Pneumatic test instead of hydrotest

[S.Mohammed]

Dear all

We.need to.conduct HT at 36bar but due to some water disposable prob,

we need to.switched pneumatic test with nitrogen at 30bar.
Line is CS and 1km.dia is 6".

NDE RT  50%.

Is allowed by code 31.3 this  switch over?

Or we need to take 100%RT for.this switch.over?

[in...@pieper-qsi.nl]

Dear Madam / Sir,

Thank you for your e-mail but unfortunately I’m out of office till September 22. I don’t have access to my e-mail account during this period and therefore can’t answer and /or react on any e-mail.
If necessary I will reply a.s.a.p. after I’m back in my office.

Best Regards,

Herman Pieper

[M.Sathiya Narayanan]

Dear Mohammed 

switch over is allowed safety is the concerns

345.5.1 Precautions. Pneumatic testing involves

the hazard of released energy stored in compressed gas.

Particular care must therefore be taken to minimize the

chance of brittle failure during a pneumatic leak test.

Test temperature is important in this regard and must

be considered when the designer chooses the material

of construction. See para. 345.2.2(c) and Appendix F,

paras. F323.4 and F345.5.1.

345.5.2 Pressure Relief Device. A pressure relief

device shall be provided, having a set pressure not

higher than the test pressure plus the lesser of 345 kPa

(50 psi) or 10% of the test pressure.

345.5.3 Test Fluid. The gas used as test fluid, if not

air, shall be nonflammable and nontoxic.

345.5.4 Test Pressure. The test pressure shall be

not less than 1.1 times the design pressure and shall not

exceed the lesser of

(a) 1.33 times the design pressure

(b) the pressure that would produce a nominal pressure

stress or longitudinal stress in excess of 90% of the

yield strength of any component at the test temperature

Regards

Sathiyanarayanan