Section 1 applies to screwed couplings of the compressible ring joint type for effecting joins in pipelines in food processing plants; it also includes a modified ring joint type with flush seal commonly used with the object of better filling the crevice between the mating fittings or pipe ends. Section 2 is aligned with ISO practice for screwed pipe couplings with trapezoidal thread. Both sections specify dimensions, tolerances, surface roughness, materials, assembling and hygienic requirements for both welded-type and expanded-type male parts and liners and for nuts and ring joints or gaskets.