NKS, MKS - Bopp & Reuther Sicherheits- und Regelarmaturen GmbH

2 NKS, MKS
Introduction
Gate valves are generally used in the nuclear power plant
industry to securely isolate water and steam lines.The main
advantage over globe valves is the extremely low pressure
drop across the gate valves.
Two main types are the wedge gate and parallel gate valves.
On wedge gate valves the tapered configuration of the seat
allows the generation of high additional sealing forces, thus
ensuring increased safety during operation. Additional advantage
over parallel slide gate valves: the sealing surfaces
touch each other only in the final closed position. The guides
in the body prevent a permanent contact during opening
and closing, resulting in a longer, trouble-free service life.
For low differential pressure (∆p) applications the wedges are
additionally spring loaded to ensure the gate is pushed onto
the sealing surface for better sealing properties. The required
spring force is individually calculated based on the case data,
in particular the differential pressure (∆p).
Gate valves can be hand or electrically actuated (or both).
Special requirements such as tightness and functionality
even after a malfunction of the actuator limit switches
have been implemented in special designs, based on calculations
and proven by extensive testings.
Special hard facing of the seat either with Cobalt (Stellite 21)
or without (NIBORIT 40-P) ensures long service life and excellent
sealing properties over extended periods of operation.
The bodies can be made of ferrite or from austenite materials
as is appropriate. The bodies of low and medium pressure
gate valves are made from dye forged shells that are welded
together using the most modern arc welding technology and
materials.
The shell construction enables a perfect flow through the
valve while reducing the overall weight of the valve body.
Type
Material Ferrite, Austenite
Temperature range Max. 350 °C
Hard facing Stellite 21
Cobalt free: NIBORIT 40-P
Sizes DN 50 - 300 (dye forged shells)
DN 350 - 600 (welded)
Pressure ratings Max. PN 160 (dye forged shells)
High Pressure Gate Valves (DN 50 - 600, max. PN 350):
see separate product sheet