Attachment of support lugs to vessel

[alan54]

in the 4th edition of Dennis Moss' Pressure Vessel Design Manual (p. 188), he says "the base plate of the lug can be attached to the shell wall or unattached." Anyone have experience doing this? We would like to minimize heat loss; and where base sits on the structural steel is a big heat sink. --- Thanks!

 

[r6155]

See PIP (Process Industry Practices) VEFV1000 Vessel/S&T Heat Exchanger Standard Details.
Required thickness and dimensions must be determined by calculations using the design loads and allowable stresses at design temperature.

Regards
r6155

 

[TGS4]

Balancing the thermal design with the mechanical design can be challenging. I definitely have experience doing so - it's not as straight-forward as it might appear.

The PIP details that r6155 refers to, above, are a good place to start, but they don't address the thermal aspects.

 

[alan54]

Thanks r6155 & TGS4, I will take a look at that PIP. Several books that say different things in passing; i.e. Moss vs Brownell & Young who say "the top and bottom plates should have continuous welds as the maximum compressive and tensile stress occurs in these two plates". I am thinking Moss really means when it is low enough load that a Wolosewick approach with just 2 vertical gussets at each lug can get the job done (I have a large diameter incinerator full of refractory ...). COMPRESS uses the Bednar procedure and just assumes all the welds are the same, so I think I will look at it using a RISA 3D plate model and taper the bottom plate at the shell to a thickness where a full penetration weld is enough to take the tension. And, we're looking at putting some ceramic thermal standoffs between the lugs and structural steel. Appreciate any further comments!