Precision Sealing: The Critical Step of De-Greasing FD Fan Blade Spindles (FAF19-9.5-1) for Zero Leakage

The Overlooked Step: Ensuring Mating Surface Cleanliness

When overhauling the FAF30-16-1 Forced Draft (FD) Fan and installing the FAF19-9.5-1 Blade Spindle Seal, a seemingly minor yet crucial step is often overlooked: de-greasing the mating surface before connecting the actuating rod to the blade spindle shaft end.

According to the DL/T 468-2019 Guideline for Selection and Use of Fans in Power Station Boilers: “Before installing the sealing system, mating surfaces must be clean and free of oil.” This requirement is vital not only for sealing effectiveness but also for the service life of supporting components like shrouds and end covers.

The Technical Failure Mechanism: The "Elastic Oil Film"

The FAF19-9.5-1 blade spindle seal uses a combined "O-ring + Labyrinth Gland" structure. Its sealing performance relies heavily on the precise axial positioning and uniform compression of the blade spindle. The actuating rod is the key component that transmits the pitch adjustment force and secures the spindle's position.

If oil or grease remains on the connecting surfaces, tightening the self-locking nut will squeeze the lubricant, creating an “elastic oil film.” This film causes the actuating rod to be improperly seated or "false-connected," meaning the blade spindle is not truly home. This results in slight spindle tilting or axial play.

The immediate consequence is uneven O-ring compression—one side is over-compressed while a gap appears on the opposite side. Hot lubricating oil or flue gas dust then penetrates this gap, initiating seal failure.

The Consequences of Neglecting to De-Grease

The ramifications of a leaky seal are significant:

• Short-Term Leakage: Oil traces appear within hours of operation, contaminating the fan interior and potentially triggering alarms.
• Pitch Control Seizing: Oil and dust mix to form a sticky sludge, clogging the labyrinth passages and leading to sluggish or failed pitch adjustment.
• Repeated Maintenance: A seemingly successful installation leads to leakage within a week, forcing a costly second shutdown and compromising unit reliability.
• Chain Damage: Leaking oil can contaminate the fan's actuator coupling or the control rod copper bushings, triggering a cascading failure.

The Solution: Precision Cleaning and High-Performance Seals

1. The Correct Procedure:

The solution is straightforward: Use a non-woven cloth dampened with industrial alcohol to thoroughly wipe the blade spindle shaft end and the inner bore of the actuating rod. Ensure the surfaces are dry, oil-free, and contaminant-free before tightening the self-locking nut to the specified torque of 210℃.

2. The Premium Seal Choice:

Selecting the right seal is paramount. Hua Kai Sheng Rui specializes in power plant fan seals and offers the FAF19-9.5-1 Blade Spindle Seal, specifically designed for high oil temperature, high dust, and high-frequency adjustment conditions:

• Fluoroelastomer (FKM) O-rings: Temperature resistance up to 200℃, highly resistant to oil and aging.
• Precision Stainless Steel Labyrinth Structure: Works synergistically with the end cover and frame oil seal to create a triple sealing barrier.
• Special Surface Treatment: Effectively resists flue gas corrosion and fretting wear.

This seal is currently operating stably for over 18 months in multiple 300MW to 660MW units, achieving zero leakage and zero re-work.

Complementary Products for FD Fan Reliability

In addition to the FAF19-9.5-1 blade spindle seal, we offer a full range of supporting products for the critical components of your FD Fan:

HKZX-2025-10-24