Thoughts on HAZOP
I am posting after a long hiatus (blogging is for me the most difficult task to get myself motivated). After a long time I had an opportunity to be the Chairman of a Hazop Study and the excitement and satisfaction of that experience is substantially responsible for reviving this blog, and for which I have selected some random thoughts on Hazop.
Hazop Study, in addition to a review of the HAZARD and OPERABILITY of the process also serves two other important purposes:
•It offers an excellent learning session in Process Design and Engineering for rookie engineers of the EPC Company.
•It provides an excellent refresher course for the client’s operating personnel.
Both these are possible if the client participates in the process with great gusto, which unfortunately is not always the case. Many clients are content with the EPC Company carrying out the review on their own and are only interested in the getting the report that has to be furnished to bodies like the Factory Inspectorate for obtaining the required statutory approval. In this way an important learning opportunity is squandered away.
Hazop is a clinical and structured investigation of the P& I Diagram. This is done by examining each line and equipment or a cluster of lines and associated equipment, termed as ‘NODE’ (I prefer the nodal approach as it is far more elegant than the line approach) for deviation from the intent. This deviation is discovered by using a set of ‘GUIDE WORDS’ originally proposed by ICI and later augmented by others. Against each deviation, the CAUSE, CONSEQUENCE and SAFEGUARDS have to be recorded. It looks simple, but quite often engineers tend to confuse these three apparently simple concepts and this is where the stewardship of the Hazop Chairman is needed.
Another common pitfall is that many engineers discover the ‘safeguard’ first and jump to the conclusion that the ‘cause’ and the ‘consequence’ are unlikely. Here again the Chairman has to intervene and force the team to think through the process sequentially and hierarchically. The ‘cause’ for the deviation is not always easily apparent. If after some brainstorming the team fails to discover the ‘cause’ it is prudent to drop the deviation from further analysis. ‘Consequence’ is either an undesirable event or an excursion of the process parameters. ‘Safeguards’ can be of two kinds:
•a measure which prevents the ‘cause’ event
•a measure which detects or mitigates the consequence
The following would qualify as ‘safeguards’
•Alarms
•Interlocks and plant shut-downs
•Standby equipment
•Safety valves
•Appropriate choice of design pressure, temperature and material of construction
Some gray areas always crop up during every Hazop. These pertain to the maintainability, availability and reliability of the hardware, and are a separate subject in itself.
Hazop Study, in addition to a review of the HAZARD and OPERABILITY of the process also serves two other important purposes:
•It offers an excellent learning session in Process Design and Engineering for rookie engineers of the EPC Company.
•It provides an excellent refresher course for the client’s operating personnel.
Both these are possible if the client participates in the process with great gusto, which unfortunately is not always the case. Many clients are content with the EPC Company carrying out the review on their own and are only interested in the getting the report that has to be furnished to bodies like the Factory Inspectorate for obtaining the required statutory approval. In this way an important learning opportunity is squandered away.
Hazop is a clinical and structured investigation of the P& I Diagram. This is done by examining each line and equipment or a cluster of lines and associated equipment, termed as ‘NODE’ (I prefer the nodal approach as it is far more elegant than the line approach) for deviation from the intent. This deviation is discovered by using a set of ‘GUIDE WORDS’ originally proposed by ICI and later augmented by others. Against each deviation, the CAUSE, CONSEQUENCE and SAFEGUARDS have to be recorded. It looks simple, but quite often engineers tend to confuse these three apparently simple concepts and this is where the stewardship of the Hazop Chairman is needed.
Another common pitfall is that many engineers discover the ‘safeguard’ first and jump to the conclusion that the ‘cause’ and the ‘consequence’ are unlikely. Here again the Chairman has to intervene and force the team to think through the process sequentially and hierarchically. The ‘cause’ for the deviation is not always easily apparent. If after some brainstorming the team fails to discover the ‘cause’ it is prudent to drop the deviation from further analysis. ‘Consequence’ is either an undesirable event or an excursion of the process parameters. ‘Safeguards’ can be of two kinds:
•a measure which prevents the ‘cause’ event
•a measure which detects or mitigates the consequence
The following would qualify as ‘safeguards’
•Alarms
•Interlocks and plant shut-downs
•Standby equipment
•Safety valves
•Appropriate choice of design pressure, temperature and material of construction
Some gray areas always crop up during every Hazop. These pertain to the maintainability, availability and reliability of the hardware, and are a separate subject in itself.
posted by chemingineer @ 10:29 PM
0 comments
0 Comments:
Post a Comment
<< Home