14 reasons for boiler tube burst and preventive measures

Boiler tube burst refers to the situation where the water-cooled wall tubes, convection tubes, and economizer tubes in the heat exchange surface of the boiler during operation burst under the combined effect of various reasons such as overheating, wear and corrosion, and high-temperature boiler water leaks, causing the boiler to be unable to operate normally. Through years of theoretical accumulation and field practice, it is found that boiler tube bursts are mainly caused by 14 reasons.

1. Poor water supply quality

Poor boiler water supply quality, no water treatment or incorrect water treatment methods, and failure to discharge sewage according to relevant regulations, causing scaling or corrosion on the inner wall of the pipeline. The main reason for this situation is that some boilers use water from underground, which is high-hardness water and contains high sulfur and iron content. Once the water is improperly treated, it is easy to burst the tube, resulting in forced shutdown of the boiler for repairs, which has a great impact on production and life.

2. Stress concentration
During the manufacturing, installation and maintenance of boiler pipelines, stress concentration and mechanical performance degradation will occur at the welds. Pipeline bursts will occur at these key locations where stress concentration and mechanical degradation occur, which will also cause the boiler to malfunction and make it difficult to supply production and living needs.

3. Impurities fall during installation or maintenance
During the installation or maintenance of the boiler, impurities fall into the pipes, causing blockage in the pipes, poor water circulation or complete destruction.

4. Scale falls off the inner wall
The scale of the pipe falls off from the inner wall, "bridging" and putting the water circulation in a bad state.

5. The water level is too low
If the water level is too low during the operation of the boiler, the water circulation will also be poor. In this case, the local temperature of the pipeline will be too high, deforming and even bursting.

6. Design and installation problems
When designing and installing oil boilers, gas boilers or coal boilers, some boiler pipelines will overheat due to incorrect adjustment of the nozzle angle.

7. Worker operation problems
If the ignition and shutdown operations are not correct, the furnace tubes are blown by cold wind, and the tubes expand and contract too quickly or too frequently, harmful stress will be generated.

8. Fire wall damage
The fire wall of the flue and combustion chamber is damaged, causing the flue gas to short-circuit and cause the heat concentration of the local furnace tubes to burn the furnace tubes.

9. Equipment aging
Corrosion and equipment aging usually occur in the economizer tubes of the tail heating surface. The reason is acid corrosion caused by too low exhaust temperature or too low feed water temperature.

10. Local smoke velocity is too fast
The local smoke velocity is too fast. When installing and repairing the heating surface pipes, the pitch of the heating surface pipes and the distance between the heating surface pipes and the furnace wall do not meet the design requirements, forming a local smoke corridor between the pipes or between the pipes and the furnace wall, or the local pipes are out of the line, causing the heating surface pipes to accumulate dust and bridge, causing the local smoke velocity to be too high, thereby increasing the wear and overheating of the pipes in this part.

11. The furnace wall is not sealed well
Due to careless construction, the furnace wall seal is not strictly sealed according to the construction requirements, so that vortices are formed at the air leakage. In this case, the pipeline will be locally overheated or unevenly heated, and the air leakage will also increase the flue gas flow rate behind, which will harm the tail heating surface.

12. Too high temperature
The high temperature operation of the pipe is also an important reason for the boiler tube burst. Overheating and over-temperature tube burst is due to the decrease of mechanical properties of the pipe under overheating. The pipe undergoes plastic deformation, that is, creep cracks, under the action of pressure, resulting in tube burst.

13. Influence of the operating environment
The influence of the operating environment can also cause the furnace tube to rupture, such as frequent start and stop of the boiler, drastic changes in load, improper adjustment of the center of the flame, primary and secondary air scouring of the water-cooled wall tube, rapid cooling of the shutdown furnace, etc., all of which leave hidden dangers for the boiler tube burst.

14. Chemical reaction - carbon dioxide corrosion
The boiler heating system network or steam condensate network has carbon dioxide corrosion or oxygen corrosion. When oxygen and carbon dioxide are present in the boiler return water system at the same time, the corrosion of the system network steel will be more serious. Carbon dioxide makes water slightly acidic and destroys the protective film of the pipeline. As the oxygen content increases, the carbon steel equipment and pipeline of the heating system will have ulcers of varying sizes, accelerating the corrosion. As a result, the return water or condensate water will be yellow, red, or even soy sauce-colored, with high iron ion content and steel pipe perforation. This is the reason for the common corrosion, perforation and leakage of steam pipes and condensate pipes. This is also the reason why the service life of some newly built boiler carbon steel pipes is only 4-5 years.

6 measures to prevent boiler pipe bursts:

In order to reduce and eliminate pipe bursts and ensure the needs of production and life, the six measures to prevent boiler pipe bursts are as follows:

1. Strengthen the management of water treatment and water quality monitoring, increase deoxygenation and iron removal equipment, change from primary softening to secondary softening, so that the boiler water meets the national standard and ensures the safe and economical operation of the boiler.

2. Make full use of the maintenance time after the shutdown, and ask the municipal boiler inspection institute and other authoritative institutions to conduct comprehensive internal and external inspections of the boiler, find and deal with problems in time, and ensure the healthy operation of the boiler.
3. Strengthen the management during operation, organize reasonable combustion conditions and appropriate flame centers, prevent cold wind from blowing the furnace tubes, improve measures to prevent wear and corrosion, and carry out reasonable sewage discharge.
4. Descale and clean the smoke pipes in time after the shutdown, and do a good job of maintenance.
5. Appropriately increase the exhaust temperature (recommended 150-170 degrees Celsius), take into account safety and energy saving, and eliminate energy waste and avoid the generation of tail condensate.

6. Add high-efficiency boiler anti-corrosion and anti-scaling agent BF-30a to prevent the metal surface of the boiler from depositing scale in high hardness water.

Read more: Suggestions for selecting boiler tube materials or Boiler tube standards