Chemical and Process Engineering
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A S Jessup-Bould: Process Safety in Design
Process Safety in Design (PSiD) is a method of identifying areas of a process design that warrants specific focus with respect to maximizing process safety. Each area is given the appropriate level of consideration, is documented and then subjected to independent verification during the design development. Ideally the process design should be assessed during the early stages of a project. BG standard BGA-ENG-PROC-TS-0015 provides guidance on Process Safety in Design and was used as the basis for retrospectively assessing existing BG natural gas processing facilities in Tunisia. The output from PSiD assessments are a report which includes record cards showing the findings of the review. The findings are coded according to the severity of any issues found. For the assessment of these existing facilities, verification actions are allocated a risk based action code as follows: · Code 1 – The weakness identified is such to represent a high / unacceptable risk for the asset. The resolution of this weakness requires urgent attention from the asset’s senior management team in order to develop and implement an improvement plan. · Code 2 – The weakness identified represents a significant risk for the asset and timely action is necessary to address this matter. · Code A – Design is safe and meets the required standard. The areas of the process design that the team assessed were: Philosophies For this PSiD a rationalised list of design, control, isolation, relief, ESD and other philosophies were reviewed. Relief and Blowdown This assessment comprised the following steps: · Identification of the pressure system around the relief device on the P&IDs · Identification of available information regarding the under / over pressure protection device · Identification of the potential causes of under and over pressure · Determination of the expected relief rates from the various relief scenarios · Determination of the required relief device size (independent of the contractor calculations) Andrew Jessup-Bould was approved as a competent person to work on the safety critical area of pressure relief devices. HP/LP Interfaces This was a review of the high and low pressure interface register against P&IDs. Layers of Protection This assessed whether or not the design incorporated secure layers of protection in order to reduce the risk to a manageable level. Hazard Identification As an existing asset the HazId report was not available and therefore only the HazOp report was reviewed. The review included terms of reference, identification of all documentation, appropriate size and complexity of nodes as well as completeness of node and deviation cause descriptions. The consequences were also assessed in relation to resulting deviations from intended range of normal operation and close outs checked.