% x ray 2

[Cuyanausul]

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

 

[metengr]

This is up to the Owners Engineer to decide on increased inspection of failed welds.

 

[Cuyanausul]

Well thanks, I thought it was a standar. In other projects we had doubled and then 100%

 

[Bonswa]

A common practice that i've found with owners is to x-ray 2 tracer welds by that particular welder. if one of those fails, you shoot two more x-rays. if another one fails, shoot them all and kindly ask the welder to put down the stick.

like metengr said, it's up to the owner/user.

 

[Ballbearing1]

I do not have access to B31.4 or B31.8 but the requirements for rejected welds are clearly spelt out in B31.3 if you are working to that code.
Do B31.4 and B31.8 not deal with rejects and additional testing requirements ?
Regards,
BB

 

[Mr168]

Ballbearing1: Several other ASME codes do not have re-shoot/progressive sampling requirements.

 

[Cuyanausul]

metengr
If we already started the project, how can I support the desition for the % of increased Xrays? is it writeen somewere?

 

[Bonswa]

This is where we get our acceptance criteria. Granted, it's B31.3, but it may be what you need.

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.

 

[BUTCHCWIQAM]

1st. For inspection to the B31.4 code for rejections from X-rays you need to look at API 1104 according to 434.8.5 welding Quality in the B31.4 API 1104 states that all rejected area need to be replaced and re-inspected with same method of 1st inspection and any other inspection is at discretion of owner.
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.

 

[Ballbearing1]

BUTCHCWIQAM,
As far as I am aware API 1104 is generally 100% RT so there is no need for tracers,
Cheers,
BB

 

[BUTCHCWIQAM]

Ballbearing1 I agree but this whole thing is not that stright by using the b31.4 and B31.8 they dictate how much x-ray is required for those codes and refer to the part in API 1104 for rejections and repairs so if you read what the other 2 codes direct us to read it states this is up to the owner it is late tonight I will re-read both codes and verify my statement

 

[Cuyanausul]

Thank you all

I found in the original bid it was stated 100%, what happens whe a weld is rejected?

 

[metengr]

what happens whe a weld is rejected?

You repair it. What else?????????????????

 

[Cuyanausul]

metengr

Of course, but is there a criteria for keeping a welder in a project, or will he be mistaking and repairing on and on?

 

[Ballbearing1]

Cuyanausul,
That is generally dealt with in the site specifications and not in the code / standard,
Regards,
BB

 

[racookpe1978]

You have to be "prudent" and "use your engineering judgement" - particularly in matters of life, injury, and broken equipment from a bad welder.

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.

 

[Cuyanausul]

rakoopke
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 ...

 

[BigInch]

A lot of owners put a limit on the number of repairs before a total cutout and replacement is required.

If its B31.4/8, see API 1104, as was mentioned above.

**********************
"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/

 

[BigInch]

BTW, its not unusual at all to spec 100% x-ray on offshore, or pipelines passing "critical", or "sensitive" areas.

**********************
"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/