AU2011202156B2 - Pipe Field Closure - Google Patents

Abstract

Abstract A method of accessing a lined pipeline comprising: a) cutting a hole in the wall of the pipe; s b) removing lining adjacent the hole; c) replacing the removed lining with new lining to define a tapered edge at the hole; d) fitting a prelined cover to the hole the lining of the cover having a similar tapered edge; 10 e) welding the cover to the hole from the exterior; and f) attaching a shrink sleeve to the pipe over the cover. 26666461 (GHMatters) P83819.AU.1 1005111 LIL-

Description

AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant (s): TYCO WATER PTY LIMITED Invention Title: Pipe Field Closure The following statement is a full description of this invention, including the best method for performing it known to me/us: AUSTRALIA Patents Act 1990 COMPLETE SPECIFICATION Standard Patent Applicant(s): TYCO WATER PTY LIMITED Invention Title: Pipe Field Closure The following statement is a full description of this invention, including the best method for performing it known to me/us: - 2 Method of Accessing a Pipeline Introduction This invention relates to a method of accessing a lined 5 pipeline. Background of the Invention During the construction of large cement mortar lined (CML) pipelines, it is advantageous to have man entry points at 10 strategic locations to allow workmen to enter the line and effect the internal welding and CML reinstatement of the joints. These entry points allow the continuous laying of pipes without relying on entry to the pipeline from an end. Because the exact location of the required entry 15 point is generally determined in the field, prefitted manhole openings are not usually practical. The current method used to enter pipes of this kind is to cut a hole through the pipe and then weld to the cut pipe 20 a manhole flange branch. This is an expensive and labour intensive exercise incorporating quite expensive componentry. There is also an ongoing problem with external corrosion protection when pipes have had flange branches installed. 25 It is these issues that have brought about the present invention. Summary of the invention 30 According to the present invention there is provided a method of accessing a lined pipeline comprising: a) cutting a hole in the wall of the pipe; b) removing lining adjacent the hole; c) replacing the removed lining with new lining to 35 define a tapered edge at the hole; d) fitting a prelined cover to the hole the lining of the cover having a similar tapered edge; 2666646_1 (GHMatters) PB3819AU.1 10/05/11 -3 e) welding the cover to the hole from the exterior; and f) attaching a shrink sleeve to the pipe over the cover. 5 Description of the drawings An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings, in which: 10 Figure 1 is a perspective view showing part of a cut hole viewed from the inside of a pipe; Figure 2 is a similar view of the cut hole after is reinforcement has been replaced; Figure 3 is a similar perspective view showing the hole with a cover in place; 20 Figure 4 is a perspective view from the top showing a cover plate lowered into the hole and attached to the pipe through welding; Figure 5 is a part perspective view of a gusset attached 25 to the periphery of the cover plate; Figure 6 is a perspective illustration of a cover with side gussets and a mould; 30 Figure 7 is a cross-sectional view of the pipe with a cover in place. Description of the preferred embodiment The accompanying drawings illustrate a process for 35 accessing large cement mortar lined (CML) pipelines. These pipelines comprise lengths of steel pipe often with external diameters of about 2m. It is understood that the 26666461 (GHMatters) P83819.AU.1 10/05111 -4 process is applicable to any lined pipe that requires internal access. The pipes are lined with a cement mortar lining and are welded together end to end at predetermined intervals. The laying process requires both internal s welding and reinstatement of the cement mortar lining. This usually requires entry of the pipe and it is desirable that there are man entry points at strategic locations to provide access to the interior of the pipe. This process relates to the provision of this access. 10 The first step of the process is shown in Figure 1 and that is to cut a 600mm diameter hole 10 into the pipe P. The cutting process is usually carried our using an oxygen acetylene torch. The existing cement mortar lining L is 15 then removed from the periphery of the hole for a distance of approximately 50mm. The lining is removed manually by use of a hammer and chisel or by a grinder. The hole 10 with the removed CML 11 is shown in Figure 1. 20 The next step is to dress the exposed steel around the opening to remove any sharp edges. The CML is then reinstated with a high strength repair mortar which is put, in slurry form, into a shaped mould 35 (Figure 6) that is positioned around the periphery of the hole to 25 ensure that, as the mortar sets, the correct shape and thickness of the reinstated CML lining is provided. The mould is clamped into the opening from the outside and the area between the mould and the CML is reinstated. The mould is removed after a suitable curing period leaving 30 the completed reinstated lining 15 as shown in Figure 2. The mould which provides the reinforced CML also ensures that the periphery of the reinforced CML 15 has a tapered edge 16. 35 A pre-prepared steel cover 20 is then applied to the hole. The steel cover has an outer periphery of greater diameter than the cut hole 10. The cover 20 is supplied with an 26666461 (GHMatters) P83819 AU.1 10/05/11 -5 inbuilt CML lining 21 using a similar mould to ensure that the CML matches the reinstated hole. The CML lining has a tapered periphery 22 which accommodates the taper 16 on the reinstated CML 15 around the hole 10 in the pipe. An s amount of non-shrink slurry grout is applied to the tapered surface 16, 22 of both the reinstated lining 15 and the lining 21 on the underside of the cover 20 and the cover 20 is pressed into position on and into the hole 10 as shown in Figure 3. The tapers 16, 22 on the respective 10 linings ensure positive location of the cover 20 over the hole 10. As shown in the cross-sectional view in Figure 7, the cover 20 has a periphery that is larger than the periphery of the hole 10 so that the cover actually overlaps the hole with the lining 21 being a flush fit 15 within the lining 15 of the hole. The tapers 16, 22 vary as the pipe diameter varies. Once the cover 20 has been positioned over the hole 10, a suitably sized fillet weld 25 can then be positioned 20 around the periphery of the cover 20 to weld the cover to the external surface of the pipe P. For further and additional reinforcement, it is also understood that steel gussets can be positioned at spaced intervals around the cover of the pipe which would be welded to the cover and 25 the outer surface of the pipe, again using fillet welds, to provide additional reinforcement. The number and size of the gussets may vary and other forms of reinforcement could be used. Furthermore, there may be occasions when the use of reinforcement is not required. 30 Finally, to ensure that the external pipe is corrosion resistant, a shrink wrap sleeve (not shown) is wrapped around the periphery of the pipe in the area of the hole to seal the exterior of the pipe against the elements and 35 thereby reduce the likelihood of corrosion. The shrink wrap sleeve is one of many commercially available sleeves but a preferred version is the sleeve made by Canusa and 2666646_1 (GHMatters) P83819.AU I 10/05/11 -6 sold under the trade mark WRAPID SLEEVE. To apply the sleeve, the external surface of the pipe is first cleaned, the sleeve is then cut to the appropriate length and the pipe is preheated to a temperature of approximately 600C. 5 The sleeve is then applied in an overlapping fashion to totally cover the covered hole in the pipe. Many sleeves incorporate a second layer which is then positioned over the seal and pressed into position. A gas torch is then used to heat the outer sleeve and consolidate the two io components of the sleeve. A gloved hand is used to smooth out any wrinkles and to work the two sleeves together in a direction away from the centre. The sleeve then cools down and shrinks. During the recovery, the adhesive in the sleeve softens and flows to form a perfect bond with is the pipe's surface providing protection against corrosion. The radiation cross linked outer layer forms a tough barrier against mechanical damage and moisture transmission and provides long term protection for the pipe after the cutting and covering of the hole. 20 The process described above provides a simple and effective means of providing a one off access to the pipe during the laying process. The componentry associated with a man entry point is not expensive and much cheaper 25 than the use of a fixed flanged manhole. The cost of installation is also kept to a minimum due to the use of simple and effective techniques to cut, form and fill the hole. The process can be carried out quickly in the field and does not require specialist tools. The high quality 30 external fillet weld provides a leak-tight seal and the use of reinforcing gussets ensures that the cover can withstand large internal pressures. The replacement of the CML lining and the matching taper ensures integrity of the lining to protect the pipe interior. Finally, the 35 application of a shrink sleeve provides a very cost effective method of providing external corrosion protection. 2666646_1 (GHMatters) P83819.AU.1 10/05/11 -7 In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary s implication, the word "comprise" or variations such as "comprises" or "comprising" is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention. 10 26666461 (GHMatters) P83819.AU.1 10/05111

