Upgrading Safety Systems in the Petrochemical Industry: Basic Guidelines

Related Vendors

DÜPERTHAL Sicherheitstechnik GmbH & Co. KG

Italvacuum, Srl

Donadon SDD Srl

Rockwell Automation GesmbH

Safety Systems Require Detailed Planning

In addition to the build and test records that the system manufacturer produces, the engineering team should produce comprehensive and detailed work packs that include method statements, implementation details, reversionary plans and check sheets to verify the installation, commissioning and handover of the system. This is essential in recording – to the satisfaction of the certifying authority – the work undertaken in implementing the upgraded system.

Installing and migrating to the new system – Once the new system has been tested and shipped, it can be installed and commissioned. The following is an overview of the steps needed to migrate from the legacy system to the new system during live operations. It is at this phase of the project that the detailed planning and preparation already undertaken will prove critical to the successful migration of your safety system.

• Fully verify the functionality of the existing legacy system, including any standing inhibits or overrides retained from that system.

• Install the new system in its final location. Once installed, carry out basic functional tests – often called ‘travel-well’ tests – to help ensure that the system is fully operational ahead of the system migration.

• Remove one ‘side’ of the legacy system (in this case, side ‘B’ – see figure 2). This is one of the risk areas due to the possibility of inadvertent operation of the system, such as loose wiring disturbance. The system is now in the degraded state.

Hook up the field inputs, such as fire and gas detectors, to the new system, while retaining the inputs to the legacy system. The new system can now ‘see’ the same inputs as the existing system but, because the outputs are not hooked up, the new system is not carrying out any executive actions (see Figure 3).

Putting It to the Test

Fully test that both systems see all inputs and that logic solver output actions implemented are identical to the legacy system. In this instance ‘like for like’ functionality (i.e., both the old and new systems respond in exactly the same manner to field input conditions) is critical unless otherwise noted. This can be done by temporarily disabling the appropriate outputs, which can be time-consuming and may not be operationally acceptable, or by observation of the new logic solver against the design documentation.

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