Boiler safety is a critical factor that cannot be overlooked. Ensuring proper maintenance and awareness can help foster a safe work environment while avoiding costly repairs or dangerous accidents.

Boiler explosion is an instantaneous energy release phenomenon caused by excessive boiler pressure load. Such as lack of water in the boiler, excessive scale, and excessive pressure will cause the boiler to explode. Once a boiler explosion occurs, it will cause great damage to surrounding buildings and personnel.

Boiler Explosions Causes 

Atmospheric pressure boilers are also called pressureless boilers, and atmospheric pressure boilers are generally not in danger of explosion.Unless the boiler explodes due to:

1. A valve is installed at the air vent of the boiler.

2. The heating piping system of the boiler is installed incorrectly.

3. Severe fouling of the boiler.

The pressure boiler is a pressure vessel and has the danger of explosion. Therefore, a pressure gauge and a safety valve must be installed. The safety valve is a safety protection valve. Its opening and closing parts are in a normally closed state under external force. When the safety valve sets the pressure, it will automatically open and release the pressure to ensure that the medium pressure in the boiler is below the set pressure, protect the equipment and pipelines from working normally, and prevent explosion accidents. Therefore, as long as the safety valve and other safety accessories are sensitive, the pressure-bearing boiler will There is no danger of frying, unless the boiler is dangerous due to the following reasons.

1. The safety valve and other safety accessories fail.

2. Severe fouling of the boiler.

3. The boiler is short of water and dry.

Measures to be taken to prevent boiler explosion

Preventive Measures for Pressure Vessel Explosion Accidents

1.In terms of design, a reasonable structure should be adopted.

2. When repairing, installing, and transforming, strengthen welding management, improve welding quality, and conduct heat treatment and flaw detection according to specification requirements;

3. Strengthen material management and avoid using defective materials or wrong steel and welding materials.

4. Strengthen the use management to avoid operating errors, over-temperature, over-pressure, overload operation, failure to check, disrepair, failure of safety devices, etc.

5. Strengthen the inspection work, find defects in time and take effective measures.

Preventive Measures for Reburning at Boiler Tail

1.Minimize the loss of incomplete combustion as much as possible, and reduce the number of startup and shutdown of the boiler.

2. Strengthen the soot blowing on the heating surface of the tail to ensure that the various door holes of the flue and the flue baffles are well sealed.

Preventive Measures for Boiler Furnace Explosion Accidents

1.According to the capacity and size of the boiler, install a reliable furnace safety protection device.

2. Try to improve the anti-knock ability of the furnace and rigid beams.

3. Strengthen the use management and improve the technical level of the firemen.

Preventive Measures for Boiler Steam Drum Lack of Full Water

1.Water shortage accident

(1) When there is a slight lack of water, you can immediately fill the boiler with water to restore the water level to normal.

(2) In case of severe water shortage, the furnace must be shut down urgently.

2. Flooding accident

Close the water supply valve to stop water supply to the boiler, activate the recirculation pipeline of the economizer, weaken the combustion, open the drain valve and the drain valve on the superheater and steam pipeline; after the water level returns to normal, close the drain valve and each drain valve; check Clear the cause of the accident and eliminate it, and resume normal operation.

Boiler Safety Requirements

Article 6.1.15 and Article 6.1.16 of TSG G0001-2012 "Boiler Safety Technical Supervision Regulations". The statement is: "The appearance of the safety valve is in good condition. After verification, it should be locked or sealed, and the lead seal should be kept intact; regular verification and discharge tests should be done.

After the safety valve has been checked, it shall be locked or sealed with lead. The safety valve of the boiler in use shall be checked at least once a year. In order to ensure the safe operation of the boiler and avoid the valve core and valve seat of the safety valve sticking due to long-term inactivity, manual steam exhaust operation must be performed regularly.

Each boiler shall be equipped with at least two safety valves (including drum and superheater safety valves), and if one of the following requirements is met, only one safety valve may be installed.

(1) Steam boilers with rated evaporation less than or equal to 0.5t/h;

(2) Steam boilers with rated evaporation less than 4/h and equipped with reliable overpressure interlock protection device;

(3) Hot water boilers with rated thermal power less than or equal to 2.8MW;

On-site judgment method: according to the boiler technical files, check the number of boiler safety valves, check the number of safety valves on site, the consistency between the test report and the on-site verification mark, whether the appearance of the safety valve and the platinum seal are intact, and whether there is a manual discharge test record.

According to Article 6.2.3 of TSG G0001-2012 "Boiler Safety Technical Supervision Regulations". The terms are stated as: "The appearance of the pressure gauge is intact, and after the pressure gauge is verified and passed, the lead seal must be kept intact."

