Threads: Threads are British Standard taper to IS07 and BS21. All male threads are BSPT and female threads are BSPP. Materials: Whiteheart malleable cast iron, grade W40-05 according to ISO5922/DIN-1692, and tested in accordance with ISO-49/DIN-2950. Media: Suitable for the flow of water, steam, gas or other non aggressive media. Surface Finishing: Two types are available: Black: With an anti-corrosive varnish to protect against rust after installation prior to plant conditioning. Galvanised: Hot-dip zinc coated to give additional resistance to corrosion, meeting the requirements of ISO-1460.