Joining materials for high temp service
Joining materials for high temp service
(OP)
Hello
I have a high temperature service item a .375OD, .035 wall tube. The service will be 500 - 750 deg C at 1000 psi internal pressure. The service will also be of a corrosive nature. I am considering 316 SST, Inconel 625 or Hasteloy X for the tube materials. I am considering welding or brazing the tubes together possibly with nickel. I am having trouble locating any high strength data on brazing materials such as the nickel. Oh, by the way I will have Hydrogen flowing through the tube, don't know if this is a problem with embrittlement?
Can anyone suggest a source for the material data or possibly another fastening material?
Thank you for any assistance
I have a high temperature service item a .375OD, .035 wall tube. The service will be 500 - 750 deg C at 1000 psi internal pressure. The service will also be of a corrosive nature. I am considering 316 SST, Inconel 625 or Hasteloy X for the tube materials. I am considering welding or brazing the tubes together possibly with nickel. I am having trouble locating any high strength data on brazing materials such as the nickel. Oh, by the way I will have Hydrogen flowing through the tube, don't know if this is a problem with embrittlement?
Can anyone suggest a source for the material data or possibly another fastening material?
Thank you for any assistance





RE: Joining materials for high temp service
Using the highest temperature of 750 deg C as your design basis, there will be limited tube materials. For proper selection taking into account reduced mechanical properties, creep deformation and creep rupture strength, I would recommend you review ASME Section II, Part D.
Last item, brazing is not recommended for these service conditions. I would weld.
RE: Joining materials for high temp service
AMS 4779 (BNi-4) is recommended as good heat resistant alloy for brazing of highly stressed parts.
I do not know the brazed strength of this particular alloy but should be in the range of 14ksi-32ksi single shear.
RE: Joining materials for high temp service
At 1000 psi internal pressure at 1300 deg F, you should be looking at butt welded, full penetration, strength welded joints. I would agree with you if this was an external attachment to a tube or for hot gas flowing internally at less than 15 psig pressure.