Functional Principle


THANKS TO THE CONICAL INNER CONTOUR of the LOKRING, the diameter of the outer tube is reduced during assembly to such an extent that the inner tube and the outer tube create a hermetically sealed metal-to-metal connection. 

The lifetime gas-tightness of the fitted connection is ensured by the state of permanent elastic pre-tension, which is produced by the radial forces of the LOKRING acting in the opposite direction to the connection between the outer tube and the inner tube.

Design and calculation

REQUESTED INFORMATION. Due to the wide range of size and tolerance of tubes, it is unfortunately not possible to catalogue all of the available LOKRING sizes in this brochure. The individually required LOKRING

SINGLE RING is designed according to the tube samples and details that are provided by the customer. To enable the design and calculation of the most suitable LOKRING the following information is required:

  • tube materials, tube dimensions, dimensional tolerances and the wall thickness of tubes
  • location of the joining, which may cause stress such as vibration or torsion to the connection point
  • any physical or thermal manipulation on the tubes following the assembly of the LOKRING like bending or brazing
  • the refrigerant that is used in the system

DESIGN, CALCULATION AND ARTICLE CODE. Based on the information provided by the customer, VULKAN Lokring will be able to both calculate and design the most suitable LOKRING SINGLE RING. VULKAN Lokring will supply an application drawing to the customer that will confirm the tube dimensions and tolerances, as well as the suitable LOKRING SINGLE RING, by article code. This will be tested on the tube samples that are provided in their final configuration (flared, downswaged, straight) by the customer according to VULKAN Lokring’s application drawing or just straight, for aluminium tubes that the customer will flare with VULKAN Lokring’s flaring tool.

Single Ring Kalkulation_en.jpg


Operating pressure:*   PN (nominal pressure) = 25 bar (362,5 psi) up to 50 bar (725 psi)
Test pressure:            PP (4 x PN) = 100 bar (1450 psi) up to 200 bar (2900 psi)
Temperature range:     -50 °C to +150 °C (-58 °F to 302 °F)
Tube wall thickness:   0.5 mm to 1.5 mm
Tube diameter:           1.6 mm to 16 mm

* Depending on tube materials.