Weld Inspeccion

[gwapa]

Dear Friends
I am using A53Gr B for ammonia suction at -35ºC
I know that the ASME code allow this practice as long the pressure is low and tempereature is low.

However I wish to inspect with x Ray some pipe welds to be sure .

In orther to meke the contract with the X rays company I would like to know what I should as for

I have heard I should inspect 10 % of the total welds. If one of those has a "defect" I should ask to inspect all welds.

what kind of defects?
What the code specific?
What you recomend?
I appreciate your comments
gwapa

[Kevin_N]

Greetings from Germany,

in germany we inspect 10% of the total welds, with a radiographic test on new ammonia refrigeration plants.
But only when no pressure test is possible, or when it is cheaper to test 10% of the welds an do a leak test with nitrogen at maximum operating pressure.

No welding is perfect, we use the :
ISO 5817:2003
Welding - Fusion-welded joints in steel, nickel, titanium and their alloys (beam welding excluded) - Quality levels for imperfections
to evaluate the welds.

Ask the x-ray company which standard they use to evaluate the welds.
If you have done a pressure test before running the system, it's not neccessary to do a radiographic test on the welds.

some examples of defects according to ISO 5817:2003
(in German)
Link:
schulbuchzentrum-online.de/pdf/978-3-14-235025-7-2-l.pdf


kind regards
Kevin