Factor for hydrostatic test

[songkarn]

Dear sir,
Refer to B31.3 Code ,Why we take 1.5 x Design pressure not 1.6 for hydrostatic test
Best regards,
SK.

 

[LittleInch]

Why indeed. I would suggest decades of experience has shown it balances too low a pressure which doesn't find faults which could develop over time into cracks and fails and too high which results in too many failures due to too much pressure.

Once something is set and used for a long time there is a large resistance to change....

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[XL83NL]

Doesnt the factor for basis of design stress as outlined in 302.3.2(d)(2), two-thirds of the yield, relate to the factor 1.5?

 

[bimr]

Per B31.3, the allowable stress values at the design temperature for piping materials shall not exceed two-thirds of the corresponding yield strength.

With hydrostatic testing set at 1.5 times, the yield strength will not be exceeded during the hydrostatic test.

 

[songkarn]

Dear sir,

Why pneumatic test used 1.1 and vessel section VIII Div.1 used 1.3 ?

SK.

 

[bimr]

Many people do not know or are not realize that a pneumatic pressure test can be very dangerous with 200 times more energy is stored in compressed gas compared to water at the same pressure and volume.

For that reason, pneumatic pressure tests have lower pressure limits.

http://www.wermac.org/others/ndt_pressure_testing.html