DK-Lok’s fittings and valves serve most stringent industry standards

Tube Fitting DKDK-Lok has developed leak-free performance in twin-ferrule designed fittings

The three main features are:

Corrosion resistance ferrule with unique selective case hardening technology

DK-Lok has developed patented selective case hardening process where only the nose part of back ferrule is hardened with no intergranular corrosion. All the other competitors use entire surface hardening technology with changing back ferrule design due to increased torque level. DK-Lok’s corrosion resistance surface treatment technology keeps the torque level as reasonable as conventional carburised, but corrosive, back ferrule, without having to change back ferrule design.

Full-scale ASTM F-1387 intermix text 

A fitting is made of the four components; body, front ferrule, back ferrule and nut. Fourteen different combinations are possible if one makes fittings with intermixed components. Test procedures of fittings are defined at ASTM F-1387 and the company has done all the nine mandatory tests and two supplement tests with 14 different combinations at five different sizes and not a single leak point was observed. All test procedures were witnessed by TUV Rheinland and they issued test certificates for those tests.


Quality control through statistical process control (SPC)

DK-Lok adopts SPC (Statistical Process Control) in QA process. We have been keeping the Single PPM certificate since 2007, which is authorised by the Korean Government and issued to companies which show less than 10 failures for million parts. In addition to the already highest-level QC certificate where only pass or fail is counted, we extended the quality control measure by employing another dimension. A newly-developed datum gauges to check out the critical dimension points helps us integrate the Cpk (Process Capability Index) data to foresee the quality performance tomorrow or even further in order to supply our products with high-consistency.

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For more information, visit

Alain Charles Publishing, University House, 11-13 Lower Grosvenor Place, London, SW1W 0EX, UK
T: +44 20 7834 7676, F: +44 20 7973 0076, W:

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