Patent ID: 6899358

Claim:
A hammer union comprising a thread end having a conduit section providing first flow passage, a set of coarse external threads and a first groove for receiving a seal assembly, a nut end having a second flow passage communicating with the first flow passage and a seal seat for abutting the seal assembly, the first groove being open at a first end juxtaposed to the nut end and having a shoulder at a second end spaced from the nut end, the shoulder being non-adjustably fixed to the conduit section, a length between the shoulder and the seal seat being variable between hammer unions; a hammer nut comprising a collar surrounding the hut end and having coarse internal threads mating with the coarse external threads thereby captivating the thread end to the nut end and compressing the seal assembly and at least one ear projecting from the exterior of the collar for receiving an impact from a hammer, the seal assembly comprising an annular metal insert received in the first groove and providing a second groove facing the thread end and facing the seal seat and a third groove facing the shoulder, a seal in the second groove sealably abutting the thread end and abutting the seal seat and substantially isolated by the annular metal insert from the first flow passage; and a compressible member in the third groove biasing the seal away from the shoulder into sealing engagement with the seal seat whereby any abnormal length of the first groove in a direction parallel to the flow axis is accommodated by movement of the insert toward the nut end by a force generated by the compressible member, the compressible member being in a single fixed position between the thread end and the annular insert; the arrangement between the nut end and the thread end providing a sole independent leakage path closed by the seal in the second groove.