Mr. R. R. Diwanji Techniques for Safety Improvements

Searching for hazards  Intuitive methods  Inductive Methods  Key points check lists  Failure mode and effect analysis  Decision Table Technique  Incident sequence Analysis  Hazard and Operability Studies (HAZOP)  Action Error Analysis  Deductive methods The Fault Tree Techniques

Developed by ICI Six Stages of Study Study 1 - To identify the basic hazard of material and operation. Study 2- To identify the significant hazard at the project definition stage and determine the appropriate design features. Study 3- This is hazard & operability study (HAZOP). To identify hazards operability problems after project / plant is designed. Hazard Study

Study 4- Before introduction of process material proper checks are introduced for the hazard identified in study 1 to 3. Study 5- To check whether project meets company & Legislative requirements Study 6- Performed after months of continuous operation the checks introduced after hazard study 1 to 4 are properly functioning. Hazard Study

How do I carry out HAZOP ? Assemble a team of min-3 and max 5 people Experts required from  Process  Maintenance  Design  R&D  Safety Safety personnel acts as a study leader Focus on Guidewords

Guidewords

HAZOP -A STEP by STEP APPROACH 1. Select a line from P& I diagram. 2. Explain intention of the line. 3. Apply first guideword. 4. Develop meaningful deviation. 5. Examine possible causes. 6. Examine consequences. 7. Detect the hazard. 8. Make suitable record. 9. Write corrective actions

POSSIBLE PARAMETERS Flow Pressure Temp Mixing Level Viscosity Phase Addition TransferControl MaintainPart. Size PH Sequence Speed Signal Time Start / stop

SUPPLY OF CHLORINE -Example Proposal- Supply of Chlorine gas from caustic soda plant to chlorination unit at M. C. B. Plant. Define Intention- To supply dry pure chlorine gas at 1 to 1.5kg/cm 2 pressure at the rate of 200 to 250 5kg/hr. to chlorination unit at M.C.B. plant. Apply Guideword to - Dry, Pure, Pressure, Rate etc.

Application Mainly used for continuous plant operation. Eg. Distillation columns, Complex automatic Plants, Critical parts of the system

Advantages of HAZOP Study Structured process Improves operability Moderator supports systematic procedure.

Disadvantages of HAZOP Study  Higher time commitment (mainly for larger systems)  Considers Technical aspects mainly only normal operation but start up - shut down procedures  Assumes previous analysis of chemical process risks

RISK ANALYSIS & PROCESS SAFETY Developed by CIBA- Geigy for searching hazard using check list What is Hazard? The possibility of undesirable event that could take place What is risk? Evaluation of hazard in terms of probability & Severity

Sources of Hazard  Chemicals themselves  Chemical reactions  Energies used for the process  Installations (Equipments).

Sources of Deviation  Technical defects  Human Error  System Error

How do I carry out Risk Analysis? I. Collection of Basic data Physical / Chemical / Toxicity / Reaction data. II. Safe condition / Limitations III. Systematic search for the hazard. IV. Analysis of hazard according to severity& probability V. Listing of Risks. VI. Suggesting measures. VII. Residual risk.

Sample Check List 1. Process conditions What happens if wrong R.M. is charged? What happens if sequence of R. M. is charged? What happens if rate of R.M. charge increases or decreases? What happens if temperature is high? What happens if pressure increases etc? 2. Interruption in Utilities Power Failure Cooling Failure Heating Failure Nitrogen Failure

Application  Mainly to the batch process.  Auxiliary plants with manual operators  Checking of process.  Start up shut down procedures.

Advantages  Screening procedures  Relatively less time required for data collections.  Gives a first quick overview.

Disadvantages  Additional investigations may be required for data collections.  No fully developed check lists available for complex process.

Accident Investigation Why accident investigation? - To determine the cause of accident and not to identify scape goat. - Uncovering problems that did not directly lead to the accident. - On going effort to reduce likely hood of accident. - Prevent similar accidents in future.

As soon as all emergency procedures have been completed. Reason being -More likely to get more accurate information. -Information becomes fade in people’s mind. -Likelihood of accident scene may get changed. -Human nature encourages people to change their stories with those of other witnesses. When to investigate?

- Minor injury the supervisor of injured person - Team should be consist of - Plant I/C, - Safety personnel, - Maintenance man and - Immediate supervisor. Who should investigate?

Root Cause analysis There may be many reasons why an accident occurs. Define Problem Diagnose all Causes Identify Solutions Implement Review Diagnose Symptoms Identify Solutions

 Define the problem / incident accurately  Ask the question “WHY did the problem occur”?  List down all possible causes as you brainstorm  Keep asking a series of “WHY” for each cause until the most fundamental cause is identified  Event Tree or Fish bone techniques can be used to pictorially represent all causes  Highlight all root causes  Prioritize them  Implement actions to prevent recurrence of the root causes  Fix the problem for ever How a root Cause Analysis is done?

 The analysis must be initiated within 24 hours  Root Cause Analysis must be done by a team  Adequate Representation from various functions  Written Report to be prepared  Immediate causes (symptoms) & Root (underlying) Causes to be identified  Action Plan to prevent recurrence to be prepared Structure of RCA

 a structured method  to identify all possible causes of an accident  to seek a preventive solution Advantages: