NDT % vs. Joint Efficiency - ASME B.31.1

I would also like to know.

... however being in the NDT field myself, I think it is a combination of the following:

the welding repair rate of the company that do the welding work,

the insecurity of the inspector requesting the welds that needs NDT,

the amount of money that can be spent on NDT,

the end users needs.

If you are ever able to fully understand a specification, it will be a joy working to it, but most of us are left in the dark and sometimes uncertain on what to actually do.

Hi friends,

AFAIK, B31.1 requires in paragraph 102.4.3 a "Weld Joint Efficiency Factor" (E) which must account in the calculations. E factors depending on weld type are given in Table 102.4.3.

Paragraph 136.4 send you to Table 136.4 for the extent and type of NDE according to weld type (longitudinal, branch, fillet...) having into account that applies only to "pressure welds or welds to pressure retaining components".

Nor paragraph nor table 136.4 make differences on "E".

Any other weld not included in Table 136.4, must be just visually inspected as per paragraph 136.4

Kind regards

Yes, is O'right. But how to define the Random %. What's the meaning of .85 or .60, or .75. Is there an specific value for each E and the NDT% ????

Thanks for your attention

Hello,

There's no random %. The only applicable Table is that 136.4

The factor "E" .85, .60 etc. is just for design, as for example for determining the minimum wall thickness in straight pipe:

As you can see, for identical conditions, the lesser the "E" value, the greater the thickness you get. But once you've got your thickness, just apply 136.4.

Kind regards

Not having the spec in front of me, the implication at .85 would be either 85% or 15%. If this is to be a coded vessel, than I would contact my local AIs and ask what they would expect to see.

My very general rule of thumb would be to inspect all welds 100% Magnetic Particle 72 hours after welding or while still accessible and ultrasonic critical / high stress welds 2 angles after 72 hours. This is done at the time of manufacture and will not necessarily be done again. If the material is not self stress relieving like T-1, then inspect as soon as possible after welding. Pay close attention to surface discontinuities as these will cause you the most grief.

If you are out in the field doing the inspection for someone else, it is usually their responsibility to determine the amount and location of the sample(s). If this responsibility has been foisted-off on you, then do a visual scan first and concentrate on welds in areas that look the most worn or 'beat'.