Data:
Material: Pipie, E304L
Thickness: around 25mm
Consumables: Er-308L using GTAW(1st. and 2nd Passes)+ E308L using SMAW(Other Passes)
Problem:
The root pass is suspeced to weld by using wrong filler wire(Er-70s-6).
How can we detect the wrong welded root pass?
Or, please let us know by using of which devices we can detect the wrong welded joints?
If the matter in not clear we can describe it schematically by sending a picture to your mail box.
With bes regards,
Arash Mohammad Pour
If it has already cracked, you may find the improperly welded joints by radiography. If you have access to the inside surface, polish and etch with 20-25% nitric acid should show the much less corrosion resistant deposit by the dark staining compared to the 304 pipe. Otherwise, you won't find it until it fails in service. If it were my responsibility, I would have the welds cut out and replaced if there is good reason to believe ER70S-6 was actually used.
If access was possible to the root, would a magnet do any good?
Perhaps. There might be some magnetism present in a 308 root pass due to ferrite content, but it should be more magnetic with a ER70S-6 root. It would help to weld a sample with an ER70S-6 root for comparison and to evaluate different ways of detecting it. A ferrite gage might be one way to do it from the OD if the weld was not so diluted on the cover pass to make it indestinguishable. If the ID is accessible a ferrite gage would probably detect the difference easily.
What are you working on? A vessle, power house, or what?
We are working on piping of Air Seperation Plant
If there is access to the ID and enough room, I would suggest using a Alloy materials analyzer like a Niton unit. We recently had the same sort of problem except the wrong consumable was used on the outside of the tubing. Our Niton worked great and was well worth the money we spent for it. The website: www.niton.com. Usually you can subcontract with an inspection agency or NDE firm.
Do you have access to the root pass? If so use some acid cleaner on the root. If the root turns black and will not shine up, you will see a dark root pass. If the root shines up good, your in good shape. I had a guy weld up a but seam on 304L with E71T-1 FCAW. The weld looked ok but when we started acid washing the tank the weld turned dark and rusted a few hours later after washing the acid off. I'll let you know what acid we used if your interested.
If you can say with confidence that it was all done right or all wrong then digging down to the smallest bit of root proves the case one way or the other and isn't too expensive to repair. If you can't say that and the pipe is too small to crawl then one of the robotic pipe inspection devices might be able to be rigged to do the job. If the pipe is too small for that then perhaps it could be flooded with acid, drained, and a small tv camera pulled through to inspect it.
Just brainstorming, not really my line.
Bill
Hi Arash,
i'm not sure when this was posted nor how many welds you were trying to address.
If your a member of AWS and get those literature magazines, there are metal analyzers noted there that only takes a couple minutes " or less " to give you an analysis of the material in question.
If the root is questionable " 1 weld " I would jsut cut it out to eliminate the doubt.
I would also look into the welding consumable tracking program for outages.
Good Luck
By -
Date 05-18-2005 16:49
If the welder could not tell that he was using a carbon steel electrode to weld stainless steel, he needs some further welding education. The welder is the first line of inspection, anyway, so he should have known something is drastically wrong if he used, or tried to use, a carbon steel filler on the SS.
CM
An eddy current inspection might be possible, but with the c/steel about 7/8 inch away from the testing side ...it might be out of range. You would have to weld up a small section of pipe as a calibration sample ...one sample area with a carbon steel root and one without the carbon steel root pass. Then see if the eddy current unit could resolve the difference.
