The full-lift safety valve A68Y-64 is an overpressure protection device designed for power plant boilers and pressure vessels. Its core function is to achieve dynamic balance of system pressure by quickly discharging the medium. The valve adopts a spring-loaded structure, and the valve seat and valve disc sealing surface are usually made of carbide materials to withstand high-temperature steam environments of 425℃ to 500℃. Its core design features include:

I. Structural design and rapid pressure relief mechanism of full-lift safety valve

Full-lift valve core structure: The valve disc opening height reaches more than 1/4 of the flow channel diameter, making the discharge area equal to the flow channel area, significantly improving the discharge efficiency;

Two-stage action control: When the pressure reaches the set value, the valve core is quickly lifted to the full open position to avoid the response delay caused by the progressive action of the micro-lift valve;

Closed discharge design: The discharge medium is directed out through the exhaust pipe to reduce the scouring damage of high-temperature steam to surrounding equipment.

The realization of rapid pressure relief capability depends on the optimization of fluid dynamics by its structure. When the system pressure exceeds the set value, the medium force overcomes the spring preload, and the valve core opens to the maximum height instantly, forming a resistance-free discharge channel. This process can shorten the discharge response time to milliseconds, effectively suppressing further pressure increases.

II. Impact of critical parameters on boiler overpressure protection

The performance of the safety valve A68Y-64 is directly restricted by the following critical parameters, which together define its effectiveness boundary in overpressure protection:

1. Set pressure (opening pressure)

The set pressure is the trigger threshold for the action of the safety valve and needs to be set according to the maximum allowable working pressure of the boiler. According to the TSG 21-2016 specification, the set pressure of the power station boiler safety valve is usually 1.05-1.1 times the design pressure. The fast response characteristics of the full-open structure require that the set pressure error be controlled within ±1% to avoid system risks caused by premature or delayed action.

2. Discharge pressure and overpressure ratio

The discharge pressure is the system pressure when the valve disc is fully open, and the difference between it and the set pressure must meet the requirement of ≤10%. The full-opening design of the full-opening safety valve A68Y-64 significantly reduces the overpressure ratio by maximizing the discharge area, so that the system pressure returns to the safe range in a short time, avoiding plastic deformation or bursting caused by pressure accumulation.

3. Seat return pressure and opening and closing pressure difference

The seat return pressure is the system pressure when the valve is closed, and the difference between it and the set pressure directly affects the stability of boiler operation. Excessive opening and closing pressure difference will cause the safety valve to open and close frequently, accelerating the wear of the sealing surface; too small may cause continuous leakage of the medium. The safety valve A68Y-64 controls the opening and closing pressure difference within a reasonable range of 3%-7% through precision spring stiffness matching and valve seat cone angle optimization.

4. Medium temperature and material tolerance

The high-temperature steam environment places extremely high demands on the thermal fatigue resistance and oxidation resistance of the valve body material. The safety valve A68Y-64 adopts a carbide sealing pair and an austenitic stainless steel valve body, which can maintain sealing performance for a long time at 500°C, avoiding jamming or leakage caused by differences in thermal expansion coefficients.

III. Dynamic regulation of system protection by rapid pressure relief characteristics

In actual boiler operation, the rapid pressure relief characteristics of the full-lift safety valve A68Y-64 achieve precise suppression of overpressure risks through the following mechanisms:

1. Active suppression of pressure fluctuations

When the boiler load changes suddenly or the combustion is abnormal, the steam pressure may rise exponentially. The millisecond response of the full-lift valve can quickly establish a discharge channel and limit the pressure growth slope to the pressure limit of the equipment. For example, when the steam pressure reaches 103% of the set value, the valve has entered the fully open state, avoiding the pressure overshoot caused by the staged opening of the traditional micro-lift valve.

2. Prevent secondary damage from the water hammer effect

Rapid pressure relief can reduce the sudden change amplitude of the steam flow rate and reduce the impact force generated by the water hammer effect in the pipeline. The closed exhaust pipe design of the full-lift safety valve A68Y-64 further ducts condensate through the drain pipe to avoid liquid hammer damage to the internal structure of the valve body.

3. Collaborative protection linked with the control system

In supercritical and ultra-supercritical units, the full-open safety valve A68Y-64 needs to be integrated with the boiler main control system. When the pressure is detected to be close to the set value, the system can adjust the combustion parameters or start the backup feedwater pump in advance, and the safety valve, as the final barrier, only acts when the automatic control fails, forming a three-level protection system of “prevention-regulation-emergency”.

The power station high-temperature and high-pressure full-open safety valve A68Y-64 has built an irreplaceable safety margin in boiler overpressure protection through its rapid pressure relief characteristics. The quality of its performance directly depends on the synergy of critical parameters such as set pressure, discharge efficiency and material tolerance.

When looking for high-quality, reliable boiler safety valve, YOYIK is undoubtedly a choice worth considering. The company specializes in providing a variety of power equipment including steam turbine accessories, and has won wide acclaim for its high-quality products and services. For more information or inquiries, please contact the customer service below:
E-mail: sales@yoyik.com
Tel: +86-838-2226655
Whatsapp: +86-13618105229

Yoyik offers various types of spare parts for steam turbines, generators, boilers in power plants:
Slide Gate Valve Spare Parts 200×200 PN1.0
Stop valve J61Y-1500SPL
Dermal vesicle NXQA-40/20-L-EH
Support ring Y10-4
Skin NXQ-A25/31.5-L-EH
Vacuum stop valve DKJ41H-10C
Check valve H67Y-500
gravity float valve PY-40
Three-way valve J21H-600CL
Vlv,Solenoid 4WE6D6X/EG110N9K4/V (REXRTOH)
Pressure regulating valve DBDS15GIO/5/1
gate Z41W-63P
PRESSURE CONTROL VALVE F3-CG2V-6FW-10
Accumulator Bladder NXQ1-F16/20-H
installation screen by switching piece JL1-2.5/2
Hydraulic Servo Valve DEC21NF58N
valve SV13-16-C-0-00
turbine lubricant oil cooler sealing strip WJ60F-1.6P
Safety valve A42Y-25
Spring Y7-11
Hydraulic station accumulator NXQ1-F10/20-H
SLEEVE,SHAFT 100AY67X6-43
Valve ALR
EH oil regeneration pump 2PB62DG28P1-V-VS40
Electric stop valve J9B41H-64
Stop valve J61Y-160
Bladder QXF-5
Block valve SD61H-100I WC6
Bearing assembly P8011D-00
Solenoid Valve 4WE10Y-L3X/CG220NZ5L
test solenoid valve 22FDA-F5T-W220R-20/LBO
Reheater outlet plug valve SD61H-P58.564V SA-182 F91
Globe Valve 3-WD210-ER103-00003
Throttle valve L41H-100