RISK & RELIABILITY

JRB assists the operating companies and engineering designers in implementation of Safety Instrumented System as per IEC 61508/ 61511. SIS implementation will be carried out by the team led by Certified Functional Safety Expert.

The objective of SRS is to specify the requirements for each SIS, in terms of the required Safety Instrumented Functions and their associated safety integrity, in order to achieve the required functional safety. The SRS will become the main reference source of information for the initial design of the system and to validate that all of the requirements have been satisfied at the completion of the project.

As part of the SIS detailed design, SIL verification needs to be performed. The SIL verification shall calculate the Probability of Failure on Demand (PFD) for the Safety Instrumented Functions. The following quantitative techniques are applicable for verifying that the Safety Integrity Level is achieved:

• Fault Tree Analysis;
• Markov Modeling.

The SIL shall be verified by the application of Fault Tree Analysis or Markov Modeling Techniques. Markov Modeling Technique is the preferred method considering that these models provide the most accurate analysis. Internationally reputed software tools such as exSILentia, Isograph will be used for SIL verification. The SIL verification will be performed by Functional Safety Consultant with CFSE certification, trained in LOPA analysis.

SIL validation

SIS safety validation refers to all necessary activities to validate that the installed and mechanical completed/ commissioned SIS and its associated Safety Instrumented Functions, meets the requirements as stated in the Safety Requirement Specification. Validation includes study of all documents, review of SIS certificates, validation of SIS at site, preparation of pass/fail certificate etc.

Functional Safety Assessment & Audit

The primary purpose of the FSA is to judge the functional safety of SIS (i.e. after an initiating cause initiates or begins propagation of a hazard, the ability of SIS functions to take the process to safe state or to avoid the hazard) and hence scope of FSA study includes the SIS covered under the scope of the project including the vendor packages. Only items in IEC 61511 that directly affects the functionality of SIS will be considered for FSA. FSAs may be performed in 5 or more stages as per IEC 61511-1: 2004 section 5.6.2.1 with the stage 3 FSA ( i.e. After SIS installation, pre-commissioning and final validation, and operations and Maintenance procedures have been developed and before commissioning) being mandatory. FSA will be conducted through interviews, document reviews and workshops by an experienced functional safety consultant with CFSE certification assisted by a scribe.

The primary objective of the SIS audit is to determine whether SIS procedures, activities and documentation comply with the planned arrangements and are implemented effectively. The Audit determines whether the item exists but does not necessarily ascertain its functional effectiveness. The objective of the activity also includes the verification of compliance of facility SIS to the IEC 61511 clauses. SIS audit is carried out after 3 years of operation and thereafter, once every three years. Audit will be carried out through interview, document review and site inspection.

Reliability

Reliability, Accessability & Maintainability (RAM) studies

• The main objectives of the RAM study are, to estimate the unavailability and fractional loss of production capacity due to failures of equipment and extreme events, and where possible, to propose improvements which will help to reduce unavailability.
  

Performance Standards for Safety Critical Element/ HSECES