High Temperature Flange Bolting
High Temperature Flange Bolting
(OP)
On a ss304H Sect.8, Div.1 pressure vessel with a design temperature of 1380 F, and max. operating temperature of 1310 F there is a class 600 flange subjected to high external nozzle loads. Per my Compress program if the loads were imposed on the flange, the flange would need to be a class 1500 flange for sustained loads and class 2500 for occasional loads. However the client has accepted a ASME, Sect.3, NC3658 analysis showing a class 600# flange is suitable. The Compress program will only allow an SB-575 bolt which conforms to both the temperature limit, and high strength bolting for a class 600# flange. However the client would rather use A453 Gr.660 class C bolting because it has a 85 ksi yield strength, as opposed to the SB-575 bolt which has 35 ksi yield strength. The A453 Gr.660 bolts per Compress and ASME sect.2,Part D are limited to 1000 F. Applying the B31.3, 301.3.2 the oper temp can be reduced by 80% which gives 1048 F,which is still over the ASME limit. Any ideas for an appropriate bolt selection?





RE: High Temperature Flange Bolting
RE: High Temperature Flange Bolting
Look at Refractaloy 26. It might be expensive, but it is used on high pressure steam turbine bolting at 1050 deg F.
RE: High Temperature Flange Bolting
"Creep resistant, nickel-base superalloys can provide acceptable mechanical properties for use as fasteners up to 1600 °F (870 °C), dispersion strengthened nickel and cobalt-base alloys or refractory metals can be used. Care must be taken to protect materials from oxidation and scaling at these temperatures. Closure fasteners for this temperature range are seldeom required in the chemical process industry.(Most bolts of this type are used in jet engines and turbines.)"
I guess the Refractaloy 26 mentioned by metengr falls in this range.
Have a look at these websites. They discuss material issues on turbines in ultra supercritical steam.
http://www
http://www
RE: High Temperature Flange Bolting
RE: High Temperature Flange Bolting
COMPRESS uses the paragraph NC-3658 method when analyzing Section VIII Div 1 App 2 flanges. It can be seen that the formulas are identical to the method used to derate "standard" flanges (discussed at http://www.codeware.com/support/faq/1051.html)
Tom Barsh
Codeware Technical Support