Hammer Union Seals are commonly applied in applications like the Chemical Processing, Offshore Drilling, Petrochemical, and Water and Gas industries. It helps prevent leakage in hammer union pipe connections. Generally, materials include Nitrile (NBR), FKM, HNBR. In addition to the standard elastomer materials, anti-extrusion rings can be reinforced in Stainless Steel or Brass. It is also known as WECO Hammer Union Seals, 602/1002/1502 Hammer Union Seals

JST has tested the 3 Inch Hammer Union Seals with brass ring at 140Mpa.

• Product and Installation

• Test Standard

Refer to API Spec 16C-2th , Choke and Kill Systems, Annex B 9.4.3, Design Validation Procedures.

1.1  Test cycle procedure test, test medium is nitrogen(N2).

Test cycle conducted as per following steps, including five pressure holding cycles:

1.1.1  Apply pressure to the rated working pressure at room temperature and hold for 1h after the pressure is stable;

1.1.2  Release test pressure;

1.1.3  Raise temperature to the Maximum (+ 121℃)；

1.1.4  Apply pressure to the rated working pressure and hold for 12h after the pressure is stable;

1.1.5  Release pressure and raise temperature;

1.1.6  Raise temperature to the Maximum (+ 121℃);

1.1.7  Apply pressure to the rated working pressure and hold for 1h after the pressure is stable;

1.1.8  Release pressure and raise temperature;

1.1.9  Cool down to the Minimum (- 46 ℃);

1.1.10  Apply pressure to the rated working pressure and hold for 1h after the pressure is stable;

1.1.11  Release pressure and cool down temperature;

l.1.12  After stabilizing at room temperature, apply pressure to 200 PSI (1.4 MPa); Hold for 1h after the pressure is stable;

1.1.13  Apply pressure to the rated working pressure and hold for 1h after the pressure is stable.

• Acceptance standard

There should be no visible leakage during pressure holding period.

• Disassembly inspection

Disassembly inspection after testing. Fig. 15 is fixture picture at -46℃, Fig. 16 is fixture picture after disassembly, Fig. 17 is the seal picture after testing:

Fig. 15: Fixture picture at -46℃

Fig. 16: Fixture picture after disassembly

Fig. 17: Seal picture after testing

• Test conclusion

The conclusions of each cycle test are as follows:

1. At room temperature and under 20000 PSI, test pressure drop by 450 PSI during pressure hold period (1h), which meets the acceptance standard;

2. At 121°C and under 20000 PSI, test pressure drop by 350 PSI during pressure hold period (12h), which meets the acceptance standard;

3. At 121°C and under 20000 PSI, test pressure drop by 156 PSI during pressure hold period (1h), which meets the acceptance standard;

4. At -46°C and under 20000 PSI, test pressure drop by 332 PSI during pressure hold period (1h), which meets the acceptance standard;

5. At room temperature and under 200 PSI, test pressure drop by 9 PSI during pressure hold period (1h), which meets the acceptance standard;

6. At room temperature and under 20000 PSI, test pressure drop by 155 PSI during pressure hold period (1h), which meets the acceptance standard;

The test results show that the 3 inch hammer union seal passed the above cycle test and meets the acceptance standard.