Hydrostatic Test 1

[Leo165]

Hello !
I am new to this topic and want to know what is significance of term "[38°C (100°F) pressure rating]" in ASME B 16.34 Hydrostatic test section ( pressure is 1.5 times the 38°C (100°F) pressure rating of the body)??
If your valve design Pressure is 17 bar at 200 C then hydrostatic pressure is simply 25.5 bar (1.5 times) . Is it true ? Design Temperature is not significant ?

ahmad

 

[bimr]

Cold Working Pressure (CWP) Rating. The maximum allowable working pressure of a valve in ambient conditions, usually from –20 to 100°F (–28 to 37°C).

The terms shell test, proof test, and hydrostatic test often are used synonymously. Each refers to a test to check for leaks and verify that there are no structural weaknesses in the valve or system. The component shell test and the system hydrostatic test are done at 1.5 times the CWP or the system design pressure, respectively which raises the stress level to a value close to the minimum yield strength of the material. Therefore, these tests would show significant distortion if any pressure containing parts were overstressed.

Shell Test (Proof Test). A test of valves, defined by B16.34, whose purpose is to check for distortion and external leakage, but not seat leakage. B16.34 requires valves to be tested with water or other suitable fluid at 1.5 times the 100°F valve rating for 15 seconds or longer. The valve is partially open. This test is done by the valve manufacturer when required.

Hydrostatic Test. A pressure test of a finished system, required by piping codes such as ANSI B31.1. It is done at 1.5 times the system design pressure, with water, for at least 10 minutes, and its purpose also is to check for distortion or leakage. System valves are partially open during the test.

 

[Leo165]

If your valve design Pressure is 17 bar at 200 C then hydrostatic pressure is simply 25.5 bar (1.5 times) . Is it true ? System Design Temperature is not significant ?

ahmad

 

[LittleInch]

Ahmed,

No, that's not my interpretation. Your valve dp at 200C is essentially a derating of what the valve design pressure would be at 38C.

Therefore, assuming the test temperature is 38C or less, the test pressure is 1.5 times the pressure at 38C.

I don't have the code in front of me and you don't say what material your valve is but lets say the valve rating pressure at 38C is 30 barg, but at 200C it's 17 barg, then the test pressure would be 45barg assuming the test temperature is 38C or less.



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[bimr]

Ahmad165,

As stated above, the Shell Test is done at 1.5 times the CWP.

The system hydrostatic test is done at 1.5 times the system design pressure,