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Significant Potential Incident
Significant Potential Incident
Unauthorized Weld on Pressurized Water LineUnauthorized Weld on Pressurized Water Line
Timmins, Ontario, CanadaTimmins, Ontario, Canada
October 17, 2011October 17, 2011
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SERIOUS INCIDENT REVIEWSERIOUS INCIDENT REVIEW
• Equipment: Steam Generator 1
• Time/Date: Reported date October 17, 2011
• Location: Timmins, Micronizing Plant
• Conditions: Normal Running Conditions
• Workgroup: Maintenance
• Supervisor: Ray Drouin
• Manager: Yahia (John) Aoumer
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Scenario description
A boiler feed water leak was discovered on the 2” feed water piping between steam generator 1 thermizer and super heater 1.The employee informed the Process Technologist who was supervising another job in the boiler room.
While discussing the repair options for the leak it was pointed out by the Millwright employee that a larger section of pipe should be replaced. He identified where a previous patch weld repair was performed.
The employee then showed the Process Technologist the location of the weld repair. The patch weld repair was located on the side of the 2” boiler feed water line. This line routinely experiences temperatures in the 250 ˚F range and pressures in the operating range of 400 to 600 psi.
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Risk Score= Consequence × Likelihood
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Consequence Descriptors
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Likelihood Descriptors
Likelihood Likelihood description Frequency Substance Exposure
ALMOST
CERTAIN
Recurring event during the life-
time of an operation /
project
Occurs more than twice per
year
Frequent (daily) exposure at >
10 x OEL
LIKELY
Event that may occur
frequently during the life-
time of an operation /
project
Typically occurs once or twice
per year
Frequent (daily) exposure at >
OEL
POSSIBLEEvent that may occur during
the life-time of an operation
/ project
Typically occurs in 1-10 years
Frequent (daily) exposure at >
50% of OEL
Infrequent exposure at > OEL
UNLIKELYEvent that is unlikely to occur
during the life-time of an
operation / project
Typically occurs in 10-100
years
Frequent (daily) exposure at >
10% of OEL
Infrequent exposure at > 50%
of OEL
RARE
Event that is very unlikely to
occur very during the life-
time of an operation /
project
Greater than 100 year event
Frequent (daily) exposure at <
10% of OEL
Infrequent exposure at > 10%
of OEL
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What Happened
• Maintenance Leader found a small leak from a pressurized water line in the boiler room
• Maintenance Leader took it upon himself to patch weld the leak
• Maintenance Leader did not inform the Plant Supervisor of his actions.
Immediate Response
• When Management becomes aware of the weld, the whole pipe is replaced immediately
• Incident rated as a Significant Potential Incident
• Taproot investigation begins.
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Photos of the incident site and scene
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Weld on pipeWeld on pipe
pipe removed and in the recycle bin in this picture
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Winter Snap ChartWinter Snap Chart
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Mitigating FactorsMitigating Factors
• Employee eventually reported the welding job 9 weeks later to a Member of Management.
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Contributing / Causal Factors
• No Preventive Maintenance exists for inspections on water/steam lines
• No Supervisory Personnel notified of leak
• Welding event does not get reported to Management
• Employee decides to perform repairs to water line
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Root Cause & Corrective Actions
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Root Cause & Corrective Actions
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Root Cause & Corrective ActionsRoot Cause & Corrective Actions
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Root Cause & Corrective ActionsRoot Cause & Corrective Actions
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Root Cause & Corrective Actions
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Root Cause & Corrective Actions
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Root Cause & Corrective Actions