A total of 1600 safety interlocking
devices from Netherlocks B.V. have
been installed at the Shell Eastern
Petroleum Ethylene Cracker
Complex in Pular Ular, Singapore.

The main applications for the
interlocks are for the decoking
process, and on isolation valves for
PSVs (Pressure Safety Valves).

The interlocks use a linear key
transfer system to ensure that
processes can only be carried out in
the correct order, ensuring each part
has been safely completed before the
next can be started. Safely completing
the previous step in the process
sequence will release a unique key
that then unlocks the next step; only
when a mistake is made will the
operator be prevented from
proceeding by a key that doesn’t fit
or a valve locked in position. This
simple principle can be propagated
to more complex procedures, but in
every case it physically ensures that
safety protocols and work orders are
followed exactly, leaving no scope for
human error.