| |
Preventive Maintenance of Major Steam Valves |
 |
Steam control valve with reduced unstable flows
Conventional Valve: Unstable flows are generated under specific conditions.
Improved Valve: The modified valve shape allows reducing unstable flows regardless of load conditions.
Modified Flow Pattern |
Modified Valve |
Oxidation-Resistant & Wear-Proof Valve
Scales due to oxidation and wear cause valve sticking.
Technology to Prevent Sticking
| |
EXISTING |
IMPROVEMENT |
EFFECT |
| STEM |
12Cr Steel |
Incolloy |
High Creep Rupture Resistance
Low Oxidized Scale Generation |
| BUSH |
12Cr Steel |
Stellite |
High Oxidizing Resistance
Low Oxidized Scale Generation |
|
 |
 |
| Stellite Welded Bush |
Effect of Improvement Scale Growth Rate |
Erosion-Resistant Bypass Valve in Main Stop Valve
Conventional: The conventional bypass valve is subject to erosion due to scales from a boiler or water droplets.
Improvement: The erosion-resistant bypass valve has a lot of small holes. The impact of steam flow through these holes is reduced by losing its kinetic energy and this prevents erosion of the valve.
|
|
