Standard hammer union seals for Fig 206 and 602 are produced from oil-resistant 85-durometer nitrile (NBR) for working pressures to 6,000 psi. Their self-energizing lip design ensures tight sealing even with slight misalignment common in field assembly, reducing downtime during rig-up and rig-down operations on location https://globalsealstech.com/product/hammer-union-seal-2/