Classification of Accidents
Deviations, i.e., abnonnal conditions that can lead to failure and/or an accident, generally occur because of:
1. Abnorlnal telnperatures 2. Abnorlnal pressures 3. Material flow stoppage 4. Equiplnent leaks 5. Equiplnent spills 6. Materials failure due to wear 7. Materials failure due to iInperfections 8. Materials failure due to poor lnaintenance 9. Materials failure due to corrosion
SOUle specific operational failures include:1
1. Blocked outlet 2. Opening/closing valve 3. Cooling water failure 4. Power failure 5. InstruUlent air failure 6. Thennal expansion 7. Vacuuul problenls
Specific coullnents/recoul1nendations/or procedures for the potential failure of equiplnent that can be found in a process plant are beyond the scope this text. However, a short list of the writs of concern follows:
1. Heat exchangers should be constructed in accordance with applicable codes and regulations. Materials of construction should be carefully selected to resist corrosion and fouling. These units should be equipped with relief valves, bypassing piping (or the equivalent), and adequate drainage facilities. Only sealnless tubes should be used for exchangers where tube leakage or rupture nlay result in an adverse reaction or excessive pressure. Heat exchculger tubes and piping should also allow for thermal expansion and contraction \vithout causing excessive stress on connections. A proactive operation, Inaintenance and inspection (OM&I) progralll is a lllUSt.