against damage by such impact or abrasion. This is clearly desirable even though a cathodic protection may also be provided, because quite severe damage may otherwise occur in the pipe laying operation. At the same time, the barrier must permit a system of cathodic protection to function by allowing the electrical current that is generated to reach any areas of metal which are exposed as a result of local-ised damage to the protective coating or wrapping which may, despite the barrier, have occured.
It is an aim of the invention to provide a pipe with a wrapping -1- ~
. ' ,, : .
11~ 3141 structure which may be used to provide such a barrier.
The invention provides a pipe laid or to be laid below the ground or sea, the pipe being protected by a wrapping structure having a plurality of ribs and a plurality of apertures between the ribs, the structure being flexible and being wrapped around the pipe, with the surfaces of the ribs which are the parts of the structure in contact with the pipe lying in a generally cylindrical sur-face, and the apertures being exteriorly uncovered.
The apertures of the structure may each have an area of from 0.4 to 6.5 cm2, and may together occupy from 40% to 90% of the area of the structure.
The ribs of the structure may be at least 0.2 cm deep, perpendicular to the general plane of the structure.
According to another aspect of the invention a pipe laid OT to be laid below the ground or sea is protected by a wrapping structure having a plurality of ribs and a plurality of apeTtureS between the ribs, the ribs having a height of at least 0.2 cm perpendicular to the plane of the structure, the apertures each having an area of up to 6.5 cm2 and together occupying from 40%
to 90% of the area of the structureJ and the structure being of flexible plastic material and being elongate, the surfaces of the ribs which are the parts of the structure which are in contact with the pipe lying in a generally cylindri-; 2Q cal surface, the apertures being exteriorly uncovered and the structure offering an exterior discontinuous surface which is free of projections. The structure may be of a polymeric material which is also resilient, such as air entrained polyethylene. The ribs of the structure may be rounded on the side of the structure adjacent the pipe, and the apertures may occupy about 50% of the area of the structure.
The ribs may be from 0.3 to 0.6 cms wide parallel to the general plane of the structure, and the ribs of the structure may be spaced apart by a distance <L .~
, ~
"
1~3~41 corresponding to the width of the rfbs.
The ribs of the structure are preferably parallel to each other, and the structure may comprise two sets of parallel ribs, the ribs of the sets being inclined to each other and the apertures being defined between the ribs. Alter-natively the sets of ribs may be perpendicular to each other.
The ribs may be up to 0.9 cms deep, perpendicular to the general plane of the structure.
According to another aspect of the invention a pipe laid or to be laid below the ground or sea is protected by a wrapping structure comprising first and second mutually perpendicular sets of ribs with apertures defined between the ribs, the ribs having a height of at least 0.2 cm perpendicular to the plane of the structure, the apertures each having a surface area of up to 6.5 cm2, the structure being of air entrained polyethylene so as to be flexible and resilient, and being elongate and wrapped around the pipe by being helically wound thereon or while extending longitudinally therealong, the surfaces of the ribs into which are the parts of the structure in contact with the pipe lying in a generally cylindrical surface, and the apertures being exteriorly uncovered. The apera-tures may be 2.2 cms long by 0.5 cms wide, the ribs having a depth of 0.4 cms and a width of 0.7 cms.
The structure may be such that, when laid flat, all the ribs lie in a single plane.
The present invention will now be described, by way of example, with reference to the accompanying drawings, wherein:
Figure 1 is a top~plan view of a portion of a length of a pipe wrapping s:tructure suitable for use ~n the present invention;
Figure 2 is a cross~sectional view of the structure shown in Figure 1, Figures 3A and 3B show two methods of fixing of the pipe wrapping ~2a-.j .
' ; ` .
11~3~
structure shown in Figures 1 and 2, and Figure 4 shows another form of pipe wrapping structure suitable for use in the present invention.
Referring initially to Figures 1 and 2 the pipe wrapping structure 10 comprises an elongate web 11 with a plurality of longitudinally extending, later-ally spaced parallel rounded ribs 12 on one side. Intermediate the ribs 12, elongate apertures 13 ar0 provided in rows in the web. As shown in Figure 1 the apertures 13 in adjacent rows are staggered with respect to each other.
