Nylon 6/6: How to Prevent Leakage Around Metal Terminals?

Typically the terminals would be potted with a 2-part epoxy (non-conductive!).

Yes , Thats how we prevent it from leaking now , however it is with a thread sealant. We want to eliminate the thread sealant and the associated labor of manually sealing the part . Thanks

Without seeing the design, I suggest you try to design the seal so the applied pressure pushes the nylon against the metal. The elastic modulus of nylon is 1/10 of most metals and will easily deform under pressure. If that deformation pushes the nylon against the metal, you will form a better seal than if it pushes the nylon away from the metal.