【Mechanical Equipment Technology Exchange Edition】Mechanical Equipment 【Daily Question】20190807

During operation, for some reason, the wall temperature of the pipe may exceed the design value; as long as the excess temperature is not too large, no immediate damage will occur. However, when the pipe operates at elevated temperatures for an extended period, the microstructure of the steel changes, the creep rate increases, and its endurance strength decreases, resulting in premature failure due to explosion before its service life reaches the intended value. This type of damage is known as long-term over-temperature tube rupture. The characteristics of the fracture caused by long-term over-temperature tube rupture are as follows: the fracture presents as a large opening with a rough, brittle fracture surface; the wall thickness of the tube does not decrease significantly, and creep deformation of the tube is also not notable; often, there is a thick layer of iron oxide on the inner surface of the fracture.

During operation, for some reason, the wall temperature of the pipe may exceed the design value; as long as the excess temperature is not too large, no immediate damage will occur. However, when the pipe operates at elevated temperatures for an extended period, the microstructure of the steel changes, the creep rate increases, and its endurance strength decreases, resulting in premature failure due to explosion before its service life reaches the intended value. This type of damage is known as long-term over-temperature tube rupture. The characteristics of the fracture caused by long-term over-temperature tube rupture are as follows: the fracture presents as a large opening with a rough, brittle fracture surface; the wall thickness of the tube does not decrease significantly, and creep deformation of the tube is also not notable; often, there is a thick layer of iron oxide on the inner surface of the fracture.

During operation, for some reason, the wall temperature of the pipe may exceed the design value; as long as the excess temperature is not too large, no immediate damage will occur. However, when the pipe operates at elevated temperatures for an extended period, the microstructure of the steel changes, the creep rate increases, and its endurance strength decreases, resulting in premature failure due to explosion before its service life reaches the intended value. This type of damage is known as long-term over-temperature tube rupture. The characteristics of the fracture caused by long-term over-temperature tube rupture are as follows: the fracture presents as a large opening with a rough, brittle fracture surface; the wall thickness of the tube does not decrease significantly, and creep deformation of the tube is also not notable; often, there is a thick layer of iron oxide on the inner surface of the fracture.

During operation, for some reason, the wall temperature of the pipe may exceed the design value; as long as the excess temperature is not too large, no immediate damage will occur. However, when the pipe operates at elevated temperatures for an extended period, the microstructure of the steel changes, the creep rate increases, and its endurance strength decreases, resulting in premature failure due to explosion before its service life reaches the intended value. This type of damage is known as long-term over-temperature tube rupture. The characteristics of the fracture caused by long-term over-temperature tube rupture are as follows: the fracture presents as a large opening with a rough, brittle fracture surface; the wall thickness of the tube does not decrease significantly, and creep deformation of the tube is also not notable; often, there is a thick layer of iron oxide on the inner surface of the fracture.

During operation, for some reason, the wall temperature of the pipe may exceed the design value; as long as the excess temperature is not too large, no immediate damage will occur. However, when the pipe operates at elevated temperatures for an extended period, the microstructure of the steel changes, the creep rate increases, and its endurance strength decreases, resulting in premature failure due to explosion before its service life reaches the intended value. This type of damage is known as long-term over-temperature tube rupture. The characteristics of the fracture caused by long-term over-temperature tube rupture are as follows: the fracture presents as a large opening with a rough, brittle fracture surface; the wall thickness of the tube does not decrease significantly, and creep deformation of the tube is also not notable; often, there is a thick layer of iron oxide on the inner surface of the fracture.

For some reason, the wall temperature of the tube may exceed the design value; as long as the degree of overtemperature is not too great, no immediate damage will occur. However, when the pipe operates at elevated temperatures for an extended period, the microstructure of the steel changes, the creep rate increases, and its endurance strength decreases, resulting in premature failure due to explosion before its service life reaches the intended value. This type of damage is caused by long-term overheating leading to tube rupture, also known as long-term overheat-induced tube failure, or simply general creep damage. Piping failure due to prolonged over-temperature usually occurs on the fire-facing side of the outer tubes in the outlet section of the high-temperature superheater. Based on recent investigations and analyses of superheater tube failures, approximately 70% of these failures are caused by prolonged overheating. Such explosive damage can also occur occasionally in water wall tubes, slag tube bundles, and economizer tubes. The characteristics of cracks caused by long-term overheating and tube bursting are as follows: the crack presents as a large opening with a rough, brittle fracture surface; the wall thickness of the tube does not decrease significantly, and creep deformation of the tube is not very pronounced; moreover, there is often a thick layer of iron oxide on the inner surface of the crack. Certain characteristics of the cracks are related to the continuous corrosion of the material as its structural structure changes over time due to prolonged exposure to excessive temperatures. It first generates fine creep cracks and stress corrosion cracks; as overheating continues, these fine cracks keep forming and growing, eventually leading to tube rupture

