Confused by ULT-27 Thickness of shell

[wangzh2k]

Hi all,

I am confused by ULT-27 about the determination of shell minimum thickness. Per ULT-27(a) and ULT-27(b), it sounds that:

Design pressure = MAWP+Loadings(per UG-22) for instance,

Before the shell norminal thickness selected, how can I know MAWP?

As far as I know it:
MAWP may be equal to or greater than the design pressure.

Is the MAWP defined in ULT-27 different from the meaning in other places?


Thanks in advance.