In the harsh working conditions of extremely low-temperature media such as liquefied natural gas (LNG) and liquid nitrogen, ordinary valves are very easy to fail. Cryogenic valves ensure safety and reliability thanks to their special design, such as extended rods. Behind it, it is inseparable from the strict support of a series of international standards and classification society certifications, which is the core of ensuring the trouble-free operation of LNG, liquid nitrogen, liquid oxygen and other cryogenic media conveying systems, and it is also the guideline that must be followed when selecting.

Introduction to Cryogenic Valves: Characteristics and Key Designs

Cryogenic valves are critical equipment for harsh applications with media temperatures below -40°C (O F), and are widely used in industrial fields such as liquefied natural gas (LNG), liquid nitrogen, liquid oxygen, liquid argon, and ethylene. Unlike ordinary valves, they must address a range of challenges such as material embrittlement, seal failure, and freezing of operating mechanisms due to ultra-low temperatures. Its unique design is at the heart of ensuring the safe and reliable operation of the system.

Core design: Extended bonnet

This is the most striking external feature of cryogenic valves. Its main purpose is as follows:

• Protect the packing material and ensure operability: By extending the valve cover, the position of the valve stem packing box is raised to keep it away from the low-temperature media runner and keep it close to the ambient temperature. This effectively prevents the packing material from hardening and shrinking due to low temperatures, which can cause the seal to lose its tightness or prevent the valve from opening and closing properly.
• Reduced Cooling Loss: Extends the heat exchange path between the medium and the atmosphere, reducing cold loss and preventing frost from forming on the outer surface of the valve and causing injury to the operator.

The extended length of the bonnet is not fixed, but is scientifically determined based on the material, operating pressure and minimum operating temperature.

Key Feature: Material Selection

Low temperature will lead to “brittle transformation” of carbon steel and other materials, and the toughness will drop sharply, making it easy to crack. Therefore, the selection of materials for cryogenic valves is crucial:

• Body/Cover Material: Typically made of austenitic stainless steel (such as SS304, SS316), which has excellent low-temperature toughness. Low-temperature carbon steel (e.g., LCA, LCB) can also be used.
• Internal Materials: Stems, seats, etc., typically made of stainless steel, undergo proper heat treatment for strength.
• Sealing materials: Soft seals usually use polytrichloroethylene (PCTFE), modified polytetrafluoroethylene (PTFE), etc.; Metal seals require special alloys.

All materials must provide a low-temperature impact toughness test report that meets the requirements.

Mainstream cryogenic valve type recommended

According to different application conditions, the following valve types mainly perform well:

• صمام كروي مبرد
  

  

  • Features: Fast opening and closing (only 90° rotation), small flow resistance, good sealing performance.
  • Recommended scenarios: When it needs to be quickly cut off or opened, it is the first choice valve for LNG receiving stations, liquefaction plants, and cryogenic tanker loading and unloading systems
• صمام بوابة التبريد العميق
  

  

  • Features: The runner is direct, and the flow resistance is extremely small when fully open, which is suitable for full open or full closed working conditions.
  • Recommended scenario: Pipeline cutting that requires low pressure drop is a key shut-off valve for air separation units, natural gas liquefaction lines and storage tank inlet and outlet pipelines.
• صمام كروي مبرد
  

  

  • Features: It has good flow regulation characteristics, reliable sealing, but large flow resistance.
  • Recommended scenarios: It is ideal for regulating and controlling the flow and pressure of LNG, liquid nitrogen and other media, and is commonly found at pressure regulating stations and vaporizer inlets.

More صمام التبريد العميق Selection Ultimate Guide《دليل اختيار الصمامات المبردة: المبدأ والنوع والمخطط (-196 درجة مئوية ~ -269 درجة مئوية)》

Core international standards: manufacturing and testing benchmarks for cryogenic valves

To ensure the reliability and safety of cryogenic valves in extreme environments, it is not enough to rely on excellent design and materials. International valve standards (e.g. BS 6364, ISO 28921-1) provide unified and authoritative technical benchmarks and testing requirements for the design, manufacture, inspection and testing of cryogenic valves. Following these standards is a hard indicator to measure whether a cryogenic valve is qualified.

