Gas Detection System for a Jack-up Drilling Rig.
Uniting Redundancy with Reliability in Sleek Packaging
Monitor Systems have recently delivered an upgraded Gas Detection System for a Jack-Up Rig off Western Australia. The new system connects to the 42 existing combustible gas and H2S sensors throughout the rig.
Client Requirements
The existing Gas System on-board was obsolete, with the inability to reliably source spare parts and several non-conformance's with DNV and MODU requirements.
Monitor Systems were approached to engineer and build a replacement system which meets the current regulatory requirements and could guarantee system availability well into the future.
Three HMIs were required for the system. One built directly into the process enclosure and another for the OIMs office. The third HMI for the driller was built suitable for installation in a zone 2 hazardous area.
The new system, with the enhanced redundancy and functionality was to fit inside the existing envelope from the obsolete system.
Robust Compliance
To meet the stringent DNV requirements the entire system was provided in a redundant configuration from the PLC all the way to the IO connection.
The PLCs and High Feature IO racks were connected in a ring configuration with a managed fibre SCALANCE switch using MRP - Media Redundancy Protocol to IEC 62439-2.
Enhanced Functionality as Standard
Where the previous system displayed a list of detector alarms the visualisation of the new system was substantially improved via the use of additional graphics for showing detectors in position over rig layouts for easy identification of areas in alarm.
Siemens standard library blocks for redundancy are used on the software side of the CPU to ensure the integrity of the field signals. First, the input parameters are checked for the correct value ranges to prevent any action starting with invalid values. The IO are then checked for validity, and only then is any operation or process implemented. Reducing the risk of false trips due to implausible signals.
A secure remote access SCALANCE is provided with the system for remote support when required. This, when enabled by the rig crew, allows a Monitor Systems Engineer to access the system via a secure Siemens SINEMA server from our headquarters in Aberdeen or anywhere in the world.
Alex Burgess - Senior Project Engineer commented - "We have implemented a substantial amount of redundant and fault tolerant CPUs over the past several years however those which include redundant IO are reserved the most safety critical applications, this recent project shows Monitor Systems commitment to raising our own high standards to meet, and wherever possible exceed, industry requirements where it can improve safety and operational efficiency."
Engineered for Ease of Installation
The process enclosure was designed so as to simplify the installation works required on-site. Allowing for a swift upgrade with minimum downtime.
All new enclosures were designed to fit into the areas available without modifications to the room structures or surrounding enclosures.
