Process Safety in Chemical Plants with Focus on HAZOP Title: HAZOP in Practice 09-10 December 2008 Second World Congress on Disaster Management Process Safety in Chemical Plants with Focus on HAZOP by S. S PIPARA Faculty at AVVIARE Educational Hub, Noida and Ex. Joint President GRASIM Industries Ltd., Nagda (India) Chilworth Safety & Risk Management P. Ltd.

Process Safety Management Root cause analysis of incidents The hazards associated with Unit processes and Unit operations Process Safety and Equipment Health

Hazard Identification Techniques Techniques in use are in one of three categories: Techniques 1 2 3 Experience Based Checklists and What-If / Checklists Indices and Layers of Protection Analysis (LOPA) Analytical Failure Mode and Effects Analysis (FMEA) Fault Tree Analysis and Event Tree Analysis Creative Brainstorming HAZOPS

Definitions Process Hazard Analysis Catastrophic Release An organized and systematic effort to identify and determine the significance of the hazards associated with the handling and processing of highly hazardous chemicals and assess the effectiveness of safeguards. Catastrophic Release Major uncontrolled emission, fire or explosion that causes serious danger to employees in the workplace Highly Hazardous Chemical a substance that has toxic, flammable, explosive or reactive properties. Process Any activity including use, storage, manufacturing, handling or on-site movement of a highly hazardous chemical Safeguard Procedures and devices used to control process hazards and manage risk. Preventions Procedures and devices intended to stop the initiation of an undesired event or interrupt the escalation of an event sequence. Mitigations Procedures and devices intended to respond to events and reduce the magnitude of undesired consequences.

Experience Based Hazard Identification Techniques Title: HAZOP in Practice 09-10 December 2008 Experience Based Hazard Identification Techniques Checklist What-If/ Checklist Natural extension of simple checklist Begins to introduce a customization of the checklist to better fit the process Best if done by experienced personnel Most effective in early design stage of new projects. Most often guided by a checklist of topics Can be applied to a limited scope Individual (of most limited value) Informed Individual (safety specialist) Outside standards such as: Center for Chemical Process Safety (CCPS) National Fire Protection Association (NFPA) Chilworth Safety & Risk Management P. Ltd. 5

What-If Spreadsheet Example Process Upset Causes Consequences Safeguards Action Items What if sample is spilled on operator Bottle breaks Operator error Operator burned, LTI   Procedures and training PPE Modify procedures to stress issue What if batch temperature is too high? Control failure No issue, material is thermally stable Procedures and training DCS What if reactor leaks? Corrosion Maintenance Error Clean up costs only PM Program ERP  Ensure adequate spill clean up materials are on hand What if spill ignites and pool fire occurs indoors? Leak plus spark from equipment Operator fatality possible   Big $$$ loss Fixed Sprinklers Adequate drainage Ensure adequate PM of electrical devices Note: Action items are often abbreviated during the review and expanded to include additional explanation in the final report.

Fault Tree Analysis Analytical Hazard Identification Techniques Title: HAZOP in Practice 09-10 December 2008 Analytical Hazard Identification Techniques Fault Tree Analysis Use of a logic diagram to plot the path from an undesired outcome back to the basic equipment, systems and human failures, the Basic Events; Predominantly used for high consequence, low frequency events, to determine the adequacy of safeguards; Graphical representation of the combination of faults leading to a predefined undesired event This methodology uses logic gates to show all the credible paths from where the undesired event could occur A top down approach where each level is required to allow the next; The analyst asks what is required for the upper event or condition to exist? The pathway is plotted on the diagram using standard symbols Chilworth Safety & Risk Management P. Ltd. 7

Basic Fault Tree And Bad Consequences Likelihood = FxP Initiating Event(s) Failure of Protective Systems Frequency = F Probability of Failure on Demand = P Community ERP Site ERP 2nd Containment ERS SIS Auto Shutdown Alarms/Intervention Process Control Procedural Checklist Procedures/Training Mech Design/PM Process Design Equipment failure: Corrosion Fabrication error Design error Fire Exposure Collision Operator error Maintenance error

