Blind flange Calculations??
Blind flange Calculations??
(OP)
hello, i am trying to calculate some blind flange thicknesses but when i compare my values to those being used in B16.48, some thicknesses are off whereas others match up. I am currently using a yield strength of 38,000, gasket diameters from B16.20 & B16.21 and the equation:
t= d_g*(3P/16SEW)^.5 + c. Do you know what values are being used for the quality factor E? Also, should i only be using 90% of my yield strength? I am also using 0.05" for my corrosion allowance. Thanks in advance.
t= d_g*(3P/16SEW)^.5 + c. Do you know what values are being used for the quality factor E? Also, should i only be using 90% of my yield strength? I am also using 0.05" for my corrosion allowance. Thanks in advance.





RE: Blind flange Calculations??
The formula you mention is correct as per B31.3, clause 304.5.3, formula (15).
The S value is selected from Table A-1 of B31.3 (not 90% of yield) and the E is selected from Table A-1A or A-1B (page 190, 191 of B31.3). Use the corrosion allowance as directed by your customer or use a value confirmed by a competent engineer, in accordance with the process requirements. In corrosive environment, the corrosion allowance would be most likely 1/8", not 0.05".
cheers,
gr2vessels
RE: Blind flange Calculations??
Remember that for a blind flange you must also check out the thickness required for the edge bending moment caused by the bolt loading not just use the equation you quote.
RE: Blind flange Calculations??
RE: Blind flange Calculations??
Why not just use the standard thickness from the flange code?
When I calculate the the thickness of flanges using pressure vessel code rules I always get thicker flnages than the flange codes but using less bolts/studs can get the thinkness down.