Pigging safety systems supplied to Indian company

18 January 2010

Netherlocks has been chosen to supply its trapped key interlocking safety systems by India’s largest engineering and construction conglomerate, Larsen & Toubro. The company has ordered Netherlocks products to secure and safeguard pigging operations for two major projects.

Pigging safety systems supplied to Indian company

A project in conjunction with Cairn Energy India, involves 39 pig launcher and receiver systems along a cross country pipeline. The other is from L&T’s Qatar office, with Qatar Petroleum for the SGP project, where initially 12 of the pigging systems will be protected by the interlocks.

Pigging is undoubtedly a very effective and efficient cleaning method for pipelines, not interrupting process, but it does carry a potentially high risk factor due to the high pressures and dangerous gasses involved. Although nothing should go wrong if the safe procedures are followed correctly, there is always the chance (mostly attributable to human error) that the procedure itself will not be followed exactly. The trapped key interlocking systems from Netherlocks ensure that each stage of the process can only be started - that each valve can only be operated - once the stage before has been safely completed. In this way, the system mechanically enforces a strict and absolute adherence to safe procedure.

The exact number of locks required varies according to each individual pigging system and client specification, as their processes will be subject to differing numbers of variables - vent, drain, kicker, main, throttle, balance and so on. This then requires different complexities of interlocking systems such as locks on manually and motor operated valves and closures. Because pigging procedures are often non-linear processes, requiring steps that may need to be repeated at different stages, or that are dependent on several previous actions, Netherlocks designed the MPCU. The MPCU acts as a ‘mechanical PLC’, checking each stage of the process and releasing keys according to pre-programmed parameters, meaning that the operation can only be performed according to safe procedure.

Interlocking systems such as these provide such an effective baseline safety standard that they are rapidly becoming standard for pigging systems. The simple principle of mechanically enforcing safe working methods significantly reduces risk by essentially taking the ‘human factor’ out of the equation, without negatively affecting performance.