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

Hazop Study

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

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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.” Shows how to apply the …

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Does LOPA really replace 90% of the QRA?

Does LOPA really replace 90% of the QRA?

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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 that definition of the term …

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Engine Fire

Confusion in Terminology: DOUBLE-JEOPARDY versus SIMULTANEOUS FAILURES versus COMMON CAUSE

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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. In LOPA terminology, one or …

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Well Fire

ESTIMATES of ACCIDENT FREQUENCY – Per Scenario and per Site

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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 identification and SIL determination) have …

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Hazop Study

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

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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), occur or exist at the …

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Hazop Study

HAZARD EVALUATION SCOPE versus TOOLs/METHODs for use in the HAZARD EVALUATION

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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 scope of qualitative risk evaluation …

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Process Improvement Institute course setting

Enroll in a Process Safety Course from Process Improvement Institute!

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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 have a course brought onsite. …

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The Benefits Of HAZOP

The Benefits of HAZOP

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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 fully competent and experienced PHA/HAZOP …

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Accounting for Human Error Probability in SIL Verification

Accounting for Human Error Probability in SIL Verification

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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 PLUS the probability of the …

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Chemical Tanker Piping

Failure Rates of Piping

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There is data in the new book, Guidelines for Initiating Events and Independent Protection Layers, 2015, CCPS/AIChE. (It is finally published as of January 8, 2015.) The failure rate is presented in probability of failure (due to damage mechanism such as corrosion) per meter of pipe. Two different values (for different diameter ranges) are presented for piping in non-materials sensitive …

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