The PAT type full capacity safety valve is used on steam medium equipment and pipelines in large thermal power plants as an overpressure protection device. The design, manufacturing, and inspection of the product are in accordance with JISB8210-1978 "Technical Conditions".

This valve has the characteristics of high emission coefficient, accurate opening pressure, small opening and closing pressure difference, good sealing performance, and easy adjustment. Its main features are as follows:

1. Nozzle shaped valve seat: Designed based on the principle of the Laval nozzle, the steam flow velocity at the outlet of the valve seat is supersonic with a high emission coefficient. The sealing surface of the valve seat is plasma sprayed with cobalt based hard alloy, which is wear-resistant, erosion resistant, and has a long service life.

2. The valve disc adopts a thermal stress compensation structure, which is divided into two parts: the valve disc and the hot valve disc. The purpose is to fully utilize the thermal deformation of the valve disc to achieve sealing. The hot valve disc is made into a tongue shaped structure to prevent leakage by utilizing its small elastic effect.

3. Lower adjustment ring: A circular space is formed between the lower adjustment ring and the lower plane of the valve disc, and this space is adjusted by the lower adjustment ring to obtain the appropriate opening pressure.

4. Upregulation of the integral ring: The function of upregulation of the integral ring is to change the direction of fluid flow discharged from the valve seat, thereby changing the reaction force of the fluid on the valve disc. The position of the upregulation of the integral ring directly affects the opening and closing pressure difference of the valve.

5. Safety device: The safety device separates the valve body from the spring to reduce the thermal impact on the spring, ensuring that the temperature of the spring does not exceed 200 ℃, guaranteeing the stiffness of the spring, and stabilizing its performance.

6. Adjustment sleeve: The adjustment sleeve is used to adjust the back pressure of the valve, and the lower cone and exhaust chamber form a regulating body. Adjust the sleeve up to reduce the back pressure of the valve, adjust the sleeve down to increase the back pressure of the valve.

7. Spring: The spring is a key component that determines the performance of the safety valve. Different springs are designed for different set pressures and opening and closing pressure differentials.

8. The quick contact area between the valve stem head and the valve disc gasket is welded with cobalt based hard alloy, which has high hardness, wear resistance, and long service life.