New Valves at a 67 year old 20” Pump Station

Client requested

What are the options to isolate a pipeline to replace aged and leaking valves?

Understanding the best solution

1. Purge – Displace the produce from the next US valve to the next DS valve.
2. Full bore line stop – Utilize external hardware to tap a full diameter hole and use an articulating plug.
3. Drain up – Allow product to gravity feed until pipe is empty.
4. The IsoTool – Remotely operated pig that holds back fluid and pressure.
   

All choices have their correct application, often where the others fall short.  Multiple repairs in a single section of pipe favors a purge.  If elevations align a drain up can be quick and efficient.  A line stop is the only option if you have a large restriction or a stuck pig.

Planning and delivery

For this project the client weighed the benefits and advantages of each option: a drainup was unfeasible, a purge would have involved displacing 32 miles (62,000 bbls) and an extensive outage, and a line stop left unwanted fittings on the line. 

The IsoTool was selected as the most resourceful and cost effective method.

Two IsoTools were launched 2000’ apart.  The reason for this sizeable separation was that the isolation zone was at a localized high point, and it provided a buffer for parking, and insurance for pig separation issues. 

The IsoTools were successfully parked on either side of the station and achieved set in less than 1 hour.  After the Isolation Assurance Test the above ground piping was drained, and the two mainline valves were replaced.  

Service completion report

Once everthing was torqued up, the removed product was returned to the pipe, and the internal by-passes in the IsoTools were opened to equalize pressure across the tools before they were unset. 

Both tools were tracked by Integral trackers to trap and removed.