Title: HAZOP in Practice 09-10 December 2008 Event Tree Analysis An event tree is a graphical representation of the logic model that identifies and quantifies the possible outcomes following an initiating event. Use of a logic diagram to plot the path from a single initiating event through each decision point where consequences can be altered to arrive at the final potential consequence. At each decision point success or failure diverts the path. Event trees are used to identify the various accidents that can occur in a complex process Can be used with FMEA to develop safety oriented mechanical integrity programs. Chilworth Safety & Risk Management P. Ltd. 9

Event Tree Analysis Example Quantified Incident development path Outcome Frequency YES 50% Vapor Cloud Explosion 0.5% YES 10% NO 50% Pool Fire 0.5% Flammable Liquid is Released Delay? NO 10% Reportable Environmental Incident NO 90% 9.0% Ignition? Minor in-house incident YES 90% 90%

Failure Mode Effect Analysis Title: HAZOP in Practice 09-10 December 2008 Failure Mode Effect Analysis Failure Modes and Effects Analysis (FMEA) is methodology for analyzing potential reliability problems early in the development cycle where it is easier to take actions to overcome these issues, thereby enhancing reliability through design. FMEA is used to identify potential failure modes, determine their effect on the operation of the product, and identify actions to mitigate the failures. An assessment of equipment, components and systems to determine the way in which failures can occur and the consequences of component failure on systems and units. Most often qualitative but a quantitative assessment can be made. A “Bottom Up” approach Spreadsheet style documentation Chilworth Safety & Risk Management P. Ltd. 11

FEMA Title: HAZOP in Practice 09-10 December 2008 Chilworth Safety & Risk Management P. Ltd. 12

Selecting a Hazard Identification Technique Title: HAZOP in Practice 09-10 December 2008 Selecting a Hazard Identification Technique Considerations Information available Project stage Personnel requirements Personnel skill level System complexity System type Schedule and time restrictions Chilworth Safety & Risk Management P. Ltd. 13

Selecting Technique Title: HAZOP in Practice 09-10 December 2008 Chilworth Safety & Risk Management P. Ltd. 14

Creative Hazard Identification Techniques Brainstorming Title: HAZOP in Practice 09-10 December 2008 Creative Hazard Identification Techniques Brainstorming An unstructured technique used by a team to gather all ideas about a topic, without specific analysis of those ideas. The scribe will typically write down all that is said by the team members for later analysis. (Flip Chart) May be leader or checklist driven: “How can the pump fail?” Common method within a PHA team The classic method encourages free thinking and creativity, no idea is turned away. Only after the team’s brainstorming has reached a logical end, are documented ideas analyzed, and possibly discarded. Brainstorming can be a good way of encouraging team participation. Chilworth Safety & Risk Management P. Ltd. 15

HAZOP - HAZard & OPerability Title: HAZOP in Practice 09-10 December 2008 HAZOP - HAZard & OPerability First developed at ICI in the UK in 1964 this method is a natural extension of standardized checklists. Where checklists count on past experience, HAZOPs develops ‘synthetic experience’ by hypothesizing deviations from desired performance. Most applicable to new and novel processes where experience is lacking. Chilworth Safety & Risk Management P. Ltd. 16

HAZOP - HAZard & OPerability Title: HAZOP in Practice 09-10 December 2008 HAZOP - HAZard & OPerability The basic premise of HAZOPS is: All hazardous material incidents are instigated by a deviation from the desired operating state or condition. If we can predict all deviations and analyze them before we operate a new process then we can head off the undesired consequences. Forewarned is Forearmed Chilworth Safety & Risk Management P. Ltd. 17

HAZOP Approach Define Intended Process Repeat Parameter + Guided words Deviation Cause Consequence Safeguard Action Define Intended Process Repeat

Title: HAZOP in Practice 09-10 December 2008 HAZOP APPROACH Intention: The Intention defines, How the selected section/unit is expected to operate Parameters: Aspects of a process that describe it physically or in terms of what is happening Some Parameters: Flow Pressure Temperature Level Phase Viscosity Concentration Loss of containment is a critical consideration and must be included. Flow Rate Flow Amount Agitation Aging Ph Conductivity Catalyst Activity Time Chilworth Safety & Risk Management P. Ltd.

