Acceptable field hardness testing of weld
Acceptable field hardness testing of weld
(OP)
Hi all,
I have conducted hardness testing on etched samples as stated in the NACE MR0175 traverse for shop testing to test the Metal, HAZ, and weld. Is there a way to test in the field on production weld to verify that the weld is not too hard or to excuse certain construction from Post weld heat treatment.
1. how is the test done is it is possible
2. can it be used to test HAZ also, I assume the weld (cap) and base metal will not be a problem
3. If this test (if possible) is done, how dependent is the hardness number derived this way...
4. how easy/difficult is it to conduct
Thanks for your help.
I have conducted hardness testing on etched samples as stated in the NACE MR0175 traverse for shop testing to test the Metal, HAZ, and weld. Is there a way to test in the field on production weld to verify that the weld is not too hard or to excuse certain construction from Post weld heat treatment.
1. how is the test done is it is possible
2. can it be used to test HAZ also, I assume the weld (cap) and base metal will not be a problem
3. If this test (if possible) is done, how dependent is the hardness number derived this way...
4. how easy/difficult is it to conduct
Thanks for your help.
As much as possible, do it right the first time...





RE: Acceptable field hardness testing of weld
RE: Acceptable field hardness testing of weld
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Without knowing your capabilities and equipment, the real fun begins;
1. You can test the weld cap and surrounding base material, away from the weld region. The HAZ will be a problem because of location in relation to surrounding base material.
2. You should have personnel qualified to use a portable hardness tester with a hardness testing procedure to assure consistency in the field.
3. Surface preparation will be critical for portable hardness testing. Your procedure should detail field metallographic grinding/polishing methods and a suitable chemical etchant to delineate the weld heat affected zone in the base material.
3. I would hire this service out in lieu of trying to so this in-house unless you have lots of production welds and it is worth a dedicated team of technicians to qualify and perform polishing, etching and hardness testing.
Here is some background information that may help you;
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RE: Acceptable field hardness testing of weld
RE: Acceptable field hardness testing of weld
On the other hand, if a FLAT area is ground or filed on the weld, the previously mentioned telebrineller or pin-brinnell device will give very accurate measurements. These are the only devices that have proven themselves to me to actually work on in-situ pipe welds. Yes it is OLD technology, but it actually works.
RE: Acceptable field hardness testing of weld
RE: Acceptable field hardness testing of weld
RE: Acceptable field hardness testing of weld
Yes, if we will do it, it'll have to be done by a third party. I'm asking because we are planning to say, "test for hardness and if the material is soft enough, then forgo PWHT, but if it's hard, just PWHT"
from what I'm hearing, does it sound like the testing might be just as much work as the PWHT? to where we might just go ahear and PWHT and not worry about hardness testing...
THIS IS FOR SOUR AREAS ONLY
thanks again.
As much as possible, do it right the first time...
RE: Acceptable field hardness testing of weld
RE: Acceptable field hardness testing of weld
As much as possible, do it right the first time...
RE: Acceptable field hardness testing of weld
RE: Acceptable field hardness testing of weld
Can you provide any references that discuss the Unocal failure?
I regularly encounter cases of poorly trained NDE techs playing Russian Roulette with refinery vessels and exotic boiler alloys. The deficiencies typically include any number of the following:
- No metallurgical training,
- Inappropriate test method,
- No task-specific procedure,
- No knowledge of applicable ASTM testing standard,
- No/wrong calibration,
- No surface preparation,
- Permitting heat treaters to check their own work,
- Repeating tests until happy results are found,
- and a few more that don't come immediately to mind
The most recent horror show was two techs getting double overtime to test the HAZ of fillet welds(!!) One was a level 2 visual inspector. I earned less performing a related failure analysis than they got to generate a sheet with random numbers which naturally were lower than realistically possible ... and presumably a PE oversaw the task from his desk.
Even with the appropriate equipment, I believe that more than 4/5 of field hardness testing is done wrong.
RE: Acceptable field hardness testing of weld
The involved vessel was altered by adding at least one shell course. The R-Stamp holder made the welds with the SAW process, first (primarily) on the OD side and subsequently on the process side. A monel liner was attached as well by fillet welding to the carbon steel shell using the GMAW process. The liner weld terminated adjacent to the shell course, circumferential weld addition which failed in the HAZ. Hardness in the HAZ was > 260 BHN (determined during the failure analysis).
I believe that this failure was the first failure attributed to SOHIC but don't quote me on that. My involvement was during the discovery phase at the initial law suits. The failure prompted examination of numerous vessels in similar service at other refineries; a number of refiner's found similarly cracked welds some nearly 1/2 wall.
RE: Acceptable field hardness testing of weld
Ever arm-wrestle with a shop foreman who thought your suggested sequence was irrelevant? Just one of a long list of reasons I no longer inhale fumes on a daily basis (and the callous on my forehead has nearly faded away).
I shall see what I can discover in the vast googleverse.