The types of stainless steel boiler tube failure include overheat burst tube, wear failure, corrosion failure, welding leakage, and misused steel. The failure characteristics and causes are analyzed, and the corresponding preventive measures are put forward.
Relative to mechanical equipment, stainless steel boiler tube has no movement machinery that severe problem such as wear and tear, vibration, high fatigue, but because of its working conditions, by the quality of soda, operating conditions, such as flue gas flow conditions, the influence of explosive leakage accident more, prevent boiler tube leakage, stainless steel, therefore, it has become the key to improve the safe and economic operation of power plant.
The types of stainless steel boiler tube failure are: overheat burst tube, wear failure, corrosion failure, thermal fatigue failure, welding leakage, wrong steel, etc.
1. Pipe detonation due to overheat
1) Long-term overheat tube detonation
Failure reason: The stainless steel boiler tube is in overtemperature state operation for a long time, long-term overtemperature may be due to boiler overload, poor soda circulation, combustion center deviation, tube inner wall scaling, etc.
Preventive measures: Stabilize operating conditions, monitor operating temperature, adjust and improve combustion conditions, perform boiler pickling, remove inner wall scaling, etc.
2) Short-term overheat tube explosion
Failure reasons: Foreign matter blocking stainless steel tube, boiler combustion instability, low steam flow rate or steam stratification, temperature regulation is not correct, scale.
Preventive measures: Remove foreign bodies, stabilize operating conditions, and improve combustion conditions in the furnace.
2. Wear and tear
Failure reason: poor coal quality, hard particles in fly ash, scour the surface of stainless steel tube.
Preventive measures: Select the appropriate type of coal, rationally design the economizer structure, eliminate the excessive local smoke speed, add the equal-flow baffle, and add the anti-wear cover plate on the surface of the stainless steel tube.
Failure reason: a) The passivation film on the inner wall of the pipe is broken, and electrochemical corrosion occurs at the rupture point. b) The stress concentration at the elbow promotes pitting. c) The elbow is subjected to thermal impact, which causes fatigue cracks to occur on the inner wall of the elbow. d) There is water in the pipe when the furnace is shut down.
Preventive measures: Strengthen the protection of stainless steel boiler tube before use, keep the water quality qualified, strictly control the PH value and oxygen content, and pay attention to stop the furnace protection.