Safety interlocking devices from
Netherlocks B.V. have been
successfully installed at the
Shell Eastern Petroleum (SEPL)
Ethylene Cracker Complex in Pular
Ular, Singapore. The main
applications for the 1600 interlocks
are for the decoking process, and on
isolation valves for PSVs (pressure
safety valves).

Netherlocks’ 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 is 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.