As part of the Nord Stream natural gas pipeline project, Netherlocks has been chosen to provide an electro-mechanical control cabinet in combination with an interlocking system for the pigging process. A custom, explosion-proof and climate controlled control cabinet was designed and manufactured in close co-operation with Siemens AG. The Nord Stream pipeline runs through the Baltic Sea from Russia to Germany.

Pigging is a notoriously complex and dangerous process, but one which can be made significantly safer by using mechanical interlocks. A standard interlocking system guides the operator through the sequence safely. Typically though, it does not include monitoring, it is not linked to the various pressure levels, and would not include the facility for remote operation of MOVs (Motor Operated Valves).

The control cabinet that Netherlocks has designed for this project integrates all these aspects into one unit: remote MOV operation controls are included, and correct pressure and position of MOVs are conditional requirements to release the keys for each stage of the process. By locking the keys in place in the MPCU (Mechanical Process Control Unit) that forms part of the cabinet, only the correct process steps can be made and only when it is safe to do so.

For this particular project the control cabinet also displays the launcher and receiver layout, indicating vessel and pipeline pressure and MOV position at each stage of the sequence. This custom designed solution from Netherlocks therefore combines the key cabinet, display, MOV control system and MPCU into one unit, meaning that the pigging operation is as centrally located as possible, but still mechanically safeguarded by the interlocking system.

Following the Netherlocks philosophy, this project demonstrates that the intelligent use of electro-mechanical safety systems and key interlocking processes allows the potential risk of human error to be eliminated.

Email: Srini@halma.com