kevin.mitchell@kenexis.com

/Kevin Mitchell

About Kevin Mitchell

This author has not yet filled in any details.
So far Kevin Mitchell has created 17 blog entries.

Systematic Safety Integrity; what you need to know.

By |2018-07-06T12:24:59+00:00July 6th, 2018|Kevin Mitchell, News, Safety Instrumented System, Services, Vertigo|

There's a lot of confusion about Systematic Safety Integrity in new IEC61511.  We are starting to see devices certified for SIS applications to have a rated Systematic Capability (SC) of 2.  What does this mean?  Is this yet another hurdle I need to jump over to meet a SIL target?  Let's shine some light on Systematic [...]

Comments Off on Systematic Safety Integrity; what you need to know.

When all your eggs are in the BPCS and SIS protection layers

By |2018-01-26T12:22:25+00:00January 26th, 2018|Arbor, Kevin Mitchell, News, Safety Instrumented System, Vertigo|

During Layer of Protection Analysis (LOPA) of high hazard scenarios, we often rely on a diversity of protections including instrumented and non-instrumented safeguards.  Invariably, we run into situations where instrumented safeguards must bear the full weight of risk reduction.  Of course, we never want to design a Safety Instrumented Function to a SIL 4 or [...]

Comments Off on When all your eggs are in the BPCS and SIS protection layers

How do I decide on the need for toxic gas detection?

By |2018-01-26T11:43:48+00:00August 10th, 2017|Effigy, Fire and Gas Systems, Kevin Mitchell, Safety Instrumented System|

We were recently asked about placing Hydrogen Sulfide (H2S) gas detectors in an area of the process where no H2S gas is normally present. Does the possibility for process upset conditions to abnormally result in the presence of toxic gas give rise to a requirement for detection? There was no way to simply answer the [...]

Comments Off on How do I decide on the need for toxic gas detection?

Do you really know the worst case for atmospheric dispersion of a gas release?

By |2018-01-26T11:43:59+00:00July 27th, 2017|Fire and Gas Systems, Kevin Mitchell, News|

Dispersion of an elevated release Often atmospheric dispersion models are needed to determine the potential for a gas release to impact workers or the public.  This is typically encountered during Fire & Gas Mapping.  There are quite a few decisions that go into a well-designed dispersion model, not the least of which are [...]

Comments Off on Do you really know the worst case for atmospheric dispersion of a gas release?

Brittle Fracture Hazards in Carbon Steel AMSE-Rated Equipment

By |2017-08-07T10:49:47+00:00January 20th, 2016|Kevin Mitchell, Process Hazards Analysis, Safety Instrumented System|

Whenever a PHA or LOPA considers a low temperature hazard for carbon steel equipment, the team examines the P&IDs and possibly the mechanical data file to find the mechanical temperature rating.  The upper temperature limit is usually shown on P&Ds with the corresponding design pressure (MAWP).  Less frequently is the Minimum Design Metal Temperature (MDMT) [...]

Comments Off on Brittle Fracture Hazards in Carbon Steel AMSE-Rated Equipment

Fire & Gas Mapping: Actual Engineering or Fancy Computer Aided Graphics ?

By |2017-06-25T19:58:12+00:00November 2nd, 2015|Effigy, Fire and Gas Systems, Kevin Mitchell, News, Products, Services|

With the relatively new and growing interest in design of Fire & Gas systems using computer-aided mapping for detector placement, these software tools are rapidly evolving.   Full disclosure here; Kenexis develops and licenses a very good software tool called Effigy™ for Fire & Gas Mapping, which is a component of the Kenexis Integrated Safeguard Suite.  [...]

Comments Off on Fire & Gas Mapping: Actual Engineering or Fancy Computer Aided Graphics ?

5 things you should know about OSHA’s latest PSM interpretation

By |2017-06-25T19:58:12+00:00September 11th, 2015|Author, Kevin Mitchell, News|

On June 8, 2015, OSHA issued a formal Letter of Interpretation regarding the application of Recognized and Generally Accepted Good Engineering Practices (RAGAGEP) to the Process Safety Management (PSM) Standard 29 CFR 1910.119.  The requirements to comply with RAGAGEP are located in subpart (d) Process Safety Information and subpart (j) Mechanical Integrity. The new information [...]

Comments Off on 5 things you should know about OSHA’s latest PSM interpretation

Advances in Design of Gas Detection Systems

By |2017-06-25T19:58:12+00:00August 21st, 2015|Author, Kevin Mitchell, News|

Designers of fire and gas systems have long struggled with the question of how many detectors are required and where those detectors should be located.  Historically, decisions about the number and location of detectors were made based on heuristics, expert judgement, or rule-of-thumb.   The first step forward in gas detector placement came in 1992 with [...]

