Be aware that if you use Inc.800 types and the sum of Ti+Al is more than 0,7%, PWHT is nescessary when the operation temperature is between 500 - 750 C.
Reason : prevention stress induced cracking during operation. A crack type that occurs within 2 years of operation. Recommended : PWHT 3 hours...
I agree with metengr. Use a standard duplex fillermetal because, looking to the ferrite-austenite ratio after welding, the duplex fillers are overmatched in nickel content mostly 3 or 4 % more than the basemetal.
Important for the ratio in the HAZ is the nitrogen content in the basematerial...
the most possible reason is hydrogen embrittlement because this type of steel is martensitic with high hardness.
and Chloride SCC can not occur in this type of steels only pitting.
The cathodic hydrogen caused by the corrosion reaction can occur the embrittlement. Cl SCC in 17/7 or 17/4 does not...
metengr
I am concerned about the two types of hydrogen problems that can occur in the syngas-environment.
Normally syngas evironment means resistance against Nelson attack and therefore this material choice.
Creating the nescessary carbides only by half bead or temperbead or whatever is not...
Yes sorry I mean Inc.625
You are right, but than do not allow side bend testing during the qualification tests other wise you can run in a lot of discussions with respect to fitness for purpose.
Choosing 316 SS is asking for problems with such a high level of chlorides.
The best economical choice is using the standard ferritic-austenitic steel type "Duplex" (2205) with a minimum level of nitrogen of 0.15 %.
schrijen
I think that based on the proces conditions the material choice is based on resistance against Nelson Hydrogen Attack . Is this the case than is welding without PWHT not possible because your missing the stable mix carbides in the HAZ. For the resistance against Nelson Attack you need...