Hammer Union Seal Identification Guide

Hammer union seals should be identified from the actual union and operating conditions. Nominal size alone is not enough: different figure numbers, pressure classes, manufacturers and groove arrangements can require different seal geometry or backup components.

1. Identify the union

Record the manufacturer marking, figure number, nominal size and any pressure or service markings visible on the wing nut, segments or related documentation. Do not infer pressure capability from the seal color. The union assembly—not the replacement elastomer alone—determines the rated system.

2. Inspect the existing seal and groove

Measure the seal only after cleaning it and note that used elastomers may be swollen, compressed or damaged. Where possible, measure the metal groove and compare it with the equipment drawing. Record outside diameter, inside diameter, cross-section, lip or profile details and the position of any backup ring.

3. Confirm construction

Some configurations use an elastomer seal alone, while others include a metal or polymer anti-extrusion ring. Photograph both faces and the side profile. Note whether the backup ring is separate, bonded or mechanically retained. Do not substitute a visually similar ring without checking fit.

4. Define service conditions

Provide the medium, temperature range, working and test pressure, cycling frequency and any sour-service or decompression requirement. NBR, HNBR and FKM labels describe material families, not a complete qualification. A compound must be reviewed against the specific duty.

5. Check before installation

• Confirm figure and nominal size against the equipment.
• Inspect the groove and sealing faces for damage or corrosion.
• Verify seal orientation and backup-ring position.
• Use compatible assembly lubricant where permitted.
• Follow the equipment manufacturer’s assembly and test procedure.

If markings are unclear, send Royal Way clear photos of the complete union, markings, groove, old seal and a ruler or caliper reference. Add the medium, temperature, pressure, quantity and destination through Request a Quote. We will identify the information still needed before quoting.

Related Products

Review the available Hammer Union Seals after confirming the union figure, nominal size, groove and required construction.

Reference sources

Manufacturer documents such as the TechnipFMC flowline catalog illustrate why figure, size and service information must be matched to the union assembly.