Golden Welds in HDPE pipelines as per CSA Z662-15.

[bdp6632]

Hello, I am working on a 30" HDPE pipeline which has been built in various sections by various contractors at various times. Every contractor is being asked to individually test his scope following CSA Z662-15 (@1.25 DP and for around 6 hours, including stability time and hold time). The last contractor is expected to go in and construct his section and then perform one test for the entire for the entire length. CSA allows you to perform only leak test @ Max Op Pressure in such cases where the sections have previously been individually tested if we can expose the tie in joints. In our case, we don't want to expose the joints. Hence we want to declare the tie in joints as golden welds (as those are called in Carbon Steel case). Is there such section in CSA Z662 for HDPE pipelines which allows you to use golden welds and if yes, what would be the testing criteria for these kind of joints. I know CS pipes need to go through additional NDE if those are to be declared as golden welds but for HDPE, there is no NDE applicable. Can anyone share the experience?

Second question in the same context is how to test the underground flange which connects ASME B31.3 design and CSA Z662 for HDPE. Can that be declared as golden fusion weld?

 

[Dhurjati Sen]

When you are carrying out the hydro-test entirely then why not carry out visual examination of the joints, too? You'd be using this pipeline for at least 15 years and why do you want to commission it with some flaws (if any)?

If the client really accepts this golden scheme, then the hydro-test could be okayed by observing the pressure gauge only (ensuring zero pressure drop), though it won't be full proof.

A flange joint is a flange joint, why treat it like a weld? You can always tighten the bolts during commissioning.

DHURJATI SEN
Kolkata, India