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Pipeline Investigation Report P12H0103

Ignition and fire in isolation valve MOV-0409 enclosure
Westcoast Energy inc., carrying on business as
Spectra Energy Transmission
Compressor Station N4
Near Wonowon, British Columbia
23 June 2012

The Transportation Safety Board of Canada (TSB) investigated this occurrence for the purpose of advancing transportation safety. It is not the function of the Board to assign fault or determine civil or criminal liability. This report is not created for use in the context of legal, disciplinary or other proceedings. See Ownership and use of content.

Summary

On 23 June 2012, at approximately 1200 Mountain Standard Time, an ignition and fire occurred in a valve-enclosure structure at Spectra Energy Transmission Compressor Station N4, located approximately 160 km northwest of Fort St. John, British Columbia. Two maintenance employees sustained burn injuries when sweet natural gas that had been leaking from a station valve ignited. The 2 employees were performing annual inspection work on motor-operated valves. The injured employees were air-lifted to the Fort St. John Hospital. One employee was released later that day, while the second employee was transferred to a burn unit in Vancouver.

Factual information

Westcoast Energy Incorporated, carrying on business as Spectra Energy Transmission (Spectra), was conducting an inspection of the motor-operated valves (MOV) in Compressor Station N4 (CS-N4) during its annual maintenance shutdown. CS-N4, a compressor station that forms part of Spectra’s Transmission North pipeline, is located approximately 160 km northwest of Fort St. John, BC (Figure 1).

Figure 1. Map of the occurrence location (Source: Spectra)
Map of the occurrence location

The accident took place within the weather enclosure structure that was housing MOV-0409 (Figure 2). This motor-operated valve controls the 91.44-cm (36-inch) loop discharge pipeline for the compressor station.

Figure 2. Aerial view of weather enclosure structures
Aerial view of weather enclosure structures

In 1993, MOV-0409 and MOV-0417 (in operation since the 1960s) were enclosed within weather protection enclosure structures. The 2 enclosures shared a common wall, with an opening to allow inside access between the enclosures (Figure 3). MOV-0409 controls the 91.44-cm (36-inch) loop discharge pipeline, and MOV-0417 controls the emergency blow-down pipeline for the compressor station. MOV-0409 and MOV-0417 are both equipped with 130 volts-direct-current (VDC) motor operators, enclosed within the limit-switch housing. There is no other electrical equipment in these enclosures. Under normal operating conditions, MOV-0409 is left in the fully-open position, meaning that high-pressure gas will flow through the valve unobstructed. If an emergency shutdown sequence occurred at the compressor station, MOV-0409 would move to the fully-closed position automatically. The maintenance work on MOV-0409 required the line to be pressurized.

Figure 3. Schematic of enclosure structure for MOV-0409 and MOV-0417 (Source: GC Phillips report)
Schematic of enclosure structure for MOV-0409 and MOV-0417

The enclosure structure around MOV-0409 is approximately 2.4 m by 3.7 m (8 feet by 12 feet). The enclosure structure around MOV-0417 is approximately 3.7 m by 3.1 m (8 feet by 10 feet).

Spectra transports natural gas from its Fort Nelson gas plant to the Canada-USA border. The section of pipeline that travels from Fort Nelson to CS-2 has a capacity of 50.72 million cubic metres (1.8 billion cubic feet) of gas per day. There are 4 intermediate compressor stations (CS-N2, CS-N3, CS-N4, and CS-N5). At the time of the occurrence, only 2 compressor stations were required to meet production and supply demands.

The product in the pipeline was sales-quality, sweet non-odourized natural gas. Natural gas is predominately (95%) methane gas, and is non-toxic. It is extremely flammable, and can form an explosive mixture when mixed with air. It is a known asphyxiant, and can displace oxygen in an enclosed space. The methane concentration in air at which a flammable or explosive mixture occurs is in the range of 5% to 15%.

On the day of the occurrence, the operating pressure for the 91.44-cm (36-inch) compressor-station discharge piping was 4 295 kilopascals (kPa) (623 pounds per square inch gage (psig). For the compressor-station piping, the operating pressure in the station piping was 4 309 kPa (625 psig).

