BPVC Div 1 Bolt Load Mandatory Appendix 2.

[Gavin_UK]

I am trying to design a flange using Div 1, Mandatory Appendix 2 Bolted Flanges.

But because of the gaskets and bolts the flange is getting very thick, which I am trying to avoid

Most of that is driven by using the bolt load, I know using Torque to set Bolt load is quite inaccurate especially if just using a torque wrench, no washers and uncontrolled lubrication. So I presume there are some pretty significant Factors of Safety built in.

Has anyone got any experience of modifying these equations through ASME assessment for using a more controlled method of setting bolt load?

I know bolted connections are incredibly complex if you start looking in too much detail and I don’t want to go too far down that rabbit hole, but it seems to be over engineering the design currently. If anyone can offer and help or any relevant Code Cases I would really appreciate it.

 

[Krausen]

Ah yes, welcome to the world of overdesigned flanges, brought to you by VIII-1, MA 2. One quick tip that may be helpful is to use a gasket with lower "m" & "y" values. In other words, ignore the "m" & "y" values shown in MA 2 for gasket types. This is done often with Kammpro type gaskets (which don't exist in MA 2), using m = 2.75 & y = 3,700 psi. I've seen calcs that will use even lower "m" & "y" values than that for Kammpro type gaskets. Lowering these gasket factors will help lower your required bolt loads on the gasket, and help lower your stresses in the flanges.

 

[Trestala]

Have you kept the radial distance between the bolt circle and the gasket load reaction diameter to a minimum? And probably use more bolts (and smaller size) to keep that further closer to reduce that moment arm.

 

[r6155]

More info: design pressure / temperature, material, diameter, service,.....etc.

 

[XL83NL]

MA2 is for sizing the flange. Getting into actual bolt assembly stress and bolting methods will go via Appendix S into PCC-1. These are two different topics that shouldn’t be mixed up for sizing a flange, or you’ll get some heavy overdesign in there.