Claims (9)

1. A method of accessing a lined pipeline comprising: a) cutting a hole in the wall of the pipe; 5 b) removing lining adjacent the hole; c) replacing the removed lining with new lining to define a tapered edge at the hole; d) fitting a prelined cover to the hole the lining of the cover having a similar tapered edge; 10 e) welding the cover to the hole from the exterior; and f) attaching a shrink sleeve to the pipe over the cover. 15

2. The method according to claim 1 comprising dressing the cut hole before replacing the removed lining.

3. The method according to either claim 1 or 2 further comprising attaching gussets to the cover and welding the 20 gussets to the pipe exterior.

4. The method according to any one of the preceding claims wherein grouting is applied between the cover and the lined hole. 25

5. The method according to any one of the preceding claims, wherein the lining adjacent the cut hole is replaced by attaching a preformed mould to the hole and filling the mould with cement mix, curing the mix and 30 removing the mould.

6. The method according to claim 5 wherein a similar mould is used to preline the cover. 35

7. The method according to any one of the preceding claims wherein all steps are executed in the field. 70645381 (GHMatters) P83819.AU.1 15/01/16 - 9

8. The method according to claim 1 wherein steps (a) to (c) and the lining of the cover are carried out at and by the manufacturer. 5

9. A method of accessing a lined pipeline substantially as described herein with reference to and as illustrated in the accompanying drawings. 2666646_1 (GHMatters) P83819.AU.1 10/05/11