HAZOP.
By Manoj Kumar( HSE Professional).
( hseguru@yahoo.in / +91-8252771261).
The Hazard and Operability (HAZOP) study is a structured and systematic
assessment of a complex system, (such as process facility) in order to identify the
hazards that can cause potential danger to Personnel, Equipment, Environment,
as well as system operability. HAZOP study is considered as primary hazard
identification tool in Process safety industry.
Objective Of HAZOP Study
The primary objective of the HAZOP study is to identify and
evaluate Health, Safety and Environment( HSE) hazards caused by
Process deviations/System failures/Human error. It also helps in identifying
operability issues which, are not potentially hazardous, but can
compromise the plant’s ability to achieve its design intent and productivity.
The secondary Objective of a HAZOP study is to identify the deviations and
make sure that there are control panels in place to protect the process.
Importance of HAZOP in Oil & Gas Industry
The Oil and Gas industry is a high-risk industry, with potential risks that can
cause significant damage to Personnel, Equipment, & Environment. HAZOP
analysis is thereby a valuable tool for risk management and risk assessments in
the oil and gas industry.
Here’s how HAZOP analysis can be used to improve risk management in the oil
and gas industry:
Hazard Identification in new and existing processes: HAZOP analysis
can be used to identify potential hazards in new and existing systems, such
as pipelines, processing plants, and drilling rigs. This information can then
be used to develop risk assessments and risk mitigation strategies.
Evaluating the adequacy of safety controls: HAZOP analysis helps
evaluate the adequacy of safety controls in place to prevent and mitigate
risks. This information can be used to identify areas where safety controls
need to be improved.
Improving the design and operation of processes and systems: HAZOP
can identify design and operational improvements that can reduce the risk
of accidents. Example, a HAZOP analysis might identify the need to add
additional safety controls, Modify the existing design of a process or
system, or develop new operating procedures.
HAZOP study in chemical plant
HAZOP Study determines the Process Hazards which may incur sufficient damage
or injury if not appropriately controlled. It is also used for determining
equipment failures that would result in process failures or accidents inside the
Plant which is being examined during a HAZOP Study. A HAZOP analysis is
applicable to any level of an organization from a small Unit process to entire
Plant
HAZOP study procedure is applicable to every definite operational sequences in
planned and existing systems. HAZOP Analysis is most effective when held during
the conceptual design stage in which recommendations impacting the general
design may be fabricated.
HAZOP & HAZID Difference:
HAZOP is a more structured and systematic technique. It typically involves a
team of people with expertise in the process being studied using a set of
guidewords to identify potential deviations from the intended design or
operation. The team then assesses the severity and likelihood of each deviation,
and develops recommendations for mitigating those hazards.
HAZID (Hazard Identification) is a less formal and structured technique. It
typically involves a team of people with expertise in the process being studied
brainstorming potential hazards. The team then assesses the severity and
likelihood of each hazard, and develops recommendations for further evaluation.
HAZOP Methodology
The HAZOP technique consists of a systematic analysis of the design in order to
assess any
operability problems or process-related hazards. The HAZOP Review is developed
reviewing
each P&ID using a structured step-by-step approach that allow to
comprehensively analyses
the whole process via suitable guidewords, used to identify credible deviations
from the design intent.
The method detects hazards and provides likely accident sequences that could
occur as a result of these hazards; innovative thinking then identifies the impacts
of these situations.
HAZOP Basic Rules and Assumptions
The following ground rules were set before proceeding with the HAZOP Session,
and the HAZOP Chairman presented a summary at the start of the first day of the
workshop:
Equipment has been designed with adequate design envelopes for start-up,
operation and shutdown;
Equipment is designed and installed as per installation code requirements;
Equipment and instrumentation are selected and installed compatible to
local conditions;
Double jeopardy’ failures are not considered. Common mode failures are
assessed as they are considered a ‘single jeopardy’ failure;
Flange/gasket leakages are not considered as a cause;
Spontaneous pipe or vessel rupture is not considered as a cause;
Single check valves are not generally considered an adequate safeguard
against a hazardous backflow on their own; nevertheless, since they
provide mitigation against it, they have been recorded as safeguard, when
present;
Minor changes to the P&IDs will be noted clearly on the master P&IDs in
red pen, instead of recording as a recommendation at each occurrence;
however, when the change is deemed to be significant, this will be also
recorded in the HAZOP log sheets;
Prolonged & side discussion shall be avoided. The objective is to identify
potential hazards not to design them out during the workshop; when
disagreement arises, a recommendation will be issued;
Time will not be spent on finding solutions, unless solution is obvious;
Sections of the existing plant will not be considered in detail; only impacts
to/ from the new Project facilities to these sections will be assessed.
