Extrusion Welding in Chinese Wastewater Treatment Plant

Laiz hou, a small town near Qingdao – the city where the sailing competitions were held during the 2008 Summer Olympics – is currently undergoing an economic boom. This may be attributed in part to its favorable transport connections and to the unique media attention that it attracted in connection with the Games. Xin Li Composite Materials Co. Ltd has been among those companies to benefit from this unparalleled opportunity.

Over the past few years, it has greatly expanded its product range, transforming itself from a simple supplier of corrosion-resistant containers to a complete provider of wastewater treatment plants for the chemical, medical and metal industries. In doing so, the company has also extended its sales area, now maintaining a network of branches covering western China, including the far north.

Pipeline Processing with Hand Extruders

PE and PVC are used in almost all products made by Xin Li. Some of the prefabricated products are manufactured using extrusion processing or injection molding; however, these processes are only suitable for relatively small components and for a limited range of shapes. With a steadily increasing demand in the Chinese market for large containers and pipes with complex forms, extrusion welding has become the method of choice when joining bigger, more intricate parts.

Temperature and Quality Control

No manufacturer can afford to have welding quality issues when producing large containers or large-diameter continuous piping. For this reason, manufacturers most closely monitor temperature to prevent weak weld joints or overheating – PVC is very sensitive to fluctuations. To do this, Xin Li uses the WELDPLAST S2 PVC hand extrud er from Leister, which is equipped with an electronic temperature control, as well as a display that shows both the pre-heat hot air and weld zone temperatures.

Simple, Efficient Welding

Major projects are often executed in very tight timeframes, putting those working on material processing under a great deal of pressure for efficiency. Liu Maokai, Vice President of Xin Li, recalls that prior to using Leister PVC hand extruders, each seam had to be welded several times. However, the WELDPLAST S2 PVC typically only requires one pass. Now that the company employs five WELDPLAST S2 PVCs, it is able to tender competitively for even the most technically demanding projects.

Additionally, as a general rule, pipes with a diameter of less than 3.28 feet are assembled at the factory and larger elements are welded directly at the construction site. With the WELDPLAST S2 PVC, elbow fittings and T-fittings can be welded easily and then polished to achieve good surface quality.

HDPE Pipe Welding

Xin Li also has a FUSION 2 hand extruder, which was in use before the WELDPLAST S2 PVC, for the welding of HDPE pipes. Both hand extruders enable welding parameters (temperature and output) to be quickly adjusted according to the material used, thus creating consistent, reproducible welding results.

Resulting Company Growth

Despite a slowing economy, Xin Li is receiving more orders than ever before. Liu Maokai attributes these increased orders to the considerable investments made by the Chinese government and the efficiency and built-in quality controls of his equipment.

Furthermore, the production of pipes for wastewater treatment plants has risen as more people invest in protecting the environment.

For more information, contact a Leister Authorized Master Distributor: Assembly Supplies (Western U.S.), 800-694-1472, Web: www.hotairtools.com; Heely-Brown (Southeastern U.S.), 800-241-4628, Web: www.heelybrown. com; Industrial Heat Sources (Midwestern U.S.), 800-635-0384, Web: www.industrialheatsources.com; Malcom Company (Northeastern U.S.), 888-807-4030, Web: www.malcom.com, STANMECH Technologies (Canada), 888-438-6324, Web: www.stanmech.com.