Introduction

In the field of industrial refrigeration and low-temperature applications, the reliability and sealing performance of valves are critical to the safety and efficiency of the entire system. Shandong Dofun’s low-temperature alloy precision casting process is specifically designed to meet the demands of harsh industrial low-temperature environments (ranging from -46°C to 120°C), ensuring long-term stable operation under sustained low-temperature conditions. This article provides a comprehensive breakdown of the precision manufacturing process from mold to finished product, and how we guarantee the core performance of valves under extreme working conditions.

The Core Value of Precision Casting for Low-Temperature Valves

The precision casting process enables the integrated formation of valve bodies with complex structures and precise dimensions. It is particularly suitable for manufacturing low-temperature valves that require highly complex internal flow channels, exceptional dimensional consistency, and superior surface integrity. Compared to traditional machining methods, precision casting offers the following advantages:

• Integrated Forming: Reduces welds, fundamentally eliminating the risk of weld brittleness at low temperatures.
• Excellent Material Properties: Castings possess a dense microstructure, better resisting material contraction and internal stress at low temperatures.
• Design Freedom: Enables the production of internal cavities that align more closely with fluid dynamics, reducing pressure loss.

Complete Breakdown of the Core Process

Stage 1: Digital Design and Mold Manufacturing

• 3D Fluid Simulation and Structural Design: Uses CFD software to optimize the internal flow channels of the valve, reducing turbulence and cooling loss; employs FEA to ensure the structural integrity of the valve body at -46°C and under working pressure.
• High-Precision Mold Manufacturing: Utilizes CNC machining and 3D printing technology to create wax patterns or molds, ensuring part dimensional tolerances are controlled within ±0.15mm, laying the foundation for subsequent sealing surface machining.

Stage 2: Melting, Pouring, and Forming

• Low-Temperature Alloy Melting: Uses AOD (Argon Oxygen Decarburization) or VIM (Vacuum Induction Melting) processes to refine austenitic stainless steels like CF8M (316L), strictly controlling carbon, sulfur, and phosphorus content to enhance low-temperature toughness.
• Constant Temperature and Pressure Pouring: Pouring is conducted in a protected environment to prevent gas entrapment, ensuring the castings are free from internal defects like porosity and slag inclusions.

Stage 3: Heat Treatment and Precision Machining

• Solution Treatment: Heats the castings to 1050-1150°C followed by rapid cooling (quenching) to fully dissolve carbides and obtain a uniform austenitic structure—a key step in ensuring low-temperature toughness.
• Cryogenic Treatment​ (Optional Process): For components with higher requirements, cooling them to -70°C to -100°C and holding for a period stabilizes the microstructure and further reduces residual stress.
• Precision CNC Machining: Performs finish machining on key areas such as sealing surfaces and flange end faces using five-axis machining centers, ensuring flatness, surface finish, and mating accuracy meet zero-leakage requirements.

Quality Assurance: Dedicated Testing System for Low-Temperature Applications

Material-Level Verification

• Chemical Composition and Metallographic Analysis: Ensures materials comply with standards like ASTM A351, with a uniform and defect-free metallographic structure.
• Low-Temperature Impact Test: Conducts Charpy V-notch impact tests at -46°C to verify the material’s impact energy at low temperatures.

Component and Whole-Valve Testing

• Pressure Testing: Shell strength test at 1.5 times the design pressure; seal test at 1.1 times the design pressure.
• Low-Temperature Leak Test: Places the valve in a low-temperature test chamber, cools it to -46°C, stabilizes it, and then performs helium mass spectrometry leak detection or high-pressure bubble leak test to ensure absolute sealing reliability.
• Cycle Life Test: Simulates actual working conditions, performing thousands of ambient-to-low-temperature-to-ambient pressure cycles and open-close cycles to verify long-term reliability.

Application Practice of Dofun Low-Temperature Valves

Typical Application Scenarios

• Industrial Refrigeration Systems: Key control components in large cold storage facilities, food processing, and ammonia or freon refrigeration systems.
• Process Cooling Systems: Used in chemical and pharmaceutical industries requiring low-temperature cooling processes.

Our Technical Assurance

To ensure performance at the application limit of -46°C, Dofun valves incorporate the following designs:

• Extended Bonnet Design: Ensures the stem packing is located in a relatively higher temperature zone, preventing packing freeze and ensuring flexible operation.
• Anti-Blowout Stem Design: Guarantees safety even under low pressure or vacuum conditions.
• Targeted Seal Materials: Selects PTFE, reinforced PTFE, or special metal seal materials that maintain elasticity at low temperatures based on medium characteristics.

Conclusion: Safeguarding the Safety Baseline of Low-Temperature Systems with Precision Manufacturing

From digital model to final product, Dofun implements precision control and verification that exceeds standards in every manufacturing step of our low-temperature valves. We understand that valve failure in a low-temperature system can mean significant safety risks and economic losses. Therefore, we provide not just products, but a performance guarantee that remains robust even at -46°C.

Choose Reliable Assurance for Your Low-Temperature System​

[Download Dofun Low-Temperature Valve Product Brochure and Technical Parameters]

[Obtain Our Material Certification and Low-Temperature Test Reports]

[Contact Our Application Engineers for Customized Solutions]

Shandong Dofun Refrigeration Technology Co., Ltd. specializes in the industrial refrigeration valve sector. Its precision cast valve series products are all designed and validated for industrial application environments ranging from -46°C to 120°C, serving global cold chain, industrial refrigeration, and process cooling projects with exceptional reliability.