Fan Blade Bolt Failure UY2614G03: Boiler System Deep Dive and Solutions

In power plant boiler systems, the Primary Air (PA) Fan is a critical player—it's responsible for blowing cold air into the boiler furnace to mix with the fuel for combustion. If it fails, the entire rhythm of boiler operation is thrown into chaos. Within the PA fan's components, the seemingly insignificant UY2614G03 blade bolt is supremely important. It's specifically adapted for boiler fans, capable of withstanding a pulling force equivalent to four family cars. Normally, it should work reliably for over 15 months, enduring vibration, high temperatures from the boiler surroundings, and constant dust erosion. However, a bolt fracture in the PA fan of Boiler No. 3 at a certain power plant recently almost led to a major incident.

Unpacking the Failure: Multi-Factor Degradation

To understand why the bolt broke, the fracture surface was the first clue. Lab analysis showed the break was not a clean slice but covered in wave-like patterns, much like beach marks—the definitive sign of fatigue failure. Like repeatedly bending a metal wire, even if the force isn't large each time, accumulated stress eventually leads to structural failure. Further investigation revealed a complex set of problems:

• Material Purity Flaw: Microscopic examination revealed fine sulfide inclusions within the metal structure. These impurities acted as "micro-cavities" where stress concentrated under load, initiating cracks. Although the UY2614G03 standard allows for minor impurities, the fractured bolt had an impurity content 12% higher than the specified limit, a manufacturing flaw that set the stage for failure.
• Installation Error (Insufficient Pre-tension): During PA fan operation, changes in air pressure cause the blades to oscillate, forcing the bolt to endure alternating "tension-compression" forces. The investigation found that two UY2614G03 bolts in the set were under-torqued—the standard requirement was 900N·m, but the actual value was only 800N·m. This inadequate pre-tension meant these bolts couldn't properly bear the load, shunting the excess stress onto the others, effectively accelerating their 15-year lifespan wear and tear.
• Harsh Environment (Thermal and Dust Stress): The boiler environment added significant stress. The surrounding temperature frequently hit 60, causing gradual degradation of the metal's properties. Moreover, fine dust infiltrated the contact surface between the bolt and the flange, preventing uniform load transmission, increasing local pressure, and hastening crack initiation. Compounding this, the anti-corrosion coating on one bolt was scraped during installation, allowing workshop humidity to cause rust and further reduce its load-bearing capacity.

Systemic Fixes: A Proactive Protection Scheme

The immediate emergency response involved replacing all UY2614G03 bolts on Boiler No. 3's PA fan with new, rigorously tested units. Installation adopted a refined method: "Smart Torque Wrench + Temperature Compensation." Since the boiler area is hot and bolts expand, a temperature compensation value was calculated and applied before tightening the bolts to the standard high pre-tension, ensuring uniform stress. Spot checks on other PA fans across the plant also revealed four under-torqued UY2614G03 bolts, which were immediately corrected, proactively eliminating risks.

The UY2614G03 bolt failure, while seemingly a small component error, was actually a compounding effect of material issues, installation failures, and environmental stress. The PA fan is central to the entire power plant's stability; its operation is non-negotiable. Solving this required more than a simple bolt replacement—it demanded a full-chain management system from procurement to installation to maintenance.

Materials must be qualified, installation must be standardized, and maintenance must be timely. Only by rigorously focusing on every detail can each bolt fulfill its function, guarding the bottom line of boiler safety. After all, in a power plant, any problem with a small component can lead to a major headache, and there is absolutely no room for carelessness.