Calpeda 14012120000 Impeller Nut - M8 x 1 AISI 316
The Calpeda 14012120000 is the genuine impeller nut in AISI 316 stainless steel, an M8 x 1 fine pitch hexagon nut 5 mm high made to UNI 5589. It threads onto the end of the pump shaft and clamps the impeller back against its shoulder, and while the key handles the torque, this nut is what holds the impeller in position along the shaft and keeps it from walking forward under hydraulic thrust.
Three details in that description are doing real work. The fine 1 mm pitch gives more thread engagement in a short nut and resists loosening under vibration better than a coarse thread would. The 5 mm height is a thin-nut dimension chosen because there is only so much shaft protruding past the impeller - a standard-height nut will not fit, and a nut that bottoms out before it clamps is worse than useless. And 316 stainless is there because this fastener is permanently submerged in whatever the pump moves, in a spot where a rusted nut cannot be reached without stripping the wet end.
That last point is the practical one. A corroded impeller nut is one of the classic ways a straightforward impeller change turns into a much longer job: the hexagon rounds off, the nut welds itself to the shaft thread, and the shaft end gets damaged in the recovery. Fit a fresh one rather than reusing an old nut whose flats are already rounded. Assemble with clean, dry threads or a stainless-safe anti-seize, tighten firmly without heroics, and check that the impeller runs true and does not rock before closing the casing.
Key Features
- Genuine Calpeda spare part
- AISI 316 stainless steel for permanently wetted service
- M8 x 1 fine pitch thread for better engagement and vibration resistance
- 5 mm nut height to UNI 5589, sized for the short shaft protrusion
- Clamps the impeller against its shoulder and resists hydraulic thrust
- Stays removable, so the next impeller change does not become a shaft repair
Applications
- Calpeda centrifugal pumps using an M8 x 1 impeller nut
- Impeller replacement and full wet-end overhaul
- Replacing a nut with rounded flats or corrosion damage
- Seawater, brackish water and aggressive liquid duties
- Workshop spares stock and service kits
- Marine, dockside, industrial and agricultural pump service
Specifications
- Brand: Calpeda
- Manufacturer: Calpeda Spa
- Manufacturer Part Number: 14012120000
- Part Type: Impeller nut, hexagon
- Thread: M8 x 1 (fine pitch)
- Nut Height: 5 mm
- Standard: UNI 5589
- Material: AISI 316 stainless steel
- Quantity Used: One per impeller
- Condition: New
Frequently Asked Questions
Q: Can I use a standard M8 nut from the workshop drawer?
Almost certainly not. A standard M8 nut is coarse pitch and will not even start on a fine 1 mm thread, and a standard-height nut is too tall for the shaft protrusion. The thread pitch alone rules out most substitutes.
Q: Which way does the thread go?
Check before you apply force. Some pumps use a left-hand thread at the impeller so that running torque tends to tighten rather than loosen the nut, and applying real effort in the wrong direction is how shaft ends get damaged.
Q: Should I use a thread locking compound on it?
Only if your pump documentation calls for one. Many impeller assemblies rely on the clamping load alone, and adding locking compound to a small stainless fastener mainly makes it harder to remove later without gaining much security.
Q: How tight is tight enough?
Firm and steady, using a correctly sized spanner rather than an adjustable one. The nut has to hold the impeller against its shoulder, not stretch itself, and a short stainless fastener of this size is easy to over-torque and strip.
Not sure this is the right part? Send us a Picture of the pump plate on your pump and the CLR Marine team will confirm the correct impeller nut before you order.
CLRMarine
