Process Improvement Institute Blog – news related to process safety, process reliability, and human reliability

/Process Improvement Institute Blog – news related to process safety, process reliability, and human reliability/

Black Swans or Wild Geese?

The term Black Swan is certainly over-used. We did a study a couple of years ago on 50 major process safety events over a 25 year span. Of those, none were black swans... but, some in the industry (some managers & process safety speakers) referred to them as black swans... "how could we have known?" [...]

By | May 4th, 2016|PHA|0 Comments

New Papers in Free Resources on Identifying SIF-SIL as part of PHA/HAZOP, PHA of Non-Normal Operation Modes, and Writing Operating Procedures and Troubleshooting Guides

Just posted in the Free Resources section of the Process Improvement Institute website are three new and invaluable papers related to issues important to process safety management professionals everywhere: Identify SIF and Specify Necessary SIL, and other IPLs, as part of PHA/HAZOP Learn why it is not necessary to “Boldly Go Beyond HAZOP and LOPA.” [...]

By | April 22nd, 2016|HAZOP, PHA, SIF, SIL|0 Comments

Does LOPA really replace 90% of the QRA?

Well, that depends on what you call QRA. Some companies (the folks they have taught) define QRA as only the high level risk assessment that may be performed at the early design phase of a project to make large siting and fire protection (and other mitigation) decisions. LOPA does not replace that specific QRA. But [...]

By | August 26th, 2015|CCPS, HAZOP, LOPA, PHA, QRA|0 Comments


In the world of HAZOP/PHA, double-jeopardy (D-J) is defined as a scenario where two independent causes exist at the same time. One Cause (in LOPA terms, one Initiating Event) can occur in time much earlier than another, and not be corrected or maybe not even discovered. Then a second cause occurs and the scenario progresses. [...]

By | August 14th, 2015|Double-Jeopardy|1 Comment

ESTIMATES of ACCIDENT FREQUENCY – Per Scenario and per Site

Do Not believe the math as black and white or as accurate. When we accept a risk of 10-3 per year per facility, we are not necessarily saying we accept 1/10 deaths per year for the facility... we are actually guessing at both factors. 1) The factors we use for LOPA (and for SIF need [...]

By | August 14th, 2015|LOPA, PHA, SIF|0 Comments

Is Consideration of Double-Jeopardy valid in PHA/HAZOP Discussion?

Double-jeopardy (D-J) is NOT an independent protection layer (IPL) failure after an initiating event (IE). All PHA/HAZOP scenarios are of the type of: IE occurs, then IPL 1 fails, then...., leading to Consequences. However, the definition of double jeopardy (D-J) is when two initiating events, which are independent (or we had hoped they were so), [...]

By | August 13th, 2015|Double-Jeopardy, HAZOP, PHA|0 Comments


We use the terms of tool and method interchangeably. Methods/tools include HAZOP of continuous mode, HAZOP of steps for non-continuous modes of operation, What-if, Checklist. The scope and goals establish the Qualitative Hazard Evaluation that you need to accomplish using one or more of these tools/methods. So, a Process Hazard Analysis (PHA) is a specific [...]

By | June 29th, 2015|HAZOP, PHA|0 Comments

Enroll in a Process Safety Course from Process Improvement Institute!

Process Improvement Institute, Inc. (PII) has 15 experts on staff (each with over 25 years of industry experience; including 10 to 35 years of process safety experience) who teach PSM, PHA Leadership, MOC, LOPA, Procedure Writing, and other specific courses on process safety, as well as Human Factors. You can attend publicly available courses or [...]

By | June 15th, 2015|Human Error, OSHA, PHA, PSM|0 Comments

The Benefits of HAZOP

The HAZOP method is pretty good, if done right. IF you apply it to continuous mode correctly using nodes and all applicable deviations, and adding loss of containment deviation for damage mechanisms; and then if you apply it separately to analyze deviations from steps in startup, shutdown, and online maintenance; and IF you have the [...]

By | June 15th, 2015|HAZOP, PHA|0 Comments

Accounting for Human Error Probability in SIL Verification

One critical defect in the SIL standards (and technical reports from ANSI/ISA 84 committees) to remember is they do NOT account for specific human errors of mis-calibration (especially critical for SIFs with multiple sensor) and or leaving in bypass. So, the PFD to use for the IPL is the PFD(avg) from the SIL verification calc [...]

By | May 19th, 2015|Human Error, SIF, SIL|0 Comments