Faq

Fully open safety valve：

A safety valve is classified as a full-lift type if its disc opening height is equal to or greater than one-quarter of the seat throat diameter.

Micro-opening safety valve：

Safety valves with a valve disc opening height of 1/40 to 1/20 of the seat throat diameter are classified as lift-type safety valves.

A safety valve is an automatic valve that discharges a predetermined quantity of fluid without external force, utilizing the medium's own pressure to prevent system pressure from exceeding a predetermined safety threshold. Once pressure returns to normal, the valve closes to prevent further fluid discharge.

The load rate of a steam trap refers to the percentage of the actual heat condensate discharge volume during the test period relative to the maximum heat condensate discharge volume at the test pressure.

The operating temperature of a steam trap refers to the temperature at the inlet end of the steam trap under working conditions.

The back pressure of a steam trap refers to the pressure at the outlet end of the steam trap under operating conditions.

The back pressure tolerance of a steam trap should be as high as possible.

The higher the back pressure tolerance, the higher the pressure allowed at the outlet end of the steam trap during actual operation. In other words, steam traps with higher back pressure tolerance are more suitable for high back pressure working conditions.

The absolute value of the difference between the condensate temperature and the saturation temperature at the corresponding pressure is the degree of subcooling.

The valve opening subcooling refers to the absolute value of the difference between the valve opening temperature and the saturation temperature at the corresponding pressure.

Shut-off supercooling refers to the absolute value of the difference between the shut-off temperature and the saturation temperature at the corresponding pressure.

The subcooling at valve opening is greater than the subcooling at valve closing.

The pressure measured relative to atmospheric pressure (set as zero) is called gauge pressure.

Absolute pressure is measured relative to absolute vacuum pressure (defined as 0).

Absolute pressure is the sum of gauge pressure and atmospheric pressure.

Gauge pressure is the difference between absolute pressure and atmospheric pressure.

Sensible heat:

The increase or decrease in heat does not alter the state of matter but merely causes a change in temperature. This type of heat is called sensible heat.

Latent heat:

During a phase transition, the temperature remains constant while the state of matter changes. The heat absorbed or released by the substance at this time is called latent heat.

1. Since the drainage capacity of steam traps is measured under continuous drainage conditions, but virtually all steam traps do not operate continuously in actual service—typically discharging intermittently—the pause time during actual operation must be taken into account.
2. Even when the capacity of steam-using equipment is clearly defined, this capacity refers solely to the load condition during normal operation. When steam-using equipment begins operation (during startup), also known as the “preheating phase,” both the equipment itself and the heated material are at ambient temperature. At this stage, steam consumption increases significantly. In other words, steam-using equipment often generates large amounts of condensate during the preheating phase.

For the above two reasons, when selecting steam traps, the drainage capacity of the steam trap must be multiplied by a safety factor.

Several factors must be considered when selecting the appropriate steam trap, but the primary factors are as follows:

1. Select different types of steam traps according to the specific application.
2. Select the appropriate connection size based on actual operating conditions.
3. Select a steam trap with appropriate pressure and temperature ratings based on the actual operating conditions.
4. Based on the potential condensate volume generated by steam heating equipment during normal operation, multiply by a selection factor of 2 to 4, then select the trap based on its actual discharge capacity.

During the phase transition of water, the system in which the two phases of water and water vapor coexist in equilibrium is called saturated. This saturation state exists a critical point, the temperature of this critical point becomes the critical temperature, the value of 374.15 ℃.

The pressure at the critical point is the critical pressure and has a value of 22.12 MPa.

The steam leakage rate of steam traps is categorized into load leakage rate and no-load leakage rate.

Steam leakage rate under load:

The steam leakage rate under load refers to the ratio of steam leakage volume under load to the actual condensate discharge volume during the test period.

Unloaded steam leakage rate:

The no-load steam leakage rate refers to the ratio of no-load steam leakage volume to the maximum condensate discharge volume at the corresponding pressure.

The primary function of a steam trap is to promptly discharge condensate from steam heating equipment or steam piping systems while preventing steam leakage. This enhances the efficiency of steam-using equipment and achieves energy conservation. Therefore, the key indicators for evaluating a steam trap's performance should be its drainage capacity and steam-blocking capability. Based on the definition of steam leakage rate, the magnitude of a steam trap's leakage rate comprehensively reflects the quality of its drainage and steam-blocking performance.

A steam trap is a valve that automatically removes condensate from steam lines and steam-using equipment while preventing steam leakage.

There are nine performance metrics for steam traps: shell strength, operating performance, minimum working pressure, maximum working pressure, maximum backpressure ratio, steam leakage rate, air venting capacity, discharge temperature, and discharge volume. 

Due to the large contact area between the body and plug of the plug valve, significant torque is generated when rotating the plug. Surface corrosion rapidly compromises the sealing integrity of the closing mechanism and increases the torque required to operate the plug valve.

Steel and cast iron plug valves used for corrosive media shall be equipped with phenolic protective coatings and other plastic protective coatings.

The national standard GB/T 12237 "petroleum, petrochemical and related industrial steel ball valves" in the provisions of the ball valve stem should be designed to the pressure of the medium, the removal of the stem sealing packing (such as the removal of the packing gland), the valve stem will not be washed out of the valve body structure.

One-way sealing butterfly valve:

Unidirectional sealing butterfly valves feature a disc that faces the flow direction of the medium when closed. The medium flows in only one direction, and the valve body must display an arrow indicating the flow direction. During installation, pay attention to the direction of medium flow.

Double-sealed butterfly valve:

Bidirectional sealing butterfly valves feature a disc that can face either direction relative to the flow of the medium. Installation does not require consideration of the medium flow direction, and the valve body lacks arrows indicating flow direction. The stem of a bidirectional sealing butterfly valve experiences greater forces than that of a unidirectional sealing butterfly valve. In design, for butterfly valves of the same diameter and pressure rating, the stem diameter of a bidirectional sealing butterfly valve is larger than that of a unidirectional sealing butterfly valve.

The horizontal projection of the pivot pin axis of the swing check valve is perpendicular to the axis of the valve body's water passage and inclined at an angle to the sealing surface.

For standard globe valves, the medium flows into the valve from below the valve disc and out from above the valve disc. If the globe valve has a double valve disc, the medium flows into the valve from above the valve disc and out from below the valve disc. Globe valves with DN greater than 250 mm permit the medium to flow into the valve from above the valve disc.

When conducting performance tests on steel gate valves, care must be taken to avoid applying external forces at both ends of the valve that could affect leakage at the sealing surfaces.

The national standard GB/T 12234 "steel gate valve with bolted bonnet for oil and gas industry" stipulates that the stem nut should be loaded from the upper part of the bracket, and the upper part of the stem nut of the gate valve should be a prismatic body, a cylinder with a keyway, or a structure of equal strength connected with the handwheel. When the valve is opened, the handwheel can be removed without causing the stem and gate to fall to the closed position. If a bearing gland with threads is applied, it shall be secured by spot welding or other means.