Hello Blaster;
I've tried experiments as you have. The difference being that I tested my samples in a guided bend tester using a plunger and die with a 1 1/2 inch diameter plunger.
In my case, I attempted to bend welded samples prepared in accordance with D1.1 and bent them while they were still hot from grinding the backing bars off. I found that the samples that were bent while still too hot to hold in my hand (without gloves) usually failed. The samples that were allowed to cool to the point where I could handle them comfortably bent without cracking. The results appeared to contradict some literature that states the ductility increases with increasing temperature and strength and hardness decrease with temperature. However, the general statement doesn't consider the blue brittle range where some steels experience increased embrittlement at elevated temperatures that are still below the lower temperature of transformation.
I have even welded test coupons in the vertical position using rather large single pass groove welds with E7018. I tossed the red hot coupons into the snow and into water. In both cases the guided bend tests for both face and root passed the bend tests. The steel coupons were 3/8 inch thick ASTM A36.
Like you, I was curious to see what would happen. Once I was satisfied with the results I used to drive the pipefitter crazy when I would weld my coupons and toss them into the cold water to cool them just before cutting them for bend testing. “It’s going to crack when you bend them!”
To their surprise they never did crack. They would just shake their heads and say, “You’re just lucky this time.” I won my fair share of free coffee from the fitters. That being said, playing games in the welding booth is not the same as welding on the job. There is too much at stake to play games on the job site. The approved WPS is the working document that I used to work with. Right or wrong, I did what it said. If I disagreed with it, I made my concerns known, but until the WPS was changed, I followed it to the letter.
It is all in knowing what you are working with. Low carbon steel will not harden too much when heated and quenched. Mild steel will harden to a limited extent and high carbon steel will harden easily when quenched from the austenitic temperatures.
That is why it is so important to understand the fundamentals of metallurgy for the material you are welding. In this case, the line pipe can range from low carbon steel to high strength low alloy steel. The differences can be significant and their response to heat treatment can vary coinsiderably. Regardless of the steel alloy, the greatest response is when the steel is quenched from austenitic temperatures, i.e., above red heat. In this case, I doubt the welds and the adjacent heat affected zones are still austenitized when the contractor pours water on them. Still, until proven otherwise, a little caution is always prudent.
I agree with Henry's council. It is the inspector's responsibility to notify the client of his concerns and it is the Owner's responsibility to initiate appropriate action if he has any concerns. The written report can be an appropriate vehicle for the inspector to use to inform the different parties of those concerns. It is rare that the inspector has the authority to pull the plug on a project. That being said, it sounds as if the inspector has been retained by the contractor. Who does the inspector complain to if that is the case?
Since it appears that the field foreman and the welder have taken it upon themselves to hasten the cooling rate, the inspection report may still be the best vehicle to make known the inspector’s concerns. Upper management may be totally in the dark with regards to the field crew’s practices.
The bottom line is that the inspector could lose his job if he does not tread lightly. A few well phrased questions to the appropriate people might be in order. Perhaps the inspector could ask the contractor’s upper management for clarification on how the welds should be "artificially cooled" before being radiographed. A simple question might tweak their interest as to why an inspector would ask such a question. I can imagine the expression on a manager's face when he reads the report and ask, "What the heck does artificially cooled mean?"
If the contractor hired the inspector to radiograph the completed welds, it isn't the inspector's responsibility to question the contractor's procedures. It is the inspector's responsibility to determine if the welds are sound at the time they were radiographed. It can be a sticky situation for the inspector to say the very least.
With regards to who trained the welder or the foreman; who says they received any training other than on-the-job experience? It is common practice to make the individual with the least knowledge and skill the foreman. After all, there's little else he can do that is usefull, so make him the foreman!
Best regards – Al
By the way, Happy Father's Day!