Material specifications for API 6A metal seals include soft iron grades for general service, Type 304 or 316 stainless steel for corrosive environments, Inconel 625 or 718 for extreme sour service, and specialized alloys for hydrogen sulfide resistance. Hardness requirements typically range from Rockwell B 70 to 90 providing sufficient plasticity for deformation while maintaining stru... https://globalsealstech.com/product-category/oil-gas-seals/api-6a-wellhead-equipment-seals/