head min thick

[engineer54]

I had a customer who stated that the 2:1 elliptical head min was governed by the straight flange min.
The Knuckle min is less than the straight flange min. for example, the head nom is 1.25" thick. the straight
flange min is 1.117". The head knuckle min is 0.89". Customer states that the knuckle min listed on the paperwork
should not be less than 1.117" because full vacuum governs? I don't understand the reasoning. Full vacuum governs for the straight flange , but not the knuckle per calculation. Has anyone ever heard this?

 

[Don56]

The min of the SF should be the same as the min of the shell.

 

[gr2vessels]

The minimum wall thickness is governed by the code (UG-32 and UG-33). The knuckle minimum thickness is called minimum thickness after forming of the head. Typically, the plate material used for the forming of heads is thicker than the final knuckle thickness, due to forming process. It could be that the full vacuum condition governs the design calculations per UG-33. I would advise you put together the calculation sheet as per UG-32 and UG-33, present it to the Client and ask him to comment on your calculations. He might change his mind if your calcs are correct.
Cheers,
gr2vessels