Itis generally believed that failure is a process of slow degradation and if leftunattended interrupts the continuity of production leading to loss of assetavailability, that could perhaps lead to a threat to life, therefore we musttry to eliminate or mitigate the effect of losses due to failures that could bean eventual hazard, where even the safeoperating procedures (SOP) are no saviors in detecting disasters, but one canmitigate catastrophic failure by incorporating risk analytical capabilities. Asystem of safeguards needs to be built into the system. The goal is to reducethe likelihood of being caught unprepared and to mitigate the impact ofunexpected events an effort that isdirected towards reducing the failure effects and also eliminating the loss inas much the same way as Six Sigma approach attempts to do so. Costof potential failure (COPF) is a vital parameter analogous to cost of poorquality in six sigma, that determines the approach to safeguard.
This paperprovides a framework for evaluating cost of potential failure, based onPredictive Risk Index and FMECA inputs, which finally dictates the rigor neededfor the safeguards. 1.0Introduction: – No matter howrobust the design is yet there is a chance failure.
Risk management addresses these uncertainties. Riskmanagement and compliance may be non-negotiable, but cost often dictates theneed. The safeguards needed to mitigate the failure could be rigorous or may besimple depending upon the perceived threat. More rigorous the safeguard, more is the cost and vise-versa.
Cost of Potential Failures (COPF) is a risk dashboard to enable betterstrategic thinking on safety performance enhancements that is optimum that isneither too rigorous nor is too lax. Two tools Viz;Predictive Index Rating(PRI) and FMECA provides a framework for COPFcalculations upon which hinges the rigor required for safeguard. The synergiesbetween PRI and FMECA must uncover the strategic application of program toaddress these issues leveraging better and safe operations.
2.0 TheRisk Index (RI) Concept:- Seniormanagement don’t want to waste precious time chasing poltergeist, theyneed alarms to sound early particularly when the issue is plant safety, so thatserious accident and thereby loss to human life, equipments, are avoided,therefore management must ensure that its potential disaster are undercheck. This can be achieved by:1) Findingtangible, predictive indicators for the effectiveness of safety management,using interview and questionnaire techniques, audits and incident reportingdata.2) Integratingthe management effectiveness indicators in an operational index forsite-dependent and safety dependent performance.
Suchan index should reflect the current safety performance and help inpredicting potential risk in theoperation or in the facility can bepredicted in advance, so that proactive actions can be taken in advance toavoid or reduce the occurrence of the incident. Anappropriate measure of the safetyperformance is crucial for effective safety management of hazardous facilitiesand operations. Numerous method exists for measuring safety performance such asaccident statistics, accident control charts,and attitude scale. These are generally passive or subjective butnot quantitative. They also reflect inadequate information. Safety climate inan industry is dynamic, depends upon the perception of the worker andmanagement enforcement of safety regulation, workplace ergonomics, hazardousmaterial handling etc. 3.
0Evaluating Risk Index (RI):- Aninjury caused by accident, which in turn is caused by unsafe acts orconditions. Insufficient unsafe acts or conditions may give rise a near miss orlearning event. It should be possible to formulate a predictive model that canreflect the current status of safety activities in a work place throughcontinuous observations, recording and analysis of unsafe actions of workers orunsafe conditions in workplaces. Thenumber (frequency) and potential severity (consequence) of unsafe events may bea good indicator for the current status of safety climate in the processplant.
By continuously observing thechange in safety climate through some quantification of these events it isindeed possible to forecast the occurrence of a real incident. Theunsafe factors contributing to accidents are classified and graded according tothe four factors: · Probability ofdanger (PD)- the likely hood of danger in the observed event to become real.· Frequency ofwork exposure (FE)- the likelihood of worker exposed to the danger in the observed event.
