Abstract: A seal assembly for use in completion and production operations of a subterranean hydrocarbon well for sealing the annular space between the production casing and tubing, which assembly generally includes primary seal members having a circular, oval or elliptical shaped cross-sections, and secondary seal members having convex sections for abutting the primary seal members. The assembly further includes retainers on the tubing which define the seal bore into which the seal members are positioned, and a polished surface on the casing for allowing movement of the seal members against the casing.

Abstract: A method for constructing inspectable welded joints which are resistant to marine biofouling, and the welded joints formed thereby, are disclosed. The method comprises bonding a first coating of a substantially dielectric material to the welded joint and bonding a second coating of a marine growth-inhibiting material to the first coating. The first coating preferably is less ductile than the underlying welded joint. The second coating is electrically insulated from the underlying welded joint by the first coating and provides a source of a biocide which prevents the accumulation of marine biofouling encrustations. Fatigue cracks occurring in the welded joint propagate through the coatings and are readily visible on the outer surface of the second coating. Further, fatigue cracks in the welding joint may be detectable through the use of nondestructive testing techniques prior to the time when they are visible on the outer surface.