Hammer unions are quick-connect fittings widely used in the oilfield industry for connecting high-pressure pipelines and equipment. They are named-for their installation method-tightened or loosened by hammering the lugs on the nut.
1, Structure
A standard hammer union consists of three main parts:
1, Made sub-welded or threaded to one end of the pipe, has external threads.
2, Female sub-connected to the other end, has internal threads and a nut with lugs.
3, Seal ring-typically a nitrile O-ring or metal-to-metal seal, ensuring leak-free connection under high pressure.
The connection is made by bringing the male and female subs together and hammering the nut lugs to tighten.
2, Common Models and Pressure ratings
Each hammer union model is identified by a figure(Fig.) number, which indicates its pressure rating, seal type, and often a color code for easy identification.
Fig. Number | Pressure (psi) | Seal type | Color code | Typical Application |
Fig 100 | 1000 | Nitrile O-ring | Blue | Low-pressure water, mud lines |
Fig 200 | 2000 | Nitrile O-ring | Gray | Low-pressure air, water, oil |
Fig 206 | 2000 | Nitrile O-ring | Gray | Full-flow line |
Fig 400 | 4000 | Nitrile O-ring | Green | Medium-pressure fluid service |
Fig 602 | 6000 | Nitrile O-ring | Red | High-pressure, acid service |
Fig 1002 | 10000 | Nitrile O-ring | Orange | High-pressure Oil & gas |
Fig 1502 | 15000 | Metal-metal/Nitrile O-ring | Yellow | Ultra-high pressure(frac, test lines) |
Note: Hammer unions with different fig. Numbers must not be mixed, as their threads, seat angles, and pressure ratings differ. | ||||
3, Key features:
Advantages:
-Quick and easy assembly/disassembly
-High-pressure and shock-load resistance
-Available in multiple seal materials(NBR, VITON, HNBR, metal seal)
-Field-replaceable parts
Precautions:
-Never mix different figure unions
-Regularly inspect threads and seal surfaces
-Use safety clamps or chains for high-pressure applications
4, Typical Applications
-Drilling mud and cement lines
-Fracturing and acidizing manifolds
-Well testing lines
-High-pressure fluid transfer
-Industrial hydraulic system
