Not Considered items in Hazop study??

[reena1957]

Friends,
I recently came across a HAZOP study which included the following in NOT CONSIDERED list:
1. Failures of Manual valves
2. Operator Error
3. Passing of NRVs and PSVs
Is it OK?
Pl give your views.
Thanks in advance.

 

[GregLamberson]

reena1957

The idea of a HAZOP is to identify hazards and risks to a system. To specifically list the 3 hazards/risks mentioned indicates there was some sort of thought process that went into it, I don't understand what it was. Perhaps they were covered under a separate risk assessment, but if so it would have been prudent to note.

A HAZOP, risk assessment, constructability review and other similar processes will only provide optimum results if the proper personnel are gathered to do them. Garbage in = Garbage out.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[EmmanuelTop]

Hello reena1957,

As far as I know, the failure of manual valves should always be included in HAZOP scope. Operator errors is quite a bit large area for risk analysis and is usually carried out separately - mostly included in extended plant operating manual, incidents & near misses worksheet or some other type of risk assesment. For NRVs and PSVs issues I cannot recall they were being part of HAZOP risk items.

Regards,

http://antwrp.gsfc.nasa.gov/apod/astropix.html

 

[gkennedy34]

My non-HAZOP-expert experience is that PSVs or other relief devices are not considered in the HAZOP methodology. They would be listed as a HAZOP recommendation when it is determined there is a loss of mechanical integrity. Manual valves would be failed "open or left open, human error" or "closed or left closed, human error" depending on their normal position. So, yes, we consider manual valves and also human error (unless your operators are of a different species).

 

[GregLamberson]

reena1957

There are several sources that address HAZOP's - API 750, Management of Process Hazards; the AIChE-CCPS book,
Guidelines for Hazard Evaluation Procedures; and OSHA 29
CFR 1910.119. Also API 580, Risk Based Inspections.

There are also other methodologies besides HAZOP's that are used to achieve quantitative risk assessments - Failure Mode & Effects Analysis (FMEA), and Fault Tree Analysis. And there are just standard design risk assessments.

That is why I mentioned above that because those items were specifically mentioned as not being addressed by the HAZOP, chances are they were addressed by another means.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[BenThayer]

could they have been possibly been "not considered" as in addition to the primary cause?

there is sometimes quite a bit of debate in HAZOP's of what constitutes "Double Jeopardy" and perhaps this is what is referenced.

if it is a HAZOP that is worth its salt, it should have the names of those involved and you should ask them.

 

[MedicineEng]

I agree with teh others. Unless it is clearly stated the reasons why these 3 items were not considered (and frankly I can only see the reason of being adressed in other separte studies), I don't think that it is acceptable to have an HAZOP without counting with human error and valve failure factors.

 

[JLSeagull]

Any process hazardous analysis only catches the items identified by the attendees. Sometimes a facilitator will flag some ideas not raised. Experienced operating and design personnel are essential. Nothing should be taken off the table. However, it is very easy to miss things not listed on a checklist.

 

[shahyar]

"Operating error" is part of HAZOp but not sabotage.

 

[GregLamberson]

shahyar

Sabatoge should be covered under a security risk assessment.

Greg Lamberson, BS, MBA
Consultant - Upstream Energy
Website:

http://www.oil-gas-consulting.com

 

[BigInch]

These should be considered, but are often not when the failure of any one would automatically revert to a shut-down initiation sequence (SDS). In such a case it only must be assured that failure of those devices will indeed activate the SDS and that the operation of the devices utilized in the SDS are evaluated.

http://virtualpipeline.spaces.msn.com

"We can't solve problems by using the same kind of thinking we used when we created them." -Albert Einstein