The wrapping structure, which may be of a polymeric material or other suitable material, may be made by extrusion or moulding. If desired the elongate apertures 13 may be formed by punching after the web 11 with the ribs 12 integral therewith has been formed.
~2b~
., , :: -:, .. : , ~ ~
1113 3~1 The pipe wrapping structure shown in Figures 1 and 2 may be wrapped helically about a pipe 14 to be covered ~Figure 3B) or may be arranged so that the ribs 12 extend generally parallel to the longitudinal axis of the pipe 14 as in Figure 3A. In either arrangement only the ribs 12 contact the surface of the pipe 14 with the web 11 spaced from the pipe, and the area of contact between the wrapping structure 10 and the pipe 14 is kept to a minimum.
In the case of the pipe wrapping structure 10 being secured with the ribs 12 parallel to the longitudinal axis of the pipe 14 the longitudinal edges of the web, or webs in the case of two or more leng~hs of material being used, to surround the pipe, are held in butting relationship by laces 15 which pass through the apertures adjacent to the butting edges of the web or webs or by means of non-metallic clips which encircle the wrapping struc-ture 10 when in position about the pipe and clamp it to the pipe 14. An alternative is to use straps or tapes which self-lock, e.g. by being provided with a ratchet mechanism.
In the embodiment shown in Figures 1 and 2, the ribs 12 are 1/4 inch (0.6 cm) wide at their maximum width, extend the same amount upwardly from the web and are spaced approximately 1/2" ~1.25 cm) between centres.
The apertures 13 are made as large as possible consistent with maintaining the desired strength in the web and yet small enough to ensure that aggregate is kept clear of the pipe surface. This ensures that if cathodic protection has to be used then the large number of apertures permit the passage of the electrical current therethrough. Typically the apertures are 5/8" ~1.6 cms) long~ l/4" ~0.6 cm) wide and are separated lengthwise by 1/8" ~0.3 cm). The apertures thus comprise just under half the area of the web.
Figure 4 shows an alternative embodiment of wrapping structure com-' ~. ' :
1~3~4~
prislng two sets of parallel ribs extending at right angles to one another.
Rectangular apertures (41) are accordingly provided in the structure, and it will be seen that the ribs are rounded to one side of the structure, this being the side which is placed upon a pipe. The other side of the structure is substantially planar. The wrapping structure of this Figure is again attached by clips, laces or straps to the pipe with the rounded sides of the ribs in contact therewith, or is helically wound on the pipe.
In one embodiment according to Figure 4, the ribs have a maximum depth of about 0.4 cms, and a width of 0.7, the apertures being 2.2 cms long by 0.5 cms wide.
Although two alternative embodiments of the wrapping structure 10 have been described it should be understood that the wrapping structure may take many other forms. In general the wrapping structure has a small area of surface contact with the pipe and at the same time provides a large over-all passage for the flow of electrical current in the event of cathodic protection having to be used.
Preferably the wrapping structure will be of the order of 36 inches ~approximately 90 cms) wide. Any length of structure can be provided.
-::
It is well known that steel pipelines, whether buried in the ground, or resting on the surface of the sea-bed, can be protected with coating com-positions or wrappings. In order to prevent localised corrosion occurring at holes or tears in these protective coatings or wrappings, cathodic protec-tion is often employed as a second line of defence. This cathodic protection involves placing adjacent to the pipe an anode of a metal which is higher than iron in the electrochemical series, or the impression of electrical current. The cathodic protection is normally only required when the protec-tive coating or wrapping becomes damaged, although, of course, with a buried or submarine pipeline one cannot know whether this has happened.
