how to read pid for risk analysis

Delivering Values to Customers

HOW TO READ A P&IDFOR

RISK ANALYSIS


P&ID IS A PIPING AND INSTRUMENTATION

DIAGRAM


TO IDENTIFY RISK FROM A SET OF P&ID YOU MUST

HAVE CLEAR UNDERSTANDING OF

THREE THINGS


#1 - UNDERSTAND THE

PROCESS

#2 - UNDERSTAND THE

FAILURES

#3 UNDERSTAND THE

CONSEQUENCE


LINES ARE USED FOR SHOWING PIPING, EQUIPMENT AND INSTRUMENT CONNECTIONS


..SO PEOPLE CAN COMMUNICATE THE PROCESS SEQUENCE AND THE RELATIONSHIP OF DIFFERENT EQUIPMENT


EQUIPMENT & INSTRUMENTATION ARE CONNECTED BY LINES

HERE ARE SOME COMMON CONNECTIONS..


PIPE

COMMON FAILURE MODES COLLAPSE

BURST/RAPTURE

CORROSION

EROSSION


ELECTRICAL SIGNAL

COMMON FAILURE MODES OPEN CONNECTION

ELECTRICAL SHORTING

ELECTROMAGNETIC INTERFERENCE


PNEUMATIC SIGNAL

COMMON FAILURE MODES LOSS OF PRESSURE

LEAKAGE

HIGH COMPONENTS FRICTIONLEVEL


DATA SIGNAL

COMMON FAILURE MODES RADIO INTYERFERENCE

LOSS OF SIGNAL

PACKETS LOSS

SIGNAL FILTERING


FLEXIBLE PIPE

COMMON FAILURE MODES COMPRESSIVE FAILURE

TENSILE FAILURE

OVERBENDING

RAPTURE


SOME EQUIPMENTS ARE USED TO ADD OR REDUCE ENERGY IN THE MATERIAL


BLOWER

COMMON FAILURE MODES FAIL TO OPERATE ON DEMAND

LOSS OF PRESSURE


FURNACE

COMMON FAILURE MODES FLAME OUT


PUMP

COMMON FAILURE MODES FAIL TO OPERATE ON DEMAND

LOSS OF PRESSURE

OVER PRESSURE


COMPRESSOR

COMMON FAILURE MODES FAIL TO START

DAMAGE DUE TO LIQUID

OVER PRESSURE

EXCESSIVE VIBRATION


HEAT EXCHANGER

COMMON FAILURE MODES LEAKAGE

CORROSION

PLUGGED


PLATE HEAT EXCHANGER


CORROSION

PLUGGED


AERIAL FAN

COMMON FAILURE MODES LOSS OF AIR CIRCULATION


SOME EQUIPMENTS ARE USED FOR MATERIAL STORAGE


FLOATING STORAGE TANK

COMMON FAILURE MODES OVERFLOW

LEAKAGE


SPHERE TANK

COMMON FAILURE MODES OVER PRESSURE


PRESSURIZED VESSEL



SOME EQUIPMENTS ARE USED TO SEPARATE MATERIAL


HORIZONTAL SEPERATOR



VERTICAL SEPERATOR



COLUMN

COMMON FAILURE MODES OVERPRESSURE

CORROSION

PLUGGED


TRAY COLUMN

COMMON FAILURE MODES OVERPRESSURE

CONTAMINATION


VALVES ARE USED TO CONTROL THE FLOW OF MATERIAL


MANUAL VALVE

COMMON FAILURE MODES EXTERNAL LEAKAGE

INTERNAL LEAKAGE

INADVERTENT POSITION


CONTROL VALVE

COMMON FAILURE MODES FAILTO CLOSE ON DEMAN

FAIL TO OPEN ON DEMAN

SUPRIOUS OPERATION

LEAKAGE


SOLENOID VALVE

COMMON FAILURE MODES STRUCTURAL FAILURE

SEAT LAEAKGE

SEAL LEAKAGE

LOSS OF ACTUATOR


MOTOR OPERATED VALVE

COMMON FAILURE MODES MOTOR FAILURE

FAIL TO STROKE


BUTTERFLY VALVE

COMMON FAILURE MODES FAIL TO CLOSE ON DEMAND

FAIL TO OPEN ON DEMAND

SPRIOUS OPERATION


GLOBE VALVE



SPRIOUS OPERATION

LEAKAGE


NEEDLE VALVE



SPRIOUS OPERATION

LEAKAGE


BALL VALVE



SPRIOUS OPERATION

LEAKAGE


CHECK VALVE


STUCK AT OPEN POSITION


SOME EQUIPMENTS ARE USED TO RELIEF PRESSURE IN THE PROCESS


RELIEF VALVE

COMMON FAILURE MODES FAIL TO OPEN


CURVED GAS VENT

COMMON FAILURE MODES PLUGGED


RAPTURE DISC

COMMON FAILURE MODES CORROSION


CONTROL SYSTEM ARE USED TO MANAGE THE BEHAVIOUR OF THE PROCESS


PLC

COMMON FAILURE MODES SOFTWARE ERROR

EXECUTION ERROR


SHARED DISPLAY & CONTROL

COMMON FAILURE MODES SOFTWARE ERROR

EXECUTION ERROR


SENSORS ARE USED TO MEASURE THE PHSICAL PROPERTIES OF THE PROCESS AND CONVERT IT INTO A SIGNAL


FT/PT/LT

COMMON FAILURE MODES LOSS OF MEASUREMENT

SPURIOUS MEASUREMENT


NOW LETS IDENTIFY THE RISK OF THIS PROCESS..


STEP 1: UNDERSTAND THE PROCESS

1. THERE IS A LOW PRESSURE STEAM FLOWING INTO THE VESSEL

2. THE STEAM COOLS AND FORMS CONDENSATE IN THE CONDESATE POT

3. THE LEVEL OF THE CONDESATE LIQUID IS CONTROLED BY LEVEL CONTROL LOOP

4. CONDESATE DRAINED OUT THE BOTTOM OF VESSEL

STEP 2: IDENTIFY POSSIBLE FAILURES

1. THE CONTROL LOOP CAN MALFUNCTION CAUSING THE VALVE TO FAIL IN THE CLOSED POSITION


STEP 3: ASSESS THE CONSEQUENCES

1. THE LEVEL CONTROL FAILS IN THE CLOSED POSITION CAN MALFUNCTION BLOCKING THE DRAIN LINE

2. HAZARD IS HIGH LEVEL AND HIGH PRESSURE IN THE TANK

3. POTENTIAL CONSEQUENCES OF LOSS OF CONTAINMENT AND EQUIPMENT DAMAGE WITH $$$$ LOSSES.


NOW YOU HAVE IDENTIFIED THE CAUSE OF THE OVERPRESSUREHAZARD, CAN YOU IDETIFY THE SAFE

THE PRESSURE RELIEF WITH A SET POINT OF 700 KPA WILL OPEN AND REDUCE BUT NOT ELIMINATE THE RISK OF RAPTURE

BY UNDERSTANDING THE P&ID YOU CAN CLEARLY ASSESS RISK IN YOUR OPERATION AND NAKE GOOD DCISIONS


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how to read pid for risk analysis

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