Saturday, April 10, 2010

[MW:4783] PWHT of Hydrotesting vents in Sour gas service

we have sour gas pipelines with higher & lower pressure. All the
pipelines are with Hydrotest vents which will be closed after
Hydrotest.

For low pressure pipelines we use flanged joint with a Blind flange.
For high pressure pipe line with flanged connection there is
intermittent leakages which needs immediate attention even sometimes a
shut down.

We intend to use a threadolet as vent & will be plugged & seal welded
after hydrotest. The problem is with PWHT. As all the lines in Sour
gas services shall be PWHT.

We want to avoid PWHT of this small fillet joint, Due to the location
of these joints & difficulty in PWHT. but it is dangerous to leave it
without PWHT as it may crack due to residual stresses.

Can you suggest any welding procedure & electrode to have this welding
with reduce hardness HRC 22 Max by which PWHT can be avoided.

Thanks

Suresh

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