Safety Instrument System Audit of Coal Ship Loader
||The Port of Gladstone is one of the world's top five coal export ports, handling in excess of 38 million tonnes of coal per annum. Coal is the port's largest trade, representing over 70% of the total cargo exported through the port. R G Tanna Coal Terminal (RGTCT) consists of three shiploaders and handles 40Mtpa.
||The client brief was to provide an audit of the installed Safety Instrumented System (SIS) on Ship Loader no 3. From the audit results a practical way forward to bring the Shiploader and in particular the SIS up to appropriate standards was developed and implementation assistance was provided.
The implementation of the control system and the SIS on shiploader no 3 had already been designed and implemented by the time SYNERTEC was engaged.
The design included multiple Risk Assessments, Safety Audits and HAZOPs. Functional descriptions, drawings and other design documents were available together with the PLC and PILZ code.
The first step was a thorough analysis of the documentation provided to produce a cross reference of those risks that were to be reduced by the SIS and also produce a list for confirmation of those risks that had other methods of protection such as guarding. A gap analysis of the requirements and known implementation was performed and rectification of missing system initiated.
The second step was to audit the implemented system to ensure that the designed system met the safety requirements of the HAZOP/Risk Assessments. This was to ensure, for example, that systems deemed to require Category 4 rating had been designed and implemented to Category 4 requirements.
This audit covered the entire loop from:
- Field Sensor / Actuator
- Field Cabling
- Safety PLC
- Safety PLC logic
- On-going Maintenance procedures
The last step in the audit was to go through the testing/commissioning records to determine if correct testing had been performed on the system.
A GAP analysis for all of the above steps was undertaken to determine what additional work needed to be performed to ensure that the safety system met appropriate Australian Standards. In particular AS 4024 Safety of Machinery and AS61508 Functional Safety of Electrical\Programmable Electronic Safety Related System.