How are the medium and low pressures of boiler tubes classified and based on?

Overview of the classification of medium and low pressures of boilers:

In the field of boilers, boiler tubes are divided into different pressure levels according to their working pressures. These levels mainly include low pressure, medium pressure, high pressure and higher pressure ranges. For medium and low pressure boiler tubes, their working pressure is usually lower than a certain value, which may vary in different standards or specifications, but generally the pressure of low-pressure boilers does not exceed 2.5MPa, while the pressure of medium-pressure boilers is between 2.5MPa and a higher pressure value, but it does not reach the scope of high-pressure boilers.

Basis and standards for the classification of medium and low pressures of boilers:

The classification of medium and low pressures of boiler tubes is mainly based on the maximum allowable pressure during their design and operation. For example, in China, the commonly used classification standards refer to relevant national standards and industry specifications, such as TSG 21-2016 "Regulations on Safety Technical Supervision of Stationary Pressure Vessels". These standards clearly stipulate the safety technical requirements, design and manufacturing principles, and use and management specifications of boilers of various pressure levels, ensuring that the boilers operate in a safe and efficient state.

1) Chinese Standard (GB/T 16508-2013 Shell Boiler):

Low Pressure Boiler: ≤2.5 MPa (gauge pressure)
Medium Pressure Boiler: 2.5~3.8 MPa
High Pressure Boiler: >3.8 MPa

2) International Standard (taking ASME as an example):

Low Pressure Boiler Tube
Pressure Range: ≤1.03 MPa (≈150 psi)
Temperature Range: Usually ≤121℃ (saturated steam)
Standard Based on: ASME BPVC Section IV (heating boiler)

Medium Pressure Boiler Tube
Pressure Range: 1.03~3.45 MPa (150~500 psi)
Temperature Range: 121~260℃ (can produce saturated or superheated steam)
Standard Based on: ASME BPVC Section I (power boiler)

High Pressure Boiler Tube
Pressure Range: >3.45 MPa (>500 psi)
Temperature range: >260℃ (mostly superheated steam)

Analysis of medium and low pressure pipelines of boilers:

1. Definition and use
Medium and low pressure pipelines of boilers mainly refer to the pipeline systems used to transport water, steam or other fluids in low-pressure and medium-pressure boilers. These pipes are usually made of high-quality metal materials to withstand the corresponding working pressure and temperature. Their main function is to transfer the heat energy generated by the boiler to the required place through the fluid, such as heating, power generation or heating needs in industrial production processes.

2. Materials and manufacturing process
Medium and low pressure boiler pipelines are generally made of high-quality carbon structural steel, alloy structural steel and other materials, which have good mechanical properties and high temperature and corrosion resistance. In terms of manufacturing process, these pipelines usually undergo strict heat treatment, non-destructive testing and pressure testing to ensure that their quality and safety meet the requirements of relevant standards and specifications.

3. Application scenarios and maintenance management
Medium and low pressure boiler pipelines are widely used in various industrial and commercial places, such as power plants, chemical plants, textile mills and large commercial buildings. During use, correct maintenance and management are essential. This includes measures such as regularly checking the status of the pipeline, replacing aging parts in time, keeping the pipeline clean, and avoiding excessive pressure or temperature fluctuations, thereby extending the service life of the pipeline and ensuring its safe and reliable operation.

Conclusion and Outlook:
Through the classification of medium and low pressure boiler tubes and the detailed analysis of medium and low pressure pipelines, we can better understand the importance and application of these equipment in energy conversion and industrial production. With the advancement of technology and the development of the industry, we may see the emergence of more efficient, environmentally friendly and intelligent boilers and pipeline systems in the future, bringing greater convenience and benefits to my country's energy utilization and industrial production.

Read more: High pressure boiler tube material or  Boiler tube materials and standards