A106 for Spent Catalyst Lines

[massiveT]

I am told that A106 is typically used in Fluid Catalytic Cracking Units (FCCU) for unloading spent catalyst from the regenerator to a spent catalyst hopper. These lines run at around 1100 degrees F. Most would agree that A106 is not appropriate for these temperatures. I assume that A106 is used for economic reasons based on the fact that the lines are used infrequently and are at low pressures. Does anyone know how you can use A106 for this service and still meet the requirements of ASME B31.3.

 

[metengr]

According to the 2002 Edition of ASME B31.3, Appendix A, Table A-1, A 106 Grade B pipe material has a listed maximum service temperature of 1100 deg F, with an allowable stress value of 1 Ksi. Therefore, other than taking into account all of the cautionary statements, reduction in mechanical properties and known damage mechanisms for this material at 1100 deg F, B31.3 does not prohibit the use of this material.

 

[NickelMet]

massiveT:

Your assumption is correct on the economic reasons of infrequent use and low pressure. The majority of refineries in our corporation have carbon steel in that service.

You may want to consider contacting UOP for their current recommendations on FCCU construction materials. For example, I have information from a second-hand source that suggests that 1¼Cr-½Mo piping is being used in conjunction with fins (on the outside diameter) in order to combat material degredation problems as well as heat dissipation. However, I haven't seen this application in person...yet.

~NiM