Cryogenic Top Entry Ball Valve API 6D Top Entry Ball Valve Cryogenic Valves

Specification

I. Product Overview

TIANYU’s cryogenic top – entry ball valve emerges as a cutting – edge solution meticulously crafted for the rigors of ultra – low – temperature industrial landscapes. Aligned with API standards, this valve marries a top – entry structural ingenuity with state – of – the – art cryogenic – resistant technologies. It is purpose – built to govern the flow of cryogenic media such as liquefied natural gas (LNG), liquid nitrogen, and liquid oxygen, which often operate at temperatures plummeting to – 196℃. The top – entry configuration revolutionizes maintenance paradigms, while the astute selection of materials and sealing systems guarantees unwavering performance in the harshest cryogenic climes. This makes it an indispensable linchpin in sectors like LNG processing, air separation, and low – temperature chemical engineering.

II. Key Attribute Specifications

A. Dimensional and Pressure Parameters

Nominal Diameter: Spanning from DN25 to DN300, it caters to the diverse flow demands of pipelines. In LNG transfer setups, a DN50 valve can adeptly manage a flow rate of up to 80 m³/h, striking a harmonious balance between flow capacity and system compactness.
Pressure Rating: Adhering to API 6D, it supports pressure classes including Class 150, 300, and 600. A Class 300 valve, for instance, can bear a working pressure of 5.17MPa, making it a perfect fit for medium – pressure cryogenic storage and transportation systems.
Temperature Range: Engineered to operate steadily between – 196℃ (the boiling point of liquid nitrogen) and 100℃. Special thermal insulation designs are integrated to curtail cold energy loss and fend off external moisture condensation on the valve surface.

B. Material Composition

Valve Body and Ball:
- For standard cryogenic applications, low – temperature carbon steel like ASTM A352 LCB is employed. LCB boasts exceptional toughness at low temperatures, with a Charpy impact energy of ≥27J at – 46℃, effectively warding off cold brittleness.
- In more corrosive cryogenic environments, stainless steels such as ASTM A351 CF8 (304 stainless steel) or CF8M (316 stainless steel) are utilized. These materials offer superior corrosion resistance against cryogenic media laced with impurities, such as wet LNG.
Sealing Components:
- Primary seals leverage polytetrafluoroethylene (PTFE) with spring pre – loading. PTFE retains good elasticity at low temperatures and has a low coefficient of friction, ensuring a dependable seal even amid thermal contraction.
- For high – pressure cryogenic scenarios, metal – to – metal seals (e.g., Inconel 625 coating) are available. These seals can withstand higher pressure differentials and exhibit remarkable wear resistance.

C. Structural and Operational Features

Top – Entry Design: The valve body is furnished with a top – mounted access flange. During maintenance, there’s no need to disconnect pipeline flanges; instead, internal components like the ball, stem, and seals can be directly removed and replaced from the top. This design slashes maintenance downtime by over 50% compared to side – entry valves.
Stem Sealing: A multi – layer sealing structure, combining graphite packing and O – rings, is adopted. It effectively thwarts the leakage of cryogenic media and the ingress of external air, preserving the low – temperature environment inside the valve.
Operation Mode: It can be outfitted with manual, pneumatic, or electric actuators. For remote – controlled LNG terminals, electric actuators with explosion – proof certification are often chosen, enabling precise flow regulation.

III. Feature Description

A. Top – Entry Design for Efficient Maintenance

The top – entry design is a game – changer in valve maintenance. In traditional side – entry ball valves, replacing internal components entails disconnecting the pipeline, a process that is both time – consuming and wasteful. In contrast, TIANYU’s top – entry valve allows maintenance personnel to directly lift the bonnet assembly after removing the top flange bolts. This not only saves the time required for pipeline disassembly but also averts the loss of cryogenic media during maintenance. In an LNG receiving station, this design can pare down the maintenance time of a single valve from 8 hours to 2 hours, significantly boosting operational efficiency.

B. Cryogenic – Resistant Sealing Technology

At ultra – low temperatures, the volume contraction of materials and the hardening of seals pose formidable challenges to sealing performance. TIANYU’s cryogenic ball valve tackles this issue with a dual – stage sealing design:

The primary seal uses PTFE with a spring pre – load. The spring compensates for the volume contraction of PTFE at low temperatures, ensuring continuous contact between the seal and the ball.
The secondary metal backup seal springs into action when the primary seal fails (such as during a fire or extreme temperature fluctuations), preventing large – scale leakage of cryogenic media.
In tests simulating – 196℃ conditions, the leakage rate of the valve is less than 1×10⁻⁶ cm³/s, far below the API 6D leakage standard.

C. API Compliance and Safety Assurance

As an API – compliant product, the valve undergoes stringent testing and certification:

Pressure Testing: It endures a hydrostatic test at 1.5 times the rated pressure and a pneumatic test at 1.1 times the rated pressure to ensure structural integrity.
Cryogenic Performance Testing: The valve is cooled to – 196℃ using liquid nitrogen and subjected to multiple opening and closing cycles to verify its operational prowess at low temperatures.
Fire – Safe Design: An optional fire – safe certification (API 607) is available. In the event of a fire, the metal backup seal and graphite packing can maintain temporary sealing, preventing the leakage of flammable cryogenic media such as LNG.

D. Material Toughness at Low Temperatures

The selection of valve materials is pivotal for ensuring performance at low temperatures:

LCB Steel: Through quenching and tempering heat treatment, the grain structure is refined, and the impact toughness at low temperatures is significantly enhanced. In a Charpy impact test at – 46℃, the impact energy can reach 40J, far surpassing the standard requirement of 27J.
Stainless Steel: For media containing corrosive components (such as LNG with high sulfur content), 316L stainless steel is used. Its molybdenum content bolsters corrosion resistance, and it still maintains good toughness at – 196℃.

