1. ERT 312 SAFETY & LOSS PREVENTION IN BIOPROCESS ACCIDENT INVESTIGATION Prepared by: Miss Hairul Nazirah Abdul Halim

2. Objective To discuss the method to investigate the accidents in the plant To analyze & evaluate in a case studies

3. Techniques Learning from accidents Layered investigations The investigation process Investigation Summary Aids for diagnosis Aids for recommendation

4. Learning from accidents To avoid similar situations in the future For reporting minor accidents or near misses. Easier to correct minor problems before serious accidents occur Fundamental step in accident investigation: 1.Developing a detail description of the accident 2.Accumulating relevant facts 3.Analyzing the facts and developing potential causes of the accident 4.Studying the system & operating method relevant to the potential causes of the accident 5.Developing the most likely causes 6.Developing recommendations to eliminate recurrence of this type of accident 7.fact-finding not fault-finding.

5. Layered Investigations First layer: immediate technical recommendations, Second layer: recommendations to avoid the hazards, Third layer: recommendations to improve the management system.

6. Example 12-1 Illustrate the layered investigation process to develop underlying causes of a municipal pool accident. A drowning accident occurred during an open swim period. Approximately 100 children, ranging between 5 and 16 years old, were in and around a pool (3 ft to 9 ft deep). An older child unknowingly pushed a 5-year-old into the deep water. The pool was relatively crowded, and the 5-year-old slipped under the water without being noticed by others, including the lifeguard.

7. Solution The facts uncovered by an investigation team are 1. the pool did not have deep and shallow markings, 2. the older child was engaged in horseplay, 3. the younger child did not know how to swim, 4. the lifeguard had many blind fields of vision, 5. the pool was overly crowded, 6. the pool did not have an orientation program, and 7. the pool did not offer swimming lessons.

8. First layer recommendations: Immediate technical recommendations 1. Paint pool depths at the pool edges. 2. Add more lifeguards. 3. Reduce the number of swimmers. Second layer recommendations: Avoiding the hazard 1. Prohibit horseplay. 2. Zone pool to keep smaller children at shallow end of pool. 3. Add swimming lessons for all age groups. 4. Give all new swimmers (especially young children) a pool orientation. 5. Add a roving lifeguard to monitor and control pool behavior. Third layer recommendations: Improving the management system 1. Train lifeguards to alert supervision of observed potential problems. 2. Assign the supervisor to make formal (documented) audits on a regular basis.

10. Investigation Process Steps (1) Investigation team (2) Brief survey (3) Set objectives and delegate responsibilities (4)Preincident facts - flowsheets, procedures, photograph (5)Accident facts - photos, inspections, hypothesize the sequences of event, cause of accident, extent of damage, (6) Research and analyses (7) Discussion, conclusions and recommendations (8) Report

11. Accident Investigation Report format should be flexible and designed specifically to best explain the accident. The format may include the following sections: (1) introduction, (2) process description (equipment and chemistry), (3) incident description, (4) investigation results, (5) discussion, (6) conclusions, and (7) layered recommendations.

12. Investigation Summary Summarizes the events and recommendations in a diagram

14. Aids for Diagnosis The data collected during accident aare studied and analyzed to find the cause of accident Specific cause might be: a) Fire b) Explosions c) Sources of ignition in vessel d) Pressure Effects e) Medical Evidence

15. Pressure Effect Investigation on pipe and vessel Pressure necessary to produce a specific stress in a vessel depends on: - thickness of the vessel - vessel diameter - mechanical properties of the vessel wall

16. For cylindrical vessel (pressure p < 0.385S M ) For cylindrical vessel (pressure p > 0.385S M ) Where:p is the internal gauge pressure, S M is the strength of the material, t V is the wall thickness of the vessel, and r is the inside radius of the vessel.

17. For spherical vessel (pressure p < 0.665S M ) For spherical vessel (pressure p > 0.665S M )

19. Example 12-3 Determine the pressure required to rupture a cylindrical vessel if the vessel is stainless 316, has a radius of 3 ft, and has a wall thickness of 0.5 in. Solution Because the pressure is unknown, Equation 12-4 or 12-5 is used by trial and error until the correct equation is identified. Equation 12-4 is applicable for pressures below 0.385S M. Because S M (from Table 12-3) = 85,000 psi, 0.385S M = 32,700 psi r = 3 ft = 36 in t v = 0.5 in. Therefore Equation 12-4 is applicable, and a pressure of 1170 psi is required to rupture this vessel.

20. Example 12-4 Determine the pressure required to rupture a spherical vessel if the vessel is stainless 304, has a radius of 5 ft, and has a wall thickness of 0.75 in. Solution Equation 12-6 is applicable if the pressure is less than 0.665S M S M for Stainless 304 = 80,000 psi 0.665 S M = 0.665(80,000) = 53,200 psi. Using Equation 12-6 for spherical vessels, we obtain The pressure criteria is met for this equation. The pressure required to rupture this vessel is 1990 psi.

21. Aids for Recommendations To develop recommendations to prevent a recurrence To prevent similar accident within the company /industry Control Plant Modifications Often not given the same attention/concern as a new plant design Many accidents are result of plant modifications Recommendations to prevent this problem: a) All modification must be authorized. b) The modification design should have same quality of pipes/equipments as the original design c) Safety review – HAZOP d) Training – operators & engineers e)Audit

22. Preventive Maintenance - failure of emergency protection equipment such as cooling water pumps, instruments and deluge system can cause major accident. -Protective equipments failed due to no preventive maintenance -Preventive maintenance programs must be organized, managed & fully supported by management. -Must have maintenance schedule