The following table summarizes the positioning and relationship between the main standards and the certification system:

International product standards: the cornerstone of technology and performance

These standards directly specify the technical requirements that cryogenic valves should meet.

1. BS 6364: Cryogenic valves
   • Status: This is one of the most classic and widely cited dedicated standards in the field of cryogenic valves, and can be called the cornerstone of the industry.
   • Core Requirements: It comprehensively specifies the design, material selection, manufacturing, and testing requirements for gate, globe, check, and ball valves suitable for temperature ranges from -50°C to -196°C. Its most famous feature is the mandatory low-temperature type test of valves to verify their sealing performance (leakage rate) and operational performance under simulated working conditions.
2. ISO 28921-1: Industrial valves – Isolation valves for cryogenic conditions – Part 1: Design, manufacture and type testing
   • Status: This is an international standard that is gradually developing and popularizing, and its technical content has many similarities with BS 6364, but is more internationally applicable.
   • Core Requirements: Design, materials, and comprehensive testing requirements are also covered. Compliance with ISO standards is becoming increasingly important for manufacturers and users looking to enter the global market.
3. MSS SP-134: “Requirements for Steel Valves with Flanged and Butt Welded Connections for Use at Low Temperatures”
   • Status: The standards set by the American Valve Manufacturers Standardization Association, which have a large influence in the North American market.
   • Core requirements: Specific requirements are put forward for pressure bearing parts, bolted connections, welded ends, etc. of valves containing austenitic steel at low temperatures, and regulations for low temperature testing are included.
4. ASME B16.34: Valves – Flanges, Threads, and Welded Ends
   • Status: This is the basic pressure-temperature rating standard in the field of valves, not for low temperatures, but the bottom line requirements of all valve designs.
   • Core requirements: It specifies the basic requirements of the valve, such as pressure-temperature rating, wall thickness, and material grouping. Any cryogenic valve must first meet the requirements of its corresponding pressure rating.

Test standards: key links to verify performance

Standards are credible because of their rigorous verification methods. The testing of cryogenic valves goes far beyond conventional housing tests and sealing tests.

• Cryogenic Type Test: This is the “graduation exam” for cryogenic valves. The valve is to be completely submerged in liquid nitrogen (-196°C) or other corresponding cryogenic medium and carried out at its nominal pressure:
  • Shell test: Check the pressure-bearing integrity of the valve body and valve cover at low temperatures.
  • Low-pressure sealing test: Verify the sealing performance of the valve seat at low temperatures.
  • High pressure seal test: Same as above, tested at higher pressure.
  • Operational Torque/Thrust Testing: Measure the torque or thrust required for the valve to open and close in a low-temperature environment to ensure it is operable.
• Leak rate requirements: The standard has extremely strict quantification of the leakage rate of the stem and seat (usually no more than a very small value), far exceeding general valve test standards such as API 598.

In summary, international product standards define “what constitutes a qualified cryogenic valve”, and rigorous testing is the “only way” to prove that it is qualified. For users, requiring manufacturers to provide certificates and type test reports that meet the above standards is the most critical step in selection and procurement.

Key Classification Society Certification: Pass to Maritime & Energy

In the international maritime and energy sector, especially in high-value projects such as liquefied natural gas (LNG) carriers, floating production storage and offloading units (FPSOs), and offshore liquefaction units, it is not enough to meet international standards. The certification of major classification societies is a mandatory “pass” for equipment access. They represent the highest level of recognition of a manufacturer’s quality system, production process control, and the product’s ability to adapt to harsh offshore environments.

The core value of classification society certification

Unlike international standards (such as BS 6364) that focus on the performance of the product itself, classification society certification focuses on the “process” and “system”:

• Quality assurance system audit: Conduct a rigorous evaluation of the manufacturer’s full-process quality management system from raw material procurement, manufacturing, inspection and testing to factory delivery.
• Material traceability: All pressure bearing materials must have a complete traceability chain, usually a 3.1 or 3.2 material certificate.
• Personnel Qualification Certification: Verify the operational qualifications of key positions such as welders and non-destructive testing (NDT) personnel.
• Process Specification Certification: Welding Process Specifications (WPS/WPQR) must be approved by classification societies.
• Specific Environmental Requirements: Ensure that the valve can withstand special working conditions such as ship movement, vibration, tilt, and marine corrosion environments.

