Compliance to the international Standards such as IEC 61508 and IEC 61511 are imperative to meeting the Functional Safety requirements for many processes and have formed part of the quality management systems of many companies. Provision of Functional Safety Services in line with the Phases and Activities detailed in the Safety Life-cycle is an area in which our consultants are able to demonstrated experience and expertise.
Process Hazard Assessment
We can provide Process Hazard Analysis (PHA) and HAZard and OPerability (HAZOP) study chairpersons. Our expert PHA facilitators hold certification in conducing HAZOP, HAZAN and CHAZOP.
Function Safety Assessments
We can provide independent Functional Safety Assessments to judge if the functional safety and safety integrity has been achieved by the Safety Instrumented System in accordance with IEC 61511.
Safety Requirements Specification
We can produce conceptual and detailed Safety Requirement Specifications based on well-established templates traceable to the requirements of IEC 61511.
Quantitative Risk Assessment
We can calculate risk quantitatively by demonstration of IRPA, PLL and carry out cost benefit analysis for assessment of High Integrity Protection Systems (HIPS).
We can provide SIL Determination studies using the following techniques; Risk Graph (including extended Risk Graph), Risk Matrix, Layer Of Protection Analysis (LOPA) and Fault Tree Analysis (FTA). We consider ourselves experts in the application of quantitative and semi-quantitative SIL Determination studies (FTA/LOPA) and have accumulated a significant database of equipment failure rate.
We can verify the capability of a Safety Instrumented Function (SIF) in accordance with IEC 61508 and IEC 61511 against the Quantifying the effects of random hardware failure, Hardware safety integrity architectural constraints and Systematic capability. These assessments can be carried out using the FSCL configured spreadsheet or exSILentia software package.
SIS Conceptual Design
Selecting the correct equipment and architecture are key requirements to ensure Functional Safety and reliability targets are achieved. We can carry out Safety Instrumented System (SIS) conceptual designs, selecting appropriate equipment based on integrity and functional requirements.
Operation and Maintenance
We can carry out review studies and provide consultancy to ensure Functional Safety requirements are maintained during Operation and Maintenance. Including proof testing, Management of overrides, Recording failures and demands and Management of change.
Functional Safety Lifecycle / Management
The Functional Safety Lifecycle is one of the two concepts of IEC 61508 and IEC 61511 (the other being Safety Integrity Levels (SILs)). This is a key requirement demonstrating how Functional Safety is to be implemented and achieved. Functional Safety Management relates to how Functional Safety requirements and procedures are implemented during a project. We can provide assistance or create and maintain in its entirety a Functional Safety Lifecycle and Management requirements for clients in accordance with IEC 61511.
One area of confusion for many clients is in understanding their requirements for existing Safety Instrumented Systems (SIS) that were not designed in accordance with IEC 61511. ProSIS can review the existing system and identify any areas for improvement to demonstrate compliance with the “Spirit” of IEC 61511. We have considerable experience in this area and provide practical solutions with a focus on applying appropriate levels of rigor.
IEC 61511 requires devices that make up a Safety Instrumented Function (SIF) to be either, assessed against the requirements of IEC 61508 or against the requirements of “Prior Use”. Many facilities utilise equipment that is used in both Safety and Control functions and the operator has gained experience and confidence in these devices. In these circumstances Prior Use may be considered a more suitable (and logical) alternative to replacing these devices for IEC 61508 assessed items of which the operator has no experience. We can carry out Prior Use assessments of sensing elements, logic solvers and low complexity devices such as solenoid valves, actuators, valves and relays. A key requirement of Prior Use is recording and analysis of failures encountered during operation, if necessary we can assist in putting in place a strategy to achieve this.
Proof Testing is one of the main requirements to ensure the Functional Safety is maintained throughout the operational phase. We can provide complete proof testing strategies including the creation of detailed proof testing procedures. Our proof testing strategies includes consideration of the following factors: • Proof testing frequency; • Proof testing coverage (traceable to values claimed in the hardware reliability assessment (SIL verification)); • Minimising process disruptions through implementing partial/part proof testing; • Information provided in equipment manufacturers IEC 61508 safety manual; • Methodology for the reporting of failed/incomplete tests.