WO1998050724A1

WO1998050724A1 - Pipe lining

Info

Publication number: WO1998050724A1
Application number: PCT/GB1998/001156
Authority: WO
Inventors: Brian Edward Mcguire
Original assignee: Bg Plc
Priority date: 1997-05-08
Filing date: 1998-05-07
Publication date: 1998-11-12
Also published as: GB2325038B; AU7218498A; AR015645A1; GB2325038A; GB9709220D0; GB9809680D0

Abstract

A lining method for a host pipe (10) including lubrication of the host pipe (10) prior to insertion of a thermoplastic liner (11) using tight fit techniques. After allowing the inserted liner (11) to relax, the liner (11) is partially pulled from within the host pipe (10) and clamped to allow fitting of a special flange (40) thereto by butt fusion, for example. Thereafter the liner (11) is allowed to revert so as to abut a flange (12) fitted to the host pipe (10). The technique is repeated at the other pipe end.

Description

PIPE LINING

The invention relates to pipe lining. In pipeline systems it is known to line

them with plastic pipe for refurbishment when corrosion puts the integrity of

the existing pipe at risk or when a suitable barrier is required to prevent

corrosion occurring. The existing host pipe may be steel, cast iron, asbestos

or other rigid material. Polyethylene is typically used for the liner and

provides a corrosion barrier for the oil and petrochemical industry for

example.

To maximise the bore diameter it is preferred that the liner be a tight fit within

the host pipe. An existing system utilises polyetliylene piping which is forced

through a die to compress its overall diameter as it passes in the pipe to aid

insertion. Such a technique is employed in the Swagelining (RTM) pipelining

system.

There is established a number of other lining systems which when installed

are not tight fit liners. This in turn means that there is an annulus between the

liner pipe and the host pipe. Where an annulus exists it is possible for permeability to occur, which in turn

can cause pressure balancing which could lead to implosion of the liner and

consequential failure of the system.

With the Swagelining pipelining system, no amiulus is present and

permeability through the liner is thus almost impossible.

The technical requirements for lined pipes may typically call for flanges every

500 metres which using non tight fit liners is achieved by drawing out the

liner at each end of a lined pipe and butt fusing a polyethylene flange thereto;

the line then being allowed to slip back within the host pipe. It has not been

possible to deal with tight fit liners in this manner so as to allow flanges to be

fitted.

The present invention is concerned with a mechanism for allowing flanges to

be fitted to tight fit liners, typically polyethylene, within a host pipe.

According to the invention there is provided a method of lining a host pipe

including the steps of: lubricating the host pipe along an internal face for an

elongate portion at each end of the host pipe; lining the pipe with a tliermoplastic liner using a tiglit fit teclmique; allowing the inserted pipe liner

to relax; pulling a portion of the liner from the host pipe using limited force;

affixing a thermoplastic flange thereto by a sealing technique; and allowing

the liner to revert within the pipeline so as the thermoplastic flange abuts a

flange on the host pipe.

Further according to the invention there is provided a puller device for pipe

lining including fixing means for affixing the device to a rigid pipeline flange

attached to a host pipe; gripper means for gripping a thermoplastic liner

witliin the host pipe to allow a portion of the liner to be pulled from witliin the

host pipe; means for holding the liner portion pulled from the pipe to allow

a thermoplastic pipe flange to be fitted prior to release of the liner.

Still further according to the invention there is provided a thermoplastic pipe

flange including a first portion for butt fusion to a liner pipe and a second

portion for affixing to a flanged portion of a rigid pipe.

In existing tight fit arrangements such as the Swagelining (RTM) pipelining

system, the polyethylene pipe is forced through a die and this allows the

temporarily reduced diameter pipeliner to slide within the host pipe to the desired length. The liner then returns to its oπginal diameter to fit hard

against the internal surface of tl e host pipe, hi tlie present invention modified

insertion procedures are required to handle very long pipelines which may be

made up from portions of about 500 metres in length, for example.

hi order to carry out the lining procedure, suitable pressure rated steel flanges

are fitted to the pipeline which is to be lined.

Prior to fitting the plastic tight fit lining, the inside of the host pipe is

lubricated for a suitable length at each end, typically for 10 metres. The

special lubrication is applied throughout 360° within the liner pipe wall. The

length of pipe lubricated is typically dependent on the length of pipe to be

lined. Thereafter the pipeline is lined with polyethylene or other

thermoplastic material using a tight fit technique (e.g. Swagelining (RTM)

pipelining).

After insertion, the pipe is allowed to fully relax to fill the void and to ensure

no longitudinal or hoop stresses are left in the liner. Once this state has been

reached, a liner pulling device is affixed to one of the host pipeline flanges,

which also has a portion which is configured to grip the inner liner. The gripper is designed to exert an effort that is not more than half the yield of the

liner material.

The end of liner under pulling action from tlie puller will be stretched and due

to tlie lubricant will emerge from tlie host pipe. Tins action will continue until

a suficient length is exposed to allow a suitable flange to be fitted.

The clamped liner is then trimmed to the correct length and a purpose

designed polyethylene flange is butt fused to the liner.

After the butt fused joint has cooled the clamp can be removed and this

allows the liner to relax back into the host pipeline. Reversion may be

assisted by pushing the polyethylene flange towards the metal pipeline flange.

Once the flange fitting has been completed at one end the whole process is

repeated at the other end of the liner and host pipe.

Under existing circumstances, with a tight fit liner, it would not have been

possible to draw the liner out without stressing the liner beyond acceptable

limits. The present arrangement, however, achieves the desired technique

without damage to the liner or causing undue stress.

Claims

1. A method of lining a host pipe including the steps of: lubricating the

host pipe along an internal face for an elongate portion at each end of the host

pipe;

lining tlie pipe with a thermoplastic liner using a tight fit tecl ique; allowing

the inserted pipe liner to relax; pulling a portion of the liner from the host pipe

using limited force;

affixing a thermoplastic flange thereto by a sealing technique; and allowing

the liner to revert within the pipeline so as the thermoplastic flange abuts a

flange on the host pipe.

2. A method as claimed in claim 1, wherein the thermoplastic flange is

attached to the liner by butt fusion.

3. A method as claimed in claim 1 or 2, wherein a thermoplastic flange

is attached to each end of the liner.

4. A method as claimed in claim 1 , 2 or 3 including the step of affixing

a flange to the host pipe.

5. A method as claimed in any one of claims 1 to 4, wherein the liner is

pulled from the host pipe by means of a combined puller/clamp.

6. A method as claimed in any one of claims 1 to 5, wherein the liner is

passed through a die to compress the pipe during insertion.

7. A method as claimed in any one of claims 1 to 6, wherein the liner and

flange are of polyethylene.

8. A method as claimed in any one of claims 1 to 7 including the step of

trimming the liner prior to fitting the flange.

9. A puller device for pipe lining including fixing means for affixing the

device to a rigid pipeline flange attached to a host pipe; gripper means for

gripping a thermoplastic liner within the host pipe to allow a portion of the

liner to be pulled from within the host pipe; means for holding the liner

portion pulled from the pipe to allow a thermoplastic pipe flange to be fitted

prior to release of the liner.

10. A thermoplastic pipe flange including a first portion for butt fusion to

a liner pipe and a second portion for affixing to a flanged portion of a rigid pipe.

1 1. A method of lining a host pipe substantially as described herein.

12. A puller device for pipeling substantially as described herein.

13. A the╧Çnoplastic pipe flange substantially as described herein.