Pressure rating of boiler tubes and their applications

Definition:

The pressure rating of boilers refers to the maximum pressure value that the boiler withstands when it is working. It is generally expressed in MPa or kgf/cm2.

The pressure rating of boiler tubes and their applications are key factors in boiler design and operation. The following are the main contents:

1. Pressure rating

The pressure rating of boiler tubes is usually divided into the following categories:

a. Low-pressure boiler tubes
Working pressure ≤ 2.5MPa, suitable for small industrial boilers and heating systems. Working temperature is below 450℃. Common low-pressure boiler tube pressure levels are: 0.8MPa, 1.0MPa, 1.25MPa and 1.6MPa.

b. Medium-pressure boiler tubes
Working pressure is between 2.5MPa and 9.8MPa, commonly used in medium-sized industrial boilers and cogeneration systems. Working temperature is below 450℃. Common medium-pressure boiler tube pressure levels are: 2.5MPa, 4.0MPa, 6.4MPa and 9.8MPa.

c. High-pressure boiler tubes
Working pressure ≥ 9.8MPa, mostly used for large industrial boilers and power station boilers. Working temperature is between 450℃ and 650℃.

d. Ultra-high-pressure boiler tubes

Working pressure ≥ 13.7MPa, mainly used for large power station boilers and special industrial boilers. Common pressure levels of high-pressure boiler tubes are: 13.7MPa, 15.9MPa, 20.0MPa, 24.0MPa and 32.0MPa, etc.

2. Application and safety requirements of each pressure level

The application scenarios of boiler tubes of different pressure levels are as follows:

a. Low-pressure boiler tubes: suitable for small industrial boilers, heating systems and domestic low-temperature hot water systems. The safety requirements are relatively low, but regular inspection and maintenance are still required to ensure safe operation.

b. Medium-pressure boiler tubes: commonly used in industrial boilers, thermal systems and small power station boilers. At this level, the selection, design, installation and maintenance of pipes and valves must strictly comply with relevant specifications to prevent safety accidents such as leakage and explosion.

c. High-pressure boiler tubes: common in high-pressure thermal systems such as large industrial boilers, power station boilers and high-temperature and high-pressure steam systems. This level has higher requirements on the pressure resistance and sealing performance of the equipment, and it is also necessary to be equipped with a complete safety valve and control system.

d. Ultra-high-pressure boiler tubes: mainly used in large power station boilers, ships, nuclear power station boilers and special industrial boilers, such as petrochemicals. At this level, special design and manufacturing processes must be adopted, as well as more stringent safety management measures.

3. Material selection

The material of the boiler tube needs to be selected according to the working pressure and temperature. Common materials include:

Carbon steel: Carbon steel boiler tubes are suitable for low-pressure and medium-pressure boilers.
Alloy steel: Alloy steel boiler tubes are mainly used for high-pressure and ultra-high-pressure boilers, with good high temperature resistance and corrosion resistance.
Stainless steel: Stainless steel boiler tubes are mainly used in special environments, such as high temperature, corrosive media, etc.

4. Manufacturing standards

The manufacturing of boiler tubes must comply with relevant standards. Common standards are:

ASME: American Society of Mechanical Engineers Standard.
GB: Chinese National Standard.
DIN: German Industrial Standard.

5. Inspection and maintenance

To ensure safe operation, boiler tubes need to be regularly inspected and maintained, including:

Non-destructive testing: such as ultrasonic and radiographic testing.
Pressure test: Perform water pressure tests regularly.
Corrosion inspection: Check corrosion regularly and replace damaged pipes in time.

Precautions for use:

During the use of the boiler, it is necessary to strictly abide by the national safety standards and operating procedures, rather than blindly pursuing high pressure levels to avoid casualties and property losses. During the use of the boiler, regular maintenance is also required, and attention should be paid to the safety of water quality and fuel to ensure the normal operation of the boiler.

In short, understanding and following the pressure level standards of boiler pipelines is crucial to ensure the safe operation of the boiler system. All relevant units and individuals should strictly abide by relevant regulations to ensure the safety of personnel and equipment.

Read more: American standard for low and medium pressure carbon steel boiler tubes or High pressure boiler tube material