Yamada 631331 Flat Washer for NDP-50 and NDP-80
The Yamada 631331 is the genuine replacement flat washer specified for NDP-50 and NDP-80 Series pumps. It is the correct grade and length for the joint it belongs to.
Fasteners in a pump like this are replaced for three reasons: corrosion has taken the head or the thread, the thread has been stretched by overtightening, or one has simply gone missing during a previous strip down. Any of them leaves the joint clamping unevenly, and an uneven clamp around a diaphragm bead or a manifold face is what turns a sealed joint into a weeping one.
Key Features
- Genuine Yamada replacement flat washer
- Fits NDP-50 and NDP-80 Series pumps
- 28 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-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: 631331
- Part Type: Flat Washer
- Fits: NDP-50 and NDP-80 Series pumps
- Quantity Used: 28 per pump
- Series Port Size: 2 in on the NDP-50 Series
- Condition: New
Frequently Asked Questions
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.
Q: What torque should I use?
The factory figure for that joint, applied in sequence across the joint rather than around it. Even clamping is what keeps the sealed faces sealed.
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 washer.
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