MAWP Determination - Unknown Materials

[Joss10]

As per API 570:
MAWP Determination:
For unknown materials, computations may be made assuming the lowest grade material and joint efficiency in the
applicable code.
It means S=15000 psi and E=0.6 ??

 

[racookpe1978]

If yo do not know the material, how are you supposed to assume the thickness and the underlying code the fittings and pipe were supposedly made to?

 

[Joss10]

Racookpe1978,
API 570 about the thickness for calculation states : "the wall thickness used in these computations shall be the actual
thickness as determined by inspection minus twice the estimated corrosion loss before the date of the next inspection
(see 6.3.3)", so the thickness is not supposed to be assumed.