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December 22, 2009

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Safety Interlocks- Trapped-key interlocking

India’s largest engineering and construction conglomerate, Larsen Toubro Ltd, has ordered trapped-key interlocking safety systems from industrial valve and safety supplier Netherlocks
B.V. to safeguard ‘pigging’ (pipeline cleaning operations for two major projects.

Pigging involves high pressures and dangerous gasses, and Netherlocks says its interlocking systems will ensure that each stage of the process can only be started once the stage before has been safely completed. In this way, the system mechanically enforces a strict adherence to safe procedure.


Because pigging procedures are often nonlinear processes, Netherlocks designed the MPCU, which is said to act as a ‘mechanical PLC’, checking each stage of the process and releasing keys according to pre-programmed parameters. To find out more, call +31 (0)172 471 339, or visit


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