Integrated Control & Safety System (ICSS)

The objective of the Integrated Control & Safety System, or ICSS, is to enable offshore platforms to operate in unmanned mode. The ICSS enables this by offering full offshore control together with full status information being available onshore via Telemetry.

The innovation is in the integration of the Fire & Gas detection and emergency shutdown systems, both sharing the same facilities, but operating in a different way. It is because of this difference that up until now the two systems have normally been separated into distinct operating units.

Systems Description

The Alderley ICSS system is designed to provide combined protection against both fire and process hazards on the NUI platforms. This involves the continual monitoring of fire and gas detectors in addition to the monitoring of separator pressures and levels.

ESDV System

The ESDV system is solid state and monitors the majority of the IPS I/O. The system uses a range of Alderley’s input modules to interface to the detectors. The input modules drive conventional relays, the contacts of which are configured to provide the necessary logic and voting. The ESDV system has a number of inputs which are:

Open path gas detector inputs

Point gas detector inputs

Pressure detector inputs

Fire detector inputs

The following is a list of the ESDV outputs:

LP separator dump valve output

LP separator UMV A&B valve output

HP separator dump valve output

HP separator UMV A&B valve output

Sealine A&B valve output

The system logic is simple. With the exception of the smoke detector inputs, any input can cause an output shutdown individually. Smoke detectors are configured to provide 2ooN voting to reduce the probability of spurious trip. Compressor smoke detectors are not voted.

In parallel with the solid state logic which is detailed above, a Modicon PLC monitors the status of the ESDV input modules. Should input conditions demand a shutdown of any of the ESDV outputs, then the PLC is also able to initiate the shutdown. A relay is driven by the PLC whose contacts are in series with the other ESDV logic relay contacts. As such the PLC can provide increased assurance of correct shutdown without unduly increasing the probability of a fail-to-operate failure.

PSD System

It will be noted that apart from the additional I/O detailed below, the PSD and ESDV systems are virtually the same system. The only significant differences are that the ESDV system uses solid-state relay logic to drive the outputs whilst the PSD can initiate the same shutdown via software and a separate relay contact as a back-up. The PSD system also interfaces to an increased number of I/O.

The PSD system uses many of the components of the ESDV system, and monitors all ESDV inputs in addition to other inputs which are:

Workshop smoke detector input

Vesda system status inputs

Level control loops