Hammer Union Fig Series Complete Guide: Fig 100 to Fig 1502 Pressure Ratings & Applications

A hammer union is a high-pressure temporary pipe connection consisting of three parts: a male sub (threaded or butt-weld to the pipe), a female nut (rotating collar with hammer lugs), and a seal ring between them. You make up the connection by swinging a hammer against the lugs on the nut — hence the name. No tools, no flanges, no torque wrenches. Just a hammer.

The Fig (Figure) number identifies the pressure rating and dimensional standard. It's an API 6A legacy system: each Fig number maps to a specific cold working pressure (CWP), and the sub-and-nut geometry is standardized so any manufacturer's Fig 1502 nut fits any manufacturer's Fig 1502 sub — interchangeability is the whole point.

What does CWP mean? Cold Working Pressure — the maximum pressure the union can handle at ambient temperature. At elevated temperatures (above 250°F), you must derate. For frac operations where fluid temperatures can spike during pumping, this matters more than most people realize.

Here is every Fig number in the API 6A hammer union family, organized by pressure rating:

| Fig | CWP (PSI) | Common Size | End Connection | Typical Service | |-----|-----------|-------------|----------------|-----------------| | Fig 100 | 1,000 | 2"–12" | Threaded | Low-pressure water, mud mixing, tank lines | | Fig 200 | 2,000 | 2"–8" | Threaded | Water transfer, low-pressure cementing | | Fig 206 | 2,000 | 2"–6" | Butt-Weld | Same as Fig 200 but welded (no thread leak path) | | Fig 400 | 4,000 | 2"–6" | Threaded | Well testing flowback, low-pressure gas | | Fig 602 | 6,000 | 2"–4" | Threaded | Cementing, acidizing, intermediate frac lines | | Fig 1002 | 10,000 | 2"–4" | Threaded | Cementing, fracturing, well testing (most common) | | Fig 1003 | 10,000 | 2"–4" | Butt-Weld | Same as Fig 1002 but welded for sour gas / H₂S | | Fig 1502 | 15,000 | 2"–4" | Threaded | High-pressure fracturing, HPHT well testing |

The most commonly ordered Figs are 1002 and 1502 — 1002 for standard cementing and moderate frac jobs, 1502 for high-pressure shale and deepwater stimulation. Fig 206 and 1003 are the welded variants; fewer leak paths in sour service.

This is the question that generates the most RFQs. Here is the decision logic:

Choose Fig 1002 when:
- Your maximum surface treating pressure is below 10,000 PSI
- You're running standard cementing jobs or moderate-rate fracs
- Budget matters — Fig 1002 unions cost roughly 30–40% less than 1502
- You need larger diameters (Fig 1002 goes to 4", same as 1502)

Choose Fig 1502 when:
- Surface treating pressure exceeds 10,000 PSI (common in deep shale plays)
- You're operating in HPHT conditions where every component must handle 15K
- You need future-proofing — the 1502 gives you headroom for higher-pressure jobs later
- Safety margin is non-negotiable (offshore, sour gas, high-H₂S)

The physical difference: Fig 1502 subs and nuts have a different thread profile and larger cross-section than Fig 1002. They are NOT interchangeable. If you try to make up a Fig 1502 nut on a Fig 1002 sub, the threads will not engage properly — you'll have a mismatch and a potential failure point under pressure. Color-coded nuts (red for 1502, blue for 1002 in most manufacturer schemes) help prevent field mix-ups.

Threaded hammer unions (Fig 100, 200, 400, 602, 1002, 1502) are the industry standard — fast to install, easy to replace. But in two scenarios, butt-weld ends (Fig 206, 1003) are worth the extra fabrication:

Use butt-weld when:
- You're handling sour gas or H₂S — threads create crevice corrosion initiation points
- The line sees cyclic pressure loading (frac pump discharge) — threads can loosen over time
- You need a permanent installation rather than a temporary rig-up
- Operating temperature exceeds 300°F — thermal cycling loosens threaded connections faster

Stick with threaded for:
- Temporary rig-ups (cementing spreads, frac manifold trailers)
- Applications requiring frequent make-and-break
- When field replacement speed matters more than the marginal improvement in leak integrity

JLD Energy supplies both threaded and butt-weld variants across the Fig 206 and Fig 1003 series, with full EN 10204 3.1 material traceability.

Beyond the Fig number, five specifications determine whether you get a reliable union or a field headache:

1. Material traceability: Require EN 10204 3.1 certification for all pressure-containing parts. If the supplier cannot produce mill test reports, walk away. 2. Heat treatment: Subs and nuts should be quenched and tempered (Q&T) alloy steel — AISI 4130 or 4140. Ask for hardness certificates (typically 18–22 HRC for subs). 3. Seal ring material: Nitrile (NBR) is standard. For high-temperature frac fluids (>250°F), request HNBR or Viton seals. For sour gas, specify H₂S-resistant elastomers. 4. Interchangeability guarantee: The union must interchange with other API 6A-compliant manufacturers. If it doesn't, it's not a real hammer union — it's a proprietary connection that will trap you into one supplier. 5. Pressure test certification: Every union assembly should come with a hydrostatic test certificate at 1.5× CWP. For 1502 unions, that means a 22,500 PSI shell test.

JLD Energy hammer unions ship with MTRs, hardness certs, hydro-test reports, and an interchangeability statement.