We are qualifying a hot tap procedure to section IX. What has been the approach to get around the thickness range limitation of fluid backing and >T in 290?
In this case yes. The client requires a section IX WPS and the conditions will require a temper bead to achieve the acceptable hardness values. The material is 516, 3/4" WT, 0.49 CE (ASME), and water as cooling medium. Temperature is going to be around 5 Deg.C day of the work. My issue is I would like to make a broad WPS and not job sepcific as it seems 290 will force me to do.
Generally it's not the ambient temp that you should be concerned with. It's the water temperature. The surface temperature will be close to that of the water temp inside the pipe which, I suppose, could be 5 C. Too be honest with you, I don't know why your Client insists on QW-290. It is not needed to provide a sound weld free from hydrogen cracking potential. Neither ASME I, VIII, B31.1 or B31.3 require PWHT for T = 3/4" in SA-516 material. Or was the pressure part PWHT for Service? If so qualify the WPS as fully instructed by the Owner.
What is the maximum permitted hardness? Assuming that you are welding a set-on nozzle to the tank shell when the tank is filled with water, the root area including adjacent HAZ will only be subject to the service. It will be tempered by subsequently deposited beads. The surfaces can be preheated and maintained to further lower hardness.
hmmm...the cooling test (250 to 100) I was getting times of 11 seconds to 18 seconds. I didnt think I would be able to preheat that in any sort of reliable fashion. Maybe in the shop but in the field...
I was aiming for 350 HV10 but do recognize that we can be somewhat higher since the rod is 7018 H4 and the CE is .49...
Also you would only worry about the inside hardnesses? You would worry about outside the nozzle and the repad to tank weld?
"Also you would only worry about the inside hardnesses?"
Interesting question; is the tank shell steel hardenable? Of course it isn't. Will you melt the steel on the interior? Nope; that would give a leak. Thus = impossible to harden the interior of the tank.
Why use 7014; 7018 is the standard for a malleable & strong weld deposit? Run a small mock-up coupon, and section the weld. The Vickers hardness traverse needs to include Shell basemetal, shell HAZ, weld root, weld interior, weld cap. Might as well include Hot-tap nozz hardness too. IMHO, any hardness below [BHN = 200] is acceptable, and there are arguments for harder welds being OK.
You will have no problem getting below 350 HV10, In fact you will have no problem getting below 300 HV10 in the HAZ at the OD surface. Tempering of the initial beads by the subsequently deposited beads will further lower hardness in both the weld metal and HAZ - generally below 220 HV10. The deposited weld metal will have hardness < 200 HV10 -typical Carbon contents of E7018 H4 are 0.05%.
We completed the testing over the weekend and our hardness test with full out buttering just sqeeked by 350. Our sample with a simplified temperbead (which was suggested to me, ASME technique) was 400+. With a straight fillet relying on the subsequent passes to temper I would guess it would have been 450 ish. I talked to the client and they pretty much laughed at the suggestion that just because we were completing welds where the welds wouldnt be exposed to the product we could get away without the hardness control/testing.
