Understand Globe Valve Types from Diverse Perspectives

 
In the industrial sector, globe valves are a crucial component of fluid control systems. Their structural features, design requirements, and manufacturing standards directly affect the performance and reliability of the system. Understanding the structural characteristics and application fields of different types of globe valves can help users select the most suitable valve to meet specific operating conditions. This article will delve into the structural features, application fields, design requirements, and manufacturing standards of common globe valves, providing you with comprehensive reference information.

Structural Features

 
In valve design, structural and design features determine its performance and applicability in specific applications. Different types of globe valves have different advantages and characteristics in terms of fluid control, sealing, and durability. Below are several common types of globe valves and their design features.

1. Needle Globe Valve

 
The needle globe valve is mainly used for precise flow control. Its valve plug and stem are integrated, and the valve head is designed in a needle shape, with a high degree of precision in matching with the valve seat. The stem thread of the needle globe valve has a small pitch, and the valve seat hole size is usually smaller than the pipeline size, making it suitable for pipelines with a small nominal diameter, especially outstanding in sampling valves and precise flow control applications.
Application Range: Pipelines with a small nominal diameter, sampling valves.

2. Straightway Globe Valve

 
The stem of the straightway globe valve forms a certain angle with the fluid passage, and the sealing surface of the valve seat also forms a certain angle with the import and export channels. This design almost does not change the flow direction of the fluid, reducing flow resistance and minimizing flow loss. The sealing surfaces of the valve seat and valve plug of the straightway globe valve are usually hard-faced with hard alloy, enhancing the ability to resist erosion and corrosion.
Application Range: Alumina systems, pipelines containing solid particles.

3. Angle Globe Valve

 
The angle globe valve can be installed at the corner of the pipeline system, saving 90° elbows and facilitating operation. The valve body is divided into integrated and split types, and the valve plug can use STL hard alloy steel balls or sintered ceramic balls at high temperatures, increasing the service life and reliability of the sealing surface.
Application Range: Fertilizer plant synthetic ammonia production system, refrigeration system.

Application Fields

 
Under different operating conditions, the design and material selection of globe valves directly affect their performance. Understanding the performance requirements and design features of globe valves in various special applications helps to select suitable valves to meet operational needs. Here are several special application fields of globe valves and their characteristics.

1. Globe Valve for Power Plant

 
The design of high-temperature high-pressure power plant globe valves focuses on stability in high-temperature and high-pressure environments. The valve body and bonnet use pressure self-tightening sealing or clamp-type connections, and common materials include chromium-molybdenum steel or chromium-molybdenum-vanadium steel, with the sealing surface hard-faced with hard alloy. This design makes it widely used in high-temperature high-pressure pipelines of the thermal power industry, petrochemical industry, and metallurgical industry.
Application Range: Thermal power industry system, petrochemical system, high-temperature high-pressure pipelines in the metallurgical industry.

2. Globe Valve for Oxygen Pipeline

 
The design of the oxygen pipeline globe valve strictly follows the requirements of the oxygen pipeline, with a tightly sealed external packing box to prevent dirt from entering. The valve body flanges at both ends are equipped with grounding devices to prevent static ignition. Materials are usually austenitic stainless steel or copper alloy, and the sealing pair material is polytetrafluoroethylene (PTFE).
Application Range: Oxygen pipelines in the metallurgical system, oxygen pipelines in other industries.

3. Globe Valve for LPG

 
The LPG globe valve is specially designed for the pipeline of liquefied petroleum gas, paying attention to fire prevention requirements in the structure. The packing is made of PTFE to ensure reliable sealing. Suitable for LPG pipeline systems and other pipelines with temperatures not exceeding 80°C as a shut-off valve.
Application Range: LPG pipeline systems, other pipelines with temperatures not exceeding 80°C.

Design Requirements

 
When selecting and designing globe valves, considering different operating conditions, the choice of stem design is crucial. Here are several design requirements for globe valves, each with its own structural design to adapt to different working environments and medium conditions.

1. Upper Threaded Stem Globe Valve

 
The stem of the upper threaded stem globe valve does not directly contact the medium, suitable for pipelines under various conditions. The shell material and sealing pair material can be selected according to actual needs, for example, carbon steel with alloy steel or stainless steel, suitable for water, steam, and oil pipelines. Its maximum nominal size is generally DN200, and it is recommended to set up an internal or external bypass valve to reduce the operating torque.
Application Range: Water, steam, oil pipelines, pipelines with corrosive media.

2. Lower Threaded Stem Globe Valve

 
The threaded part of the lower threaded stem globe valve directly contacts the working medium and is susceptible to medium erosion. Suitable for clean media in instrument valves and sampling valves, with a nominal size generally between DN6 and 150.
Application Range: Instrument valves and sampling valves for clean media.

Manufacturing Standards

 
Manufacturing standards determine the overall quality and scope of application of the valve. Different standards correspond to different materials, designs, and manufacturing processes. Here are several common manufacturing standards and their application fields.

API 602 Globe Valve

 
Globe valves designed according to the API 602 standard are made of carbon steel or stainless steel forgings for the valve body and bonnet, with connection methods including bolted, threaded, and welded connections. Sealing pair materials include Cr13 series stainless steel, acid-resistant stainless steel, STL hard alloy, etc., and the packing can be flexible graphite or PTFE. Suitable for pressure classes Class 150 to 1500, with nominal sizes from NPS 1/4 to 4.
Application Range: Various industrial pipelines, especially high-pressure environments.
 
In summary, different types of globe valves show their own advantages and characteristics in design and application. Whether it is a needle globe valve for precise flow control or a high-temperature high-pressure power plant globe valve for extreme conditions, each type of valve has its unique design and application field. Understanding the structural characteristics and applicable scenarios of these valves is crucial for optimizing system performance and improving work efficiency. It is hoped that this article can provide valuable reference for your valve selection and design.