YARWAY BLOW-OFF VALVES
YARWAY BLOW-OFF VALVES
SEATLESS, HARDSEAT AND UNIT TANDEM
Designed for blow-off service in boiler systems with pressures of 3206 psig
• Designed according ASME section 1, ASME B31.1, ASME B16.34.
• For boiler systems up to 3206 psig.
• Rugged construction to withstand high pressure and high velocities.
• Excellent resistance to cleaning acids and wear caused by precipitated solids.
• No Seat
- will not score or plug with dirt
- will not leak
• Live-loaded packing
- will not leak after packing
• Slow opening
-will not rapidly drain boiler drum
Unit tandem valves
• Combination of hardseat and seatless valves in a single body
- eliminates pipe joints
- reduces potential leaks
- fits into a confined space
• Stellite seat faces
- resists wear
provides long service life
Blow-off service in boiler systems to remove dirt, sediment and scale as well as maintain boiler level surge.
Size range: NPS 1, 1¼, 1½, 2, 2½
[DN 25, 32, 40, 50, 65]
Pressure Rating: Up to 3206 psi Connection: Flanged, Socketweld, Buttweld Materials: Cast Iron, Carbon Steel
Basic requirements for the design and use of blow-off valves are established by the ASME Power Boiler Code, Section l. The general form of a valve, the materials of its construction, allowable boiler pressures, and the installation of the valve are all determined by the code.
Yarway blow-off valves are designed in conformance with all code requirements (ASME Section l, ASME B31.1, ASME B16.34).
Because the primary purpose of a blow-off valve is removal of dirt, sediment and scale, the boiler code requires that valves which have dams or pockets in which sediment can
accumulate cannot be used in blow-off service. This means that ordinary globe valves cannot be used as blow-off valves.
Yarway valves are especially designed for the punishment of blow-off service in boiler systems with pressures of 3206 psi.
The rugged construction of these valves can successfully withstand the combination of problems inherent in the service - a service in which high pressures result in high velocities which can cause wire drawing and cavitation of metal surfaces.
The valves must also withstand the corrosive environment created by acid cleaning of boilers, and the potential wear problems caused by precipitated solids.
The valves are also helpful in maintaining boiler level surge within desirable limits during quick startup of high pressure systems.
Two broad categories of Yarway blow-off valves are available; those that operate on a sliding principle and those that operate on a seat-and- disc principle.