How to calculate the setting of a pressure balanced safety joint?

[shannonb2135]

I have a piping configuration where a feeder pipline (4" S/80 API 5L Gr. B) ties into a receiving pipeline subsea (as shown on the attached). The feeder pipeline travels parallel to the receiving pipeline just before it 90's into the receiving pipeline. Just before the feeder pipeline travels parellel to the receivng pipeline, there will be a pressure balanced safety joint installed. What is the "industry accepted method" of calculating the setting of the pressure balanced safety joint? I have used Ceasar II pipe stress software but my numbers do not match some hand calcs that were done. Thanks for your help.

 

[BigInch]

Set it based on the maximum tension load you can have either on the tie-in, or on the pipeline, which should be larger than the tension load indicated by your stress run.

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[shannonb2135]

By applying an axial force of 10,426 lb. to the pipeline in the direction away from the tie-in, the max axial stress created is 2,305 lb/in^2 and the max code stress created is 38,942 lb/in^2. The pipeline has an allowable stress of 46,071 lb/in^2. What should the PBSJ be set at?

 

[BigInch]

You're trying to protect the tie-in and the other pipeline. The maximum tension on the pipeline isn't what I'd be worried about. That is most likely higher than what you can have on the tie-in configuration. What is the maximum tension you can have at the safety joint without overstressing or deforming the tie-in or connecting pipeline.

You'll have to check with the mfgr about the calculations for set pressure.

"I am sure it can be done. I've seen it on the internet." BigInch's favorite client.

"Being GREEN isn't easy." Kermit

http://www.youtube.com/watch?v=hpiIWMWWVco

http://virtualpipeline.spaces.live.com