According to the relevant provisions of JG52-2013 "Elastic Element Type General Pressure Gauge, Pressure Vacuum Gauge and Vacuum Gauge":

Pressure gauges should have the following signs: product name, measurement unit and number, factory serial number, production year, measurement range, accuracy level, manufacturer's name or trademark, and the license mark and serial number for manufacturing measuring instruments.

The verification period of the pressure gauge can be determined according to the use environment and the frequency of use, and generally does not exceed 6 months.

On-site judgment method: check the ledger and verification certificate of the pressure gauge in the boiler technical file. It is consistent with the inspection mark of the on-site pressure gauge. The appearance of the pressure gauge and the lead seal are intact.

According to Article of  6.3.2 and6.3.3,The terms are stated as: : TSG G0001-2012 "Boiler Safety Technical Supervision Regulations".

"The water level gauge shall meet the following requirements:

a) The water level gauge should have obvious signs indicating the highest, lowest safe water level and normal water level;

b) The glass tube water level gauge should have protective devices, and should not hinder the observation of the real water level;

c) The water level gauge should have a water discharge valve and a water discharge pipe connected to a safe place;

d) The water level gauge should be installed in a place that is easy to observe. When the distance between the water level gauge and the operating ground is higher than 6000 mm, a remote water level measuring device or a water level video monitoring system should be installed.

The protective devices on the glass tube water level gauge include a protective cover, quick-closing valve, locking bead, etc., mainly because once the water level gauge is damaged, the quick-closing valve or the automatic locking bead closes quickly or automatically closes the steam-water connection pipe to prevent the steam-water from spraying out and causing injuries. people, but the protective device should not hinder the observation of the real water level;

It is used to release water when it is full of water. The drain pipe is connected to a safe place to prevent the discharged hot water from scalding people.

On-site judgment method: check the on-site equipment operation records; the water level can be observed normally, and the high and low water level marks are complete, and the protection is in place. The water level gauge that is inconvenient for on-site observation needs to check the remote water level measuring device.

The terms are expressed as: temperature measuring points should be installed at the corresponding parts of the boiler.

The source of the terms: TSG G0001-2012 "Boiler Safety Technical Supervision Regulations" Article 6.4.1.

On-site judgment method: The measuring point cannot be observed in the actual use of the boiler. The site needs to directly read the boiler safety technical files, ask the operating personnel, and understand the location of the boiler temperature measurement point; if there is a boiler control system, you can intuitively see the location of the temperature measurement point and the display value on the system display interface.

Boiler safety protection devices shall meet the following requirements:

a) Steam boilers should be equipped with high and low water level alarm devices (high and low water level alarm signals should be distinguishable), and boilers with a rated evaporation greater than or equal to 2t/h should also be equipped with low water level interlock protection devices and protection devices It should be sensitive and reliable; the steam spiral boiler should be equipped with high and low water level alarms (high and low water level alarm signals should be distinguishable) and low water level interlock protection devices, and the protection devices should operate at the latest minimum safe water level.

b) Code furnaces with a rated evaporation greater than or equal to 6t/h. The steam overpressure alarm and interlock protection device shall be installed, and the action rating of the overpressure interlock protection device shall be lower than the lower rated pressure value of the safety valve;

c) For the superheater and reheater of the boiler, corresponding protection measures should be taken according to the self-control conditions of the unit operation mode and the design structure of the superheater and reheater. Prevent the metal wall from overheating; the reheat steam system should be equipped with an emergency water spray device, and it can be put into use automatically;

d) Boilers placed in multi-storey or high-rise buildings, each boiler should be equipped with overpressure (temperature) interlock protection device and low water level interlock protection device;

e) Class B pressurized hot water boilers and Class C pressurized hot water boilers with a rated thermal power greater than or equal to 7MW shall be equipped with over-temperature alarm devices and interlock protection devices. The layer-fired boiler should be installed when the pressure of the boiler is reduced to the point where vaporization occurs or the water temperature exceeds the specified value and the circulating water pump stops running suddenly. A device that can automatically cut off the blast and induced wind;

f) For steam furnaces with sub-cylinders, steam traps should be installed at the bottom of sub-cylinders, and the specifications of the traps should be selected according to the condensed water volume of the steam equipment or steam pipelines, and the steam traps should be installed with bypass water valves.

Conclusion:

Safety accidents are no small matter, especially for boilers. We should practice safety production principles bit by bit, and do a good job in every step of boiler safety production. Because only in this way can you ensure that your production will not be affected and your life and property safety will not be threatened.

If you encounter other problems during the use of the boiler, you can contact EPCB boiler at any time, and EPCB can provide you with corresponding support.

EPCB, your private boiler system expert!

Further Reading:

Safety First! You Must Know These Safety Issues of Industrial Steam Boilers

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Boiler Guidance| Industrial Boiler Operation Optimization and Adjustment Method