HNBR seals represent the premium choice for sour gas service in Hammer Unions, offering enhanced tensile strength and oxidation stability over NBR. Rated for -40°F to 350°F, HNBR withstands H2S concentrations up to 20%, critical for North Sea wells. Brass-reinforced HNBR for Fig. 1502 prevents extrusion at 15,000 psi, with RGD resistance per ISO 23936-2. JST Seals' HNBR variants show https://globalsealstech.com/product/hammer-union-seal-2/