This is the quote I got it from, from “some guy”, “shelburn” at theoildrum.com who seems knowledgable:
A 20″ ANSI B16.5 600 class flange uses 1.625″ bolts torqued to 2,044 ft-lb and is rated for about 740 psi working pressure under normal conditions. It weighs 590 pounds.
A similar 1500 class flange this size is rated for 1,850 psi working pressure and uses 3 inch bolts torqued to 13,320 ft-lb. It weighs 2,050 pounds, the bolts weigh over 60 pounds each.
Now ramp this up for the riser which is 10,000 psi working pressure plus has to take various axial and bending loads never seen by a standard flange. The BOP alone weighs 450 tons and this flange has to lift it.
I’m not able to vet whether he’s right or you’re right. Looking a bit deeper…
