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These guidelines are not intended to be a comprehensive manual on all aspects of conducting PHA studies. Rather they are intended to describe in general terms the activities and personnel responsibilities necessary to prepare for, conduct, and document a PHA study for a typical ammonia refrigeration facility.
A common methodology used for ammonia refrigeration systems is the What-If/Checklist technique. This technique is both efficient and effective in identifying potential hazards in the system and is one of the methods acceptable in the PSM regulation. The primary advantages of the What-If/Checklist technique are that it is relatively easy to use and very flexible. A potential disadvantage of the What-If/Checklist technique is that the results of a What-If/Checklist analysis will very dependent on the experience and the thoroughness of the team leader and the team.
The scope of the process hazard analyses should clarify the equipment, procedures, and modes of operations that are to be considered during the study. Typically, the analysis will focus on normal (steady-state), start-up, and shutdown operating procedures. Utility systems and equipment, such as cooling water or instrument air systems, are usually handled implicitly during the study, i.e., they are considered only as they affect the causes, consequences or safeguards of any What-If scenarios reviewed. Any need for a more detailed review of a particular utility system is noted in the study recommendations as a possible separate study.
The What-If/Checklist method involves experienced personnel posing a series of What-If questions for each part of the facility. The What-If questions evaluate the effects of equipment failures, human errors, or external events on the operation of the system. What-If questions are often taken from previous studies or structured checklists to insure consistency, but will not be limited in any way and will be open to cover any process safety concerns.
The success of a What-If/Checklist study is highly dependent upon the thoroughness of the list of What-If questions posed. Typically, the team leader will prepare an initial list of What-If questions prior to any team meetings. Existing checklists can be used to obtain some pertinent questions to get the study started. Alternatively lists of questions from previous studies may be used, or the team can brainstorm questions at the outset of the study. The What-If/Checklist process is dynamic; as one question is asked other questions will occur to the team. These questions should be documented as they occur for later consideration.
Use these Process Hazard Review Questions to help identify potential hazards. Answer each question fully, not with a simple “Yes” or “No.” Some questions may not be applicable to the review of a particular process; other questions should be interpreted broadly to include similar materials or equipment in your facility. Consider the questions in terms of all operating modes (e.g., steady state, startup, shutdown, maintenance, and upsets).
The What-If/Checklist method involves experienced personnel posing a series of What-If questions for each part of the facility. The What-If questions evaluate the effects of equipment failures, human errors, or external events on the operation of the system. What-If questions are often taken from previous studies or structured checklists to insure consistency, but will not be limited in any way and will be open to cover any process safety concerns.
The success of a What-If/Checklist study is highly dependent upon the thoroughness of the list of What-If questions posed. Typically, the team leader will prepare an initial list of What-If questions prior to any team meetings. Existing checklists can be used to obtain some pertinent questions to get the study started. Alternatively lists of questions from previous studies may be used, or the team can brainstorm questions at the outset of the study. The What-If/Checklist process is dynamic; as one question is asked other questions will occur to the team. These questions should be documented as they occur for later consideration.
Once the anticipated number of team sessions has been determined, a tentative schedule for the sessions should be prepared. The schedule should be circulated to the proposed team members. This will allow the team members to schedule their time appropriately or to alert the team leader of any known scheduling conflicts.
Equipment failures include deviations in the operation or performance of equipment from its design intent. This includes items such as vessel or line failures, leaks, pump failures, or instrumentation failures. Human error may include the failure of an operator to perform a required specific function or performing it incorrectly. Human error may also include incorrect maintenance practices, or for example, incorrect set points entered into a computer control system. External events includes items such as loss of electricity, a fire in the processing area, or issues related to facility siting.
Analysis of these deviations will include:C
Catastrophic release:
A major uncontrolled emission, fire, or explosion, involving one or more highly hazardous chemicals that presents serious danger to employees in the workplace.
Consequences:
A column in the generic What-If/Checklist Log Sheet that serves to record a description of the impact a particular scenario can have on equipment and/or employees. The consequences indicate the possible effects on the process, the operating personnel, or the environment that might possibly occur assuming the hazardous scenario were to occur.
Critical equipment:
Refers to vessels, machinery, piping, alarms, interlocks and controls determined by management to be vital to preventing the occurrence of a catastrophic release.
E
E/A Controls:
Abbreviation for "Engineering/Administrative Controls" and a column in the generic What-If/Checklist Log Sheet that serves to record the existing controls that can prevent and/or mitigate a scenario or its consequences.
Emergency Situation:
An occurrence with a system that requires immediate response from operations personnel (e.g., a large leak might be considered an emergency situation requiring isolation and pump-out of equipment).
Equipment/Activity:
A column in the generic What-If/Checklist Log Sheet that serves to record a description of the equipment, activity, or issue to which a given question and scenario apply.
"F":
A column in the generic What-If/Checklist Log Sheet that serves to record the frequency ranking that results from a qualitative consequence analysis.