When a pipeline protected by a coating or wrapping is laid in rocky terrain or a sub-soil containing sharp and abrasive aggregates, it is desir-able to protect the protective coating or wrapping against damage by abrasion or impact with such rock OT sharp aggregate by means of a barrier sufficiently robust to protect the coating or wrapping against damage by such impact or abrasion. This is clearly desirable even though a cathodic protection may also be provided, because quite severe damage may otherwise occur in the pipe laying operation. At the same time, the barrier must permit a system of cathodic protection to function by allowing the electrical current that is generated to reach any areas of metal which are exposed as a result of local-ised damage to the protective coating or wrapping which may, despite the barrier, have occured.
It is an aim of the invention to provide a pipe with a wrapping -1- ~
. ' ,, : .
11~ 3141 structure which may be used to provide such a barrier.
The invention provides a pipe laid or to be laid below the ground or sea, the pipe being protected by a wrapping structure having a plurality of ribs and a plurality of apertures between the ribs, the structure being flexible and being wrapped around the pipe, with the surfaces of the ribs which are the parts of the structure in contact with the pipe lying in a generally cylindrical sur-face, and the apertures being exteriorly uncovered.
The apertures of the structure may each have an area of from 0.4 to 6.5 cm2, and may together occupy from 40% to 90% of the area of the structure.
The ribs of the structure may be at least 0.2 cm deep, perpendicular to the general plane of the structure.
According to another aspect of the invention a pipe laid OT to be laid below the ground or sea is protected by a wrapping structure having a plurality of ribs and a plurality of apeTtureS between the ribs, the ribs having a height of at least 0.2 cm perpendicular to the plane of the structure, the apertures each having an area of up to 6.5 cm2 and together occupying from 40%
to 90% of the area of the structureJ and the structure being of flexible plastic material and being elongate, the surfaces of the ribs which are the parts of the structure which are in contact with the pipe lying in a generally cylindri-; 2Q cal surface, the apertures being exteriorly uncovered and the structure offering an exterior discontinuous surface which is free of projections. The structure may be of a polymeric material which is also resilient, such as air entrained polyethylene. The ribs of the structure may be rounded on the side of the structure adjacent the pipe, and the apertures may occupy about 50% of the area of the structure.
The ribs may be from 0.3 to 0.6 cms wide parallel to the general plane of the structure, and the ribs of the structure may be spaced apart by a distance <L .~
, ~
"
1~3~41 corresponding to the width of the rfbs.
The ribs of the structure are preferably parallel to each other, and the structure may comprise two sets of parallel ribs, the ribs of the sets being inclined to each other and the apertures being defined between the ribs. Alter-natively the sets of ribs may be perpendicular to each other.
The ribs may be up to 0.9 cms deep, perpendicular to the general plane of the structure.
According to another aspect of the invention a pipe laid or to be laid below the ground or sea is protected by a wrapping structure comprising first and second mutually perpendicular sets of ribs with apertures defined between the ribs, the ribs having a height of at least 0.2 cm perpendicular to the plane of the structure, the apertures each having a surface area of up to 6.5 cm2, the structure being of air entrained polyethylene so as to be flexible and resilient, and being elongate and wrapped around the pipe by being helically wound thereon or while extending longitudinally therealong, the surfaces of the ribs into which are the parts of the structure in contact with the pipe lying in a generally cylindrical surface, and the apertures being exteriorly uncovered. The apera-tures may be 2.2 cms long by 0.5 cms wide, the ribs having a depth of 0.4 cms and a width of 0.7 cms.
The structure may be such that, when laid flat, all the ribs lie in a single plane.
The present invention will now be described, by way of example, with reference to the accompanying drawings, wherein:
Figure 1 is a top~plan view of a portion of a length of a pipe wrapping s:tructure suitable for use ~n the present invention;
Figure 2 is a cross~sectional view of the structure shown in Figure 1, Figures 3A and 3B show two methods of fixing of the pipe wrapping ~2a-.j .
' ; ` .
11~3~
structure shown in Figures 1 and 2, and Figure 4 shows another form of pipe wrapping structure suitable for use in the present invention.
