New modular UV coating system for steel pipes
Mannesmann Line Pipe in Hamm, which produces for the gas and oil industry, has recently invested in a new coating system. The Solingen-based plant manufacturer InTEC Coating Systems developed a highly automaMannesmann Line Pipe in Germany has recently invested in a new coating system. The plant manufacturer InTEC Coating Systems developed a highly automated UV coating system for this purpose.ted and sophisticated UV coating system for this purpose.
The new plant measures 8473 mm x 3840 mm x 3913 mm (L x W x H) including both a coating and a drying chamber. Both areas are separated by iris diaphragms and mounted on roller rails, allowing them to be pulled out like drawers for maintenance work. The system is also accessible via doors on the modules or through a pit beneath the chambers.
The industrial Coating process
The steel pipes to be coated, with a diameter of up to 610 mm, are transported into the coating facility via roller conveyors. Based on these values of customers level 1 data, the system automatically adjusts all parameters for the subsequent coating and drying processes. Among other adjustments, the 2.5-tonne coating chamber is optimally adapted to the respective pipe size via a lifting system and positioned in a way that the spray guns maintain a distance of about 150 mm from the pipe.
A clamping device prevents any movement of the chambers during operation. In addition to adjusting the dimensions of the coating and drying chambers, the coating and drying parameters can also be set within seconds to suit the respective pipe diameter. The entrance to the coating chamber is equipped with bezels to create an optimal conditions for coating. Inside the system, the pipes are transported via drive rollers of which the spacing is adjusted to the minimum pipe lengths. Before entering the surface treatment area, sensors automatically measure both the diameter and the speed of the incoming pipes. In case of deviation the line will be immediately stopped.
Coating in detail
Inside the coating chamber, 16 air-atomizing spray guns are mounted on two support rings, eight on the entry side and eight on the exit side. Between the rings, there are two centrifugal separator. Each gun is fully adjustable to consider factors such as gravity. Parameters such as atomizer and shaping air or paint flow can be adjusted precisely. The flow rate of the transparent UV coating – with a solid content of about 99% – is also monitored at each individual spray gun. This ensures that the corrosion protection layer thickness remains within the optimal range.
If deviations from the norm occur, which could indicate leaks or invalid coating, operators can quickly intervene to prevent waste. Overspray is recycled using a sophisticated system. A precise air supply is introduced through the centrifugal separator of the coating chamber, which, using rotation-induced centrifugal force, directs excess paint particles to the bottom of the chamber. There, a slot collects the coating material into a recycling collection tank, whose level is constantly monitored. A recycling pump then returns the UV coating to the supply system. The fine fraction of excess paint droplets takes a different path, being directed to an exhaust air system with filters, where the coating is deposited on lamellae and also returned to the recycling tank. Any remaining paint particles in the exhaust air are captured in a fine filter, a self-cleaning wire mesh monitored by differential pressure.
The paint supply is located in a material supply container installed outside the production hall, which is maintained at a constant temperature of 23°C to 24°C. From there, a diaphragm pump delivers the UV coating through an automatic paint cleaning filter system to the application point. Specialized hoses are used on the final section of the supply line because the coating is gently heated to process temperature via indirect heating. This protects the sensitive UV coating while ensuring optimal processability and application. If the system is idle for about a week, it is advisable to flush the paint supply line. For this, both a cleaning agent and a flushing agent are used. The flushing process can also be automated.
Focus Dying
The pipes are transferred directly from the coating chamber to the drying area, which uses UV radiation. For this purpose, 16 UV lamps are used, distributed across two drying zones. Each zone contains eight UV lamps, with two rings per dryer, each with four UV lamps. The pipes enter through automatically adjustable iris diaphragms, which can adjust up to 20 mm to the respective pipe diameter. The diaphragms are made of spring steel and are resilient against mechanical stress. They minimize the spread of overspray, as does the air ring attached to the diaphragm. Inside the drying chambers, a slight overpressure is maintained, and a highly pure airflow is sustained.
These measures prevent paint particles from settling on the UV lamps. However, contamination cannot be completely avoided, so occasional cleaning is necessary. This poses no problem due to easy access and is rarely required thanks to the previously described measures. As with the coating process, the distance of the UV lamps to the individual pipe is automatically adjusted during drying, maintaining a 50 mm distance. All these process steps are even more impressive considering the pipe throughput speed of 1 m/s. This speed is only possible due to UV drying, which cures the coating within fractions of seconds. Care is taken to ensure that drying occurs from below so that the next contact point of the pipes on the rotating rollers is already dry before passing through. After drying, the pipes enter a conveyor tunnel that transports them to storage, ready for commissioning and shipment.
The new system in Germany enables the pipe manufacturer to reliably supply its customers with UV-coated pipes. The combination of advanced technology and thoughtful design makes the system a significant investment, particularly in terms of sustainability.
Further information: www.intec-lackiersysteme.de