Ultra - low temperature full - open safety valve: High - performance safety solution for extreme con

Models and Product Introduction of Full-Lift Safety Valves

1. Product Overview of Full-Lift Safety Valves

As a core safety device for industrial pressure systems, the full-lift safety valve is characterized by a disc lift height ≥ 1/4 of the flow channel diameter. It enables large-displacement pressure relief in the instant of overpressure (response time < 0.5 seconds) to prevent equipment damage caused by overpressure, and is widely applicable to compressible fluid systems (e.g., gas, steam) and some liquid systems.

1.1 Core Working Principle

The valve opening and closing are controlled by the dynamic balance between "spring force and medium pressure":

When the system pressure exceeds the set pressure (tolerance ≤ ±3%), the medium pressure overcomes the spring force, causing the disc to open fully rapidly and discharge pressure at high speed through the nozzle-type flow channel;

When the pressure drops to the reseating pressure (≥ 90% of the set pressure), the spring force pushes the disc to reset and seal, ensuring stable system operation.

1.2 Core Advantages

Large-displacement pressure relief: The full-lift structure has a discharge coefficient of 0.6-0.7 (per ASME standards), much higher than that of semi-lift valves, making it suitable for high-pressure/large-flow systems;

Corrosion resistance and durability: The main valve body is typically made of 304/316L stainless steel, with the sealing surface overlay-welded with Stellite (cobalt-based alloy), providing an erosion-resistant service life of over 10 years;

Multi-condition adaptability: Through structural optimization (e.g., bellows, heat sinks), it can handle complex scenarios such as backpressure fluctuations, high temperature, low temperature, and strong corrosion.

2. Main Model System of Full-Lift Safety Valves

Classified into four core series based on working conditions, with key parameters and application scenarios as follows:

2.1 Basic Universal Type — Series A48Y (Most Commonly Used)

Typical Models: A48Y-16C (carbon steel with stainless steel lining), A48Y-25P (304 stainless steel), A48Y-40R (316 stainless steel)

Core Parameters:

Pressure range: PN16~PN40 (1.6-4.0MPa, ASME Class 150~300);

Temperature range: -20℃ to 425℃;

Discharge capacity: Maximum 120 t/h for DN100 model (steam medium).

Application Scenarios: Conventional steam pipelines, compressed air systems, hot water boilers. For example, A48Y-25P has been used in atmospheric and vacuum distillation towers of petrochemical enterprises with no leakage for 5 consecutive years.

2.2 Backpressure Balanced Type — Series WA42Y (For Backpressure Fluctuations/Toxic Media)

Typical Models: WA42Y-16P (304 stainless steel), WA42Y-40R (316 stainless steel), WA42Y-64R3 (316L stainless steel)

Core Parameters:

Backpressure compensation: Balances ≤ 30% of the set pressure;

Temperature range: -20℃ to 425℃ (high-temperature models with heat sinks, suffix "S");

Sealing: Fully enclosed structure, leakage rate ≤ 10⁻⁹ Pa·m³/s (EC-79 certified).

Application Scenarios: Petrochemical catalytic cracking units (resistant to H₂S), pharmaceutical reactors with toxic media, systems where discharge pipes connect to public flare systems (large backpressure fluctuations).

2.3 High-Temperature & High-Pressure Type — Series A42Y-320C (For Extreme High Pressure & Temperature)

Typical Models: A42Y-320C (Cr-Mo steel), A42Y-250P (304 stainless steel), A42Y-250R (316 stainless steel)

Core Parameters:

Pressure range: PN100~PN320 (10-32MPa, ASME Class 600~2500);

Temperature range: ≤ 650℃ (for Inconel alloy material);

Structure: Integrally forged valve body (30% higher strength), high-temperature spring (Inconel X-750, elastic attenuation ≤ 2% per year).

Application Scenarios: High-pressure boilers in power plants (steam ≥ 10MPa), ultra-high-pressure reactors, main steam pipelines in nuclear power plants (RCC-M Class 1E certified).

2.4 Low-Temperature Special Type — Series DA42Y (For Cryogenic Media)

Typical Models: DA42Y-16P (304L stainless steel), DA42Y-40R (316L stainless steel), DA42Y-64R3 (super austenitic steel)

Core Parameters:

Temperature range: -196℃ (LNG) to -40℃;

Structure: Valve body undergoes cryogenic treatment (impact energy ≥ 27J at -196℃), spring chamber filled with inert gas to prevent icing;

Sealing: PTFE-modified valve seat, low-temperature hardness retention ≥ 90%.

Application Scenarios: LNG storage tanks/transmission pipelines, liquid oxygen/liquid nitrogen systems in air separation equipment. For example, DA42Y-40R has been used in an LNG receiving station with stable operation at -162℃ for 3 consecutive years.

3. Summary of Model Selection

Model selection must focus on three key factors:

Medium Characteristics: Choose 316L/Inconel for corrosive media; select fully enclosed structures (Series WA42Y) for toxic media;

Pressure & Temperature: Opt for Series A42Y-320C for high-pressure/high-temperature conditions, and Series DA42Y for low-temperature conditions;

Certification Requirements: RCC-M certification for nuclear power applications, PED certification for the EU market, and EC-79 certification for hydrogen energy scenarios.