shell test pressure

[arash807]

Dear members

According to attached drawing,the manufacturer has recommended shell test pressure=78bar.
in the other hand since the material is A494-N12MV then shell test pressure would be
1.5*41.4=62.1 bar
(41.4=working pressure @38c as per ASME B16.34)
So how can it be justified?

regards
Arash

 

[gerhardl]

arash807:

My questions and possible answer is:

What type of drawing is this, and for what purpose? The drawings show a defined valve, and must be based on an existing, already produced valve.

The drawings cite the pressure tests values you mention, but is this a test actually already done at the factory for this valve by the manufacturor? (Then your tests will follow the standards required for the whole net you are concerned with).

Do certificates follow the valve? Required certificates?

Drawing refers also to BS1868 and BS5146 for tests and construction? Does this comply with you construction requirements (for your plant?) or the ASME standards?

 

[arash807]

gerhardl:

since there is no certificate test that is why I am not sure about the exact test pressure that manufacturer has done.
regardless my plant, i want to know, why in this case shell test pressure is more than (1.5MAWP).

regards
Arash

 

[gerhardl]

... and as often else: the only one able to answer is the manufacturor. (Reasons can be several.)
Ggood luck!