OPERATION STEPS FOR REROUTING OF A PIGGABLE PIPELINE
USING 5 POSITION LINESTOP TECHNIQUE
XEL
OBJECTIVE OF THE OPERATION IS TO REROUTE THE LONG SECTION
OF PIGGABLE FLUID PIPELINE BETWEEN THE SECTIONS MARKED
WITH RED LINES.
TO REALIZE THIS OBJECTIVE THE OPERATION TO BE APPLIED IS THE 5
POSITION LINESTOP OPERATION OUTLINED BELOW
GAS FLOW DIRECTION
XEL
1.BUILDING THE NEW PIPELINE ROUTE AND WELDING OF THE FITTINGS: The operation starts by determining the new route and connection points to the existing pipeline which are
suitable for the operation. Once these are determined the new pipeline is built and prepared for commissioning and the fittings are welded using suitable in-service welding
procedures to the existing pipeline. The fittings are positioned and welded according to the diagrams below:
1- Linestop Fittings (4 sets)
TYPE : Split Tee
2- By-pass Fittings (4 sets)
TYPE : Reduced Branch Split Tee
3- Drain-Purge/Filling/Equalization Fittings (4 sets)
TYPE : Nipple Type Threaded Fittings
4- Gas Bag Fittings (4 sets)
TYPE : Threaded Fitting with Weldolet
2
1
3
4
4
3
1
2
2
1
3
4
4
3
1
2
1. BÖLGE
2. BÖLGE
SECTION 1
SECTION 2
XEL
1. SECTION 1 STATUS: All the fittings in Section 1 (for Points A and B) have been welded. The by-pass to be connected to the by-pass fittings ( 2A to 2B ) has been prepared and
tested (fill/drain connections with valves must be available on the by-pass lines).
POINT A
2
1
POINT B
1
2
XEL
2. INSTALL TEMPORARY VALVES ON POINT A: The temporary valves are placed on the upstream section (Point A). Leak tests are performed at a maximum of 10% above the
internal pressure of the pipeline. Any leakages are remediated.
XEL
3. HOT TAP FOR LINESTOP FITTING OF POINT A: The hot-tap of the linestop fitting (A1) is performed. The temporary valve is closed and tapping machine is removed.
XEL
4. HOT-TAPS OF OTHER FITTINGS FOR POINT A: Once the linestop fitting hot-tap is completed, the remaining hot-taps (By-Pass, Equalization, Gas Bag) are completed.
XEL
5. HOT-TAPS FOR POINT B: Once the hot-taps for Point A are finished, the taps for Point B are completed in the same manner.
XEL
6. INSTALLING BY-PASS BETWEEN BY-PASS FITTINGS: Once the Hot-taps of Points A and B are completed, the By-Pass connections are made between the By-pass fittings.
XEL
7. INSTALLING PLUGGING EQUIPMENT: Once the by-pass pipeline is connected, it is first filled with nitrogen and then slowly pressurized with the pipeline fluid. Both
temporary valves (A2 – B2) are opened to allow fluid to flow through the by-pass. Once the by-pass is operational, plugging machines are installed on the Linestop fittings.
XEL
8. PLUG SETTING AT POINT B: The downstream Linestop Plug at point B is inserted in the line.
XEL
9. PLUGGING & FLUID FLOW:
XEL
10. PLUG SETTING AT POINT A: Once the plug setting is completed at Point B is finished, Plug Setting operation at the upstream location Point A is also performed.
XEL
11. DRAIN/PURGE OF SECTION: Once both plugs are set flow is only through the by-pass. At this stage the fluid in the isolated section is drained/vented.
XEL
12. CLEANING OF SECTION AND INSTALLING GAS BAGS: Once the drain/vent is finished, the section between the linestops are purged with nitrogen. At this stage, the Gas-Bags
are inserted from the Gas Bag fittings to prevent any leakage from the sealing elements from reaching the hot-work section.
XEL
13. LEAK MANAGEMENT:
VACUUM DEVICE (OR OIL DRAIN PUMP)
Sızıntı gaz
XEL
14. CUT-OUT OF ISOLATED SECTION: Using cold cutting method remove a sufficient portion of the existing pipeline isolated between Point A and B to allow the connection of
the new pipeline at a later stage.
XEL
15. WELD CAPS: Making sure that the environment has been cleared from inflammable gases, caps are welded to the cold cut sections to allow for removal of linestopping
equipment.
XEL
16. RETRACTING THE PLUGGING HEAD IN POINT B: Once the Tie in is completed, the plugging head at Point B is retracted, the temporary valve is closed and the Linestop
machine is removed.
XEL
17. INSTALLING COMPLETION PLUG AT POINT B: At Point B the completion plugs on the fittings except the by-pass fitting will be placed.