Title: HAZOP in Practice 09-10 December 2008 HAZOP APPROACH Guidewords: These are simple words, which are used to qualify the intentions in order to guide and stimulate the thinking process and so discover deviations. Some Guidewords: No/None More Less Reverse Other than As well as Part of More = High for example High Pressure, High Temp etc. Similarly, Less = Low Chilworth Safety & Risk Management P. Ltd.

HAZOP APPROACH Guideword Meanings Title: HAZOP in Practice 09-10 December 2008 HAZOP APPROACH Guideword Meanings Guideword Meaning Example Parameter: Flow No/None None of design intent is achieved No Flow More Quantitative increase in a parameter More Flow Less Quantitative decrease in a parameter Less Flow Reverse Logical opposite of the design intent occurs Reverse Flow Other than Complete substitution – another activity takes place Boiling As well as An additional activity occurs Chemical Reaction Part of Only some of the design intent is achieved ----- Chilworth Safety & Risk Management P. Ltd.

Title: HAZOP in Practice 09-10 December 2008 HAZOP APPROACH Deviations: Deviation means departure from the design intent These are discovered by systematically applying the guidewords Causes: Reasons for deviations Consequences: Results of deviations Chilworth Safety & Risk Management P. Ltd.

Title: HAZOP in Practice 09-10 December 2008 HAZOP APPROACH Safeguards: Procedures or devices exists to control causes or mitigate consequences Prevention measures or Mitigation measures or Combination of both Chilworth Safety & Risk Management P. Ltd.

Title: HAZOP in Practice 09-10 December 2008 HAZOP APPROACH SUMMARY HAZOPS uses a standard list of “Guidewords” as modifiers to process Parameters to hypothesize Deviations from the desired intent. Deviation = Guideword + Parameter The Deviations are analyzed by the team to determine if a hazardous condition would occur, or if an important operating upset is discovered. Chilworth Safety & Risk Management P. Ltd.

Title: HAZOP in Practice 09-10 December 2008 HAZOP APPROACH SUMMARY Chilworth Safety & Risk Management P. Ltd.

Title: HAZOP in Practice 09-10 December 2008 HAZOP Study Team Leader Instrumentation supervisor Operator Chemist Chemical Engineer Maintenance Supervisor Specialist Operations Design Team Member Common Team Size: 4-7 people Scribe It is important to select right composition of HAZOP team. Chilworth Safety & Risk Management P. Ltd.

Hazard Studies HAZID - To identify hazards and potential accident scenarios  to be performed at the initial stage of a project HAZOP - To identify specific hazards arising from process deviation, to evaluate adequacy of existing safeguards and to identify additional mitigating measures  to be performed at different stages throughout the entire project life QRA - To assess personnel risk posed by potential hazard scenarios  to be performed at the initial stage of the project with further updating at a later stage /

Risk Identification Techniques Identifying the Risk Risk Identification Techniques When you might use them Safety Review Checklist Preliminary Hazard Analysis What-If Abbreviated HAZOP Study Used in preliminary hazard evaluation studies to provide a general overview of existing risks (Usually not too time consuming) What-If/Checklist Detailed and complete HAZOP Study Failure Mode and Event Analysis Used to develop a more detailed analysis of potential risks Fault Tree Analysis Event Tree Analysis Cause Consequence Analysis Human Reliability Analysis Used in conjunction with quantitative risk analysis to establish a high level detail about risks (Usually used for specific area or Unit Operations)

Hazard identification Scenario identification Risk Assessment Procedure HAZARD IDENTIFICATION METHODS: - Process hazard checklist - Hazard survey: DOW index - HAZOP hazard & operability study - Safety review System description Hazard identification Scenario identification Accident probability consequences Risk determination Risk & Hazard acceptable ? Modify design Accept system Y N RISK ASSESSMENT: - What can go wrong & how ? - What are the chances ? - Consequences ? EXTREMES - Low probability - Minimal consequences

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