Reasons for boiler tube rupture

Boiler tube failures are generally caused by steam overpressure, corrosion or scaling of the boiler tubes; as for superheaters, local overheating may also be a factor.

I agree with the view from the second floor; the steam flow rate in the superheater is generally quite high. This might be due to an unsuitable design of the furnace, which results in excessively high temperatures of the flue gas entering the superheater.

There may be several reasons for overheater tube bursts; (I hope this is helpful to you.) ) 1. If tube bursts frequently, it is necessary to consider whether the material of the superheater is of appropriate quality. 2. Is the heat exchange area of the superheater appropriate? 3. Installation position and angle of the superheater. It is generally installed at the flue outlet. Direct erosion leads to thinning of the superheater tubes. 4. Quality of saturated steam. Whether it meets the standards. Excessive levels of calcium and magnesium in the steam can cause localized excessively high temperatures on the pipe wall beneath the scale. The high humidity of saturated steam has a significant impact on the proper operation of the superheater.

I also agree that local overheating on the second floor, as well as scaling inside the pipes, are both possible possibilities

It is related to factors such as the material of the superheater, the gas flow velocity at the superheater during design, slag formation, fluid flow velocity, scaling, the stability of the boiler’s operating load, and corrosion.

Is it caused by overloading?

Analysis of tube rupture causes: 1. Influence of operating conditions. During operation, situations such as overloading and underloading frequently occur; additionally, an excessive heating rate during boiler startup, prolonged periods of operation at low load, and insufficient water supply for ignition can all directly affect the safety of the superheater’s operation. 2. Impact on soda water quality: The direct factor causing salt accumulation inside the superheater is the quality of saturated steam. The reasons for the decline in the quality of saturated steam can be summarized as follows: ① High salt content in the boiler water leads to salt accumulation on the inner walls of the tubes, and the possibilities for such salt accumulation include excessive dosage of chemicals or uneven distribution of these chemicals, resulting in localized salt buildup ； Unqualified quality of condensate water can also lead to an increase in the salt content in the boiler water. ② Equipment failures can result in a reduced efficiency of steam-water separation. ③ Poor deoxidation performance is another factor that contributes to a decline in the quality of boiler water. 3 Is there any foreign matter blocking the pipes? Pipe explosions caused by such blockages are a common problem in most power units during testing and operation. 4. Issues related to equipment manufacturing: substandard materials, using inferior materials in place of high-quality ones, inadequate inspection of equipment before it leaves the factory, and insufficient testing of manufacturing processes – all of these can lead to sudden changes in the material properties during operation, resulting in explosions

Superheater material (20G is commonly used; materials such as 235A are generally not selected). This is related to factors such as scaling and corrosion, as well as extremely high local temperatures on the tube walls and excessive fuel load causing overloading.

1. Improper procedures for starting up and shutting down the furnace result in significant thermal stress on the pipes. 2. During operation, if the steam pressure and temperature exceed the specified limits, or if there is a large thermal deviation, it accelerates the creep rate of the pipes. 3. Abnormal operation adjustment 4. Abnormal water circulation 5. Fly ash wear 6. Pipe wall corrosion or salt accumulation inside the pipes. When the oxygen content in the feed water is high or the flow rate is too low, pitting corrosion on the inner wall often occurs, leading to tube failure ； The quality of the boiler water is unsatisfactory, and saturated steam contains moisture, which leads to salt accumulation inside the superheater tubes; this results in overheating of the tube walls and eventual tube failure ； High-temperature corrosion is one of the causes. 7. Poor quality in manufacturing, installation, and maintenance. If the quality of the pipe is poor or the wrong steel grade is used for the pipe ； The quality of the pipe weld is unsatisfactory ； The wall thickness at the elbow is severely reduced ； Foreign objects in the pipe reduce the passage area or cause blockage ； During maintenance, tubes that had exceeded the allowable degree of creep were missed, and tubes that had become thinned were not detected.

Lack of proper waste discharge leads to scaling and corrosion, as well as high local temperatures, increasing the risk of pipe explosions! Waste discharge should be managed by discharging it frequently, in small amounts, and evenly

CFB boilers can also be subject to wear

This post was last edited by zjy_007 on 2009-5-5 12:11. Industrial furnaces are primarily affected by scaling.

It is necessary to check the boiler’s operating time (for signs of creep), the location of any tube failures (to determine if there is wear), as well as the quality of the steam and water (through laboratory tests). The operation of the temperature reducer also needs to be checked. It is advisable to cut open the tubes to examine their thickness and conduct metallographic analysis in order to determine the exact cause.

Tube rupture in a boiler superheater can be caused by thinning of the tube wall due to wear or inherent defects in the weld quality; it may also result from steam overpressure, tube corrosion, or localized overheating.

The presence of such explosive cracks is clearly caused by short-term overheating; I have experience in this area. Prolonged overheating often results in a rough surface with transverse cracks, which are relatively small in size. The surface of short-term overheating cracks is smooth, the edges of the cracks are sharp, and the cracks are large.

It would be much easier if the original poster had pictures; wear and overheating/overpressure are the main causes of boiler tube failures.

It’s a 10t furnace; the quality of the water supplied seems to be poor, which might be related to scaling in the pipes.

This kind of situation has occurred in our factory before; the ultimate cause was local overheating

It should be a tube failure caused by local overheating; there is likely local swelling

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