Referring initially to Figures 1 and 2 the pipe wrapping structure 10 comprises an elongate web 11 with a plurality of longitudinally extending, later-ally spaced parallel rounded ribs 12 on one side. Intermediate the ribs 12, elongate apertures 13 ar0 provided in rows in the web. As shown in Figure 1 the apertures 13 in adjacent rows are staggered with respect to each other.
The wrapping structure, which may be of a polymeric material or other suitable material, may be made by extrusion or moulding. If desired the elongate apertures 13 may be formed by punching after the web 11 with the ribs 12 integral therewith has been formed.
~2b~
., , :: -:, .. : , ~ ~
1113 3~1 The pipe wrapping structure shown in Figures 1 and 2 may be wrapped helically about a pipe 14 to be covered ~Figure 3B) or may be arranged so that the ribs 12 extend generally parallel to the longitudinal axis of the pipe 14 as in Figure 3A. In either arrangement only the ribs 12 contact the surface of the pipe 14 with the web 11 spaced from the pipe, and the area of contact between the wrapping structure 10 and the pipe 14 is kept to a minimum.
In the case of the pipe wrapping structure 10 being secured with the ribs 12 parallel to the longitudinal axis of the pipe 14 the longitudinal edges of the web, or webs in the case of two or more leng~hs of material being used, to surround the pipe, are held in butting relationship by laces 15 which pass through the apertures adjacent to the butting edges of the web or webs or by means of non-metallic clips which encircle the wrapping struc-ture 10 when in position about the pipe and clamp it to the pipe 14. An alternative is to use straps or tapes which self-lock, e.g. by being provided with a ratchet mechanism.
In the embodiment shown in Figures 1 and 2, the ribs 12 are 1/4 inch (0.6 cm) wide at their maximum width, extend the same amount upwardly from the web and are spaced approximately 1/2" ~1.25 cm) between centres.
The apertures 13 are made as large as possible consistent with maintaining the desired strength in the web and yet small enough to ensure that aggregate is kept clear of the pipe surface. This ensures that if cathodic protection has to be used then the large number of apertures permit the passage of the electrical current therethrough. Typically the apertures are 5/8" ~1.6 cms) long~ l/4" ~0.6 cm) wide and are separated lengthwise by 1/8" ~0.3 cm). The apertures thus comprise just under half the area of the web.
Figure 4 shows an alternative embodiment of wrapping structure com-' ~. ' :
1~3~4~
prislng two sets of parallel ribs extending at right angles to one another.
Rectangular apertures (41) are accordingly provided in the structure, and it will be seen that the ribs are rounded to one side of the structure, this being the side which is placed upon a pipe. The other side of the structure is substantially planar. The wrapping structure of this Figure is again attached by clips, laces or straps to the pipe with the rounded sides of the ribs in contact therewith, or is helically wound on the pipe.
In one embodiment according to Figure 4, the ribs have a maximum depth of about 0.4 cms, and a width of 0.7, the apertures being 2.2 cms long by 0.5 cms wide.
Although two alternative embodiments of the wrapping structure 10 have been described it should be understood that the wrapping structure may take many other forms. In general the wrapping structure has a small area of surface contact with the pipe and at the same time provides a large over-all passage for the flow of electrical current in the event of cathodic protection having to be used.
Preferably the wrapping structure will be of the order of 36 inches ~approximately 90 cms) wide. Any length of structure can be provided.
-::
Claims (21)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A pipe laid or to be laid below the ground or sea, the pipe being protected by a wrapping structure having a plurality of ribs and a plurality of apertures between the ribs, the structure being flexible and being wrap-ped around the pipe, with the surfaces of the ribs which are the parts of the structure in contact with the pipe lying in a generally cylindrical surface, and the apertures being exteriorly uncovered.
2. A pipe according to claim 1, wherein the apertures of the struc-ture each have an area of from 0.4 to 6.5 cm2.
3. A pipe according to claim 1, wherein the apertures of the structure together occupy from 40% to 90% of the area of the structure.
4. A pipe according to claim 1, 2 or 3 wherein the ribs of the structure are at least 0.2 cm deep perpendicular to the general plane of the structure.
