Feed Water Pump Inner Cartridge Nut DG600-240-01-07: Small Component, Critical Role

In a high-stakes overhaul, this is the final lock that holds a 2,200kg core assembly together against 5,000kg+ of operational load. It's not just a nut—it's the difference between a smooth run and a catastrophic shutdown.

I. Beyond the Surface: What does this nut actually do?

The FK6D32M cartridge is a massive, multi-stage assembly of impellers, guide vanes, and balance drums. The DG600-240-01-07 nut is a custom-engineered component designed specifically for the DG600-240 series feedwater pumps.

• The Precision Fit: Engineered to match the specific thread pitch of the cartridge flange.
• The Load: It fights thermal expansion at 600°C and radial impacts from high-speed rotation.

II. The Team Players: Components that must work with the Nut

Material Matter: We use 35CrMoA High-Strength Alloy Steel. Ordinary steel would deform like butter at these operational temperatures.

III. Maintenance Secrets: The 4 Traps

1. The Direction Trap

Drive-end pump shaft nuts are often left-handed, but the DG600-240-01-07 cartridge nut is Right-Handed. Forced clockwise removal will strip the flange threads permanently.

2. The Torque Trap

Tight enough isn't a measurement. Under-tightening leads to vibration loosening; over-tightening warps the flange. Use a calibrated hydraulic wrench to hit the 4780 N·m mark.

3. The Locking Trap

Thread friction alone fails against high-frequency vibration. You must use a tab washer. Never reuse old, tired, or deformed washers.

4. The Fatigue Trap

A nut can look fine but hide micro-cracks. Every major overhaul should include a Magnetic Particle Inspection (MT). If it's been through two Class-A overhauls, replace it.

IV. Reassembly: The Final Checklist

When re-inserting the cartridge (maintaining its ~8mm axial float):

1. Clean & Lube threads with high-temp anti-seize.
2. Ensure the Oil Deflector (DG600-240-05-04) is perfectly seated.
3. Perform a manual barring test after torquing. If it binds, the clamping force is uneven.

Source: Dongfang SRI Technical Dept. Reference: HKCYT-2026-1-5