Typical materials for hammer union seals include Nitrile (NBR), Viton (FKM), Hydrogenated Nitrile (HNBR), and PTFE. Each material caters to different operating conditions such as temperature, chemical exposure, and pressure. For instance, Viton offers superior chemical resistance and heat tolerance, making it ideal for aggressive fluids and elevated temperatures. https://globalsealstech.com/product/hammer-union-seal-2/