The work environment at a compressor station is classified as a hazardous area, with a Canadian Standards Association (CSA) Canadian Electrical Code designation of Class 1, Zone 0, and Group D. This designation signifies the following:

Operational events before the occurrence

A number of operational events and decisions, starting from approximately 10 months before the occurrence, is listed below. Note that the Spectra employees include:

Operational events and decisions before the occurrence

16 August 2011

Photo 1. Fugitive gas emission (FGE) tag for MOV-0409
Fugitive gas emission tag for MOV-0409

Late August 2011

Photo 2. Egress door for MOV-0409 enclosure
Egress door for MOV-0409 enclosure

08 May 2012

20 May 2012

30 May 2012

01 June 2012

08 June 2012

18 June 2012

21 June 2012

Operational events on the day of the occurrence

As part of the annual maintenance shutdown at CS-N4, the valve preventive maintenance and compressor unit test runs were to be completed on June 23. The list below summarizes the operational events and decisions on the day of the occurrence.

Operational events and decisions on the day of the occurrence (times are approximate)Footnote 2

07:00

09:00

09:15

09:30

10:00

11:00

11:15

11:20

11:30

11:40

11:50

Photo 3. MOV-0409 with operator cover fully open
MOV-0409 with operator cover fully open

12:00

Photo 4. Manual control switches
Manual control switches

12:02

On 16 July 2012, at approximately 10:45, CS-N4 was returned to normal service, following completion of repair of the seals on the valve stem on MOV-0409, and other associated repair work to the enclosure. The skylight on the enclosure had been reinstalled, having previously been removed to allow gas to escape from the enclosure.

Site examination

During the site examination, the following was determined:

Figure 4. Schematic of MOV-0409, illustrating stem seals (Source: GC Phillips report)
Schematic of MOV-0409, illustrating stem seals
Figure 5. Bull plug installed on MOV-0409
 
Bull plug installed on MOV-0409

Assessment of potential ignition sources

Spectra contracted GC Phillips Consulting Ltd (GC Phillips) to conduct an assessment of the conditions leading to the fire. Four possible sources of ignition for the leaking gas within the enclosure were examined:

  1. Electrical spark or auto-ignition from the electrical housing valve operator heater,
  2. Electrical spark from activation of the OPEN valve switch,
  3. Mechanical spark from closing the limit-switch housing cover, and
  4. Electrical spark from the motor stop switch.

The assessment determined the following:

Regulatory requirements for pipeline integrity management

Section 40 of the National Energy Board (NEB) Onshore Pipeline Regulations, 1999, SOR/99-294 (OPR-99) specifies, in part, federally regulated pipeline companies are required to develop pipeline integrity management programs and to initiate corrective action for defects which are known to exist or are found to exceed criteria established by the CSA Z662.

Section 3.2 of the CSA Z662-11 (Pipeline System Integrity Management Program) specifies, in part:

Operating companies shall develop and implement an integrity management program that includes effective procedures for managing the integrity of the pipeline system so that it is suitable for continued service, including procedures to monitor for conditions that can lead to failures, to eliminate or mitigate such conditions, and to manage integrity data. Such integrity management programs shall include a description of operating company commitment and responsibilities, quantifiable objectives, and methods for:

  1. Assessing current potential risks;
  2. Identifying risk reduction approaches and corrective actions;
  3. Implementing the integrity management program; and
  4. Monitoring results.

Spectra’s pipeline integrity management system

Spectra’s pipeline integrity management system (PIMS) manual is the governing document for managing the integrity of its pipeline facilities. This document provides a systematic approach to identifying and mitigating potential risks to the pipeline.

PIMS also provides the basis for developing the company’s annual pipeline maintenance (PM) program. Together, PIMS and PM use a risk-based process to ensure safety and service reliability of the pipeline system.

Hazard-control hierarchy

A commonly used hazard-control hierarchy for high-risk work location consists of 4 broad categories:

  1. Elimination of the hazard
  2. Alternative methods of inspection or engineering controls
  3. Administrative controls
  4. Personnel protective equipment requirements.

