Blasting of large steel structures
Aker Solutions a provider of products for the global energy industry invested in a new, fully automated production line with prefabrication, shot blasting and coating at its shipyard in Verdal, Norway. Blastman Robotics was responsible for building the automated blast cleaning system for steel components. The requirements for the planned project were high, as every aspect required a high degree of automation and an Industry 4.0 approach.
The new blasting system had to offer higher productivity, efficiency and safety in comparison to the manual blasting process. In addition, the state-of-the-art system had to be integrated into an MES that would enable the exchange of information and seamless collaboration between the production processes. The surface cleanliness had to be between Sa2.5 and SA3, with roughness values of Rz from 50 to 85 µm.
According to Blastman, this project involved the installation of the most modern blasting chamber in the world, which enables the monitoring and control of all necessary process parameters. The blasting process is fully automated and manual intervention is only required for quality control. “We are proud that we were the first of three suppliers to complete the new system and that our solution has proven to be the most efficient of all process steps. The customer can focus their energy on improving other processes as blasting is no longer a problem. Previously, blasting was one of the most challenging processes, but now everything is running smoothly,’ explains Teemu Runi, Sales Manager for Northern Europe at Blastman Robotics.
Blasting of up to 55 meters
The processed workpieces are assemblies for offshore underwater constructions such as oil drilling platforms or fish farms. On the smallest scale, pipes 8 meters long and 0.6 meters in diameter are pretreated. In the largest case, a component 55 m long and 1.5 m in diameter must be blasted, with sockets protruding 2.8 m from the centre of the workpiece. The workpieces arrive at the new production plant by ship with various degrees of rust contamination.
To meet all requirements and yield an optimal pretreatment, Blastman supplied a complete blasting chamber with scraper floor and blast media reclaim system. The blasting chamber measures LHW: 62 x 14 x 16 meters. It is equipped with an automatic, servo-controlled “Blastman B20S” robot and a “Blastman B20ML” manlift. The former is a gantry robot with a telescope and articulated arm. According to the manufacturer, the robot has an excellent reach and can blast the most complex workpieces. Among other things, this is possible due to the robot’s eight axes. All blasting programs are created by the customer with the offline programming software “Blastman Studio”.
Blasting with steel grit
Over 100 m2 of surface area can be blast cleaned per hour, even in the case of steel components with high rust grade. Steel grit is used as the blasting media. The components in the blasting chamber are monitored and controlled by a standardized control system. This creates an optimum working environment for the robot and enables savings during the blasting process by controlling the consumption of electricity, compressed air and blasting media. The centralized control system additionally enables information to be easily transferred to the manufacturing execution system (MES).
The “Blastman B20ML” gantry manlift installed on site includes a telescopic boom, which allows the operator platform to be moved around the workpiece. The manlift works like an overhead crane and offers the best possible access to large workpieces without scaffolding, moving jibs or ladders. It is mounted on the same rail as the robot and can therefore move around in the entire blasting chamber. The telescope can also be rotated to reach areas that are difficult to access. There is room for up to two people on the manlift.
Blasting fully automated
Up to two employees engage in setting up the respective workpiece. The subsequent blasting cycle is fully automatic, with employees only monitoring the process in the control room. The installed scraper floor collects the abrasive that falls onto the floor. The scraper floor is specially designed for use in robot blasting. All bearings are sealed and protected. The scrapers are articulated and therefore highly wear-resistant and virtually maintenance-free. The installed scraper plates push and pull the excess blasting material across the floor. Longitudinal scrapers cover the entire floor surface and transport the blasting material to the cross scraper.
The cross scraper is in the centre of the blasting chamber and transport the abrasive from there to the reclaim system on the outside of the blasting chamber. A cleaning system, which removes larger impurities with a drum screen, transports the blasting material back to the abrasive silo for reuse. The material is recycled 50 to 100 times. Fines are removed either by the ventilation system or the air washer of the abrasive reclaim system. Four ventilation systems – each with 30 dust filters – are installed in the blasting chamber for exhaust air purification, with the air flow running horizontally from one side of the room to the other.
Energy saving blasting
The system is designed to maximize energy savings. These include automatic ventilation and lighting control. In addition, the “Blastman B20S” robot eliminates the need for manual blast cleaning, which is a key factor for workplace safety, efficiency and quality. After mechanical pre-treatment, the components are coated with special epoxy glass flakes and polyurethane paints. The new pre-treatment process saved 32 % of the coating costs.
The training of the employees on site took place over five days for a factory team focusing operation and maintenance, and two employees were additionally familiarized with the “Blastman Studio” programming software over the same period. Furthermore, the manufacturer’s team was on site for a week to support the commissioning of the system. Checks are now carried out once a week to ensure consistently high quality.
“Blastman Robotics has been actively and professionally involved in the development of the plant, presenting ideas and proposing solutions with a focus on robotics and automation in the production line to fulfil Aker Solutions requirements and overall goal with this investment,” says Hans Haugberg, Project Procurement Manager, Aker Solutions.
More information: www.blastman.com, www.akersolutions.com