LOKRING
The Right Way to Join Pipe and Tube
The leak-free seal of a LOKRING fitting is the result of LOKRING® Technology Corporation’s patented elastic strain pre-load (ESP®). During installation, the axial movement of the LOKRING driver over the fitting body swages the body onto the pipe or tube surface, compressing the pipe/tube wall, first elastically and then plastically. The pipe/tube wall resists this swaging action, generating high unit compressive loads at the contact points between narrow sealing lands inside the fitting body and the pipe surface.
These contact stresses are sufficiently high to plastically yield the pipe/tube surface under the sealing lands, forming a perfect 360° circumferential, permanent, metal-to-metal seal between the pipe/tube and the fitting body. The driver, which experiences a small increase in diameter (elastic strain) during installation, exerts an elastic, radial preload on the metallic seals for the life of the connection.
Gas -Tight, Permanent Seal
The unique metal-to-metal seal of the LOKRING connection provides extraordinary sealing integrity in both liquid and gas services. Unlike other mechanically attached fittings, there are no elastomemeric or rubber seals, O-rings or gaskets which can degrade and leak over time from chemical attack, fire, vibration, temperature cycling, cold flow or loss of elasticity.
As a result, fugitive emissions typical of leak-prone screwed or flanged connectors are eliminated.
Helium Leak Tight
No other connector (flanged or threaded) is capable of passing helium leak testing anywhere close to the level of a LOKRING fitting.
In fact, the fitting meets all criteria of a welded connection, except that no heat is required to make the connection.
The quality of a LOKRING connection has now been recognized by the California Air Resources Board (CARB). CARB, through their equipment and process pre-certification program have granted LOKRING pre-certification status through executive order G-096-029-033. The California Air Resources Board through their evaluation program have given LOKRING equivalent to WELDED status.
Notes: Please contact LOKRING Technical Services for a copy of our preliminary Position Paper Relating to Fugitive Emissions.
Technical Approvals
- ISO 9001:2000
- Lloyd’s Register #98-00070
- CRN 927805T
- Hartford Boiler CSA-B51-95
- API-607 Rev 4 Fire Test
- ASTM-F1387 NAVSEA.
- ANSI/ASME B31.1 B31.3 B31.5
- Association American Railroad
- U.S. Coast Guard and ABS
- NFPA 30
- California Air Resources Board
- American Bureau of Shipping
ANSI B31 qualifications and testing
Both stainless and carbon steel LOKRING fittings are qualified to the requirements of the ANSI/ASME B31 pressure piping codes for pressure and fatigue design and materials of construction. Extensive mechanical and environmental testing has demonstrated the mechanical and sealing integrity of the LOKRING connection in a wide range of applications and environmental conditions.
Pressure-torsion testing
The 1/2″ NPS stainless steel test fitting was subjected to torsional loading high enough to twist the pipe in a spiral without leakage of the joint. Afterwards during hydraulic testing, the pipe ruptured at 22,000 psi (1497 Bar)
Flexural testing
The 2″ NPS carbon steel coupling above has been deflected to 3x the yield strength of the matching pipe without leaking. The performance of this fitting in severe bending, fatigue, and vibration loads is comparable or superior to a socket weld fitting.
Fire testing
The metal-to-metal LOKRING seal remains intact when subjected to extreme thermal loads, including fire (above). Both stainless and carbon steel LOKRING fittings are qualified to the Exxon API-607 Rev 4, fire test standards. Stainless steel fittings are also qualified to F1387 (U.S. Navy) fire test standards. Both are widely used on volatile and flammable services.