Major classification societies and their certifications

1. ABS ( American Bureau of Shipping)
   • Influence: Authoritative in the American market and in the global maritime field.
   • Certification Focus: The ABS specification pays special attention to the safety and reliability of equipment, and its certification process emphasizes risk prevention and control, which is an important threshold for entering the global offshore market, especially in North America.
2. DNV (Norwegian Classification Society DNV GL)
   • Influence: Formed by the merger of Norwegian Bureau of Shipping (DNV) and Lloyd’s Register (GL), it is a recognized leader in the global maritime sector, especially in LNG technology.
   • Certification focus: DNV’s specifications are known for their technical rigor and comprehensive requirements. Its certification standards for liquid cargo tank systems, fuel gas supply systems and related valves for LNG carriers are widely adopted in the industry, and are one of the preferred certifications for high-end projects in Europe and around the world.
3. LR (Lloyd’s Register)
   • Influence: As the oldest classification society in the world, LR enjoys a long history and a high reputation in the international shipping community.
   • Certification Focus: LR has a comprehensive technical specification system, and its certification is widely trusted by shipowners, shipyards, and insurers worldwide.
4. BV (French Bureau Veritas)
   • Influence: Provides testing, inspection and certification services worldwide, with a significant presence in Europe, Africa and Asia.
   • Accreditation Focus: BV’s accreditation requirements are equally comprehensive and rigorous, which is a prerequisite for its entry into many international programs.
5. CCS (China Classification Society)
   • Influence: It is one of the world’s important classification societies, and its international influence is increasing with the rise of China’s shipbuilding and marine industry.
   • Certification focus: CCS certification is crucial for products to enter China’s maritime market and participate in projects in countries along the “Belt and Road”, and is a mandatory requirement for related domestic projects.

For cryogenic valve manufacturers, obtaining certification from authoritative classification societies is an international endorsement of their technical strength, quality management level and product reliability, and is the golden key to open the high-end maritime and energy markets.

Summary: The Choice of Compliance, Safety and Reliability

When selecting valves for harsh cryogenic conditions, the decision goes far beyond comparing parameters and prices on product samples. This is a strategic choice for long-term, stable and trouble-free operation of the entire system. Your selection criteria directly determine the safety bottom line and operating costs of the project.

• Compliance is fundamental, with international standards such as BS 6364 being the minimum threshold:
  Compliance with authoritative standards for cryogenic valves such as BS 6364 and ISO 28921-1 is the most basic requirement for a product. It proves that the valve is designed and manufactured in accordance with industry consensus, passing rigorous low-temperature type tests to ensure its tightness and operability in extremely cold environments. This is the “certificate” of the product and the technical cornerstone of safety. At no time should products that do not meet these core standards be considered.
• Classification society certification is sublimation and the key to the high-end market:
  The certification of classification societies such as ABS, DNV, and CCS is far more than just the “icing on the cake”. It is a comprehensive “physical examination” and continuous supervision of the manufacturer’s overall quality assurance capabilities above international standards. It means:
  1. Greater reliability: The certification process ensures that the entire process from a single plate to the finished valve is traceable and controllable, greatly reducing the risk of quality fluctuations.
  2. Wider Applicability: It proves that the valve can meet extremely complex working conditions in specific fields such as maritime, energy, etc., such as ship swaying, vibration, and long-term offshore maintenance cycles.
  3. Stronger brand trust: Holding the mainstream classification society certificate is the most powerful proof of the manufacturer’s technical strength, management level and brand reputation, and is a hard currency that has won the trust of the world’s top customers and EPC general contractors.

Choosing a cryogenic valve manufacturer like JH Valves that strictly abides by international standards such as BS 6364 and ISO 28921-1, and holds ABS, DNV, CCS and other multinational classification societies certification, is the optimal solution to escort the project, and choosing a qualified cryogenic valve is an investment in safety; Choosing a certified cryogenic valve is an investment in reliability and future. Ensuring the perfect solution for you compliant, safe, and reliable.