XEL
18. COMPLETION PLUG INSTALLATION:
XEL
19. STATUS AT POINT B: Completion plugs are installed on the fittings which will not be used immediately.
XEL
20. RETRACTING THE PLUGGING HEAD IN POINT A: After pressure equalization the plugging head at Point B is retracted, the temporary valve is closed and the Linestop machine
is removed.
XEL
21. STATUS AT SECTION 1: When the above steps have been applied, the situation on site shall be as presented below.
This completes the operations in SECTION 1 and operations in SECTION 2 can begin.
XEL
22. POINT DEFINITIONS The main points on SECTION 2 are defined as below
POINT C
2
POINT D
1
1
2
XEL
23. HOT TAPS ON SECTION 2 POINT C: All the hot-taps on Point C of SECTION 2 shall be completed first.
XEL
24. HOT TAPS ON SECTION 2 POINT D: All the hot-taps on Point D of SECTION 2 shall be completed following Point C
XEL
25. INSTALLING BY-PASS BETWEEN BY-PASS FITTINGS: Once the Hot-taps of Points C and D are completed, the By-Pass connections are made between the By-pass fittings. Once
the by-pass pipeline is connected, it is first filled with nitrogen and then slowly pressurized with the pipeline fluid. Both temporary valves (C2 – D2) are opened to allow fluid
to flow through the by-pass.
XEL
26. INSTALLING PLUGGING EQUIPMENT: Once the by-pass is operational, plugging machines are installed on the Linestop fittings. The downstream Linestop Plug at point D is
inserted in the line.
XEL
27. UPSTREAM PLUG INSTALLATION: Once the plug setting is completed at Point D is finished, Plug Setting operation at the upstream location Point C is also performed.
XEL
28. DRAIN/PURGE OF SECTION: Once both plugs are set flow is only through the by-pass. At this stage the fluid in the isolated section is drained/vented.
XEL
29. CLEANING OF SECTION AND INSTALLING GAS BAGS: Once the drain/vent is finished, the section between the linestops are purged with nitrogen. At this stage, the Gas-Bags
are inserted from the Gas Bag fittings to prevent any leakage from the sealing elements from reaching the hot-work section.. Using cold cutting method remove a sufficient
portion of the existing pipeline isolated between Point C and D to allow the connection of the new pipeline at a later stage.
XEL
30. TIE-IN CONNECTION: Once the cold cutting is completed, a cap shall be welded to Point C and the Tie-in to the new pipeline shall be made at Point D
XEL
31. RETRACTING THE PLUGGING HEAD IN POINT C: Once the cap weld and Tie in are completed, the plugging head at Point C is retracted, the temporary valve is closed and the
Linestop machine is removed
XEL
32. COMPLETION PLUG INSTALLATION AT POINT C
XEL
33. INSTALLING COMPLETION PLUG AT POINT B: At Point B the completion plugs on the fittings except the by-pass fitting will be placed.
XEL
34. STATUS OF SITE: At this stage flow is still maintained in the by-passes and the new line is connected at the downstream end to the existing pipe.
XEL
35. REINSTALLING LINESTOP AT POINT A: The Linestop machine used in Point C is removed and relocated to Point A. The Linestop plugging head is inserted in the line and cap is
removed by cold cutting for Tie-In preparation.
XEL
36. TIE-IN AT POINT A: Tie-In procedures are applied at Point A
XEL
37. STATUS OF SITE AFTER TIE-IN AT POINT A:
POINT A
POINT D
XEL
38. FILLING/COMMISSIONING OF NEW LINE : Once the Tie-In is connected, it is recommended to fill the new section with nitrogen gas from the upstream equalization fitting
and vent the air from the downstream equalization fitting. The new pipeline shall be filled and commissioned according to the Pipeline Owner’s procedures. The filling shall
be made from the equalization fitting upstream at Point A and venting of Nitrogen in the new line shall be made from the equalization fitting downstream at Point D.
POINT A
POINT D
XEL
39. PIPELINE ACTIVATION: Once the new line is filled and pressurized, the plugging heads are retracted in the order of Upstream (Point A) and then Downstream (Point D). At
this point, the new pipeline has been activated and the by-passes can be removed.
XEL
40. BYPASS REMOVAL: The By-pass lines can now be removed and the old line should be emptied of the inflammable liquid and filled with Nitrogen or other media to make sure
there is no combustible atmosphere in the old pipe.
XEL
41. INSTALLATION OF COMPLETION PLUGS: The completion plugs blind flanges/caps of the remaining fittings shall be installed in the following order at Points A and D
consecutively:
1. Linestop fitting
2. By-pass fitting
3. Equalization fitting
POINT A
POINT D
XEL
42. FINAL SITUATION AT SITE
XEL