Squeezing Valves While Testing... 1

[Foreignkidd]

I have been told that you can no longer squeeze valves hydraulically when testing them. For instance a valve is placed in a test stand with no flanges. The flanges exist on the test stand and are O-ringed faces that make a seal for testing.

I am working on a new test stand for larger valves and a few people here seem to think we are no longer allowed to squeeze the valves hydraulically between the two plates to initiate a seal with the valve flange and the o-rings.

Any idea if or where this code adjustment may exist?

Thanks in Advance

Foreignkidd

 

[Foreignkidd]

Update: API 598 States that the equipment used by the valve manufacturer to perform the required pressure tests shall not apply external forces that affect seat leakage.

So we CAN squeeze it as long as we can prove it does not effect the seat/ball connection in any way?

This seems open to some interpretation.

 

[gerhardl]

A possible argumentation : (should be valid for any type valve test where the valve is mounted between flanges, or as end of line, either in testrig or in practical use.)

The valve is a mechanical construction and in itself made under certain rules and regulations regarding strength, dimensions, material strength and limitations regarding forces allowed for/on the construction in practical use.

The purpose of rig mounting for testing is to keep the valve in position and secure under the testing, and keep it free of leakage through the flange sealings on the rig.

As long as the forces on the valve flanges are below normal allowed rates (for mechanical pressure,stretch,temperature and bending for the flanges and valve) and excessive forces from the mounting in the rig are not transferred to any part of the valve construction, body and seat pressure tests are obviously done with the valve under 'normal limitations'.

For tests of valves with screwed or welded ends you could similarily compare with allowed mechanical values both for valves and pipeline.