An interesting comparison to OSHA NEP results for the Ammonia refrigeration industry. From July 2009 to June 2011, Workplace Health and Safety Queensland (WHSQ) conducted an audit and inspection program at 102 facilities using anhydrous ammonia-based industrial refrigeration systems. Facilities included a range of food processors (meat, dairy, processed foods), cold stores, and ice works. The program was developed in response to a number of significant ammonia-related incidents occurring in Queensland.
Since the year 2000, Queensland Fire and Rescue Service’s HAZMAT Unit, (i.e. 000) attended over 60 ammonia-based refrigeration related incidents. A number of these incidents involved significant releases of liquefied ammonia requiring a significant emergency response capability, evacuations, and disruptions to neighbouring workplaces and roadways. These incidents resulted in considerable costs to those affected businesses in lost production time, contaminated product, clean-up and recovery costs.
What was the purpose of this audit program?
This program aimed to achieve a number of objectives including:
- decreasing the risk (likelihood and consequence) of a significant incident which may lead to exposures to toxic gas
- increasing compliance with regulatory requirements
- improving engagement and collaboration with industry and workplaces involved
- providing practical information and assistance to workplaces
- increasing capacity of WHSQ inspectors to deal with hazardous chemicals management issues and enforcement.
What did the audit program include?
The program targeted 102 ammonia-based refrigeration facilities classified as Large Dangerous Goods Locations (Large DGL) under the Dangerous Goods Safety Management Act 2001 (DGSM Act). The quantity prescribed for a Large DGL in Schedule 1 of the DGSM Regulation is 500 L for anhydrous ammonia (Class 2.3 dangerous goods). The facilities were identified using the WHSQ Large DGL notification database, emergency services response information, industry information sources, feedback from the WHSQ inspectorate and other regulatory agencies. The industry profile is shown schematically in Graph 1.
The program did not include:
- facilities that stored anhydrous ammonia in high pressure vessels for distribution as fertiliser in the rural industry (shown in Graph 1 as Rural-Fixed tanks)
- industrial facilities made up of gas depots, ammonia manufacturers and explosive manufacturers (shown in Graph 1 as Industrial).
The audit and inspection process
Inspectors conducted a desktop audit of related documentation and a walk through inspection of the ammonia refrigeration plant and equipment using an audit checklist. The checklist incorporated safety-related regulatory requirements and items from relevant industry standards (e.g. AS/NZS1677.2: Refrigeration systems) to generate a comprehensive assessment tool for the industry.
The audit tool was given to each facility before the audit (typically a month or more beforehand). Enforcement activities were undertaken in accordance with the Compliance and Enforcement Policy 2009.
What did the audit program target?
The program focussed on the operational safety and emergency preparedness at these facilities within the context of the DGSM Act, and the Workplace Health and Safety Act 1995 (WHS Act).The program targeted the following areas:
- refrigeration system hazards (chemical hazards, plant hazards, work environment hazards) and associated risk assessments
- potential emergency scenarios
- emergency planning documentation (content of emergency plans and manifests)
- emergency resources maintained on site and access to additional resources
- plant safety systems (safety release devices, valve and pipework labelling, valve accessibility)
- plant room design (natural and mechanical ventilation, use of detectors, hazardous areas, electrical isolation and protection against explosion)
- operation and maintenance (safe work procedures, safety equipment, vessel and pipework inspection and testing)
- use and interaction with refrigeration contractors
- impact protection (vessels, air cooling units, associated pipework)
- spill containment systems and equipment for clean-up
- fire equipment and maintenance
- staff training and hazard awareness
- visitor’s safety
- accident investigations.
What were the results of the audit program?
Of the 102 facilities audited, a total of 451 directives and notices were issued, 435 directives under the DGSM Act and 16 Improvement notices under the WHS Act. The breakdown of directives/notices issued for specific issues are shown in Graph 2. Table 1 explains each issue (x-axis label) with a further comment about the typical scope of these directives/notices.
Collectively, hazard identification and risk assessment, emergency preparedness, and storage and handling systems (refrigeration plant), accounted for 51 per cent of all directives/notices issued. Every facility was issued with at least one directive/notice related to one of these areas.
The program showed considerable gaps in awareness of ammonia refrigeration hazards and safety obligations under the dangerous goods safety legislation. Audits also revealed considerable gaps between risk controls that had been implemented, those set out in relevant industry standards and dangerous goods safety legislation.
Hazard identification and risk assessments
Hazard identification and the associated risk assessments need to address the site as a whole (e.g. major accident scenarios), plant risks (e.g. plant integrity) and work activity risks (draining oil or replacing a system component). Audits found that risk assessments conducted by many occupiers focused on hazards associated with handling hazardous substances. These assessments satisfied the requirements for hazardous substances risk assessments under the Workplace Health and Safety Regulation 2008, but failed to address the issues identified under the dangerous goods legislation where risks to all persons (workers, emergency responders and community), property and the environment must be considered.
