Valve Hydrostatic Test 1

[sheiko]

Dear members,

We have a piping (Nominal Pipe Size = 1400 mm) with a flanged control valve. The service is water.
- Plastic (GRP) piping design pressure is 5 barg.
- Metal (SS) control valve design pressure is 2 barg (as per data sheet).

I have the following questions:

In general,
1/ Could the plastic piping be tested at Ptest = 1.5*Pdesign? in other words, can we apply ASME B.31?
2/ Shall the control valve (body + seat) be tested at the same pressure as the main line?

More specifically,
3/ If item 1/ applicable, shall we consider that the overall line (including) the valve be tested at Ptest = 1.5*2 = 3 barg instead of 1.5*5 = 7.5 barg?

Thanks

"We don't believe things because they are true, things are true because we believe them."

 

[sheiko]

Plastic (GRP) piping design pressure is 2 barg, sorry.

"We don't believe things because they are true, things are true because we believe them."

 

[vpl]

What is the piping design spec? Was it to B31.1 or 3?

Patricia Lougheed

******

Please see FAQ731-376: Eng-Tips.com Forum Policies for tips on how to make the best use of the Eng-Tips Forums.

 

[gerhardl]

This answer is based om European norms, and would not apply directly in your case if there is other norms specified. Some points:

a) Regarding the valve: the valve could have been supplied directly after the data sheet (the projects datasheet?) or it could possibly be produced/supplied to a higher standard.

Facts to be checked!

The supplier will inform you on what pressure the valve will be allowed to be tested to, with the producers product guarantee still upheld.

When asking for information you should describe your test in detail: Wether valve is open, closed, side A or B pressurized and for how long, and how many repeats etc.

Normally (for tests) the pressure allowed with valve open (body test pressure) will be higher than allowed test pressure with closed valve (seat test pressure).

b) Regarding the pipeline: Normally pipeline owners require pipelines pressure tested before formal takeover from contractors.

If the pressure test methodes and testpressures are not cleraly stated (or clearly referred to as a detailed described methode in a given pargraph in a given norm), this will often lead to discussions and requirement for overpressure tests with higher pressures than normally valves will be (allowed) qualified for when already mounted.

Fairly often valves are required to be used as test pressure holding devices for the pipeline (instead of blinds).

In some cases (and for some valves) this could be OK, in other cases this will require valves from the class above.

Anyway, both for pipeline and valves: what are required and what do the material supplier/producer allow?

Normally this will be limited to operation pressure (or in some norms allowed operation overpressure) according to the valves norm (pressure class)for mounted and closed valves.