Under what circumstances do stainless steel heat exchange tubes need to be replaced?
By: mxgy,
Stainless steel heat exchange tubes need to be replaced in the following situations, otherwise it will affect their use!
1. Serious physical damage
Corrosion perforation or wall thickness reduction exceeding 5%: Visible holes appear on the pipe wall, or local thinning exceeding 5% of the original thickness is detected during testing (such as the original 2mm wall thickness being reduced to below 1.9mm). Continuing to use at this time may cause a pipe explosion accident.
Pipe deformation and cracking: High pressure impact causes the pipe to bend into a wavy shape, or cracks appear in the weld or pipe wall (especially stress corrosion cracking that is prone to occur in chloride ion environments), which cannot be repaired.
2. Deterioration of performance indicators
Heat transfer efficiency decreases by more than 30%: scaling can cause the heat transfer coefficient to be lower than the design value by 70%. If it cannot be restored after chemical cleaning (such as soaking in citric acid) or physical cleaning (high-pressure water gun), the entire tube needs to be replaced.
Excessive medium leakage: If the pressure test finds that the leakage rate exceeds twice the standard value (for example, the allowable leakage rate is 0.1L/min, and the measured leakage rate exceeds 0.2L/min), it indicates that the connection between the tube plate or the tube body has failed.
3. Material adaptation error
Material and medium conflict: In environments with chloride ions>500ppm (such as seawater cooling systems), if 304 material is misused and pitting or intergranular corrosion occurs, it must be replaced with 316L or duplex steel pipes.
Inconsistent specification parameters: If a pipe with a wall thickness deviation greater than 0.05mm (such as replacing 2.5mm with 2.45mm in the original design) and a length error greater than 2mm is mistakenly selected during replacement, it will cause loose expansion and leakage.
4. End of life warning
Exceeding the design service life: Under normal working conditions, the design service life of 316L pipes is about 20 years. If they have been used for more than 18 years and have frequent maintenance records, it is recommended to replace them preventively.
Accumulated damage exceeding the standard: Records show that the pipe body has undergone more than 3 welding repairs, or more than 5 pipe blockage operations within 10 years (blockage rate>15%), and needs to be replaced as a whole.
When replacing, the original tube sample should be retained for material spectral analysis. The new tube should pass a 3MPa water pressure test and pass eddy current testing. Pressure relief is required before replacing pipes in industrial systems, and the pipe expander must be operated by certified personnel.
Under what circumstances do stainless steel heat exchange tubes need to be replaced?
By: mxgy,
Stainless steel heat exchange tubes need to be replaced in the following situations, otherwise it will affect their use!
1. Serious physical damage
Corrosion perforation or wall thickness reduction exceeding 5%: Visible holes appear on the pipe wall, or local thinning exceeding 5% of the original thickness is detected during testing (such as the original 2mm wall thickness being reduced to below 1.9mm). Continuing to use at this time may cause a pipe explosion accident.
Pipe deformation and cracking: High pressure impact causes the pipe to bend into a wavy shape, or cracks appear in the weld or pipe wall (especially stress corrosion cracking that is prone to occur in chloride ion environments), which cannot be repaired.
2. Deterioration of performance indicators
Heat transfer efficiency decreases by more than 30%: scaling can cause the heat transfer coefficient to be lower than the design value by 70%. If it cannot be restored after chemical cleaning (such as soaking in citric acid) or physical cleaning (high-pressure water gun), the entire tube needs to be replaced.
Excessive medium leakage: If the pressure test finds that the leakage rate exceeds twice the standard value (for example, the allowable leakage rate is 0.1L/min, and the measured leakage rate exceeds 0.2L/min), it indicates that the connection between the tube plate or the tube body has failed.
3. Material adaptation error
Material and medium conflict: In environments with chloride ions>500ppm (such as seawater cooling systems), if 304 material is misused and pitting or intergranular corrosion occurs, it must be replaced with 316L or duplex steel pipes.
Inconsistent specification parameters: If a pipe with a wall thickness deviation greater than 0.05mm (such as replacing 2.5mm with 2.45mm in the original design) and a length error greater than 2mm is mistakenly selected during replacement, it will cause loose expansion and leakage.
4. End of life warning
Exceeding the design service life: Under normal working conditions, the design service life of 316L pipes is about 20 years. If they have been used for more than 18 years and have frequent maintenance records, it is recommended to replace them preventively.
Accumulated damage exceeding the standard: Records show that the pipe body has undergone more than 3 welding repairs, or more than 5 pipe blockage operations within 10 years (blockage rate>15%), and needs to be replaced as a whole.
When replacing, the original tube sample should be retained for material spectral analysis. The new tube should pass a 3MPa water pressure test and pass eddy current testing. Pressure relief is required before replacing pipes in industrial systems, and the pipe expander must be operated by certified personnel.
