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Feild Weld rejection %

Feild Weld rejection %

(OP)
can anyone direct me to a industry publication or practice that would tell me what is the norm for acceptable weld rejection percentage for FEILD. I am hearing 5% to 7% but seems a bit high to me.

RE: Feild Weld rejection %

There is no standard of rejection percentage for field joints but 5~7% is too high.
We usually try to manage below 2%.

RE: Feild Weld rejection %

katty11,
It is usually noted in project specifications - it can vary greatly between different companies.
Another issue that can provide numerous headaches is when talking piping repairs.
Is it by joint or by length ?
On my current project there is ongoing arguements regarding this - the contractors total repair rate is 8% by joint and 0.75% by length.
Our project specification states 3% maximum (based on butt joints) but that is not for an individual welder - it is across the board project wise.
It is the contractors responsibility to set an individual welder percentage requirement that will enable him to stay under the 3% project wide.
Unfortunately for us that has not happened,
Cheers,
DD

RE: Feild Weld rejection %

The Welding Institute published a study that pegged the average repair rate between 2-3%.

My theory holds the repair rate is inversely porportional to the parallel at which welding is taking place. Just kidding...sorta...


http://www.twi-global.com/news-events/case-studies...

RE: Feild Weld rejection %

The OP is too open ended. Weld repairs for tubing, pipe, plate, boiler components, pressure vessels, or structural?

RE: Feild Weld rejection %

ISO 9001:2008, subclause 8.4; if the work is oil & gas related, try ISO TS 29001 it's a little more prescriptive. Ask to see the contractor's required data evaluation and hold them to that as a maximum value with a view to improving upon it. If you don't like the numbers, don't hire them.

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/pub/8/83b/b04

All answers are personal opinions only and are in no way connected with any employer.

RE: Feild Weld rejection %

My friend Arthur used to be a nuclear pipe welder.
That job ended with his third bad radiograph, ever.

Mike Halloran
Pembroke Pines, FL, USA

RE: Feild Weld rejection %

Wow, Oil & Gas a welder MAY be fired if he has 3 repairs IN A SHIFT!

RE: Feild Weld rejection %

Most customers I have worked with gauges rejects per welder and per task or contract. For structural work the rate is normally calculated based on linear inches of weld performed versus linear inches rejectable weld or per joint. For piping the basis is total number of joints welded to number rejected. I have not yet seen an allowable reject rate above 2.5% per welder or 3% per contract.

RE: Feild Weld rejection %

I agree with DekDee,
This criteria is usually provided with the project specs, or the client will mandate the contractor to develop it, subject to his review and approval.

There are 2 Welding Repair Rates that need to be calculated and monitored: Welder repair rate and Project Welding repair rate.
Both of them have two basis of evaluation: Linear basis and Joint basis. Joint Basis is used to evaluate both the whole project and the individual welder's performance, while the Liner Basis is mainly for monitoring individual welder's performance.
Following is the criteria we're mandating the contractor to follow on our current projects:
- Welder's Repair Rate: 0.4% Linear AND 7.5% Joint Basis (MAX.)
- Project's Welding Repair Rate: 5% Joint Basis(MAX.)
You'll see that the total project's Maximum allowed Repair Rate is more than that for the welders (5% compared to 7.5% Joint Basis). This forces the contractor to keep some welders with repair rates of less than 5% JB to balance the totals repair rates. These welders are required to be utilized whenever there are critical joints (Tie-Ins, Golden Joints, Hot Tap....etc.)

If you are setting the criteria, you can even include one more figure that's more than what's mentioned above (e.g. 7% JB for the project and 0.7 LB & 10% JB for the individual welders) to serve as the upper control limit. Above these figures, An immediate action has to be taken (More NDT for the project, or Revoking for welders). Between these figures and the previous ones, an investigation with a corrective action is required (training, directs supervision, higher inspection points...etc.)

Mohammed Diab.
Inspection Supervisor - Saudi Aramco.

RE: Feild Weld rejection %

In my opinion, it depends on what is your percentage of fiel weld inspection, I suppose you are talking obout RX control.So per each weld rejection you double your percentage of RX, if the rejection of welds increases you can achieve to a point of 100% RX.

RE: Feild Weld rejection %

I was taught 6% for ASME x-ray'd pipe buttwelds. When a rate of 6% is reached, the process is "out of control" and it is time to reevaluate the welding talent, the welding foremen/superintendent, and the filler rod. Usually, you will find out that the problem is (lack of)talent or cheap filler rod; occasionally 'overcalls' from the X-ray crew for "sidewall lack-of-fusion". If it appears to be 'overcalls' of acceptable welds*, bring in a UT shearwave technician to validate the L-o-F RT calls.

*If you have a dedicated repair welder(s), and when a weld is air-arced out - CAC, and nothing is seen on several repairs, you are having 'overcalls' from your X-ray crew.

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