Stress Releiving Calculations
Stress Releiving Calculations
(OP)
is there a standard/generic formula/table for calculating stress releif after welding?
thanks in advance
thanks in advance
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Stress Releiving Calculations
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Stress Releiving CalculationsStress Releiving Calculations(OP)
is there a standard/generic formula/table for calculating stress releif after welding?
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RE: Stress Releiving Calculations
RE: Stress Releiving Calculations
thanks
RE: Stress Releiving Calculations
You could also use AWS D1.1 Structural Welding Code post weld heat treatment guidelines, as well.
RE: Stress Releiving Calculations
RE: Stress Releiving Calculations
Further you may refer to ASME/ANSI B 31.3 for the same data for Piping.
Yes there exists a formula which acts as the basis of the Time Temp table. I had it noted down from one of the ASME but don't recollect from where i got it. I think it is in ANSI B 31.3.
Good Luck
RE: Stress Releiving Calculations
RE: Stress Releiving Calculations
Tp = T*(20+ Log t)/1000000
T = T in Centigrade + 273
t= Hours
For change in PWHT Temperature, how much shoul be the change in soaking time?
Equate Tp and solve to get the soaking time t.
Good Luck
RE: Stress Releiving Calculations
Tp is the Tempering property
RE: Stress Releiving Calculations
Please advise me about the reference of the formula. Can we use this formula for all materials?
RE: Stress Releiving Calculations
By using this option (Higher soak at lower temp) (if you have not (Welding Engineer) planned) after commencement of fabrication, you may land up in PQR related troubles (Especially if the Vessel is in Sub zero service)
Not discouraging you, but giving you the pit falls. About 4 months back i remember there were discussion on this subject (Supporting PQR).
By proper planning (By welding engineer) this can be amicably settled.
Good Luck
RE: Stress Releiving Calculations
C-Mn Steels (P. No. 1, Gr.1 or 2), Thickness<2”, Initial residual stress = 40,000psi
Remained Residual Stress After PWHT [Reduction Rate]
0 psi [100%] after 2 hours @ 1400 F
1,200 psi [97%] after 1 hour @ 1400 F
3,000 psi [93%] after 4 hours @ 1300 F
3,500 psi [91%] after 2 hours @ 1300 F
4,700 psi [82%] after 1 hour @ 1300 F
3,000 psi [93%] after 16 hours @ 1200 F
4,000 psi [90%] after 12 hours @ 1200 F
5,000 psi [88%] after 8 hours @ 1200 F
5,800 psi [86%] after 4 hours @ 1200 F
6,200 psi [85%] after 2 hours @ 1200 F
7,200 psi [82%] after 1 hour @ 1200 F
7,000 psi [83%] after 8 hours @ 1100 F
7,700 psi [81%] after 4 hours @ 1100 F
8,000 psi [80%] after 2 hours @ 1100 F
9,000 psi [78%] after 1 hour @ 1100 F
8,000 psi [80%] after 8 hours @ 1000 F
9,900 psi [75%] after 4 hours @ 1000 F
10,800 psi [73%] after 2 hours @ 1000 F
12,000 psi [70%] after 1 hour @ 1000 F
Please use this only for reference by lab test
Thomas Eun
RE: Stress Releiving Calculations
RE: Stress Releiving Calculations
RE: Stress Releiving Calculations
Can you post the Holloma-Jaffe formula please.
RE: Stress Releiving Calculations
I apologize for letting you wait that long. I didn't see your request earlier. The formula is based on L/M. It is Hollomon and Jaffe formula:
(T+273)*(20+log(te))
HJ = -----------------------
1000
te = th + tc + t
T+273
th = ---------------------
2.3*h*(20-log(h))
T+273
tc = ---------------------
2.3*c*(20-log(c))
Where:
HJ - Hollomon/Jaffe parameter
T - holding temperature [°C]
te - effective holding time [h]
th - correction in holding time for heating cycle [h]
tc - correction in holding time for cooling cycle [h]
h - heating rate [°C/h]
c - cooling rate [°C/h]
The formula was derived empirically and it seems to reflect better the effects of heating and cooling on tempering degree of metal than LM parameter. I used this formula to asess the remaining life of pressure vessels after multiple PWHT cycles. It was also used to set the parameters of PWHT simulation cycles.
Regards
JacekM