Coating is a crucial stage of pipes for long life cycle. Especially under some special applications like gas and liquid transportation, it has special treatment requirements. Following we briefly introduce the popular five solutions used in pipe production industry.
1- Dry coating
It’s mostly used for pipe inside coating. Means the solvent must be fast drying. Under this application, air pressure is relatively high while paint volume is small and wet rate is high. After spraying, the paint will dry fastly. This is regularly for base coating and metallic coating.
2- Wet coating
It’s the opposite of dry coating. The solvent will dry slowly under low air pressure and high volume paint rate application. It requires curing in dryer.
3- Wet on wet coating
Means to apply coating without waiting the base layer coating dry first
4- Virtual spraying
Virtual spraying is for repairing purpose after color coating finished. The liquid is mixed by big rate solvent and less paint. The virtual spraying makes the path more natual between old and new paint layers. It also increases the gloss rate on varnish layer.
5- Atomizing spraying
Also known as fly spraying, it’s used when there’re strips or spots. The application process as follows
- Load the pipe in suitable position
- Adjust spray gun to pipe surface about 30～45cm
- Open spray gun to 75% volume rate and remain no change then start spraying
Above solutions are popularly used for pipe production line according to different work conditions. We might use different automatic solutions for spraying, but the basic rules keep no change. For high production rate, automatic line is highly recommended to remain a good quality and reduce hand operation.
We also need to pay attention to spray gun cleaning after job done. Especially when disassembling spray gun components, we must be familiar with the general procedures to avoid damaging. Sometimes when spray gun nozzle stuck, we try to open directly for observation. But it may bring us lots of problems such as nozzle brocken, wearing or thread broken etc.
When disassembling spray gun for cleaning, we must remember the correct procedures: dettach the needle first then the nozzle. The converse steps when assembling back.
