9Cr heat treatment for heater tubes 1

[kevlar49]

Is there a preference for the heat treatment applied to 9Cr heater tubes in an FCC (Fluid Catalytic Cracking) furnace? ASTM A234 states that tubes shall receive one of three heat treatments: full anneal, isothermal anneal, or normalized and tempered.

Operating condition will be >1000 F. Sulfur may double to 2wt%, TAN is usually <1.0.

I am requesting stress relieving at 1300-1400 F for all welds and weld repairs and hardness.

 

[kevlar49]

metengr,

You have been very helpful. I'd like to learn more about the affects of heat treatments on creep strength of other alloys. For my edification, what is a good source for looking up the 9Cr creep strength data. I've tried finding it in ASM handbooks but haven't had much luck. Would some alloy manufacturers have this data? If so, which would you recommend speaking with?

Thanks again.

 

[metengr]

kevlar49;
Unfortunately, the best source of information that I have are documents from EPRI. Our company has a program membership and access to this and other types of information makes is very convenient.

If you want to focus on Grade 9 or 91 material, I would suggest contacting Vallourec Mannesmann. I have several of their technical publications regarding Grade 91 material, it is called "The T91 Book". I would contact them for information;

http://www.vmtubes.com/jsp/epctrl.jsp?pri=vmtubes&lng=1

 

[kevlar49]

Generally do the tubes/pipe receive annealing heat treatment before or after weld repair? If before, I'd need to specify PWHT. If after, I probably wouldn't need to.

 

[metengr]

Normally before welding because the mill furnishes the individual tubes in this condition. Any fabrication welding, or bending to the tube would ocurr after the solution anneal treatment, and PWHT would be performed.