The audits also revealed that hazards identified in the dangerous goods risk assessments were either dismissed or discounted on the basis of a low frequency or low likelihood of an incident occurring. A number of the more significant ammonia-related incidents in Queensland have had significant consequences to property and the environment, without causing significant harm to anyone. However, people were still put at risk (e.g. workers and emergency responders).
Detailed risk assessments are needed where the risk is high, for example:
- anhydrous ammonia-containing plant is in close proximity to others (e.g. neighbouring businesses, residential areas, schools, hospitals, public recreational areas, transport routes, waterways)
- higher quantities of ammonia is kept in plant and equipment where a large volume release may occur
- ammonia refrigerant being circulated directly around workrooms (i.e. ‘occupied areas’).
A comprehensive site wide risk assessment demonstrates that the obligation to minimise risk as far as reasonably practicable has been met. Without this assessment, major risks and critical controls cannot be identified.
In many cases, documented emergency plans did not satisfy the requirements of section 61 of the DGSM Regulation resulting in a large number of directives being issued. The more significant findings in this area are outlined below.
- The range and scale of potential emergencies were not detailed. This was often a result of an inadequate hazard identification and risk assessment process. There was little recognition of the potential for leaks of liquefied ammonia, or gas leaks into occupied areas and other areas not associated with the plant room such as ceiling spaces and switchboard areas.
- Because of building evacuation requirements under fire legislation, there was generally an organisational structure and procedure in place to deal with an emergency such as fire, bomb threat, or civil disturbance. These plans were often provided as evidence of emergency planning, but did not adequately address ammonia-related emergency scenarios. For example, a plan may specify only one muster point which could be affected by a gas leak when located downwind of the source. An alternative mustering point must be provided to allow for changes in wind direction.
- Resources and equipment were often found to be lacking or in poor condition. There were instances where respirator canisters were stored while exposed to the plant room atmosphere, self-contained breathing apparatus (SCBA) had perished rubber seals on masks, and the use and maintenance of handheld ammonia gas detectors were not incorporated into procedures. There was a significant lack of awareness of the importance of emergency ventilation and lighting and the principles of spill containment in an emergency situation.
- Procedures often lacked:
- coverage of emergency shutdown procedures
- identifying the source of a leak safely
- the use, limitations and maintenance of handheld ammonia detectors
- specific detail on the required level of personal protective equipment.
- There was a lack of clearly articulated roles and responsibilities for refrigeration contracting personnel during an ammonia-related emergency. Cases included:
- disputes over provision of appropriate safety equipment (e.g. SCBA)
- undefined response times and availability, or
- lack of buddy systems, particularly when accessing confined areas/enclosed areas containing ammonia equipment.
- There were many instances of incomplete manifest documentation (see Schedule 4 of the DGSM Regulation for information about what should be included in manifests). Manifests are a key reference document for emergency services when they are called on to respond to an incident at a facility.
Storage and handling systems
The largest number of directives (91) was issued for storage and handling systems, which encompass all aspects of the refrigeration plant and equipment. The more significant findings in this area are listed below.
- Inadequate or unavailable documentation for testing vessel and pipework integrity and safety devices. Maintaining plant integrity plays a significant role in preventing ammonia-related emergencies.
- Inadequate ‘hazardous areas’ management. This covers items such as:
- lack of control of potential ignition sources (e.g. boiler located in same room as ammonia equipment)
- inability to isolate electrical items
- lack of mechanical ventilation to control gas levels
- lack of emergency lighting and ventilation fans suitably rated for flammable atmospheres (important for their continued operation during an emergency).
- Lack of awareness of ammonia’s flammability and potential consequences of an incident within the confines of an enclosed area such as a plant room. 25 Directives were issued to address the control of ignition sources in an indoor plant room.
- Over reliance on natural ventilation during an uncontrolled gas release, (i.e. an indoor emergency situation). This is closely linked to controlling airborne ammonia concentrations and hazardous areas management. Appropriate mechanical ventilation helps manage the risk of ignition.
- Pressure relief devices were set up to discharge within the plant room, or discharge at worker head height within the plant room, or adjacent to walkways and platforms causing an unsafe situation.
- Poor accessibility to critical valves. For example, valves positioned behind an obstacle, or at elevated and awkward positions with no appropriate access. Often a ladder was used for access.
- There were a number of examples where a pressure relief device, rated for gas only service by a manufacturer, was installed in lines that may be exposed to liquid service against the manufacturer’s specifications.
- Fixed ammonia detectors were lacking in unmanned plant areas at some facilities preventing early detection and action.
Issues with other risk control measures
Issues were also found with the following
- spills management and containment for liquefied ammonia leaks and contaminated fire fighting water spills clean-up equipment
- safe work procedures for draining oil, isolation of equipment and ‘breaking-in’ to the enclosed system, and working on ammonia pipework and fittings in enclosed areas such as ceiling spaces
- training specifically addressing ammonia hazards, emergency preparedness
- labelling of critical valves and pipework, confines spaces, and relevant safety signage
- impact protection for vessels and other equipment (e.g. cold room air chillers) where forklifts operate
- incident investigation processes and recording.
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