API SPEC 7HU2 pdf download Oilfield Hammer Unions 5Materials 5.1General The materials for segment retainer rings, resilient seals, pressure-containing parts, and pressure-retaining partsshall satisfy the requirements below.All metallic materials shall have a wrought microstructure throughout. 5.2Segment Retainer Ring Segment retainer rings shall be made of material meeting the functional requirements of 4.2.4.5.3Resilient Seal The resilient seal shall be made of...