in-process NDE requirements question
in-process NDE requirements question
(OP)
does any Code prescribe or require in-process NDE (mt, pt,ut,etc)? i have searched various Codes and cannot find any requirements. everything i see is for final inspection.
TIA
TIA





RE: in-process NDE requirements question
Codes and standards specify the minimum level of NDT required. It may not be the optimum level of NDT; it is simply the minimum level of NDT required. It is good business for a manufacturer to institute a NDT system that utilizes resources wisely to maximize the profits earned on any single item produced. It the cost of materials and labor to manufacture a widget is low, the cost of expensive volumetric NDT is not cost effective. However, as the cost in time, materials, and labor increases, it becomes more cost effective to introduce various levels of NDT during production. Back to the basic concept of why invest time, money, and labor into a part that is not acceptable?
I had a project several years ago where I was called in by a client to perform a final inspection of a component that cost many thousands of dollars. I was called in because the client's engineer saw something that "didn't look right." The problem was the manufacturer failed to have complete fusion in the root bead of a groove weld. The incomplete fusion was only discovered when the completed weldment was heat treated and machined to very cloes tolerances. The bottom line was that there was no way to repair the deficient weld and still hold the tolerances required by the design. The unit was scrapped and a new one constructed. Again the same problem was identified after all construction, PWHT, and machining was completed. I suggested to the manufacturer that some in-process NDT, i.e., MT, be performed on the component that was causing the problem. I asked the manufacture how much time, material, and labor were invested in the component while it was on the bench being welded.
The manufacturer stated that it was worth about $50. I pointed out that at that stage, if a problem was identified, it could be easily repaired for minimal cost. His reply was that it was not required by the contract and he refused to do it.
Another unit was manufactured and it was rejected for the same reason as the first two units. Incomplete fusion in the root bead. I suggested that the welders be trained to use MT to inspect the root when they back gouged the groove. It inspection was not a required inspection, no report was required, the welder did not need to be certified to perform the in-process inspection.
Again the manufacture refused and another unit was manufactured and rejected at the final (required) inspection. Once again I made my suggestion and stated that the manufacture had produced several units at a cost of many thousands of dollars and not one was acceptable and in each case the cause of the problem was the same component. Finally he was in agreement that something had to be done before the company went broke. It was only after scrapping several completed units and the recognition that the manufacturer had lost nearly a million dollars were they receptive to in-process NDT. Sometimes there is no cure for "stupid".
Once in-process NDT was instituted at a cost of less than $25 per unit, there were no more rejects during the final inspection.
Best regards - Al
RE: in-process NDE requirements question
RE: in-process NDE requirements question
One answer to the question; B31.3 requires in-process (visual) examination, of which the results shall be documented. See 344.7.
RE: in-process NDE requirements question
With respect your post is a bit misleading.
In-process inspection is not required by B31.3 - it is an alternative to NDT that may be used when authorised by the Inspector or specified in the engineering design,
Regards,
Kiwi
RE: in-process NDE requirements question
RE: in-process NDE requirements question
If you are going to weld a pipe or other equipment, that is going to be submitted to PWHT it will be useful to perform some kind of ndt before the post weld heat treatment, to save time and money.
regards
LM
RE: in-process NDE requirements question
may original question remains.
gtaw, your post is why i asked this question. i cannot seem to get it thru to some that a little in-process NDE is cheap compared to rejects or failures or safety
RE: in-process NDE requirements question
gtaw gave you the reasons for "informational" NDE; primarily cost savings. You should be able to convince your management to add NDE by evaluating current repair costs/scrapped parts with the cost of NDE to mitigate it. We often perform low cost informational NDE to mitigate repair.
I once asked a vessel supplier to PT a small portion, twice daily, of the production weld overlay to verify that the welding process was producing a quality product. PT of the completed overlay was required. The supplier refused my request, stating that the requirement was not in the P.O. He was correct of course but his repair costs were in excess of $500,000, not including LDs.
RE: in-process NDE requirements question
I'm not sure if you're just asking for interest sake, but, it's important to bear in mind that requirements found in various codes are minimum requirements and not necessarily enough to keep you out of trouble.
RE: in-process NDE requirements question
weldtek - agree on the Minimum requirements. seems butt welds are covered more than any other type of welds for NDE & i do not seem to have the same uphill battle with Sec VIII fabricators/buyers