As defined by the Quality Systems Toolbox (Figure 6), the control options are ranked in terms of effectiveness and sustainability: Footnote 5

Figure 6. Hierarchy of control methods (Source: Quality Systems Toolbox)
Hierarchy of control methods

Managing gas leaks: Elimination control

The Canadian Association of Petroleum Producers (CAPP)Footnote 6 document on best practices in the management of FGEsFootnote 7 specifies, in part:

Where feasible, repairs or replacements should be done within 45 days from the time the leak is detected. Where a major shut down is required to facilitate this work, or there are marginal economics for repairing the component, the repair or replacement may be delayed until the next planned shutdown, provided that this does not pose any safety, health or environmental concerns.

The timeline for repairing a leak is based on cost and risk. Cost is measured in terms of lost product and the associated environmental impact.

Leaks had been detected from MOV-0409 since 2006. Since that time, attempts were made on a number of occasions to install a temporary repair, using high-pressure grease. These efforts were ultimately unsuccessful. In August 2011, the FGE from MOV-0409 was quantified through a fugitive emission survey (FES). A FES is designed to identify emissions of natural gas and other hydrocarbons emanating from pressurized piping and associated equipment. The lost product from MOV-0409 was estimated to be approximately 245 tonnes CO2 (carbon dioxide equivalent). The dollar value of this lost product was about $48 000. The threshold at which a gas release must be reported to the provincial government of British Columbia is 10 000Footnote 8 tonnes. Gas releases must be reported to Environment Canada when the quantity lost reaches 50 000Footnote 9 tonnes. The FGE from CS-N4 was well below both reporting thresholds.

At the time of the occurrence, 8 of approximately 1000 valves at Spectra were experiencing gas leaks.

Based on a best practice from outside the Canadian pipeline industry, documenting and classifying hydrocarbon releases is a key performance health and safety indicator for Oil and Gas UK.Footnote 10 In North America, a classification system is being developed by the offshore industry that will define 3 health-and-safety risk categories, based on the scope of potential damage. The leak criteria for these risk levels have not yet been finalized. For federally regulated pipelines, both the NEB and the Transportation Safety Board (TSB) require the reporting of all natural gas releases.

Spectra's notification manual: Administrative control

In August 2007, Spectra's maintenance notification system was enhanced to capture the results of FESs, and to document the associated repairs at compressor stations. Within this notification system, all malfunctions are assigned a priority, which in turn determines the urgency of the required response. Spectra specifies the priority categories as follows:

Emergency: Includes work needed due to risk to personnel safety, immediate environmental impact, a breakdown affecting production or the possibility of major equipment damage. Response must be immediate and overtime is justified. This priority has a lead time set to 2 days.

Urgent: Includes work needed in a timely fashion to prevent the deterioration of a piece of equipment or operating system. There is no immediate threat, but action must be taken as soon as possible. This work does not take precedence over any scheduled work, manpower is not diverted, and overtime is not justified. This is the first work selected for the next planning period. This priority has a lead time set to 7 days.

Next PM: Includes preventive maintenance or work that will be done when the next preventive maintenance is scheduled. This priority has a lead time set to 45 days.

Routine: Includes work that is thoroughly planned and scheduled to take advantage of available capacity such as routine repairs, replacements, enhancements and project work that is not critical to the operation of the facility. This priority has a lead time set to 45 days.

Safety and Inspection: These 2 priorities are not used for notifications.

The priority assigned by Spectra to the MOV-0409 malfunction notification was “safety.” The safety priority has no associated lead time, and is not meant to be used for notifications. In this case, the repair required a station shutdown. Because the safety classification does not have a lead time, it was used when repairs were assigned to periods with lead times beyond 45 days.

Air-quality management within enclosure structures: Engineering control

When the enclosure structure was originally constructed, access to MOV-0417 and MOV-0409 was through a single-entry door to MOV-0417. Within the enclosure structure for MOV-0409, an air-inlet vent had been installed low to the ground, and an exhaust vent had been installed approximately 1 m (3 feet) below the roof of the building (Figure 7). In 2006, the man-door to MOV-0417 was equipped with an air-quality testing port and associated signage (Photo 5).

In August 2011, 2 weeks after the FGE from MOV-0409 was surveyed, a second door was installed on the enclosure (i.e., in the portion that housed MOV-0409). This second door would provide rapid egress if personnel became incapacitated on the MOV-0409 side of the enclosure. This second door was not installed with an air-quality testing port, which is a typical feature for man-door entrances to enclosure structures.

