% x ray
% x ray
(OP)
We are installing 4 lines for Gasoline, Diesel and LPG, and we are using ASME B31.4 for petroleum products and B31.8 for LPG, using 10% and 15% X ray testings respectivily, but I can´t find what would be the % after a weld is rejected? where can I find it?
Thanks in advance
Thanks in advance





RE: % x ray
RE: % x ray
RE: % x ray
like metengr said, it's up to the owner/user.
RE: % x ray
Do B31.4 and B31.8 not deal with rejects and additional testing requirements ?
Regards,
BB
RE: % x ray
RE: % x ray
If we already started the project, how can I support the desition for the % of increased Xrays? is it writeen somewere?
RE: % x ray
Like i stated before. If we find a defect, we x-ray 2 additional welds. if either of those 2 additional welds have defects, we x-ray 2 MORE welds for each defective weld. if any of those are defective, we x-ray 100%. Here's the criteria of B31.3:
341.3.4 Progressive Sampling for Examination.
When required spot or random examination reveals a
defect, then:
(a) two additional samples of the same kind (if
welded or bonded joints, by the same welder, bonder,
or operator) shall be given the same type of examination
(b) if the items examined as required by (a) above
are acceptable, the defective item shall be repaired or
replaced and reexamined as specified in para. 341.3.3,
and all items represented by these two additional samples
shall be accepted, but
(c) if any of the items examined as required by (a)
above reveals a defect, two further samples of the same
kind shall be examined for each defective item found
by that sampling
(d) if all the items examined as required by (c) above
are acceptable, the defective item(s) shall be repaired or
replaced and reexamined as specified in para. 341.3.3,
and all items represented by the additional sampling
shall be accepted, but
(e) if any of the items examined as required by (c)
above reveals a defect, all items represented by the
progressive sampling shall be either
(1) repaired or replaced and reexamined as
required, or
(2) fully examined and repaired or replaced as necessary,
and reexamined as necessary to meet the requirements
of this Code
(f ) If any of the defective items are repaired or
replaced, reexamined, and a defect is again detected in
the repaired or replaced item, continued progressive
sampling in accordance with (a), (c), and (e) is not
required based on the defects found in the repair. The
defective item(s) shall be repaired or replaced and
reexamined until acceptance as specified in para. 341.3.3.
Spot or random examination (whichever is applicable)
is then performed on the remaining unexamined joints.
RE: % x ray
2nd the B31.8has different requirements for Class 1,2 3 and 4 according to section 826.2(b)(c)(d) and the B31.8 has same requirements as the B31.4 for re-inspection according to API 1104.
the API 1104 does not require tracers unless specified by the owner.
RE: % x ray
As far as I am aware API 1104 is generally 100% RT so there is no need for tracers,
Cheers,
BB
RE: % x ray
RE: % x ray
I found in the original bid it was stated 100%, what happens whe a weld is rejected?
RE: % x ray
You repair it. What else?????????????????
RE: % x ray
Of course, but is there a criteria for keeping a welder in a project, or will he be mistaking and repairing on and on?
RE: % x ray
That is generally dealt with in the site specifications and not in the code / standard,
Regards,
BB
RE: % x ray
No, everything is not written in an easily formatted (easy-to-hide-behind) code book.
But, the goal of the increased surveillence is to find if the root cause (the bad welder, bad process spec, bad weld rod, bad position, bad luck, etc.) is determined and eliminated from (1) all the affected bad welds already present (2) future bad welds that haven't happened yet.
If there was one bad rod (or dirt or rust or a crack or oil or bad weld prep) it isn't likely to repeat.
If there is a bad spec - one that is used in lots of places, the failure is likely in lots of places.
If it is a bad welder using bad habits, he (she) is likely, almost certain, to repeat the bad weld in every similar position: good downhand, fails vertical for example. And even a good welder has failed joints: so you investigate to make sure it is not a common, repeated failure. The above guidelines are reasonable and prudent. But you (the client) can always increase them.
You are an engineer, not a lawyer. In this case (of high temperature, high pressure lines requiring Xray) the bad welds must be detected before they hurt somebody, or hurt the equipment.
RE: % x ray
Thanks, the matter here is with a large project where I am supervising and just starting so the rules have to be set, and shamely not everything was well written in the signed contract, so I have to negotiate for the largest % for security matters, this pipe system goes underground and clos to a lot of houses and industries. If we follow B31.4 and B31.8, due to a hoop stress lower than 20% of the yield strength we would nave 0% x ray in this project, so that´s why I have to do the job lawyers didn´t ...
RE: % x ray
If its B31.4/8, see API 1104, as was mentioned above.
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/
RE: % x ray
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"Pumping accounts for 20% of the world's energy used by electric motors and 25-50% of the total electrical energy usage in certain industrial facilities."-DOE statistic (Note: Make that 99% for pipeline companies) http://virtualpipeline.spaces.live.com/