exida explains Blog

Entries tagged with: IEC 61511

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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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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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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WHY are Failures Occurring at a Different Rate from Our Other Site?
  • by Ted Stewart, CFSP, exidaCSP
  • Thursday, January 14, 2016
  • Certification

WHY are Failures Occurring at a Different Rate from Our Other Site?

Site audits have shown many differences in how things are done from site to site. This impacts many variables in a safety instrumented system!

A key metric for process industry designs is called average Probability of Failure on Demand (PFDavg).  After several studies of many field failure and proof…

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Why Is Functional Safety An Important Piece of Process Safety Management?

Why Is Functional Safety An Important Piece of Process Safety Management?

It’s interesting to note that with the release of the 2016 edition of IEC61511, there’s more emphasis being placed on the need for better functional safety management.  Having taught many courses on Functional Safety over the past few years, I find that most of the…

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“Never tell me the odds”

“Never tell me the odds”

-Han Solo, Star Wars, Episode V: The Empire Strikes Back, 1980

I have enjoyed watching and reading about the actions of the fictional Star Wars character Han Solo over the years.  I recall hearing the above quotation more than once.  And as much as I enjoyed watching this character,…

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