Talk:Hazard and operability study

Major Edit
Putting this here because I intend to do more than a minor edit.

"The Hazop team then determines what are the possible significant Deviations from each intention, feasible Causes and likely Consequences."

...is reasonable...

"They then propose possible modifications to the design to remove or reduce the risk of the deviation or reduce the consequences."

Not if you want the HAZOP completed in anything like a reasonable time they don't. Rule 1 in HAZOPs I lead is that the HAZOP is NOT a design meeting. Unless the corrective action is obvious, simple, and agreed immediately by all parties, the proper course is to record the problem and give an action to the designer to address it, OUTSIDE the HAZOP meeting.

"A Hazop meeting is generally scheduled for 3 hours."

Ridiculously specific, so I intend to remove it.

"For a medium-sized chemical plant where the total number of items to be considered is 1200 (items of equipment and pipes or other transfers between them) about 40 such meetings would be needed"

Hard to understand where this comes from. These numbers seem entirely arbitrary and therefore somewhat useless, as though defining the length of a piece of string. Again, I intend to remove for this reason. —Preceding unsigned comment added by 212.188.147.34 (talk) 12:58, 18 November 2008 (UTC)


 * I generally agree with your observations and stated intentions. I also agree that a HAZOP is not a design meeting, but there is usually an opportuninty to record, not possible design modifications, but a condition or circumstance for which further protection is required.  I've also found it helpful to require that the team explicitly answer "Yes"" or "no" to the question of whether the existing protection is adequate.  If they say "YES" than they are not permitted to call for additional protection.  I found many teams wanted to say "Yes, but..."  Finally, while "3 hours" may be ridiculously specific, I've found shorter meetings to be too short to really get going on a system with any reasonable amount of complexity. Pzavon (talk) 03:02, 19 November 2008 (UTC)


 * I have restored the statement about 3 hours and size of plant. This is referenced to a study of 25 years of Hazops by notable experts in the field.Chemical Engineer (talk) 13:37, 3 January 2009 (UTC)

Recent changes
I visited the entry in following up why a passing link to HAZOP was red-linking, and had a number of issues Hence the changes - apologies for not posting their justication contemporaneously with making them Rjccumbria (talk) 23:03, 4 July 2014 (UTC)
 * the entry referenced the BS but went on to describe HAZOP as having a systematic approach based upon applying guidewords to parameters. The BS carefully explains that there are 2 possible systematic approaches (a) considering each 'element' in turn and applying each guideword in turn to that element   or (b) considering each guideword in turn and applying it to each element.  It does not describe a parameter-led approach.  One of its examples has clearly been produced by a parameter-led approach (and I do recognise the approach as looking much like HAZOP 1; which seems to me to be a HAZOP methodology even if the BS says a ‘HAZOP 1’ is now not a HAZOP ), but the article should not be written as though there is only one way to do HAZOPs (especially when the way described is not one endorsed by the BS)
 * the article talked of 'design intention' when the term of the trade (certainly the one used by the BS) is 'design intent' and gave examples which seemed to me in grave danger of leading the unwary reader to think design intent is much the same as 'intended duty' - careful reading of the BS will show that it is not
 * the BS notes both the need for a good quality discussion and for a systematic approach but the article concentrated (or so it seemed to me) on the formalism/systematicity of the approach as ensuring completeness of coverage with quality of coverage being taken as a given (hopefully not as unimportant)
 * (for example), the BS talks of the need to choose guide words appropriate to the specific study being undertaken and then gives an example of a (fairly) generic guide word set; the article would have led the unwary to think the guide word set was laid down by the BS
 * the team member role 'Specialist' had been edited to 'Human Factors Specialist' with no recognition that any other sort of specialist could exist or might be needed to attend (there are, I fear, HF specialists who take much that view)


 * As a further general remark, the BS and the article are keen on saying 'how HAZOPs should be done' but


 * 1) that involves a hefty slice of revisionist redefinition; a bit like saying that football is only football when it is 11 v 11 for 45 minutes each way on a regulation size pitch
 * 2) HAZOPs are part of a larger process, and it may from time to time be the case that an inefficient HAZOP is a price well worth paying for overall efficiency in the process (eg where a modification could have knock-on effects on a downstream plant a representative of that plant may have nothing to contribute but will want to attend to make sure their plant is given fair play) Rjccumbria (talk) 23:16, 4 July 2014

History
There is a missing part in the history: Mr R. Ellis Knowlton of Chemetics Internationnal wrote and published the first guide to the method in 1975. It was published in England. Having moved to Canada, He reviewed and adapted the publication to America in 1981. The title is: "An Introduction to Hazard and Operability Studies, The Guide Word Approach" He gave introduction sessions to Engineers across Canada. WKPROBERTB (talk) 01:41, 2 May 2016 (UTC)

Revision for clarity
I've attempted to clarify this section but I'm very aware of my limitations, both with HAZOP and Wikipedia, so my apologies if I have taken the 'wrong' approach.

I removed the example relating to design intent as it had little relevance to the topic and was potentially confusing. — Preceding unsigned comment added by Jcaiken (talk • contribs) 22:43, 25 May 2016 (UTC)

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Minor edit for Guideword Interpretation
Hello, I swapped the two cell values in the second table from the section "Guidewords and parameters" for the application of the guidewords "As well as" and "Part of" on the parameter "Time". It makes really more sense to interpret the "As well as" guideword as an extra action and "Part of" as a missing one. I verified from the sourced document "HAZOP: Guide to Best Practice (3rd ed.)." if this table is presented but it seems to be an inedit work. Cheers,81.220.111.183 (talk) 18:48, 8 April 2024 (UTC)