6" Heavy Duty High Pressure Tri Clamp, 300 PSI, M12 Bolts, 304 SS
ABOUT THIS PART
A 6 inch heavy duty tri clamp in 304 stainless, rated 300 psi (20.7 bar) at 70 F (21 C), closing on M12 x 1.75 hardware rather than the 3/8 inch bolts used on lighter clamps. $78.00, deep stock in Bend, Oregon.
This is our own casting. We drew it and had it cast thicker and heavier than a standard high pressure clamp, because we could not buy a 6 inch clamp we were willing to put on a certified machine.
Specification
| Size | 6 in tri clamp ferrules only |
| Material | 304 stainless steel |
| Pressure | 300 psi (20.7 bar) at 70 F (21 C) |
| At temperature | 200 psi (13.8 bar) at 250 F (121 C) |
| Hardware thread | M12 x 1.75, metric, not 1/2"-13 |
| Wrench size | 3/4 in on the brass nut |
| Hardware per clamp | 2 complete sets, sold separately |
| Price | $78.00 |
N.B. Oler systems are designed to 250 psi (17.2 bar), so this clamp sits above the design pressure with margin at operating temperature. The lowest applicable limit in your assembly always governs, and on most 6 inch joints that is the gasket or a sight glass, not this clamp.
Cast markings
- 6 inch SSET
- CE marking
- CA167, on both sides of the clamp
- The N.B. Oler name
Those marks identify the casting and nothing more. The CE marking is a European conformity mark, which has no role in US or Canadian certification, so it is not something to hand an inspector as qualification.
Hardware, sold separately
- A complete set is one M12 x 1.75 x 4 in stainless bolt, one stainless split lock washer and one deep brass nut. Each clamp takes two sets.
- The nut and the washer are also sold on their own, because those are the parts that wear.
- Brass only. Stainless threaded into stainless galls and seizes, and the nut ends up cut off. We do not offer a stainless nut for this clamp.
- Standard 3/8 inch tri clamp hardware will not fit, and that is the most common ordering mistake on this part.
- These get called half inch bolt clamps, but M12 is 0.472 in and a 1/2"-13 bolt is 0.500 in. They do not interchange.
Torque and service
| Elastomeric gasket, Buna-N, Viton, EPDM, silicone | 30 in-lbs |
| Rigid gasket, PTFE or Tuf-Steel | 50 in-lbs |
| Replace the clamp | Every 6 months |
| Replace the brass nut | Every 6 months |
| Replace the bolt | Every 12 months |
| Stock per 20 LB system | 10 plus 2 spares |
The gasket sets the torque, not the clamp. Over-torquing strips threads, and stripped threads are the usual way one of these dies. Replace on the interval regardless of how the hardware looks, because tri clamp hardware fails from thermal cycling long before it shows wear.
Which gasket you run decides whether you pull 30 or 50 in-lbs: Choosing the Right Gasket Material for Tri-Clamp Connections.
It fits 6 inch tri clamp ferrules and nothing else. It will not close on a 4 inch or an 8 inch joint. We had these cast in quantity and hold deep stock, so if the page ever shows low, order anyway and it usually ships the same day from Bend, Oregon.
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
What pressure is this clamp rated for?
300 psi (20.7 bar) at 70 F (21 C), derating to 200 psi (13.8 bar) at 250 F (121 C). On an N.B. Oler system the design pressure is 250 psi (17.2 bar), so the clamp sits above it with margin at operating temperature.
What markings are on the casting?
6 inch SSET, the CE marking, and CA167 on both sides of the clamp, along with the N.B. Oler name. They identify the casting and nothing more. The CE marking is a European conformity mark and has no role in US or Canadian certification, so it is not qualification to hand an inspector.
What makes this different from a standard 6 inch high pressure clamp?
It is our own casting. We drew it and had it cast thicker and heavier than a standard high pressure clamp, and it closes on M12 hardware instead of 3/8 inch bolts, which is where the extra clamping force comes from.
Is the hardware included?
No. Bolts, washers and brass nuts are sold separately, and a clamp takes two complete sets.
Will standard 6 inch clamp hardware fit this?
No. This is a heavy casting clamp and it takes M12 x 1.75 hardware, not 3/8 inch bolts. Ordering standard hardware for these is the most common mistake on this part.
Is the thread M12 or 1/2 inch?
M12 x 1.75, which is metric. These are often called half inch bolt clamps and the hardware gets listed as 1/2 inch, but M12 is 0.472 inches and a 1/2"-13 bolt is 0.500 inches. They do not interchange.
What wrench do I need?
A 3/4 inch wrench for the brass nut.
What is in a complete hardware set?
One M12 x 1.75 x 4 inch stainless bolt, one stainless split lock washer and one deep brass nut. Sold separately, two sets per clamp. The nut and the washer are also sold on their own because those are the parts that wear.
Why is the nut brass?
Stainless threaded into stainless galls and seizes, and the nut ends up being cut off. Brass on a stainless bolt does not gall, so the joint can be broken and remade over and over. We do not offer a stainless nut for this clamp.
What do I torque it to?
The gasket sets the torque, not the clamp. 30 in-lbs on elastomeric gaskets, meaning Buna-N, Viton, EPDM and silicone. 50 in-lbs on rigid gaskets, meaning PTFE and Tuf-Steel. Do not over-torque, stripped threads are the usual failure.
How often should these be replaced?
The clamp every six months, the brass nut every six months, the bolt every twelve, regardless of how they look. Tri clamp hardware fails from repeated thermal cycling long before it shows wear.
How many should I keep on the shelf?
Ten plus two spares for a 20 LB system. A few days of downtime waiting on a clamp costs more than a full shelf of them.
Do you ever run out?
Rarely. We had these cast in quantity and hold deep stock in Bend. If the page shows low, order anyway and we will tell you what is actually on the shelf.
Will it fit a 4 inch or 8 inch joint?
No. It is a 6 inch tri clamp and fits 6 inch ferrules only.