Design Code break B31.3 and B31.8 1

[svi]

Ref:

http://www.eng-tips.com/viewthread.cfm?qid=193285

Pipeline sections at stations have line taps for pressure instrument and Pig signaller. These have flanged 2" branch connections. The code break between the pipeline and the piping occurs at the first flange after the branch. If the branch pipes are to be procured in accordance to the line pipe specification, this will entail supplementary manufacturing and testing QA, which is additional to the requirements stated in the ISO 3183 Gr L450 QCS Line pipe spec. Whereas the piping component specifications are to industry standard ASTM A106 Gr B and NACE MR0175 requirements. The small size and small quantity of components will be difficult to obtain through the pipeline spec. I am inclined to procure the components to the Piping specification

What problems will I encounter if the code break is moved to the branch weld. Don't think the hydrotest is a constraint. The test pressure will be limited by the flange rating.

 

[BigInch]

To avoid any possible welding problems you should put in a short segment of L360 between the A106 and L450.


**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

http://virtualpipeline.spaces.live.com/

 

[svi]

I am told that Construction has qualified WPS available for welding an A105 branch fitting on to API 5L X65 pipe. However for the ISO pipe, it will need a new qualification, from a procedural stand point, since the ISO pipe may come under an unlisted material.

 

[BigInch]

Shouldn't be any other problems I know of.

For a gas line, its usual to design everything on the pipeline to B31.8, including pig signals and other instrument connections. You might want to double check that your designers actually intended the sig to be B31.3

I wouldn't normally change to B31.3 until actually reaching an isolation flange or some other designated point located between the station piping and pipeline piping, launchers and receivers usually being part of the pipeline scope of work.

**********************
"The problem isn't working out the equation,
its finding the answer to the real question." BigInch

http://virtualpipeline.spaces.live.com/