ASME Section VIII Div 1 UG 44 & ANSI B 16.47 for A 105 Material 1

[bmoorthy]

As per ANSI B 16.47 clause 2.6 "Ratings for CS bored welding neck flanges are based upon their hub at the welding end having thickness at least equal to that calculatedfor pipe having 40.0 KSI specified minimum yield strength."

As per ASME SEC VIII Div 1 (UG 44) if the flanges are standard design then calculation is not required so long as the allowable stress suits the tables given in the standard.

Carbon Steel Forgings A 105 does not have yield as 40.0 KSI.

Is it necessary to design flanges as per appendix 2 of ASME even for Standard (B16.47) flanges under this circumstance.

 

[Scipio]

Nope, what that refers to is the pressure-temperature rating tables (in the case of A-105 that's Table 2-1.1) are based on the thickness of the hub at the weld end being the minimum required for 40 ksi pipe. The bore on your flange is bored to match your pipe bore. Wall thickness of your piping is based on the actual pipe's spec SMYS, which would usually be less than 40 ksi (A-106B and A-333 Grade 6, for instance, are 35 ksi). That means, the wall thickness required on your flange to match your pipe is going to have to be thicker than the thickness used to arrive at the standard pressure-temperature tables. A-105N has a SMYS of 36 ksi, meaning with equal wall thickness, it can handle a higher pressure than 106B or 333 Gr 6 pipe.