Figure 7. Upper passive-venting port
Upper passive-venting port
Photo 5. Air-quality testing port and associated signage
Air-quality testing port and associated signage

Facilitating egress to the outside of enclosure MOV-0409 ensured that the structure was not designated as a confined space, as per the federal and provincial occupational health and safety regulations. Spectra classifies the MOV enclosures as enclosed spaces, rather than as confined spaces. Its operator training manualFootnote 11 indicates that, before entering valve-enclosure structures,

During a limited employee survey related to air-quality measurements in enclosure structures, the following was determined:

Work planning: Administrative controls

Spectra established its maintenance cycles for gas transmission components based on industry best practices and manufacturer recommendations. Scheduling of maintenance and repair work is coordinated by its Asset Management Group, using a work-planning software application. The repair scheduling process is conducted on a monthly basis as follows:

In the June 2012 work plan, there were 39 preventive/predictive maintenance orders relating to work at CS-N4. The malfunction notification for MOV-0409 was not listed, as it was not scheduled for repairs in June 2012 due to lack of parts. Field workers commented that it appeared that malfunction notifications often disappeared from the work plan.

Also, the work-planning system does not consider a work item to be complete until a completed time is entered. It was noted that the completed time was not entered on a consistent basis. Consequently, from a maintenance-planning and scheduler perspective, it appears that the work is incomplete, and the work ends up on a backlog list for cleanup. Approximately 65% (estimated) of the backlog items had resulted from incomplete field-data entry into the work-planning system.

Work permitting: Administrative controls

Spectra's Safe Work Permit Practice (a section within the company's Safe Work Practices Manual) defines the range of permits and their requirements. This practice indicates that station operators issue work permits to employees and contractors if there is a potential safety impact during a work activity. The permit is a single form with check-boxes that can be configured to meet all work types, including hot work, cold work, and confined-space entry. According to Spectra's Safe Work Practices Manual, issuing a hot-work permit requires gas-monitoring tests. The Safe Work Permit Practice section defines a confined-space entry permit, but does not mention nor provide guidance for an enclosed-space entry permit. On the permit itself, the issuer can select the type and frequency of atmosphere monitoring. However, there is no place on the permit to indicate whether atmosphere testing had been performed before entry.

Spectra practices relating to work permits include the following:

Work permits are used for both hot work and cold work. Some site personnel were uncertain whether the planned PM inspection work that day required a hot-work permit or a cold-work permit. However, as the scheduled work did not include welding, cutting, burning, grinding, or the use of non-intrinsically safe tools, the cold-work process was used.

At CS-N4, the field practice related to self-permitting had evolved to the point where it was not uncommon to record permitting details after work had been completed.

In Canada, the pipeline industry has developed a number of strategies to address the use of self-permitting. For example, the Canadian branch of one major oil and gas companyFootnote 13 uses a feedback mechanism, whereby an employee contacts an issuing authority before and upon completion of the work. Once the job is complete, the worker signs off the permit, and contacts the issuing authority to advise on the status of the work and report that the worker is leaving the location. Another strategy used is to integrate work-permit management into the product-maintenance scheduling software.Footnote 14

Personal gas detectors: Personal-protective-equipment control

In March 2011, Spectra initiated training in the use of handheld, personal, portable gas detectors for work at compressor stations. Spectra sent a number of employees to the manufacturer for training in the operation and maintenance of the personal gas detectors. Using a train-the-trainer approach to information dissemination, these trained employees were expected to share the information with their colleagues. At the time of the occurrence, the transition from the use of handheld portable gas detectors to wearable portable gas detectors was still in progress.

Decision-making and risk adaptation

Decision-making in high-risk contexts such as Spectra's CS-N4 is driven by experience,Footnote 15 which in turn is driven and reinforced by the outcomes from risk-management behaviours.Footnote 16 As the benefits of risky behaviors and the costs of safe behaviors increase compared to the costs of risky behavior and the benefits of safe behavior, individuals will accept more risk. The set-point that defines acceptable risk management slowly drifts toward greater perceived efficiency, and, often unknowingly, into a more risky space.

Social normalizing pressures will tend to propagate behaviors across members of a group. In the absence of identified hazards, accidents, or reported close calls, organizations may not recognize the fact that normal adaptations are adjusting the risk boundary outward into a region of increased likelihood of an adverse outcome. This process is risk adaptation.

