Minimum thickness of boiler plate PG-16

[Millar]

I was wondering if there is an interpretation regarding the application of corrosion allowance to the minimum thickness requirement of PG-16 of ASME I. This paragraph requires plates be 1/4" thick minimum and I am wondering if this is before or after any corrosion allowance is applied.

Thanks,
Millar

 

[unclesyd]

This the Minimum thickness without adding a corrosion allowance. It will 1/4" thick + the corrosion allowance or forming allowance.
1/4"min + 1/16"c.a. = 5/16" min everywhere, heads and shell.

 

[Millar]

That is what I thought. I know Section VIII is set up this way also. Thanks for the assistance.

Millar

 

[GenB]

I am sorry to tell you that you are Wrong:
The minimum is 1/4"
You can order material to 1/4" and build boilers and/or components.
1-carefull with: The nominal reqd t (for plate)is 1/4&quot;(.250&quotand if the supplier/mill send you on inspection < .250&quot; you are not meeting the required t.
2-corr. allowance is not mandatory on sec I, so you can possible go to the limit, but we always allow for corrossion for good eng. practice. so if your vessel/boiler on calculation goes beyond 75 or 80%, we have the option to jump to the next available metal T.

ER

 

[GatorOne]

unclesyd is correct. All thickness in the VIII-1 are corroded thicknesses. The allowance is always added at the end of the rule/calculation results.