Pipe expansion compensation for large seismic displacements

[Ak Mechanical]

I'm working on a project where we will have large displacement due to seismic joints on a pier. 12" pipe, aromatics, distillates, and methanol product, ~100 PSIG. The displacement due to the seismic requirement is more than can be handled with normal u bends and 90 degree piping offsets. Flexible hose piping systems are a possibility but I'm concerned with the surge when offloading begins. Pipe is normally empty and only full during offloading activity. Has anyone here had experience with ball joints or swivel joints for piping expansion in regards to 12" piping? What are some options to look at?

 

[mk3223]

I saw the swivel joint used on the ship unloading arm for the offsets between the ship and the loading berth. I didn't see it used on the piping due to the seismic movements.
Is it supposed the pipe is designed to be rigid in place during earthquake?

 

[KevinNZ]

How many mm is your relative seismic anchor movement? I guess the problem is the pier moving way from the shore.

 

[LittleInch]

Agree we need a bit more here.

what are "seismic joints on a pier"??

You might just be better off putting in a break away coupling and let the pipes detach during said seismic event (pretty rare and the jetty might not survive?)



Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Ak Mechanical]

Thanks for your comments. I'll just try to head down the list and address the questions to provide more info.

This is a marine unloading facility on a ~400' long jetty with a dock at the end. There are seismic joints at the beginning of the jetty where the land ends and the jetty begins, and then near the end of the jetty where the jetty ends and the large dock begins. Each seismic joint has a large design deflection, 18" in any direction. We will have marine loading arms at the dock for the ship, but the piping from the loading arms back to the tank yards has to cross these two seismic joints. In my experience I have used several types of systems for piping expansion. In line mechanical compensation (for steam), piping offsets and u joints (for pipelines) and even flexible metallic systems (like hyspan). I have not used a swivel joint or a ball joint for this type of system, and am just wondering what others have done in this type of situation. A designed failure point is also a consideration, as these pipes are normally empty unless unloading is happening. Maybe I can just schedule the earthquake for when the ship is not at the dock...?
I've been looking hard at flexible metallic piping, but am concerned when the flow begins how it will perform when the surge initially hits these joints. Thanks for your time and comments.

 

[LittleInch]

What you have there is not common. Your only real options are the flexibility route wit a hose type arrangement or a mini loading arm scenario.

However unless your event is quite frequent, I struggle to see why you're bothering. Just stick a couple of actuated valves and shut the thing in.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[racookpe1978]

Use a complete loop (3D expansion loop) not just the usual vertical-horizontal-vertical run.

Or expect to isolate, vent and drain the pier pipe, and just leave the isolation valves shut between loading and unloading. 99.98% of the time, no leaks will occur because no earthquake will occur.

 

[Ak Mechanical]

racookpe1978 what is a complete loop? I am not familiar with a 3D expansion loop. Would you mind providing additional information? Thanks!

 

[lilliput1]

See Arsen seismic omega (loop) connection hoses and discuss your concern with them.

 

[racookpe1978]

A 360 degree horizontal pipe bend as a continuous spiral (like a spring) large enough to allow your movement, entrant and exit pipes parallel to each other, but one lower than the other to allow continuous draining after the barge is loaded. Doesn't need to be limited to one loop, nor to 360 degree circles either: Inlet (or outlet) can be in any direction convenient to the process flow.

Alternative, perhaps a little less expensive: One (or more) set of 4x 90 degree horizontal pipes bends, each bend separated by a short straight section much like the straights between a conventional 3-corner expansion "loop". Again, to allow drainage, the inlet and exit pipes are parallel to each other, but offset in height to allow continuous drainage from inlet to outlet (or vice versa) when emptying the pipeline. If 4x 90 degree bends are used, slope the entire loop (elbows/bends/straights, and inlet/outlet runs.)

If the 360 (4x bends) is not enough, use two 360 bends/loops separated across your expected break point of maximum movement.