In addition, Klein's expectation-primed decision-making model highlights that the more skilled an individual is, the more likely that individual's decision-making will be influenced by expectation. The down-side is that expectation can mask subtle cues that indicate that the situation is not as expected, and may be more risky. The implication is that situations will appear normal or familiar, unless the “out of the ordinary” instance is of sufficient magnitude to attract attention and subsequent analysis.

Explicit effort is required to anchor behaviour such that risk is managed in the field to the same level as it is described in policy documents and manuals. Typical strategies to ensure that behaviour is aligned with risk-management expectations include reassessment of risk and risk-mitigation strategies when contexts change; developing specific, context-appropriate standard operating procedure documentation for safety-critical operations; and ensuring that operating practices align with procedures. This alignment of behaviour with policy is a critical requirement that characterizes closed-loop risk management systems.Footnote 17 In the absence of adverse outcomes, this effort is increasingly seen in terms of costs by employees and management alike.Footnote 18

Analysis

The accident

At the time of the occurrence, Spectra personnel were performing preventive maintenance and inspection on MOV-0409 as part of an overall annual inspection program for the MOVs located in CS-N4. MOV-0409 was enclosed within a weather protection structure. The maintenance work involved testing the valve limit switches and adjusting the torque settings within the housing of the electrical valve operators. Before the enclosure structure was entered, it had not been tested for the presence of gas, and the Spectra employees were not wearing personal gas detectors.

A leak had been first noted in valve MOV-0409 as early as 2006. With a continuous gas leak since at least August 2011, it is likely that the flammable mixture of gas had existed in the upper portion of the enclosure structure before the start of work. In addition, the tattle-tale vent (TTV) on MOV-0409 had been replaced with a bull plug (BP). With the BP installed, the only route for the released gas coming off the valve stem was to exit the valve body through the top of the valve actuator. Replacing the TTV with a BP negated a safety feature of the valve that was designed to warn company employees of a potentially hazardous presence of natural gas. The accident occurred when MOV-0409 was moved from the fully-closed to the fully-open position, which increased the flow of natural gas through the leaking valve stem. The pipeline gas was released through the valve stem into the enclosure structure. During the attempt to shut the valve, a spark from the motor stop switch likely occurred when the CLOSE button was activated. The spark was sufficient to ignite the flammable mixture of gas that was present in the enclosure structure, resulting in the fire, the explosion, and the subsequent injuries to 2 maintenance workers.

Management of gas leaks

Starting in August 2011, when the fugitive emission survey (FES) identified the leak at MOV-0409, a FGE tag on the outside of the man-door of the enclosure structure for MOV-0417 was used to flag this danger. However, when a second man-door for MOV-0409 was installed at this enclosure structure, no additional FGE tagging was added. When fugitive gas emission (FGE) tags are not installed at all entrances to enclosure structures where there is a leaking valve, maintenance workers may underestimate the potential dangers, increasing the risk of worker injuries and fatalities.

Cost/benefit and environmental-impact criteria are well developed triggers to motivate the repair of gas leaks. However, FGEs can be left unrepaired for 45 days or longer, depending on whether the facility must be shut down for the repair. In this occurrence, the leak was known and had been documented and tracked for at least 10 months. As repair parts were unavailable, the repair was not scheduled for the June 2012 station outage. Spectra had developed an operator training manual, which specifies the procedures for entering valve-enclosure structures. These procedures include air testing for the presence of gas and personal protective equipment (PPE) requirements. In terms of the generally-accepted hierarchy of risk-management options, risk management of this leak was administrative at the site level. Reliance on administrative procedures and use of PPE as primary risk-mitigation defences is intrinsically weaker than fixing the problem.

Air-quality management within enclosure structures

Within the enclosure structure for MOV-0409, ventilation vents had been installed low to the ground and approximately 1 m (3 feet) below the roof of the building. The placement of the upper vent was not optimal, as it allowed gas to accumulate near the ceiling. The enclosure was originally constructed with a single entrance, which was the west door to the MOV-0417 enclosure. In 2006, an air-quality testing port was installed on this door. In August 2011, when FGEs were detected from MOV-0409, a second exit door to facilitate egress was added. By focusing on the egress requirements only, Spectra installed the second door without an air-quality testing port, which was a typical feature for the other enclosures. In the absence of industry standards and/or recommended guidelines for the design, construction, and installation of enclosure structures, some enclosures may not be optimally designed to maintain air quality, increasing the risk of worker injuries and fatalities.

