Various alloys are used in manufacturing check valves. One such alloy used to manufacture such valves is the Alloy 20 Check Valve. They contain nickel chromium and molybdenum and are specifically designed to be used in applications that contain sulfuric acid. Moreover, they are also said to resist chloride corrosion cracking and pitting.
UNS N08020 Spring Check Valve is also used in off-shore drilling companies, petrochemical processing, pharmaceutical, seawater, and chemical equipment. These valves can resist acid strikes namely sulfuric acid. Moreover, a minute quantity of niobium can be added to the alloy this enhances the resistance of the alloy to sensitization.
Moreover, the addition of niobium to WERKSTOFF NR. 2.4660 Hydraulic Check Valve also makes it resistant to intergranular corrosion. The alloy used in the production of these valves is said to possess good fabricability. The size of these valves ranges from ½ inch to 48 inches.
Carpenter 20 inline Check Valve is widely used in pickling racks, tanks, food and dying industries, and other environments. These valves have a working temperature ranging from -29 degrees C to +180 degrees C and a size range of ½ inch to 4 inches. The melting point of carpenter 20 valves goes up to 1443 degrees C with a density of 8.1 g/cm3.
Dual plate check valves are designed to overcome the size and pressure drop limitations of the swing and disc type wafer check valves. The flap of the swing check valve is essentially split and hinged down its center, such that the two disc plates will only swing in one direction. The disc plates are held against the seat by a torsion spring mounted on the hinge. In order to hold the hinge in the center of the flow path, externally mounted retainer pins can be used. These retainer pins are a common source of leakage from the valve. An improved design secures the hinge internally, and as the valve mechanism is entirely sealed within the body, leakage to atmosphere is prevented.
A piston-check valve is a check valve in which the disc, sometimes called a piston, can be lifted up off its seat by higher pressure of inlet or upstream fluid to allow flow to the outlet or downstream side. A guide keeps motion of the disc on a vertical line, so the valve can later reseat properly. When the pressure is no longer higher, gravity or higher downstream pressure will cause the piston to lower onto its seat, shutting the valve to stop reverse flow.
Pressure seal construction is adopted for valves for high pressure service, typically in excess of above 170 bar. The unique feature about the pressure seal Bonnet is that the body-Bonnet joints seals improves as the internal pressure in the Valve increases, compared to other constructions where the increase in internal pressure tends to create leaks in the body-bonnet joint.
Relying on fairly simple design principles, pressure seal valves have proven their capability to handle increasingly demanding fossil and combined-cycle steam isolation applications, as designers continue to push boiler, HRSG, and piping system pressure/temperature envelopes. Pressure seal valves are typically available in size ranges from 2 inches to 24 inches and ASME B16.34 pressure classes from #600 to #2500, although some manufacturers can accommodate the need for larger diameters and higher ratings for special applications.
Sachiya Steel International Is One Of The Leading Manufacturer And Exporter Of High Quality Alloy 20 swing check valve in India. recommend the use of these valves in flue gas desulfurization, food processing, and certain pharma operations. They can be hot formed or cold worked. Moreover, they are also used in heat exchangers, condensers, pulp and paper industry, power generation, and so on.