MPI for API 5CT coupling

[gafoorkti]

I would like to know the scope of MPI (magnetic particle inspection) for API 5CT Coupling (Material Grade T-95 and size 16").

As per my below interpretation of API 5CT, Coupling receives magnetic particle inspection twice ??

** clause 9.14.2-All couplings shall be inspected on the outside and inside surfaces after finish machining and before any inside or outside surface plating, using the wet fluorescent magnetic particle method in accordance with ISO 13665 or ASTM E709.

** clause 10.15.11 and table E.62 - NDE is required for coupling stock by one or more of the following methods: UT, MPI, Flux leakage or EMI

My question is: If MPI is carried out by vendor as per clause 10.15.11 on Coupling stock at mother material mill, then can we waive MPI for coupling after finish machining?

Your earliest advice is highly anticipatad.

 

[metengr]

Without the benefit of reviewing the entire specification, yes, an MPI after final machining would be required to satisfy clause 9.14.2, as you present it. The key words are "after final machining."

 

[redpicker]

9.14-2 requires all couplings to be MPI inspected after finish machining (and prior to plating).

10.15.11 requires all coupling stock to be inspected by either UT, MPI, Flux Leakage, or EMI methods.

It is clear that the coupling stock is to receive an NDE, but it may be one of several methods. After machining, the finished coupling must be inspected per MPI, regardless of any NDE that was performed in any prior processing.

rp

 

[blacksmith37]

The intent is both NDE of the bulk and the surface.
T-95 was the first API grade that can't be made by every mill in the USA (actually when first approved, Amoco found NO USA mill could make it): The API Users wanted a very reliable product and did not care if a particular mill could produce it.