The Background.

Our client selected Booth Welsh (BW) to provide a Safety Instrument System (SIS) as a part of a wider upgrade project being implemented at their Nitrous Oxide Plant.

The SIS consisted of 12 safety instrument functions (SIF’s) with a mixture of SIL 1 and SIL 2 targets, the SIFs consisted of Temperature and Pressure sensors, trips amps/relays logic solvers and valve / switchgear final elements. The BW team took on overall responsibility of realising the conceptual SIS design by preparing and reviewing the design documentation, the panel build and the site installation, testing and commissioning records.

The Client

Our client is one of the largest producers of industrial gases.

The plant is the only one in the UK that manufacturers Nitrous Oxide (N2O) for filling cylinders for medical use.

The Solution.

In order to deal with the challenge in a systematic manner BW prepared a Safety Plan to ensure compliance with IEC 61511-1 the plan addressed the approach to the various activities including management of functional safety, lifecycle planning, auditing, assessment and verification.

Design & Engineering Documentation & Activities:
  • Safety Plan including Verification Planning
  • Develop Safety Requirement Specifications (SRS) with client
  • Cause and Effect development with client
  • SIL Verification Reports for Safety Instrument Functions (SIFs)
  • SIS Design Specification
  • Detailed Design Drawings
  • Power and Heat Calculations
  • Operating and Maintenance Manual (for future Operating and Maintenance (O&M) Phase)
  • Factory Acceptance Test Specification and Testing
  • Site Acceptance Test Specification
  • Loop Diagrams
  • Installation Inspection and Test Plan
  • Inspection / Proof Test Procedures (for future O&M Phase)
  • Functional Safety Assessment (FSA) Stage 2. by Independent Third Party
Installation and Commissioning Documentation:
  • Inspection of all installation
  • Test Sheets – Cable, Earthing, Loop Testing
Safety Validation:
  • Site Acceptance Testing
  • Functional Safety Assessment (FSA) Stage 3 by Independent Third Party

The Benefits.

Booth Welsh provide single point of contact for all Functional safety related aspects:
1. Assist the client to meet their legislative, regulatory, environmental and safety obligations.
2. Provide experienced competent Functional Safety Certified Engineers with recognised qualifications (CFSE, TUV Rheinland FS Eng) with technical knowledge and skills across a variety of process industries.
3. Avoid Common Cause design errors throughout the project lifecycle.
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4. Correct Field device specification and procurement - Review of all devices to ensure product compliance.
5. SIS Panel design, build, configuration and factory acceptance testing
6. All components installed according to Safety Manual
7. Site Installation and Supervision by competent persons
8. Validation back to the original Safety Requirement Specification