A unique wire-free device for locking the nuts of two-ferrule compression fittings on instrumentation tubing is now available from Parker Hannifin. Dubbed WireFree, the patented safety device is constructed almost entirely from 6Mo austenitic stainless steel for enhanced corrosion resistance. It has been developed at the request of a major supplier of instrumentation to the offshore oil and gas industry, which sought a better alternative to wire locking compression tube fittings on deepwater ‘Christmas tree’ fluid flow assemblies.
Parker’s two-ferrule compression fittings have been used successfully for subsea instrumentation applications for more than 40 years and there is ample field data to show that they provide reliable long-term performance – making locking devices unnecessary. However, as energy companies strive to recover oil and gas from ever deeper offshore locations, the cost of retrieving subsea equipment for routine maintenance, repair or overhaul continues to escalate. In response, some OEMs are starting to fit wire locks to instrumentation tube compression fittings for deep sea applications, primarily to indicate that the fitting is secure and has not been tampered with or undergone any mechanical change since installation. This approach suffers from a number of disadvantages, not the least of which is that wire lock fittings are expensive to install.
Wire locking is a technique that is widely used in the aerospace industry to guard against components such as securing bolts and nuts on tube fittings working loose during service. It involves the use of pre-drilled parts – which cannot easily be retrofitted – and is only suitable for some types of fittings. The wire that is used is normally stainless steel, which is sharp and difficult to manipulate. And in the case of wire-locked compression tube fittings, it is important that the wire is not tensioned in such a way that it could cause the nut to rotate slightly and potentially compromise connection integrity. Correctly installing wire locking consequently demands skill and is time consuming – it can take anywhere between 5 and 15 minutes per component, depending on accessibility. On a typical subsea Christmas tree containing several hundred instrumentation tube compression fittings this can easily account for tens of hours of extra assembly time.
Fit-and-forget solution
Parker’s new WireFree locking device is designed as a ‘fit-and-forget’ solution that overcomes all the disadvantages of wire locking. It can be fitted to standard compression fittings on new or existing systems very easily and quickly, without requiring any modification, realignment or disassembly of components. The device is also ideal for replacing existing wire locks during routine MRO (maintenance, repair and overhaul) operations – installers merely need to remove the wire before fitting the new unit.
Available in straight, elbow, tee and cross type configurations, the locking device is initially being offered in a range of sizes for use with tube fittings from 6 to 20 mm. Parker intends developing other sizes to suit market requirements.
WireFree device for compression fittings can typically be installed in under two minutes – a fraction of the time that it takes to wire lock components. To fully lock a standard 90 degree elbow fitting, for example, the installer simply places the flexible clamp arm around the two compression nuts, inserts a single cap screw through one of the support plates and tightens it to the recommended torque.
For more information contact Lisa de Beer, Parker Hannifin, +27 (0)11 961 0700, [email protected], www.parker.com/za
| Tel: | +27 11 961 0700 |
| Fax: | +27 11 392 7213 |
| Email: | [email protected] |
| www: | www.parker.com/za |
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