5. A pipe laid or to be laid below the ground or sea, the pipe being protected by a wrapping structure having a plurality of ribs and a plurality of apertures between the ribs, the ribs having a height of at least 0.2 cm perpendicular to the plane of the structure, the apertures each having an area of up to 6.5 cm2 and together occupying from 40% to 90% of the area of the structure, and the structure being of flexible plastic material and being elongate, the surfaces of the ribs which are the parts of the structure which are in contact with the pipe lying in a generally cylindrical surface, the apertures being exteriorly uncovered and the structure offering an exterior discontinuous surface which is free of projections.
6. A pipe according to claim 1, wherein the structure is of a poly-meric material which is also resilient.
7. A pipe according to claim 6, wherein the resilient material is air entrained polyethylene.
8. A pipe according to claim 1, 2 or 3 wherein the ribs of the structure are rounded on the side of the structure adjacent the pipe.
9. A pipe according to claim 1, 2 or 3 wherein the apertures occupy about 50% of the area of the structure.
10. A pipe according to claim 1 wherein the ribs are from 0.3 to 0.6 cms wide parallel to the general plane of the structure.
11. A pipe according to claim 10 wherein the ribs of the structure are spaced apart by a distance corresponding to the width of the ribs.
12. A pipe according to claim 1 wherein the apertures are formed in a web of the structure which connects and is integral with the ribs, the ribs project-ing on one side of the web towards the pipe.
13. A pipe according to claim 12 wherein the ribs of the structure are parallel to each other.
14. A pipe according to claim 1, wherein the structure comprises two sets of parallel ribs, the ribs of the sets being inclined to each other and the apertures being defined between the ribs.
15. A pipe according to claim 14, wherein the sets of ribs are perpendicu-lar to each other.
16. A pipe according to claim 1, 2 or 3 wherein the ribs are up to 0.9 cms deep, perpendicular to the general plane of the structure.
17. A pipe according to claim 1, 2 or 3 wherein the structure is heli-cally wound around the pipe.
18. A pipe according to claim 1, 2 or 3 wherein the structure is wrap-ped around the pipe while extending longitudinally therealong.
19. A pipe laid or to be laid below the ground or sea, the pipe being protected by a wrapping structure comprising first and second mutually per-pendicular sets of ribs with apertures defined between the ribs, the ribs having a height of at least 0.2 cm perpendicular to the plane of the structure, the apertures each having a surface area of up to 6.5 cm , the structure being of air entrained polyethylene so as to be flexible and resilient, and being elongate and wrapped around the pipe by being helically wound thereon or while extending longitudinally therealong, the surfaces of the ribs into which are the parts of the structure in contact with the pipe lying in a generally cylindrical surface, and the apertures being exteriorly uncovered.
20. A pipe according to claim 19, wherein the apertures are 2.2 cms long by 0.5 cms wide, the ribs having a depth of 0.4 cms and a width of 0.7 cms.
21. A pipe according to claim 1, 2 or 3 wherein the structure is such that, when laid flat, all the ribs lie in a single plane.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA353,421A CA1103141A (en) | 1975-04-11 | 1980-06-05 | Pipe wrapping structure |
Applications Claiming Priority (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB14992/75A GB1549847A (en) | 1975-04-11 | 1975-04-11 | Pipe wrapping structure |
| GB14992/75 | 1975-04-11 | ||
| GB1389/76 | 1976-01-14 | ||
| GB138976 | 1976-01-14 | ||
| CA249,984A CA1090691A (en) | 1975-04-11 | 1976-04-09 | Pipe protector |
| CA353,421A CA1103141A (en) | 1975-04-11 | 1980-06-05 | Pipe wrapping structure |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1103141A true CA1103141A (en) | 1981-06-16 |
Family
ID=27425909
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA353,421A Expired CA1103141A (en) | 1975-04-11 | 1980-06-05 | Pipe wrapping structure |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1103141A (en) |
-
1980
- 1980-06-05 CA CA353,421A patent/CA1103141A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |