Mitigating Time Blow-Outs and Productivity Loss With A More Efficient Railcar Dumper Maintenance

Unscheduled downtimes spell out major problems in the mining industry.

With customers expecting to get their deliveries on time, a major shutdown - and an unexpected one, at that - means trouble. It does not only impact their customers but also the company's bottom line.

Shut downs result in time blow outs, productivity losses, and a sharp reduction in profit.

Fortunately, these concerns can be easily mitigated. This is what the team at Norbar Technical Services (NTS) has proven to their client engaged in a large-scale mining operation, in Western Australia.

Learn more about how NTS has done it and how this state-of-the-art maintenance system can help your business, as well.

Overview of the Railcar Dumper Situation

Catering to customers local and international clients, a major mining company based in Port Hedland, in Western Australia needed to make sure all systems are constantly working efficiently.

As a massive resource of high-grade iron ore, the company supplies significant quantities of this mineral to its end customers on a global scale.

Thus, the company contracted NTS to perform the intricate bolting maintenance task. This occurred during the mega shut-down in the second quarter of 2020.

The primary goal: To address the comprehensive automated systems involved in the processing of iron ores as efficiently and as quickly as possible.

The task was carried out during scheduled downtime, which was also duly budgeted for. Hence, time blow-outs and unplanned shutdowns can be mitigated. This goal, however, is only possible to accomplish with the right professionals implementing the best techniques to make it happen.

Tasks Involved During the Maintenance Work

The rotary railcar dumper was the primary system involved in this shutdown. In particular, it was a tandem dumper, which was capable of simultaneously receiving two railcars for a more improved unloading capacity.

As these machineries are in charge of bulk-handling operations in an automated manner, it is essential to improve their efficiency. By doing so, moving commodities around the site either for transportation and storage is faster.

Furthermore, the equipment must be capable of performing an unlimited number of dumping cycles outside of maintenance operations. In keeping the railcar dumper in pristine condition, this requires the right maintenance work to meet the budgeted time. Otherwise, a railcar dumper that is out of commission can easily cost the company a million dollars' worth of loss per hour.

Three Stages of Bolting Task

The core of this maintenance work is the removal, replacement, and performance check of the ring rail and the drive track bolts. A specific torque is required for bolts, and there are three stages involved in this task:

  1. Initial Removal

    Whilst it is less technical it is still complex as access is very restricted. Standard tools will not fit safely and non-engineered workface modifications create unforeseen hazards.

  2. Alignment of the Replacement Rail

    If stage one was challenging, this second stage is even more demanding. There are complexities involved in aligning the ring rail as bolts need to be tightened, loosened, before they are tightened a few times while being aligned to the machine shell and to one another.

  3. Bolt Tensioning

    Lastly, there is the final and crucial bolt tensioning. It requires torquing, ultrasonic measuring, and adjusting, which are technical, yet instrumental to ensuring the rails' reliability. Most importantly, the correct bolt tensioning can eliminate time blow-outs during the maintenance process.

Problems Encountered In Past Maintenance Works

Prior to hiring NTS to perform the railcar dumper maintenance work, the client experienced a few problems.

For instance, they had difficulty with accessing the bolts due to the tight position.

Measuring the bolt tension using mechanical methods was next to impossible, although the client initially used vernier callipers and micrometers to measure 10% of the bolts. The result was not only time consuming but also highly inaccurate. Worse the remaining 90% of the bolts remained unmeasured.

With all these said and done, the stripdown was planned for around 40 days but had a 3-week over run. Hence, it resulted in being behind their delivery schedule, which negatively impacted their bottom line.

Additionally, there were safety risks involved in the process including risks of shattering sockets, as well as pinch point concerns.

Sound Solution to an Efficient Railcar Dumper Maintenance

NTS followed a step-by-step plan to make sure their target goals were met with as little time and budget involved as possible.

1. Preplanning

This stage involved identifying the personnel and steps required to complete the task. All risks and concerns observed in the previous time blow-out were enumerated and brought to their attention.

As part of the pre planning stage, NTS assigned 19 personnel to tackle the job - 8 bolt torquing technicians, 8 ultrasonic bolting specialists, and 3 supervisors. They also identified points for improvement, required tools and equipment, and steps involved.

2. Identifying Problem Areas

Once previous issues were presented, NTS identified points to be addressed such as the accurate measurement and logging of details about the bolt tension on both the track rails and ring-rails.

In addition, they recommended the need to develop custom sockets for accessing tight spaces without shattering sockets.

Lastly, sophisticated technology was needed to attain the specific and required torque angle (600 Nm to 1600 Nm). The use of ultrasonics for accurately confirming bolt elongation is also necessitated.

Required Tools for the Maintenance Work

To achieve maximum precision and reliability of each bolt, NTS recommended the use of the following tools and equipment.

Custom Engineered Sockets

The Norbar mechanical engineering team specifically created these torque sockets with a stepped down reduced external diameter. Hence, these can fit a limited area around the bolts. As the socket's wall thickness was stepped rather than parrallel, this improved its strength by up to 30 percent.

EBT Tool

The EvoTorque Battery Tool (EBT) is a transducer-controlled torque tool powered by batteries for a more efficient removal, replacement, and re-torquing of the track bolts and ring-rail. It also offers a faster way to achieve torques between 600 and 2700 Nm.

Boltstress Ultrasonics G5 Tension Monitor

This instrument is both highly accurate and extremely quick, typically less than 15 seconds per bolt. Hence the highly trained technicians can easily identify which bolts require adjustment to the correct bolt tension and make adjustments in less than a minute.

3. Defining Bolting Steps

With the preplanning and problem identification in place, the next stage involves defining the steps for the bolting sub-task.

These were the following:

  1. Use of EBT and custom-engineered torque sockets (stepped down & reduced diameter) for ring rail bolt removal

  2. Replacement of ring rail bolts with individually-numbered, brand new bolts. This also includes tensioning, measuring, and re-tensioning of each bolt, as well as logging elongation of numbered bolts.

  3. Removal of the drive track bolts through custom-engineered reduced diameter torque sockets and EBT.

  4. Replacement of the drive track bolts.

Successful Railcar Dumper Maintenance

With a more comprehensive technique implemented for the maintenance work, the end-result was quite impressive.

The entire work was 75% faster than what the client initially expected it to be. Each ring only took 6 hours, which was budgeted to take 24 hours.

Moreover, the tension monitoring process was more accurate and quicker. Instead testing only 10% of the bolts, the Boltstress Ultrasonic G5 made it possible to monitor the entirety of all bolts.

The possibility of shattering the sockets was also prevented by using the custom-engineered sockets.

And overall, the NTS team conducted additional tasks to further check for potential issues and mitigate them. These tasks were not a part of the project scope, yet because the team was already on-site, and with more time left to spare after completing the main tasks, they were able to help with extra work including loosening Ballast beams' bolts for lifting the cells safely from the housing.

Efficient, accurate, and proficient - these are the core features of the NTS team, which many of its clients rely on for crucial and complex maintenance work completed in the fastest and most reliable way possible. To learn more about how NTS can help you, click here.

Avoid using the wrong socket. Download our free Bolt to Nut comparison chart.