High Pressure Tri-Clamp Nut & Bolt Set, 3/8"-16, 304 SS and Brass
ABOUT THIS PART
Replacement nut and bolt sets for bolted high pressure tri clamps. Each set is one 3/8"-16 304 stainless bolt, one brass nut and one stainless split washer, sold one at a time from $4.95. Four lengths cover every clamp size from 3/4 inch to 12 inch. Brass nuts on their own are $1.65.
Which length fits your clamp
| Bolt length | Fits these clamps | Price |
|---|---|---|
| 2" | 3/4" | $4.95 |
| 2.25" | 1.5" | $5.45 |
| 2.75" | 2", 2.5", 3" | $5.95 |
| 3.25" | 4", 6", 8", 10", 12" | $6.45 |
| Brass nut on its own | All of the above | $1.65 |
- Measure the shaft only, from the base of the head to the end of the thread, not including the head. That is how these are sized and it is where most wrong orders come from.
- Each clamp takes two sets.
- These are 3/8"-16. They do not fit our 6 inch heavy duty clamp, which closes on M12 x 1.75 hardware with a larger deep brass nut. Put a wrench on the nut before you order: 5/8 inch means 3/8 inch hardware, 3/4 inch means M12.
- They do not fit standard single hinge tri clamps, which are wing nut clamps and are not bolted at all.
Why the nut is brass
The bolt is 304 stainless and the nut is brass, deliberately. Stainless threaded into stainless galls, seizes and eventually has to be cut off. Brass running on a stainless bolt does not, which is what lets these joints be broken and remade hundreds of times over the life of a system.
The trade is that the brass is the part that gives. The nut wears out well before the bolt does, which is why it is stocked on its own at $1.65 and why we keep five hundred of them on the shelf.
Torque and service
| Elastomeric gasket, Buna-N, Viton, EPDM, silicone | 30 in-lbs |
| Rigid gasket, PTFE or Tuf-Steel | 50 in-lbs |
| Clamp casting maximum | 130 in-lbf to 3 in, 200 in-lbf from 4 in up |
| Replace the brass nut | Every 6 months |
| Replace the bolt | Every 12 months |
The gasket sets the torque, not the bolt, and the gasket figure is always the lower of the two, so it is always the one that governs. Torquing an elastomeric gasket to the casting maximum will extrude it and it will leak. Replace on the interval regardless of how the hardware looks, because a brass nut deforms internally before there is anything to see on the outside.
Which gasket you run decides which torque figure applies: Choosing the Right Gasket Material for Tri-Clamp Connections.
Ordering
Sets are sold individually so you can buy exactly what you need. The 3.25 inch is stocked deep and priced to clear. If a length shows sold out, call the shop at 541-330-6409 and we will get it on order. Ships from Bend, Oregon, usually the same day.
SPECIFICATIONS
▦ IN YOUR MANUAL
This part appears in the operator manual that ships with your system. The QR code there links to this page.
◈ REFERENCE FOR THIS PART
COMMON QUESTIONS
Which bolt length do I need?
Match the length to your clamp size. The 2 inch bolt fits a 3/4 inch clamp, 2.25 inch fits 1.5 inch, 2.75 inch fits 2, 2.5 and 3 inch, and 3.25 inch fits 4, 6, 8, 10 and 12 inch.
How do I measure the bolt length?
Measure the shaft only, from the base of the head to the end of the thread. Do not include the head. That is how these are sized and it is the most common source of a wrong order.
How many sets does one clamp take?
Two. A double bolted high pressure tri clamp has two bolts.
Why is the nut brass instead of stainless?
Stainless threaded into stainless galls and seizes, and a seized nut usually has to be cut off. Brass on a stainless bolt does not gall, so the joint can be broken and remade hundreds of times. The cost is that the brass nut wears before the bolt does, which is why nuts are stocked on their own.
What torque should I use?
The gasket decides, not the bolt. 30 in-lbs on elastomeric gaskets such as Buna-N, Viton, EPDM and silicone. 50 in-lbs on rigid gaskets such as PTFE and Tuf-Steel. The casting itself takes 130 in-lbf up to 3 inch and 200 in-lbf from 4 inch up, but the gasket figure is always lower and is the one that governs.
How often should these be replaced?
Brass nuts every six months, bolts every twelve months, regardless of condition. A brass nut deforms internally before anything shows on the outside.
Will these fit my 6 inch clamp?
Put a wrench on the nut. A 5/8 inch wrench on a 3/8 inch bolt means the 3.25 inch set is the one. Our own 6 inch heavy duty clamp closes on M12 x 1.75 hardware and a deep brass nut on a 3/4 inch wrench, and this set will not fit it.
Will these fit a regular tri clamp?
No. Standard single hinge tri clamps are wing nut clamps with no bolts. These are only for bolted high pressure clamps.
Can I buy just the nut?
Yes, the brass nut is sold on its own at $1.65, because it is the part that wears out first. Five hundred are on the shelf.
What is in a set?
One 3/8-16 304 stainless bolt, one brass nut, one stainless split washer.
What if my length is sold out?
Call the shop at 541-330-6409 and we will get it on order.