Product Overview

IV. Manufacturing Processes

A. Low – Temperature Material Processing

Heat Treatment of LCB Steel: The valve body and ball undergo quenching (heating to 890 – 920℃, followed by water cooling) and tempering (heating to 600 – 650℃, followed by air cooling). This process eradicates internal stresses and optimizes the microstructure, ensuring good toughness at low temperatures.
Cold Working of Stainless Steel: For stainless steel components, cold extrusion or cold rolling processes are employed to enhance surface hardness and dimensional accuracy. After cold working, a solution annealing treatment is carried out to restore corrosion resistance.

B. Precision Machining of Top – Entry Structure

Valve Body Machining: The top – entry flange and internal flow channel of the valve body are machined using 5 – axis CNC machining centers. The flatness of the top flange is controlled within 0.05mm, ensuring a proper seal with the bonnet.
Ball and Stem Assembly: The ball and stem are connected using a spline or keyway structure, with a coaxiality tolerance of ≤0.02mm. This guarantees smooth rotation of the ball and uniform contact with the seat.
Seal Surface Lapping: The sealing surfaces of the ball and seat are lapped to a roughness of Ra ≤0.8μm, ensuring a tight seal under low – temperature and high – pressure conditions.

C. Cryogenic Testing and Validation

Deep – Cooling Treatment: The assembled valve is placed in a liquid nitrogen tank and cooled to – 196℃, maintaining this temperature for 4 hours. This process simulates actual working conditions and detects potential material defects or structural deformations.
Leakage Testing: Using helium mass spectrometry leak detection, the leakage rate of the valve is measured under cryogenic conditions. The minimum detectable leakage rate is 5×10⁻¹⁰ Pa·m³/s, ensuring compliance with strict cryogenic sealing requirements.
Cycle Testing: The valve undergoes 1000+ opening and closing cycles under cryogenic conditions to verify the durability of the seal and the reliability of the actuator.

Valve Details

V. Product Advantages

A. Uninterrupted Operation in Cryogenic Environments

The combination of low – temperature – resistant materials, advanced sealing technology, and rigorous testing ensures that the valve can operate stably for extended periods in environments as low as – 196℃. In an LNG storage tank outlet application, the valve has achieved continuous operation for 5 years without seal failure, effectively reducing maintenance costs and production downtime.

B. Efficient Maintenance with Top – Entry Design

The top – entry design obviates the need for pipeline disassembly during maintenance, which is especially crucial for cryogenic systems. In a large – scale air separation plant, maintenance personnel can complete the replacement of the valve seat within 2 hours, minimizing the loss of liquid oxygen and liquid nitrogen and ensuring the continuous operation of the production line.

C. API Certification for Quality Assurance

Compliance with API standards means that the valve has undergone rigorous testing in terms of design, materials, and performance. In international projects such as LNG export terminals, API – certified valves are often mandatory, and TIANYU’s products can smoothly enter the global market, bolstering customer confidence.

D. Enhanced Safety with Fire – Safe Option

The optional fire – safe design provides an extra layer of safety for applications involving flammable cryogenic media. In the event of a fire, the valve can temporarily prevent the leakage of LNG, buying time for emergency response and reducing the risk of explosion.

Application

VI. Product Applications

A. LNG Industry

LNG Receiving Terminals: Installed on LNG unloading arms and storage tank outlets, it controls the unloading and distribution of LNG. The top – entry design facilitates quick maintenance, ensuring the continuous supply of LNG.
LNG Transportation Pipelines: Used in medium – and low – pressure LNG pipelines, it regulates flow and isolates media. The cryogenic – resistant seal prevents LNG leakage and ensures pipeline safety.

B. Air Separation Equipment

Liquid Oxygen/Nitrogen Systems: Controls the flow of liquid oxygen and liquid nitrogen in air separation units. The low – temperature toughness of LCB steel and the reliable sealing performance ensure the purity of the product and the stability of the system.
Cold Box Pipelines: Installed in the cold box of air separation equipment, it withstands ultra – low temperatures and frequent flow adjustments, ensuring the efficient operation of the separation process.

C. Low – Temperature Chemical Engineering

Refrigerant Handling: Manages the flow of cryogenic refrigerants (such as ethylene, propylene) in chemical plants. The corrosion resistance of stainless steel and the tight sealing prevent refrigerant leakage and ensure the efficiency of the refrigeration system.
Low – Temperature Reaction Processes: Controls the feeding and discharge of materials in low – temperature reactors (such as hydrogenation reactors at – 100℃). The precise flow regulation of the valve ensures the stability of reaction conditions.

D. Energy and Storage Fields

Cryogenic Energy Storage: Used in liquid air energy storage systems, it controls the charging and discharging of liquid air. The top – entry design and cryogenic performance meet the long – term operation requirements of energy storage systems.
Aerospace Propellant Systems: In ground test facilities for aerospace propellants (such as liquid hydrogen, liquid oxygen), the valve controls the flow of propellants, with strict leakage requirements ensuring test safety.

VII. Summary and Customization

TIANYU’s API – compliant cryogenic top – entry ball valve excels in low – temperature reliability, easy maintenance, and safety. It is ideal for LNG, air separation, and cryogenic chemical applications.Customize with: 316L for corrosive media, Inconel seals for extreme temperatures, explosion – proof actuators, or extended bonnets for better insulation. Tailor it to your cryogenic system’s media, pressure, and control needs.