<b>Die Penetrant Test </b> 3

[gayaz]

This is the first time i did die penetrant test and found 4 pin holes in a distance of 6 inches on circumferential joint of 62 inch ID. my question is what is the basis of being weld acceptable or rejectable? plus can any one suggest a good website and/or book which gives me practical knowledge on how to check the welds, weld preparation etc. and what to do after u find some thing like pinhole or improper fusion etc. I may be asking basic book of quality control. help is appreciated.
thank you

 

[pipewelder1999]

The code used for construction/fabrication will usually list acceptance criteria for liquid penetrant testing.

ANSI B31.1, ANSI B31.3, ASME Sec VIII, and ASME Sec I all have acceptance criteria for non-destructive testing methods. The acceptance criteria is not all the same just becaues the product is "pipe".

The american welding society publishes a "Welding Handbook" Volume 1 which is very informative regarding NDE Metods, Welding and Inspection Processes etc..

Also Try Lincoln Electric

 

[moseley]

Gayaz,
As pipewelder said above all codes have some sort of acceptance criteria. But all reference back to Sec V. This gives you standards of accept/ reject based on the "bleed-out" of indications. This bleed out has a relevant and non-relevant standard. Again as you may know this type of test is only good for discontinuities open to the surface. Hope this helps.

 

[Pras]

Gayaz,

First of all you need to choose the applicable standard that is to be followed based on your application requirement. As mentioned by Pipewelder and Moseley various international standards are available wherein the aceptance criterion for DPT is given.
It is very important to note the type of indications formed viz. linear / rounded during examinations as this could decide if the indication seen is acceptable or not. The linear indications ( Length > 3*width) represent the presence of discontinuities like crack, which are dangerous and hence are (normally) acceptable upto max. major dimension of 1.6mm The rounded indications could represent discontinuities like blow holes which are less dangerous as they are not likely to propagte during service. Therefore theire maximum allowable dimensions are relaxed.
Hope this helps.

Pras