Sturdy valve design
Throughout their ¡°youth¡±, all gate valves do well. But with time, wear and tear takes its toll, and the differences between good and bad quality become apparent. A quality valve will continue performing effortlessly, whilst the cheap valve will require more and more maintenance at a very high cost.
Wedge stop and rolled threads ensure durability
The wedge stop provides a firm stop against the wedge nut when opening the gate valve. This prevents the wedge from compressing the stem seals and from damaging the coating inside the bonnet. Therefore, the wedge stop gives prolonged durability of the gate valve. The stem threads are rolled in a cold pressing process which maintains the steel structure and therefore increases the strength of the stem. This method also ensures a smooth thread surface that gives low operating torques of the gate valves.
Triple safety stem sealing
An NBR wiper ring protects against impurities from the outside. Tightness and low friction are provided by four NBR O-rings in a polyamide bearing or in a replaceable stem seal nut of dezincification resistant brass. A rubber manchette is the main seal to the flow, made of EPDM for water and NBR for gas and wastewater applications. The full circle thrust collar of high strength dezincification resistant brass provides fixation of the stem. It reduces the friction and thus also the torques.
Corrosion-proof gate valve assembly
The bonnet gasket fits into a recess between the valve body and the bonnet to protect it from being blown out at pressure surges. The stainless steel bonnet bolts are encircled by the bonnet gasket to ensure that no threads are exposed to the surroundings, and finally sealed with hot melt to prevent corrosion.
Three strong coatings for gate valves
The standard corrosion protection is an internal and external epoxy coating according to DIN 30677-2 and GSK guidelines. Furthermore, we offer gate valves with a highly wear-resistant internal enamel lining well-suited for abrasive media as it forms a chemical bond with the casting preventing creeping corrosion. Finally, AVK also offers gate valves with an external PUR coating according to EN 10290 type 2, class B, developed for use in steel gas pipelines with cathodic protection, but also a good choice for installation in aggressive soils.
Go to Superior coatings to find technical information