LOCATION
Mount Keith, Western Australia
Scope of Work:
BHP Nickel West Mount Keith Nickel Operation operates two 460 m³ sulphuric acid storage tanks, 36260-TK470 and 36260-TK471. The tanks are approximately 8.2 m in diameter x 9.4 m high, with self-supporting cone roofs, and were designed in accordance with API 650 and NACE SP0294-2006.
APMS was engaged to undertake the draining, cleaning and decontamination, 10-yearly inspection and associated repair work on the two sulphuric acid storage tanks.
A key component of the project was the repair of a leaking manway nozzle on TK470. To minimise tank downtime and disruption to plant operations, APMS completed the required pre-engineering and prefabrication of a replacement manway nozzle incorporating a shell insert plate prior to mobilisation to site.
This pre-planning allowed the repair to be executed efficiently once the tank was offline and maximised the opportunity to complete additional inspection and repair activities during the shutdown window.
APMS was responsible for the complete delivery of the following works:
- Tank draining, cleaning and acid decontamination
- Preparation of tanks for internal entry and inspection
- 10-yearly inspection in accordance with applicable tank inspection requirements
- Internal inspection and identification of defects and repair requirements
- Engineering and prefabrication of replacement manway nozzle and shell insert plate
- Removal and replacement of the leaking manway nozzle on TK470
- Boilermaking and coded welding repairs
- Non-destructive testing of completed repairs
- Rectification of additional minor defects identified during inspection
- Final inspection and repair sign-off
- Return of the tank to service
Where additional repair requirements were identified during the inspection, APMS was able to rapidly mobilise additional personnel, including boilermakers and coded welders, allowing the repairs to be completed without extending the planned outage.
Project Resourcing:
The project was delivered using a dedicated multidisciplinary team comprising of:
- 1x API653 Inspector
- 1x Project Supervisor
- 4x Acid Tech (High-Risk Technician)
- 1x NDT Technician
- 2x Boilermaker (additional resourcing during repairs)
- 2x Coded welder (additional resourcing during repairs)
The ability to provide specialist inspection, hazardous chemical, NDT, boilermaking and coded welding capabilities enabled APMS to deliver the project as a single turnkey service provider.
Project Achievements:
APMS carried out internal and external out-of-service inspections of the tanks in accordance with API 653 and NACE SP0294.
Working inside sulphuric acid storage tanks presented significant chemical and confined-space hazards.
APMS utilised experienced acid technicians and implemented stringent controls for tank entry and decontamination activities. Cleaning and internal works were undertaken using fully encapsulated chemical protective suits and supplied air breathing systems, providing appropriate respiratory and chemical protection for personnel working within the hazardous environment.
Both BHP and APMS carried out risk assessment to address all high-risk activities and were executed in accordance with the project’s safety requirements, with the works completed without injury, incident or environmental event.
Through detailed pre-planning, effective coordination and rapid mobilisation of additional resources, APMS successfully streamlined the inspection and repair program and completed the works within a 21-day period.
Key achievements included:
- Maintaining plant continuity by planning the works so that one sulphuric acid storage tank remained operational while the other was taken offline.
- Completing hazardous tank cleaning and decontamination using specialist chemical protection and supplied-air systems.
- Prefabricating the replacement manway assembly prior to site mobilisation, significantly reducing onsite repair duration.
- Rapidly mobilising additional boilermakers and coded welders to address defects identified during inspection.
- Completing additional minor repairs within the available shutdown window.
- Coordinating inspection, NDT, fabrication, welding and repair activities through a single APMS project team.
- Completing all repairs in accordance with the applicable inspection and repair requirements.
- Obtaining final inspection and repair sign-off from the API 653 Inspector.
- Returning the tank to service within the planned timeframe.
- Completing all high-risk works without injury, incident or environmental event.
Key Activities:
The success of the project was underpinned by several key factors:
Pre-planning and engineering of the replacement manway nozzle and shell plate before mobilization. This enabled the repair to commence immediately once tank was available.
The experience in working with hazardous chemicals, including concentrated sulphuric acid environments, enabled the team to safely undertake tank cleaning, decontamination and internal works using appropriate chemical protective equipment and supplied air breathing system.
Our close working relationship with our established NDT partner provides timely inspection and testing services throughout the project, supporting rapid identification and close out of repair requirements.
Our access to experienced boilermakers and coded welders allowed repair works to be undertaken immediately when additional defects were identified, without the need to engage and coordinate multiple external contractors.
Our ability to provide rapid mobilization of additional skilled personnel at short notice was critical to maintaining the project schedule and ensuring that unexpected and unplanned repairs did not unnecessarily extend the tank outage.