Calculating the "required thickness of seamless shell, for pressure" 1

[Shiopower]

First of all I want to say I'm a first time user of the ASME code book, so hopefully this should be a simple question. I'm designing a cylindrical pressure vessel with unstayed flat covers on either end. I am specing the heat thickness per UG-34 and am using a type (e) connection with an inner and outer fillet weld as shown in Fig UG-34. The attachment factor is C=.33*m and m is defined as the ratio of the "required thickness of seamless shell, for pressure" divided by the "nominal thickness of shell". I've calculated the minimum required thickness of the shell and maximum allowable working pressure per equations (l) and (2) under UG-27. The nominal thickness is the thickness you could go out on the floor and measure, but what is the required thickness of seamless shell, for pressure? Is it the value t for the working pressure, before it was rounded up to a nominal size, or for a corosion allowance?, since it says seamless thickness should I recalculate t with a joint efficiancy of 1?

 

[prex]

The required thickness is calculated with a joint efficiency of 1 for the design pressure (plus the liquid head at location, if applicable).
The nominal thickness of shell is the thickness indicated on the drawings less any undertolerance (where applicable and unless the drawings specify a minimum actual thickness) and less the corrosion allowance (remember that all dimensions, including the ID of shell, need be taken in the corroded condition).

prex

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[Shiopower]

Thanks alot

 

[Shmulik]

Shiopower:
One moment before you start your calculation, please make sure you didn't fall into UW-2 Service Restrictions (due to the substance your vessel is about to contain or due to low temp.) that will not allow you perform a corner joint, and UCS-6 that doesn't allow you use some grades of C.S.
Weld joint preparation of flat plates shall be examined acc. to UG-93(d)(3).