Comments Off on Advances in Design of Gas Detection Systems

PHA/LOPA Study Findings for Separation of Basic Process Control and Safety Instrumented Systems

By |2017-06-25T19:58:12+00:00July 17th, 2015|Kevin Mitchell, Safety Instrumented System|

Recently I had a customer request Kenexis conduct SIL verification analysis on several safety functions implemented in a safety-configured, general purpose controller.  This was associated with a new capital project at the customer facility.  There was a modest SIL 1 required on each Safety Instrumented Function (SIF).  The client had previously determined the target SIL, [...]

Comments Off on PHA/LOPA Study Findings for Separation of Basic Process Control and Safety Instrumented Systems

ISO 9000 Quality Management; Operations Manager Perspective

By |2016-02-23T15:12:50+00:00May 18th, 2015|Author, Kevin Mitchell, News|

Quality has long been a priority for Kenexis. The recent implementation and accreditation of our ISO 9000 Quality Management System (QMS) has focused our attention both externally and internally, ultimately greatly improving the execution of our engineering consulting services. From an external point of view, the QMS compels us to actively pursue our customers for [...]

Comments Off on ISO 9000 Quality Management; Operations Manager Perspective

Fire & Gas System Design – Update on Status of ISA Guidance

By |2017-06-25T19:58:13+00:00April 10th, 2015|News|

Working Group 7 of the ISA 84 committee continues to make progress on the 1st revision to the ISA-TR84.00.07-2010 Guidance on the Evaluation of Fire, Combustible Gas, and Toxic Gas System Effectiveness. The TR provides informative guidance on application of the principles of ANSI/ISA 84 to the subject of Fire & Gas system design. The [...]

Comments Off on Fire & Gas System Design – Update on Status of ISA Guidance

Inspection of SIS Equipment During Function Testing

By |2015-10-01T01:04:25+00:00February 27th, 2015|Kevin Mitchell|

Recently, I was reminded by a customer of the importance of “Inspection” as part of maintenance program for Safety Instrumented System (SIS). When designing SIS, we are very concerned about the type and frequency of functional testing because this is a critical input to Safety Integrity Level (SIL) verification. However, a maintenance & testing program [...]

Comments Off on Inspection of SIS Equipment During Function Testing

Acceptable Sharing of BPCS and SIS Field Measurements

By |2017-06-25T19:58:13+00:00November 30th, 2014|Kevin Mitchell, News|

Many users of safety automation equipment employ a practice of using redundant field devices on safety-critical process measurements (e.g., level transmitters, flow transmitters, pressures transmitters, etc.). These users, who are often in the petroleum refining industry, typically use these measurements in a 2oo3 (two-out-of-three) vote to shutdown using triplicated field instruments, with this logic being [...]

Comments Off on Acceptable Sharing of BPCS and SIS Field Measurements

SIS Function Testing

By |2014-11-06T09:01:52+00:00November 6th, 2014|Author, Kevin Mitchell, News|

I recently assisted a customer in testing a newly installed Safety Instrumented System (SIS) at a Natural Gas Liquids (NGL) processing facility. The activity was a Site Acceptance Test (SAT) in which Safety Instrumented Function (SIF) is thoroughly tested. The plan involved exercising each transmitter through its range of normal operation, alarm points, and trip [...]

Comments Off on SIS Function Testing

Process Safety Milestones

By |2017-06-25T19:58:14+00:00September 22nd, 2014|Kevin Mitchell|

I recently assisted a customer in conducting risk analysis to develop a Safety Instrumented System (SIS) design. The chemical process involved storage and handling of Methyl Isocyanate (MIC), and I was reminded that this coming December will be the 30th anniversary of the Bhopal tragedy, which involved the same chemical.   Bhopal was one of the [...]

Comments Off on Process Safety Milestones

Bypass of Safety Instrumented Functions

By |2014-10-07T10:27:23+00:00August 25th, 2014|Kevin Mitchell|

Kenexis is commonly asked to assist in specifying requirements for bypassing functions the Safety Instrumented System (SIS).  Most SIS share a common Human Machine Interface (HMI) with the Basic Process Control System (BPCS).  The HMI application software typically runs on a server and communicates with both the BPCS and the SIS using a digital protocol [...]

Comments Off on Bypass of Safety Instrumented Functions

SIL 3 Requirements from LOPA, Should be Challenged Before Implementing Costly Systems

By |2017-06-25T19:58:14+00:00August 15th, 2014|Kevin Mitchell|

Recently Kenexis was asked to develop an SIS design for an NGL processing facility. The hazards were associated with operation of equipment beyond design temperature and pressure ratings of equipment including pressure vessels, distillation towers, condensers, reboilers, and pressurized liquid storage tanks. A third party conducted a hazard and risk analysis to establish target Safety [...]

Comments Off on SIL 3 Requirements from LOPA, Should be Challenged Before Implementing Costly Systems