· Number ofpersons at risk (RN)- the possible number of people affected by the danger inthe observed event should the danger become real,· Maximumprobable loss or severity (MPL)- the maximum possible losses associated with thedanger in the observed event should the danger become real. Assigningweights in a scale of 1-15, with 1 being lower end of the continuumrepresenting unlikely, infrequent, less number of persons at risk, and ifincident does happens results in minor injury while a score of 15 at the other end of continuum represents certainty,that which happens several times aday with 50 plus persons at risk, andresults in near fatality. Scale 1-15 Probability of danger (PD) Frequency of work exposure (FE) No of persons at risk (RN) (MPL) Max Prob Loss 1 Unlikely though Conceivable Infrequent 1-2 Minor injury 2 Possible but unusual Annually 3-7 Treatment at hospital, Influence hearing 5 Even chance-could happen Monthly 8-15 Head injury, body chemical burn, equipment damage, environment pollution 8 Probable not surprised Weekly 16-30 Eye injury, electrical shock or causing plant shutdown. 10 Likely only to be expected Daily 31-50 Disablement 15 Certain-no doubt Several times/day 50+ Fatality The grading are subjective and likely tochange according to the particular plant/facility being applied. The Risk Index (RI) is the geometric averageof the four factors as listed above:RI = (PD x FE x RN x MPL)1/4Theuse of geometric average rather than arithmetic means is due to the fact that all factors are related to each otherrather than truly independent. 3.
1An example:- Atechnicians works at a platform in monkey board area of rig mast with a broken ring fence to service a light fitting, he has a potentialto fall from this 8 m platform. Thegrading is as under:Probabilityof danger (PD)- score =8; from safety observation it was found the platform hasbroken ring fence, hence practically no barrier. Frequency of work exposure (FE)-score =8; bi-weekly service. Number of persons at risk (RN)-score =1; one person works for this job. Maximumprobable loss or severity (MPL)-score= 10; fatality or disability in case offalling down from the platform.
RiskIndex (RI) =(8 x 8 x 1 x 10)1/4 =5.03, this is more than safe zone RI of 3,so the installation is unsafe and calls for immediate action. Thetype of factors and the grading of each factors can be adjusted according tothe type of occupancy, operation, focuson risk, etc. More factors can be added and the generalization of the RIis nth root of products of then-factors. Theobservations needs to be performed in a regular interval, to gain immediateinsight in the safety performance. A word of caution here- the observation ofunsafe acts is not an audit. The person being observed bears no penalty, however he should beinformed of the unsafe acts or condition. A record is then made of unsafe actor condition.
Operation faults that leads to onlyemergency stop of operation is not listed as incidents in the present case.Incidents occurred not in facility are also discarded. Compiling of grading of all theobservation calculate the average riskindex and compare it with incidentsoccurred.
The annual average RI is a good indicator of safety performance. 4.0Predictive Risk Index (PRI):- If we plot the time series of RI for years. The sequence of RI is scattered which reflects the statisticaldistribution of the observations. Themoving average generally give a goods insight of the time series resulting in asmooth, oscillating curve from which sufficient inference can be deduced. This movingaverage of 15 consecutive observations of RI is defined as Predictive RiskIndex (PRI). PRIis purely a moving average of past observations, yet it trend successfullypredicts the occurrence of incident. Not every peak in PRI trend leads to anaccident, but a raising PRI trend does have a greater chance of occurringincident.
PRI > 3 Warning Zone PRI > 4 Action Zone-immediate action warranted to prevent incident occurrence. PRI < 3 Safe Zone- plant considered low risk for accident. · The increasedactivities in the plant will certainly result in more unsafe acts, which meanshigher PRI. · The otherfactor affecting PRI trend is educationand training.
Effective training should bring more safety awareness to workers,reduced unsafe acts thus bring down PRI. Thus PRI can be used as a measure ofthe effectiveness of training or education. 4.1 Inference from PRI trends:- Raising PRI When PRI goes above warning level- It is likely to have an accident The PRI value after the incident may be raising or falling depends on how the incident has changed the worker’s awareness. Persistent high PRI PRI reaches a warning level but incident did not occur immediately Not every unsafe act immediately meets the condition to incident, however persistent unsafe actions or conditions eventually lead incident unless actions are taken. Oscillating PRI The PRI is raising and falling If PRI is oscillating in high level and if the incident did not raise sufficient awareness or if the action taken too late then PRI rebounds and incidents are also likely to occur, .