AM MAGAZINE SHELL - Australian Automotive Aftermarket Magazine

TECHNICAL PAPERS 2009
The Development of
Lokring
In the early 1960s, a Swedish design
engineer working at NASA designed an
alternative to the welding of fuel lines.
The concern with a weld is that unless
X-rayed, there is no way to be sure
that solder has penetrated and filled
the gap between pipes fully and that
there are no weakening bubbles
hidden within.
By designing a mechanical joint, these concerns were overcome. The Lokring system
was not immediately employed however following a tragic accident with the APOLLO
programme in the mid 1960’s, Lokring was re-assessed and implemented. It was during
this time that the benefits of Lokring as a general tube joining system were realised
and Vulkan, a German company established in the 1880’s, acquired the worldwide
rights to Lokring as a joining solution to the refrigeration industry.
The development of Applications
• Automotive Manufacturers found Lokring to be a solution to joining aluminium tubes
at evaporators in air conditioning systems. (1980)
• Appliance manufacturers began using Lokring to join copper to aluminium and
aluminium to aluminium. (1981)
• European service companies started using Lokring for service due to the
implementation initially of R134a (because of need for inner tube cleanliness and
small molecular size of refrigerant) and ultimately R600a as a refrigerant. Service
Lokrings and tooling were developed.
• Automotive AC technicians began using Lokring to join aluminium tubes on vehicles.
( 1995 – GM were the first OEM to approve and implement LOKRING) This led to
the development of a large range of fittings with Lokring as a base.
• Larger sizes (up to 35mm) were developed and found application in the HVAC field.
The cleanliness of the Lokring system did not require the purging of nitrogen during
pipe installation. The evolution of OH&S requirements such as Hot Work Permits
and other constraints involved in the welding process has seen this market expand.
In 2009 there are more than 1.2 billion Lokrings in service. Last year more than
120 million Lokrings were installed.
How does it Work
Vulkan Industries Far East Pte Ltd
12 Wollong St, Gosford, NSW 2250
Ph 02 4322 8533 Fax 02 4322 8599
www.vulkan.com.au
info@vulkan.com.au
A cutaway showing a typical
alloy to alloy connection
A typical automotive Lokring service connector consists of four separate components;
one joint, two Lokrings and an anaerobic solution called Lokprep. Lokprep is added to
the outside of the tubes which are then inserted into the union joint. Using the Lokring
hand tool, the Lokrings are forced over the joint which in turn is down-swaged onto the
tube. A hermetic metal-to-metal seal is made by this compression with the Lokprep
accounting for any longitudinal imperfections in the tube surface.
• Taper A is a leading edge that enables the Lokring to be forced onto the joint.
• Taper B is the sealing area. Somewhere along this taper the tube is compressed to
32 AU T O M O T I V E A F T E R M A R K E T M AG A Z I N E D E C E M B E R 2 0 0 9 www.aaaa.com.au