Pigging or Flushing a 15 km Non-Uniform Pipeline

[Finchh]

Hello all,

I’m looking for some guidance on cleaning a 15 km non-uniform pipeline that alternates between 4" and 6" Schedule 80 sections, with reducers, bends, and a non-barred tee section (P&ID attached for reference). We’ve calculated a total pressure loss of approximately 30 bar at a flow velocity of 1 m/s, accounting for friction, bends, and head loss. There are no vent points available, so air displacement is a concern for both flushing and pigging operations.

Pipeline Details:​

• Length: 15 km
• Diameters: Alternating 4" and 6" Schedule 80 sections
• Pressure Loss: Around 30 bar at 1 m/s flow velocity
• Tee Section: Non-barred tee included in the line
• Vent Points: None available

Given the diameter transitions and the non-barred tee section, I’m evaluating both pigging and flushing options. If anyone has insights on handling non-uniform lines with tees in terms of pig selection (such as dual-diameter or adaptable pigs) or advice on flushing setups to manage air displacement without vent points, I’d appreciate it. Additionally, any suggestions on pump requirements to consistently achieve the 30 bar head for this configuration would be extremely helpful.

Thanks in advance for your input!

 

[Lnewqban]

Welcome, @Finchh !

If not previously designed with pig traps and launchers, you will need to stop normal operation, drain the pipe, and disconnect shorter sections to be cleaned at a time.

Is the pipeline flanged or welded?
Does it have changes in elevation?
Are those 6 to 4 transition excentric or concentric?

Please, see:
https://www.petersenproducts.com/ar... hydro,cleaning needs and pipeline conditions.

https://www.parstechnic.com/Pig_Launcher_&_Receiver_Traps.html

 

[berkeman]

I have no experience with pigging, but does it work with such small diameter pipes and varying diameters like this? (not to mention such tight turns)