323.2.2(d) Note 3-B31.3

[Kivan]

Hi,

I have a question, i use 323.2.2(d) (2), because my MDT is more lower that -48C. Then by Note 3, if stress ratio is more lower that 0.3 impact test exeption is valid. In 323.2.2(d) (1) (temperature more highter that -48C) hydrostatic test shall be performed, for use impact exeption according to figure 323.2.2A.
My question, When Stress Ratio is more lower that 0.3, and note 3 is used, Hydrostatic Test is requested?

Thanks, sorry for my english.

Regards.

 

[XL83NL]

Per standard Code requirements, a hydrostatic leak test can only be exemepted for cat. D fluid services acc. 345.1(a) and 345.7 (or for e.g. golden welds, but thats a different situation - see 345.9). 345.1 (c) also provides a clause for not exempting a hydro. In all other cases a hydro is mandatory.

 

[Kivan]

Thanks, for your response, but in my piping system, originally pneumatic test will be performed (345.5), because hydro test is dificult due to, piping system is very complex for perform hydro test Based on 341.1(b). Moreover Design pressure is very low. In basic engineering considerations, MDT is more higher that -29C. But now, during building, the process engineer change this temperature and MDT is very low. I perform stress ratios, and this way i justified Impact test exception with ratios more lower that 0.3.

My question is, I need change to hydro test using 323.2.2(d) (2) Note 3 for impact test exception, or i can be used original pneumatic test?

Thanks

Regards

 

[XL83NL]

First, what is MDT? Do you mean MDMT? MDMT is a typical abbreviation used for section VIII work.
Para 341.1(b) does not exist, which para do you mean?

Maybe Im missing the point, but I dont see what Chapter III has to do with leak testing.
You still need a hydrosttaic leak test, which may only be omitted and replaced by a pneumatic leak test if the owner approves it (345.1(c)).
Unless you're the owner, yuo cant simply waive out a hydro.

 

[sneves]

Dear all,

Hydrostatic test is not only to check if there are leaks.

The hydrosstatic test is used to test design (mistakes in calculations), check materials (material defects), to check leaks and to check local plastification. Local plastification is a stress relief for critical points.

Anyway, if you want to use pnematic testing your client needs to approve but according to ASME VIII Div1 pneumatic test is only allowed when:

a) foundation is not designed for weight of the test liquid;
b) Vessel has installed internals that should not get wet (I believe that a good technical reason can be also accepted).

If you still want to go through pneumatic test, according to the code surface examination of all attachment welds is mandatory.

 

[XL83NL]

sneves, you're mixing mixing up Codes.
I think the OP clearly indicated B31.3 is the applicable Code of construction, meaning the requirements to waive a hydro to VIII-1 is not applicable for this case.
The OP has to hydro the piping system, unless the Owner approves to waive it and replace it with a pneumatic leak test.