During operation, for some reason, the wall temperature of the pipe may exceed the design value; as long as the excess temperature is not too large, no immediate damage will occur. However, when the pipe operates at elevated temperatures for an extended period, the microstructure of the steel changes, the creep rate increases, and its endurance strength decreases, resulting in premature failure due to explosion before its service life reaches the intended value. This type of damage is caused by long-term overheating leading to tube rupture, also known as long-term overheat-induced tube failure, or simply general creep damage. Piping failure due to prolonged over-temperature usually occurs on the fire-facing side of the outer tubes in the outlet section of the high-temperature superheater. Based on recent investigations and analyses of superheater tube failures, approximately 70% of these failures are caused by prolonged overheating. Such explosive damage can also occur occasionally in water wall tubes, slag tube bundles, and economizer tubes. The characteristics of cracks caused by long-term overheating and tube bursting are as follows: the crack presents as a large opening with a rough, brittle fracture surface; the wall thickness of the tube does not decrease significantly, and creep deformation of the tube is not very pronounced; moreover, there is often a thick layer of iron oxide on the inner surface of the crack. Certain characteristics of the cracks are related to the continuous corrosion of the material as its structural structure changes over time due to prolonged exposure to excessive temperatures. It first generates fine creep cracks and stress corrosion cracks; then, as overheating continues, these fine cracks keep forming and growing, eventually leading to tube rupture.

During operation, for some reason, the wall temperature of the pipe may exceed the design value; as long as the excess temperature is not too large, no immediate damage will occur. However, when the pipe operates at elevated temperatures for an extended period, the microstructure of the steel changes, the creep rate increases, and its endurance strength decreases, resulting in premature failure due to explosion before its service life reaches the intended value. This type of damage is caused by long-term overheating leading to tube rupture, also known as long-term overheat-induced tube failure, or simply general creep damage. Piping failure due to prolonged over-temperature usually occurs on the fire-facing side of the outer tubes in the outlet section of the high-temperature superheater. Based on recent investigations and analyses of superheater tube failures, approximately 70% of these failures are caused by prolonged overheating. Such explosive damage can also occur occasionally in water wall tubes, slag tube bundles, and economizer tubes. The characteristics of cracks caused by long-term overheating and tube bursting are as follows: the crack presents as a large opening with a rough, brittle fracture surface; the wall thickness of the tube does not decrease significantly, and creep deformation of the tube is not very pronounced; moreover, there is often a thick layer of iron oxide on the inner surface of the crack. Certain characteristics of the cracks are related to the continuous corrosion of the material as its structural structure changes over time due to prolonged exposure to excessive temperatures. It first generates fine creep cracks and stress corrosion cracks; then, as overheating continues, these fine cracks keep forming and growing, eventually leading to tube rupture.

During operation, for some reason, the wall temperature of the pipe may exceed the design value; as long as the excess temperature is not too large, no immediate damage will occur. However, when the pipe operates at elevated temperatures for an extended period, the microstructure of the steel changes, the creep rate increases, and its endurance strength decreases, resulting in premature failure due to explosion before its service life reaches the intended value. This type of damage is caused by long-term overheating leading to tube rupture, also known as long-term overheat-induced tube failure, or simply general creep damage. Piping failure due to prolonged over-temperature usually occurs on the fire-facing side of the outer tubes in the outlet section of the high-temperature superheater. Based on recent investigations and analyses of superheater tube failures, most tube ruptures are caused by prolonged overheating. Such explosive damage can also occur occasionally in water wall tubes, slag tube bundles, and economizer tubes. The characteristics of cracks caused by long-term overheating and tube bursting are as follows: the crack presents as a large opening with a rough, brittle fracture surface; the wall thickness of the tube does not decrease significantly, and creep deformation of the tube is not very pronounced; moreover, there is often a thick layer of iron oxide on the inner surface of the crack. Certain characteristics of the cracks are related to the continuous corrosion of the material as its structural structure changes over time due to prolonged exposure to excessive temperatures. It first generates fine creep cracks and stress corrosion cracks; then, as overheating continues, these fine cracks keep forming and growing, eventually leading to tube rupture.

During operation, for some reason, the wall temperature of the pipe may exceed the design value; as long as the excess temperature is not too large, no immediate damage will occur. However, when the pipe operates at elevated temperatures for an extended period, the microstructure of the steel changes, the creep rate increases, and its endurance strength decreases, resulting in premature failure due to explosion before its service life reaches the intended value. This type of damage is known as long-term over-temperature tube rupture. The characteristics of the fracture caused by long-term over-temperature tube rupture are as follows: the fracture presents as a large opening with a rough, brittle fracture surface; the wall thickness of the tube does not decrease significantly, and creep deformation of the tube is also not notable; often, there is a thick layer of iron oxide on the inner surface of the fracture.