exida explains Blog

Entries tagged with: IEC 61511

How Good Is Your Functional Safety Management?

How Good Is Your Functional Safety Management?

How the PHA and LOPA are going to affect your SIS

How the PHA and LOPA are going to affect your SIS

Both Process Safety Analysis (PHA) and Layer of Protection Analysis (LOPA) occur in the early stage of the Functional Safety Lifecycle, detailed in both IEC 61511 and IEC 61508. They both serve significant roles in the whole process safety management. Yet, as a facilitator…

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I Failed the CFSE Exam, HELP!
  • by Dr. William Goble, CFSE
  • Thursday, February 27, 2020
  • Certification

I Failed the CFSE Exam, HELP!

It is tough to receive an email with this message from a prospective CFSE candidate.  I know that when I have failed exams, I want to understand what was wrong so I can study those areas of knowledge more deeply and try again. Given the recognition and prestige…

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Is It Possible to Extend Proof Test Intervals?

Is It Possible to Extend Proof Test Intervals?

I am often asked whether extending proof test intervals will be a problem. 

This is a tricky question. The design and engineering SIL calculations for the Safety Instrumented Functions (SIFs) are taking credit for a specific proof test interval with a defined level of coverage, as defined within the…

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Make IEC 61511 into a Cookbook?

IEC 61508 and IEC 61511 are known as “performance” based standards.  Specific design rules, as found in “prescriptive” standards, are not included, allowing for innovation and new technology, as well as creativity and advancement.  However, it does imply that a certain level of competency is required.

Others would strongly…

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Mokveld Valves BV C-26 Cluster & B-137 A-B Well Platform HIPPS

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Practice Makes Perfect…Almost

How often do Managers see training budgets being cut, or personnel becoming blasé about training in general?  Isn’t it the norm that annual performance reviews involve reviewing training requirements?  Realistically, how often do these training requirements get ignored and/or forgotten about during the year?  The answer, I’m afraid, is…

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PRODUCT SPOTLIGHT: Practical SIL Target Selection - Risk Analysis per the IEC 61511 Safety Lifecycle

Realistic Failure Rate Data – Necessary

Realistic Failure Rate Data – Necessary

Reliability engineers have known for decades that realistic data must ultimately come from one source, quality field failure data for devices operating in a similar application. 

Perhaps that is why IEC 61511:2016, Clause 11.9.3 states

“The reliability data used when quantifying the effect of random failures shall…

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Reducing Project Lifecycle Cost with exSILentia®
  • by Kate Hildenbrandt
  • Wednesday, January 18, 2017
  • Software

Reducing Project Lifecycle Cost with exSILentia®

The international functional safety standard IEC 61511 provides the safety lifecycle as a steadfast guideline to assess and mitigate risk for manufacturing processes including refineries, chemical, petrochemical, pulp and paper, and power plants. To achieve a functionally safe system, it is essential to follow each…

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Risk Management in the News

Risk Management in the News

I just read a great article in the May issue of IEEE Spectrum magazine called “Managing Risk and Responsibility During a Crisis.”  The author Robert N. Charette says “If the American people desire the federal government to be their risk manager of first resort, then an open and…

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Safety Requirements Specifications (SRS):  The Good and the Bad

Safety Requirements Specifications (SRS):  The Good and the Bad

The IEC 61511 Standard requires the user to create a Safety Requirements Specification (SRS) for a Safety Instrumented System (SIS) that incorporates all the analysis done during the Risk Assessment, HAZOP/PHA and LOPA reviews.  The SRS falls into two types: an initial conceptual SRS, often referred to as the…

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Setting Goals for 2019: Are You Thinking About Functional Safety?

Setting Goals for 2019: Are You Thinking About Functional Safety?

When I went to set my goals for 2019, I set both personal and professional goals. One of my professional goals is to clean off my desk, but another is to get more people to think about functional safety before an accident occurs, instead of when they are normally…

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Share the Wealth (of Functional Safety Knowledge)

Share the Wealth (of Functional Safety Knowledge)

Experience is a good teacher.  But how do you get the experience?  

Formal classroom or online training is often available for more general skills, but on-the-job training usually provides a more in-depth path to gain such experience.  After doing a job for a while, working through difficulties with colleagues,…

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Site Safety Index™ (SSI) – A Simple Model for Site Variations in Safety
  • by Dr. William Goble, CFSE
  • Monday, April 11, 2016
  • Certification

Site Safety Index™ (SSI) – A Simple Model for Site Variations in Safety

In several of our technical papers over the years, we have noticed that failure rates for the manufacturer, model number are different at different sites, even when the processes were quite similar.  When I have mentioned this to end users and manufacturers, often the response is “Yes, I have…

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Still Using Excel to do PFD Calculations?
  • by Steve Gandy, CFSP
  • Monday, April 28, 2014
  • Software

Still Using Excel to do PFD Calculations?

It’s very interesting to me to find that people are still using excel to do PFD calculations.  Whereas this is probably okay for simple single element architectures (i.e. single sensor, single logic solver and single final element), it becomes extremely complicated when dealing with redundant architectures.  Moreover, for performing…

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Ten Years Later
  • by Steve Gandy, CFSP
  • Wednesday, February 19, 2014
  • Certification

Ten Years Later

It’s hard to believe that the IEC61511 standard has been in existence since 2003, and most companies operating in the process, chemical, and refining industries (or any other hazardous process manufacturer) have adopted its practices.  It’s also significant that any plants that were built back then with a…

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The Architectural Constraint Blind Side
  • by Denise Chastain Knight, P.E., CFSE, CCPSC
  • Thursday, August 27, 2015
  • Certification

The Architectural Constraint Blind Side

I did my homework, purchased certified devices, and specified physical redundancy. I expected an uneventful SIL Verification but the assessor is telling me that I have functions failing Architectural Constraints in the sensor and final element groups. How can that be? 

Low demand mode Safety Instrumented Function (SIF)…

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What is Competency Anyway?

What is Competency Anyway?

I’ve been following some discussions from one of the online forums regarding competency and it’s clear from the correspondence that the issue of competency is still very subjective.  It made me think about “what is competency?” To me it’s a blend of knowledge and experience and just how well…

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Which FSAs Do I Have to Perform?

Which FSAs Do I Have to Perform?

The new release of IEC61511:2016 has caused some confusion when it comes to the Functional Safety Assessments (FSAs). Which ones are mandatory?

The confusion comes from the wording in the standard and the clarifications in the notes. The relevant clause in the standard 5.2.6.1.4 states:

A FSA team…

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