Work planning

Scheduling maintenance and repair work at Spectra was conducted using a work-planning software application. There were a number of information deficiencies and inconsistencies relating to the use of this work-planning system, including the following:

As a result, the Spectra work-planning tool was not well aligned with the operational expectations of field technicians.

Self-permitting

Self-permitting by station operators is a necessary requirement in installations where there is normally only 1 employee. This process ensures that employees on their own still work through the hazard-assessment and risk-mitigation process. However, when the issuer and the receiver are the same person, the permitting activity becomes a reflective task; there is no dialogue between 2 people. Over time, the self-permitting process can become repetitive and lose relevance. Without appropriate reinforcement, it may be seen as a paperwork activity that interferes with efficient workflow and can be deferred to a later time.

At CS-N4, field practices regarding permitting of Spectra employees had adapted to the point where it was not uncommon to record permitting details after work activities had been completed. When work permits are not completed before the start of the work, employees may not fully consider all potential work site hazards, increasing the risk of workplace accidents.

At Spectra, there is no connection between the generation of the monthly work schedule and the associated safe-work permits, whether self-permitted or issued by the station operator. Safe-work permits are generated on site and remain at the compressor stations. This practice serves to isolate field risk-mitigation practices from back-office planners, schedulers, and the team leader. Under these circumstances, it is very difficult for management remote from the stations to detect how self-permitting is evolving. The lack of a rigorous permitting process by a CS-N4 station operator familiar with the site resulted in a lost opportunity for senior personnel to reinforce appropriate translation of corporate policies and associated documents into field practice.

Decision-making risk adaptation by maintenance workers

At the time of the occurrence, the maintenance crew's perception of risk had adapted considerably. Habituation to this long-standing leak had reached the point where entry into MOV-0409 was seen to be no more risky than entry into any of the other MOV enclosures. Factors that reinforced this risk adaptation include the following:

When risk adaptation occurs and perceived risk is diminished, cues to potentially hazardous situations (e.g., the presence of leaking gas) will be overlooked, increasing the potential for workplace accidents.

Site management practices

At Spectra, field operating procedures related to such things as permitting, enclosed-space entry, valve maintenance, and use of new PPE were managed using a largely “open-loop” approach. That is, documented policies and procedures were required to be read, and satisfactory completion of multiple-choice quizzes reinforced learning points. It was assumed that operational practices were derived appropriately. There was no site-level routine monitoring and documentation of new hazards (e.g., the leaking valve) or specific risk-assessed standard operating procedures by which field practices could be benchmarked. By contrast, “closed-loop” management systems include ongoing feedback mechanisms to ensure that the system is performing within predicted boundaries. In the absence of continuous monitoring and risk assessment, “open-loop” site-management practices can reinforce risk adaptation by employees, resulting in operational practices that are inconsistent with the risk reality.

Findings

Findings as to causes and contributing factors

  1. The accident occurred when escaping natural gas from a leaking valve stem found an ignition source and ignited.
  2. The valve stem was leaking due to the failure of 2 stem-seal o-rings for MOV-0409.
  3. Ignition of the natural gas likely resulted when the MOV’s close button was activated in an attempt to shut off the increased flow of gas. This action produced a sparking contact within the open electrical housing operator, and ignited the gas.
  4. The enclosure structure had not been tested for the presence of gas before the start of the work, and the Spectra employees were not wearing personal gas detectors.
  5. The work plan did not display the pre-existing hazard (i.e., FGE) associated with MOV-0409, resulting in a maintenance plan that did not address how the work was to be performed in the context of a leaking valve.

