Posted on 9 December 2013

Shin-Etsu replaces lockout-tagout devices with Netherlocks process interlocking systems

As part of an overhaul operation of one of its plants, Dutch based Shin-Etsu PVC, part of Shin-Etsu Chemical Ltd., recently replaced all refrigeration compressors using Freon with compressors using propylene in their Botlek plant. The Pressure Safety Valves (PSV’s) on these compressors were safeguarded by lockout-tagout systems. Michel Immerzeel, Team Leader Mechanical at Shin-Etsu PVC, explains why the new compressors are to be equipped with valve interlocks instead.

About Shin-Etsu

Shin-Etsu PVC is world leader in the production of PVC. Production in the Netherlands takes place at two modern plants. The Botlek plant produces vinyl chloride monomer (VCM), the raw material for the production of polyvinyl chloride (PVC). PVC production takes place at the Pernis site of the company. Performance, quality, innovation, environment, and safety are pivotal to the work of Shin-Etsu.

Shin-Etsu uses Netherlocks interlocks

Michel Immerzeel: “Shin-Etsu invests a great deal in safety and consequently our safety measures have to follow our high standards”


Already from the 1970’s, lockout-tagout safety devices were installed on all Pressure Relief Valves as a standard safety measure. “As we replaced all Pressure Safety Valves, the decision was made to equip them with new valve safety systems, based on the latest technologies and insights on valve safety”, says Michel Immerzeel. “Shin-Etsu invests a great deal in safety and consequently our safety measures have to follow our high standards”. Eventually, Shin-Etsu chose for process interlocking as the most effective safety measure. The first PSV systems have already been secured and gradually, all PSV systems will be equipped with valve interlocking systems.

No adjustments to valve

According to Michel Immerzeel, one of the great advantages of using valve interlocks is the fact that the characteristics of the valve remain unchanged. “Before using valve interlocks, we had to make all kinds of adjustments to the valve in order to be able to install lockout-tagout devices onto them. That all changed with the Netherlocks valve interlock, which is installed as an integral part of the valve, with the original valve lever removed and replaced by the lock with a new, same-sized stainless steel sliding lever or hand wheel”. He also adds that, in contrast to lockout-tagout devices, valves interlocks are tamperproof and cannot easily be bypassed.

Guarantee that only one relief valve is offline

Henk Riedijk, Allround Operator at Shin-Etsu, values yet another aspect of Netherlocks valve interlocks. As he puts it: “The sequence of operations simply cannot be ignored, which is of vital importance for us. In essence, Netherlocks valve interlocking systems guarantee that only one relief valve can be offline at a time”. To him, working with valve interlocking systems is easy to understand. The system simply guides the operator through a predefined sequence with unique keys for each step. “My fellow operators seem quite satisfied”, says Henk Riedijk.


Other applications

Within Shin-Etsu, process interlocking is also applied to other processes that require strict coherence to procedure. In these processes for instance, vessels are filled with substances such as propylene. “Without using valve interlocks it would be theoretically possible to open the valve to the gas venting system and the valve to add propylene at the same time, emptying the entire contents of a vessel directlyinto the venting system”, says Henk Riedijk. Valve interlocks force the operator to guarantee a predefined procedure. “Operators can only fill the vessel after closing the flare valve. It therefore is impossible to open the flare valve and the valve to fill the vessel at the same time”.


As an effective safety solution, process interlocking prevails over lockout-tagout at Shin-Etsu. Therefore, the company is evaluating which safety systems are currently used and which need to be replaced in time with process interlocking systems. Michel Immerzeel:”For some of our existing lockout-tagout devices, spare parts are no longer available. These need to be replaced by other safety devices, preferably valve interlocks”. As Michel Immerzeel explains, a plan for further phased implementation of process interlocking is being set up. In his view, this is an important and logical next step in the continuous effort of improving overall process safety within Shin-Etsu.