G
Generic:
Indicates wide applicability to facilities, systems, and equipment, irrespective of specific variations (e.g., scenarios identified for a generic compressor apply to various types, such as a rotary screw, rotary vane, and reciprocating).
H
Hazard:
A potential for an accident with undesirable consequences, usually involving a loss of containment of flammable, combustible, highly hazardous or reactive materials.
Hazard analysis techniques:
Analytical techniques which aid in identifying and evaluating process hazards. Typical hazard analysis techniques which may be used include the "What-If/Checklist" technique and the "Hazard & Operability" (HAZOP) technique. Other techniques which may be used for specific circumstances are discussed in the Guidelines for Hazard Evaluation Procedures published by the Center for Chemical Process Safety of the American Institute of Chemical Engineers.
I
Incident:
A release, a fire, or an explosion; or any event that could have resulted in a release, fire, or explosion; also referred to as "accidents," though not to be confused with occupational safety accidents, such as the laceration of a finger.
Item:
A column in the generic What-If/Checklist Log Sheet that serves as a unique identifier for a particular row in the log sheets.
P
Process:
Any activity involving ammonia including any use, storage, manufacturing, handling, or the on-site movement of ammonia, or any combination of these activities. For the purposes of this definition, any group of vessels which are interconnected and separate vessels which are located such that ammonia could be involved in a potential release shall be considered a single process.
Process hazard analysis:
The application of one or more hazard analysis techniques to aid in identifying and evaluating process hazards.
Q
Qualitative consequence analysis:
A PHA requirement that can be addressed by using a risk matrix to evaluate the consequence and frequency of a PHA scenario.
Question:
A column in the generic What-If/Checklist Log Sheet that serves to record the What-If question on which the scenario and consequences are based.
"R":
A column in the generic What-If/Checklist Log Sheet that serves to record the risk ranking that results from a qualitative consequence analysis.
R
Recommendations:
A column in the generic What-If/Checklist Log Sheet that serves to record any proposed risk-reduction measures that result from site-specific customization of the generic PHA. When a potential need for improvement, in either the physical facilities or the operating procedures is noted during a PHA, a recommendation is made. Additionally, entries are made on follow-up items and to clarify issues that may arise during a study.
S
Safeguards:
A safeguard is an engineering or administrative (E/A) control either in the design or operation of the facility which may prevent a scenario from occurring or mitigate the consequences should it occur.
Scenario:
A column in the generic What-If/Checklist Log Sheet that serves to record a description of typical events, associated with a given What-If question, which can result in a hazardous consequence.
System and subsystem:
Convenient ways to divide a process into manageable parts or segments. Each covered process is typically divided into multiple subsystems. The level of resolution depends on how detailed a study is required. The analysis is usually conducted on the subsystem level.
W
What-If/Checklist Log Sheets:
Tabular forms in which PHA results for the What-If/Checklist technique are systematically recorded (see FORM PHA-1).
What-If question:
A What-If question indicates some way that the system can malfunction, be misoperated or deviate from its design intent. The intent is to ask pointed questions that are considered relevant by the hazard analysis team. The questions address potential causes of accidents.
A hazard is an inherent physical or chemical characteristic that has the potential for causing harm. A hazard evaluation is an organized effort to identify and analyze the significance of hazardous situations associated with a process or an activity. Although there are multiple hazard evaluation techniques (Fault Tree, Hazard and Operability Analysis, Fault Tree Analysis, Failure Modes and Effects Analysis, etc., we chose to develop an interface to manage one of the most popular Process Hazards Analysis (PHA) techniques, What If Analysis. Our What If PHA provides an easy-to-use interface to efficiently organize a review of hazards for your process/system utilizing the What If Analysis technique.
Prior to embarking on a What If Analysis, particularly if this is the first study at your facility, we recommend that the designated PHA team leader in the study, as well as other members of the team, get an overview of the PHA process. This includes a full understanding of the importance of the study, guidance for assurance the team structure is comprised of the appropriate personnel, and common pitfalls to avoid when conducting the study. In addition, we provide the important foundational preparatory steps that should be followed prior to the start of the study.
What If PHA provides the framework to establish likelihood and consequence risk ranking for assets within your facility environment and allows an easy-to use interface for organizing real-life scenarios of situations that can occur or may have already occurred at your facility. The software makes the hazard evaluation process easier to achieve. However, that said, embarking on a hazard evaluation effort at your facility without the proper guidance can be daunting. The potential exists to overlook areas of risk within your facility.
WE CAN HELP. We have personnel that have decades of industry hazard evaluation experience utilizing the What If PHA technique. Their expertise includes experience within a multitude of industries that ideally suits them to provide the necessary guidance before you begin your study. We feel this guidance approach assures your study has the best opportunity for success. We perform this service world-wide (English language only at present) via the Microsoft Teams meeting interface. We include:
Our guidance will touch on each of the above topics as well any questions regarding the use of the software. Call or email for details.