A RISK BASED MAINTENANCE APPROACH for PSM FACILITIES

Transcription

1 A RISK BASED MAINTENANCE APPROACH for PSM FACILITIES Mary Kay O Conner O Process Safety Center October 2007 Symposium Adrian L. Sepeda, P.E. President, A. L. Sepeda Consulting Inc.

2 COMMON MAINTENANCE APPROACHES Preventive An effort is made to prevent failures by establishing a fixed schedule of routine inspection and service Predictive An effort is made to predict when a failure will occur and make needed repairs just before the failure Breakdown Maintenance Equipment is operated until it fails

3 MOST COMPANIES USE A COMBINATION OF APPROACHES Predictive Maintenance Breakdown Maintenance Non Routine or Emergency Maintenance Preventive Maintenance Equipment

4 BUT ONE SIZE DOES NOT FIT ALL! The issues then becomes when to use what maintenance approach for each piece of equipment and why i.e. how the decision is to be made. This paper discusses using a Risk based approach for OSHA PSM covered facilities RISK ~ Probability of Equipment Failure + Consequence of that Failure

5 OSHA PSM REQUIREMENTS (PSM) Mechanical Integrity A system to assure that equipment used to process, store, or handle highly hazardous chemicals is designed, constructed, installed and maintained to minimize the risk of releases of such chemicals. In other words, OSHA PSM Mechanical Integrity is focused on keeping chemicals contained purely a safety and environmental consideration focused on consequence reduction with NO consideration for production capability!

6 YOUR COMPANY REQUIREMENTS Reliability The probability that an item is able to perform a required function under stated conditions for a stated period of time or for a stated demand. i.e. Performance on demand So, your company is concerned about more than just meeting the OSHA PSM requirements. Your company wants equipment to work when and how you expect it to so they can make a product and profit!

7 MAINTENANCE APPROACH RISK MATRIX To solve this, we turn to our old friend.the risk matrix where we plot Probability against Consequence to determine Risk rank C O N S E Q U E N C E P R O B A B I L I T Y In this case we have defined

8 CONSEQUENCE OF FAILURE LEVELS Level 1* OSHA PSM Mechanical Integrity failures Level 2* Reliability failures Level 3* Inconveniences but not catastrophic failures * Abbreviated definitions. These are defined in more detail in the paper

9 MAINTENANCE APPROACH RISK MATRIX To solve this, we turn to our old friend.the risk matrix where we plot Probability against Consequence to determine Risk rank C O N S E Q U E N C E P R O B A B I L I T Y In this case we have defined

10 PROBABILITY OF FAILURE LEVELS Using a Layer of Protection (LOPA) approach Level 1* Two or less independent layers of protection + operator intervention Level 2* Three independent layers of protection + operator intervention Level 3* Four or more independent layers of protection + operator intervention * Abbreviated definitions. These are defined in more detail in the paper

11 MAINTENANCE APPROACH RISK MATRIX Each cell within the matrix represents one of the three maintenance approaches: Breakdown, Predictive, or Preventive C O N S E Q U E N C E P R O B A B I L I T Y

12 Feed Pipeline EXAMPLE: FLOW DIAGRAM OF SIMPLISTIC FACILITY Gas Holding Tank Steam Plant Liquid K.O. Drum Compressor & Steam Turbine Liquefier Accumulator Pump Liquefier Liquefier Accumulator Product Storage Sphere Cooling Tower Settling Pond Settling Pond Pump Filter Customer Pipeline Water to River

13 EXAMPLE: DETERMINE THE MAINTENANCE APROACH FOR THE GAS HOLDING TANK By investigation and review of the safety systems available and the mode of operations, we have determined.. Consequence of failure = Level 1 MI issues ~ loss of containment Probability of failure = Level 3 Four or more independent layers of protection + operator intervention

14 MAINTENANCE APPROACH RISK MATRIX Consequence = Level 1 Probability = Level 3 P R O B A B I L I T Y C O N S E Q U E N C E Risk Matrix Maintenance = Predictive

15 Feed Pipeline EXAMPLE: FLOW DIAGRAM OF SIMPLISTIC FACILITY Gas Holding Tank Steam Plant Liquid K.O. Drum Compressor & Steam Turbine Liquefier Accumulator Pump Liquefier Liquefier Accumulator Product Storage Sphere Cooling Tower Settling Pond Settling Pond Pump Filter Customer Pipeline Water to River

16 EXAMPLE: DETERMINE THE MAINTENANCE APROACH FOR THE CUSTOMER PIPELINE By investigation and review of the safety systems available and the mode of operations, we have determined.. Consequence of failure = Level 1 MI issues ~ loss of containment Probability of failure = Level 1 Two independent layers of protection + operator intervention

17 MAINTENANCE APPROACH RISK MATRIX Consequence = Level 1 Probability = Level 1 P R O B A B I L I T Y C O N S E Q U E N C E Risk Matrix Maintenance = Preventive

18 EXAMPLE FACILITY MAINTENANCE APPROACHES Preventive: Predictive: Breakdown: Feed pipeline Liquid KO Drum Liquefier Liquefier Accumulator Transfer pipeline Product Storage sphere Customer pipeline Liquefier Accumulator Pump Settling Pond Steam turbine Gas Holding Tank Steam Plant Compressor Cooling Tower Cooling Water piping Settling Pond liquid Filter Settling Pond Pump Note: By determining the apparent risk based maintenance approaches, rational decisions can be made for where additional consequence or probability reductions are warranted and which ones can actually pay for themselves in reduced maintenance costs!

19 MAINTENANCE APPROACH RISK MATRIX Consequence = Level 1 Probability = Level 1 P R O B A B I L I T Y C O N S E Q U E N C E Risk Matrix Maintenance = Preventive

20 THANK YOU FOR YOUR TIME AND ATTENTION..