Yamada 683812 Flat Socket Bolt for NDP-40 to NDP-80
The Yamada 683812 is a factory flat socket bolt used in NDP-40, NDP-50 and NDP-80 Series pumps. Fasteners in an air operated double diaphragm pump work for their living - the whole assembly is held together by clamping load, and that load has to stay even as the pump cycles.
Tighten in sequence to the factory figure, working across the joint rather than around it. That is what keeps the clamping load even, and it matters far more on a joint sealed by an elastomer bead than on a plain metal to metal face.
Key Features
- Genuine Yamada replacement flat socket bolt
- Fits NDP-40, NDP-50 and NDP-80 Series pumps
- 12 per pump in the assembly that uses it
- Correct grade, length and thread for the joint
- Keeps clamping load even around elastomer sealed faces
- Direct replacement for corroded, stretched or missing hardware
Applications
- NDP-40, NDP-50 and NDP-80 Series pumps
- Pump rebuilds and scheduled overhauls
- Replacing corroded or seized hardware
- Making up a complete set after a strip down
- Marine installations where corrosion takes fasteners first
- Industrial and transfer pump service
Specifications
- Brand: Yamada
- Manufacturer: Yamada America
- Manufacturer Part Number: 683812
- Part Type: Flat Socket Bolt
- Fits: NDP-40, NDP-50 and NDP-80 Series pumps
- Quantity Used: 12 per pump
- Series Port Size: 2 in on the NDP-50 Series
- Condition: New
Frequently Asked Questions
Q: Should I use thread lubricant?
An anti seize compound on the threads is normal practice on this kind of assembly, particularly in marine service where it is what allows the joint to be opened again.
Q: What happens if one is left loose?
The clamping load is uneven, the joint weeps at that point, and the remaining fasteners carry more cyclic load than they were meant to.
Q: Can I use a standard bolt from a hardware store?
It is not advisable. Grade, length and thread are chosen for the joint, and a substitute that stretches or bottoms out changes the clamping load on a face that is sealed by an elastomer bead.
Q: Why did the original corrode so badly?
Salt air and washdown get into the threads and stay there. On marine installations the fasteners are usually the first part of the pump to need attention, well before anything internal.
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 flat socket bolt.
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