Flange Checks - Input Required

[sdpipes]

Can anyone explain the fundamentals behind a PD5500 (or equivalent) flange calculation?

I have used an in-house spreadsheet a number of times, and the extent of my input has been to vary allowable stress design factors from PD5500 to API 6A values to get bolt stresses (for API flanges) to pass unity checks.

How does the code check ensure that leakage doesnt occur?

What are the physics behind the stress checks?

Unfortunately the engineer who produced the sheet is no longer with my company.

 

[billsumner]

ASME VIII and PD 5500 use the same basic method to design flanges. However, the former provides the equations whereas BS/PD 5500 gives only the graphs.

It is likely that the engineer that wrote your spreadsheet needed to include moments and axial tension effects.

You need to select a bolt tension during make-up and then check for hydrotest and operational conditions separately.

The basis of design is the Taylor Forge method developed in the 1930s by EO Walters, DB Wesstrom, DB Rossheim, FSG Williams - Trans ASME Vol 59, 1937 - Formulas for stresses in bolted flanged connexions.

It does not take into account temperature gradient effects (cold outer surface and hot inside) which produces additional bending in the flange. For that you need to develop a FE model such as described in API TR 6AF1 and 2.

Best of luck!