Safety Requirement Specification [SRS]

Why write a SRS and IEC 61511 requirements?

Safety Requirements Specification [SRS] is the “driver document” that sets the stage for SIS Design and further lifecycle implementation including operation and maintenance.

The information in the SRS must be clear, precise, verifiable, maintainable and feasible so as to ensure that the design meets the SIF integrity requirements. Without a comprehensive SRS, it is extremely difficult to complete the SIF validation on site; in other words it is a must have document.

As per IEC 61511-1, 3.2.72, a SRS is a specification document containing the functional requirements for the Safety Instrumented Functions [SIFs] and their associated Safety Integrity [SIL] requirements.

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Our approach in writing SRS?

Writing a SRS is actually a “detailed technical task” and requires core industry experience and ability to assimilate information from a variety of input documents/drawings, correlate it with the requirements of the IEC standard and then compile it into a document [called SRS] that is actually ‘’useable’’ not only by the preparer but by anyone who is involved/ would be involved in the functional safety lifecycle.

To aid in preparation, Part-1, Clause 10 lists 29 bullet points. Each point has to be detailed while writing the SRS for the document to be meaningful rather than a copy-paste document.

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How can we help?

Our Functional Safety professionals are +18 years experienced engineering professionals (certified and competent) having a wealth of industry knowledge and experience not only in process/functional safety lifecycle implementation but in connecting domains like: project management, engineering design, control system integration, EPC, PMC, Site activities, etc…. They are well versed with good engineering industry practices that aid in considering assumptions (where appropriate) to avoid project delays while still ensuring technical correctness and completeness.

We can:

• Prepare a complete SRS document from scratch
• Review and comment SRS prepared by EPC/ engineering company/contractor/others; to ensure SRS covers all requirements as per IEC 61511
• For SIS already installed and a SRS was not prepared or for SIS installed before the release of the IEC standards; we can generate a SRS by collating data/generating necessary documents with minimal efforts at your end.
• Prepare an As-Built SRS.

Update SRS documentation based on a Management of Change (MoC). Especially in the operation phase, upon changes to main design assumptions, e.g. failure rates, test intervals, SIL requirements, response times, etc.