For Cu Ni 90/10 pipe routed inside the water ballast tank

Dear Expert,

Kindly let us know the following questions answer,

  1. For Cu Ni 90/10 pipe routed inside the water ballast tank, so what type of joint is suitable & acceptable as per class rule.

  2. For Cu Ni 90/10 pipe flange and other material is NAB as per owner technical specification, let me know what is the reason there selection NAB materials for fittings?

Regards,

Mani.P