I would recommend getting in touch with OEM as well with specific case of expansion joint to better know the exact design basis.
That would just clear things out.

The existing username should work all fine with PetroNavigator application?

Yes some other useful calculations also.

Hastelloy C-276 is usually selected for a fairly specific reason: severe, mixed, localized corrosion environments where its broad resistance to oxidizing + reducing media and excellent resistance to pitting/crevice corrosion outweigh its higher cost.
C-276 is used in:
FGD absorber components ...

Use this sheet as well with the one above to understand.

I would recommend you to go through this attached sheet, and let me know if things are clear to you on basic calculations.

Thnaks.

See I would share the weaknesses of FBE system, and only those. Make a call, if that would still suit your aggressive seawater service.
Relatively thin
Mechanical damage sensitivity
Difficult to apply to some complex geometry
Heat requirement during application
Temperature limits depend strongly on ...

A plan is required to be made for such a scenario. These are all those necessary QC checks which were not rightly implemented and now people at site have to face them all.
Better you get extra resources assign for this particular inspection call.
And the call itself is required to be based upon two ...

So good!
https://migal.co/en/service/welding-cal ... calculator