Boiler Safety Series | Boiler Tube Burst Causes and Preventive Measures in Boiler Accidents

August 06, 2021

When the boiler is in operation, trial operation or pressure test, the boiler body, combustion chamber, main flue or steel frame, furnace wall are damaged, it is called a boiler accident.

when the boiler is in operation, due to the failure or damage of auxiliary equipment, such as combustion equipment, water supply equipment, water treatment equipment, ventilation equipment, and dust removal and slag removal equipment, the boiler is forced to stop operation, it is called boiler failure.

Boiler accidents and failures often occur during the operation of the boiler. In order to allow users to experience better boiler services, EPCB will prepare a series of boiler safety content for everyone from now on, analyze common boiler accidents and failure causes, and give corresponding information. The preventive measures to ensure that the boiler can run efficiently and safely and help you become a leader in the industry.

The first introduction is the common boiler fault--boiler tube burst. Boiler tube burst refers to the combined effect of various reasons such as overheating, wear and corrosion of the water-cooled wall tube, convection tube, and economizer tube in the heat exchange surface of the boiler during operation. Under the circumstances, the pipeline will burst and the high-temperature boiler water will leak, causing the boiler to fail to operate normally.

Through years of theoretical accumulation and field practice of EPCB, boiler tube bursts are mainly caused by 14 reasons.

Boiler Tube Burst Causes

boiler-tube-burst-Causes

Boiler Tube Burst Cause 1:

Boiler feed water quality is poor, no water treatment or water treatment methods are incorrect, and sewage treatment is not carried out in accordance with relevant regulations, causing the inner wall of the pipeline to scale or corrode.

The main reason for this situation is that the boiler water is taken from the ground, and the hardness is as high as 5mmol/L, which is high-hardness water, and has high sulfur and iron content;

Impact: Once the water is treated improperly, pipe bursts are likely to occur, and the boiler is forced to shut down for repairs, has a great impact on production and life.

Boiler Tube Burst Cause 2:

In the process of boiler manufacturing, installation, and maintenance, the boiler pipes will experience stress concentration and mechanical performance degradation at the weld joints, and pipeline bursts will occur at these key parts of the stress concentration and mechanical degradation.

Impact: The boiler fails and it is difficult to supply and produce.

Boiler tube burst Cause 3:

Impurities fall into the pipe during installation or overhaul of the boiler, causing blockage in the pipe, causing poor water circulation or complete destruction.

Boiler Tube Burst Cause 4:

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

Boiler Tube Burst Cause 5:

If the water level of the boiler is too low during operation, poor water circulation will also occur. After such a situation, the temperature of the local pipeline will be too high, deformed and burst.

Boiler Tube Burst Cause 6 :

When designing and installing oil-fired gas boilers, because the nozzle angle is not adjusted correctly, some boiler pipes may overheat and boiler pipe bursts may occur.

Boiler Tube Burst Cause 7:

Improper operation of raising fire, shutting down the furnace, causing the furnace tube to be blown by cold wind, the tube thermal expansion and contraction too fast or too frequently, resulting in harmful stress.

Boiler Tube Burst Cause 8:

The fire partition wall of the flue and combustion chamber is damaged, causing the short-circuit of the flue gas, which causes the heat of the local furnace tube to concentrate and burn the furnace tube.

Boiler Tube Burst Causes 9:

Corroded pipe burst and equipment aging burst pipe. Generally occurs in the economizer tube on the heating surface of the tail, the reason is that the exhaust gas temperature is too low or the feed water temperature is too low and the acid corrosion is caused.

Boiler Tube Burst Causes 10:

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 pipe row and the furnace wall do not meet the design requirements, and the pipe row is between the pipe row or the pipe row. A local smoke corridor is formed with the furnace wall, or local pipes are arranged to cause fouling and bridges on the heating surface, causing the local smoke velocity to be too high and increasing the wear and overheating of the pipes in this part.

Boiler Tube Burst Cause11:

Due to careless construction, the seal of the furnace wall is not strictly sealed in accordance with the construction requirements, causing the formation of eddy currents at the air leakage. In this case, local overheating of the pipeline or uneven heating may occur, and the air leakage will also cause the flow rate of the flue gas behind. Increase, endanger the heated surface of the tail.

Boiler Tube Burst Cause 12:

The high-temperature operation of the tube is also an important reason for the boiler tube burst. Overheating and over-temperature bursting of the tube is due to the decrease of mechanical properties of the tube under the condition of over-temperature, and the tube deforms under the action of pressure and even bursts.

Boiler Tube Burst Cause 13 :

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 flame center, primary and secondary air scouring the water wall tube, and rapid cooling of the furnace. Cause the boiler to burst.

Boiler Tube Burst Cause 14:

Excessive iron content in boiler return water will not only cause "red water" phenomenon in boiler water, but also cause corrosion under iron oxide scale. Accelerate the formation of phosphate scale in the boiler. The thermal conductivity of iron oxide scale is very poor. The heat transfer efficiency of the iron oxide scale layer is very different from the heat transfer efficiency of the furnace tube, which will seriously hinder heat transfer and cause local overheating of the heat transfer surface. It is so high that the strength of the metal decreases, endangering the safety of the boiler, causing the furnace tube to deform and cause the tube to burst.

Six Measures to Prevent Boiler Tube Burst

In order to reduce and eliminate the occurrence of tube bursts and ensure the needs of production and life, there are seven measures to prevent boiler tube bursts as follows:

1. Strengthen water treatment and water quality monitoring and management

2. Shut down the furnace regularly for maintenance, and deal with problems in time

3. Strengthen the management in operation

4. Timing descaling and smoke pipe cleaning

5. Increase the exhaust gas temperature to prevent the generation of condensed water

6. Add high-efficiency boiler anti-corrosion and scale inhibitor

FOR detail：

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

2. Make full use of the boiler shutdown and maintenance work. Please professional authoritative organizations 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, adjust the combustion, organize reasonable combustion conditions and proper flame center, prevent cold air from sweeping the furnace tube, perfect measures to prevent wear and corrosion, and carry out reasonable sewage discharge.

4. Descaling and cleaning the smoke pipe in time after stopping the furnace, and do a good job in maintenance.

5. Appropriately increase the exhaust gas temperature by 180-200 degrees to prevent the generation of condensed water at the tail.

6. Adding high-efficiency boiler anti-corrosion and scale inhibitor BF-30a, BF-30a has the dual protection function of making the boiler body metal in a passivation state and inhibiting the cathodic reaction in the metal corrosion process, effectively preventing the metal body from running and stopping. Oxygen corrosion in the furnace state, while avoiding the formation of scale deposits on the surface of the boiler metal in higher hardness water.

Conclusion:

Through the above content, you can have a comprehensive understanding of the boiler tube burst accident, understand the boiler failure and take corresponding measures to actively prevent it, and your boiler can be used more safely and lastingly.