Findings as to risk

  1. When fugitive gas emission (FGE) tags are not installed at all entrances to enclosure structures when there is a leaking valve, maintenance workers may underestimate the potential dangers, increasing the risk of worker injuries and fatalities.
  2. In the absence of industry standards and/or recommended guidelines for the design, construction, and installation of enclosure structures, some enclosures may not be optimally designed to maintain air quality, increasing the risk of worker injuries and fatalities.
  3. When work permits are not completed before the start of the work, employees may not fully consider all potential work site hazards, increasing the risk of workplace accidents.
  4. When risk adaptation occurs and perceived risk is diminished, cues to potentially hazardous situations (e.g., the presence of leaking gas) will be overlooked, increasing the potential for workplace accidents.
  5. In the absence of continuous monitoring and risk assessment, “open-loop” site management practices can reinforce risk adaptation by employees, resulting in operational practices that are inconsistent with the risk reality.

Other findings

  1. Reliance on administrative procedures and use of personal protective equipment as primary risk-mitigation defences is intrinsically weaker than fixing the problem.
  2. Replacing the tattle-tale vent with a bull plug negated a safety feature of the valve that was designed to warn company employees of the presence of gas.
  3. The Spectra work-planning tool was not well aligned with the operational expectations of field technicians.
  4. The lack of a rigorous permitting process by a CS-N4 station operator familiar with the site resulted in a lost opportunity for senior personnel to reinforce appropriate translation of corporate policies and associated documents into field practice.

Safety action

Safety action taken

On 10 July 2012, the Transportation Safety Board (TSB) sent a safety information letter to the National Energy Board (NEB) advising it of this occurrence and stating that the Spectra employees had not been wearing personal gas detectors.

The following safety action was taken by the NEB following the occurrence:

  1. An NEB health and safety officer issued an assurance of voluntary compliance (AVC) under the Canada Labour Code, which required Westcoast to submit its hazard prevention program and the hazard assessments conducted for valve-enclosures, for preventive maintenance and repairs to valves, and for working in the presence of natural gas. The AVC also required Westcoast to submit a corrective-action plan addressing the recommendations of the GC Phillips report. The NEB plans to conduct follow-up compliance activities, such as inspections, to assess Westcoast’s implementation of its commitments made in response to the AVC.

The following safety actions were taken by Westcoast following the occurrence:

  1. A natural-gas-leak survey was conducted at all facilities within the transmission business division, including compressor stations and meter stations. A leak-reporting process has been implemented to ensure that all leaks, including fugitive emissions, that are not immediately repaired are entered into Westcoast’s incident learning and prevention system, and that a maintenance notification is entered into Westcoast’s general administration system that manages facility-maintenance planning. New maintenance notifications are reviewed weekly, and leak notifications are coded to enable tracking of the repair.
  2. All fugitive emission locations were tagged and the area ribboned off. If the leak posed a threat to employees, the public, or the environment, the equipment was taken off-line and repaired, or measures were taken to mitigate the threat. All fugitive emissions that could not be immediately repaired were scheduled for repair at the next available equipment outage.
  3. A fugitive emission survey (FES) process has been developed and will take place before a major facility outage.
  4. All valve enclosures on the transmission system have been audited, and deficiencies in internal-atmosphere test ports and required signage have been corrected.
  5. The valve-enclosure design standard has been updated to address design, construction, and materials. All valve enclosures will be assessed against this standard and either upgraded to meet the standard or removed if the enclosure is no longer required.
  6. The allowable limit for certain work in a hazardous atmosphere has been reduced for transmission facilities to 0% of the lower explosive limit.
  7. Based on this occurrence, as well as current industry practices, the safe-work permit for transmission facilities has been updated to better anticipate potential workplace hazards.
  8. The valve-enclosure entry procedure has been updated.
  9. A major-incident correction-actions project has been initiated across Westcoast’s western Canadian operations, to review and upgrade, as required, Westcoast’s safety processes and standards, including work permits.
  10. The workplace hazard prevention program for Westcoast’s western Canadian operations has been revised. Workplace hazard assessments for all transmission facilities will have been completed in accordance with this program by 31 December, 2013.
  11. Field-level safety assessments are now required, and are incorporated into a safe-work plan form.
  12. Employees working on transmission facilities must wear a 4-head personal gas monitor.

Employees (management and workers) have been reminded that they must comply with safe work practices and procedures, or risk disciplinary action.

This report concludes the Transportation Safety Board’s investigation into this occurrence. Consequently, the Board authorized the release of this report on 17 July 2013. It was officially released on 26 September 2013.