High Pressure Double Bolted Tri Clamp, 1.5" to 4", to 1433 PSI
ABOUT THIS PART
A double bolted high pressure tri clamp in 304 stainless, in 1.5 inch at $12.95, 2 inch at $22.95 and 4 inch at $36.95. Built to our specification with our own logo on the casting, and stocked in Bend, Oregon.
The 1.5 inch is certified at 1433 psi (99 bar) at 110 F (43 C). A single hinge wing nut clamp in the same size, in the same report, comes in at 444 psi (31 bar). Both figures are from one third party engineering report, 3P Certz ECR-250902-R0, which names our clamps by part number.
Pressure ratings by size
| Size | Certified at 110 F (43 C) | Published at 70 F (21 C) | Published at 250 F (121 C) | Max clamp torque | Replacement bolt set | Price |
|---|---|---|---|---|---|---|
| 1.5" | 1433 psi (99 bar) | 1500 psi (103 bar) | 1200 psi (83 bar) | 130 in-lbf | 2.25" | $12.95 |
| 2" | 956 psi (66 bar) | 1000 psi (69 bar) | 800 psi (55 bar) | 130 in-lbf | 2.75" | $22.95 |
| 4" | Not covered | 800 psi (55 bar) | 600 psi (41 bar) | 200 in-lbf | 3.25" | $36.95 |
The certified column comes from ECR-250902-R0. The published columns are the catalog table for this clamp line, which is a different kind of evidence, so the two are kept apart. The 4 inch is not in that report and we do not extrapolate a figure for it.
Construction
- 304 stainless body. Appendix A of the report describes it as a high pressure tri-clamp with 3/8-16 304SS bolts, stainless steel body with brass nuts, wetted material 304 SS.
- Two 3/8-16 bolts and two brass nuts per clamp. The two bolt design puts the load into threads instead of a hinge pin, which is what lets it hold pressure a hinged clamp cannot.
- The brass nut is the sacrificial part. It gives before the stainless bolt thread does, which is what protects the bolt.
- Standard tri-clamp connection, so it fits the ferrules and gaskets you already have.
- We do not claim 3-A or food grade certification on this clamp, and we are not going to imply one.
Torque, and the PTFE question
Your gasket sets the torque, not the clamp. 30 in-lbs for elastomeric gaskets, meaning Buna-N, Viton and silicone. 50 in-lbs for rigid gaskets, meaning PTFE and Tuf-Steel. The casting will take 130 in-lbs in the 1.5 and 2 inch and 200 in-lbs in the 4 inch, and you should never get near that. Over-tightening crushes the gasket and puts the load on the threads, which is how these fail.
PTFE gaskets are fine on these clamps, whatever you have read elsewhere. Our certification report lists PTFE and Tuf-Steel gaskets as approved components on the same systems as these clamps, and our operator's manual gives 50 in-lbs for rigid gaskets. Torque to that and it is a certified joint.
Replace the nuts every 6 months and the bolts every year, regardless of how they look. Tri clamp hardware fails from thermal cycling long before it shows wear, which is why the interval beats the inspection.
Replacement hardware, and what this is not
- A 1.5 inch clamp takes the 2.25 inch bolt set.
- A 2 inch clamp takes the 2.75 inch bolt set.
- A 4 inch clamp takes the 3.25 inch bolt set.
Measure the shaft of the bolt you are replacing, from the base of the head to the end of the thread, not including the head. All four lengths are stocked on our 3/8"-16 nut and bolt set page, along with brass nuts on their own.
This is not the 6 inch heavy duty clamp. That is a separate part on M12 x 1.75 hardware, and 3/8 inch hardware will not fit it.
Which gasket you run decides whether you pull 30 or 50 in-lbs: Choosing the Right Gasket Material for Tri-Clamp Connections. 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
How much pressure will it hold?
The 1.5 inch is certified at 1433 psi (99 bar) and the 2 inch at 956 psi (66 bar), both at 110 F (43 C), in third party engineering report 3P Certz ECR-250902-R0. The 4 inch is not in that report, and the published catalog rating for a 4 inch is 800 psi (55 bar) at 70 F (21 C).
How does that compare to a normal tri clamp?
The same report rates a 1.5 inch single hinge wing nut clamp at 444 psi (31 bar). This clamp holds more than three times that in the same size.
Why is there no certified figure for the 4 inch?
Because it is not in the report, and we will not extrapolate one. The 4 inch is our best selling size, and if a future certification report covers a system with a 4 inch clamp that number goes straight onto this page.
How tight should I torque it?
Your gasket decides. 30 in-lbs for elastomeric gaskets like Buna-N, Viton and silicone, 50 in-lbs for rigid gaskets like PTFE and Tuf-Steel. The clamp will take 130 in-lbs in the 1.5 and 2 inch and 200 in-lbs in the 4 inch, but going near that crushes the gasket and loads the threads.
Can I use a PTFE gasket on it?
Yes. Some sellers say not to. Our certification report lists PTFE and Tuf-Steel gaskets as approved components on the same systems as these clamps, and our operator's manual gives 50 in-lbs for rigid gaskets. Torque it to that and it is a certified joint.
Which replacement bolts do I need?
A 1.5 inch clamp takes the 2.25 inch set, a 2 inch clamp takes the 2.75 inch set, and a 4 inch clamp takes the 3.25 inch set. We stock all four lengths. To check, measure the shaft of the bolt you are replacing from the base of the head to the end of the thread, not including the head.
How often should I replace the hardware?
Nuts every 6 months, bolts every year, regardless of visible condition. The brass nut is the sacrificial part and it protects the bolt thread.
What is it made of?
304 stainless body, 3/8-16 304 stainless bolts, brass nuts, two of each per clamp. The certification report lists the wetted material as 304 SS.
Will it fit my 6 inch heavy duty clamp?
No, and this is a different product. The 6 inch heavy duty clamp is a heavier casting on M12 x 1.75 hardware with its own bolt kit. 3/8 inch hardware will not fit it.
Is it food grade?
No. It is a standard tri-clamp connection but it carries no 3-A or FDA certification, and we do not claim one.
Is there a 1 inch?
No. We stock 1.5 inch, 2 inch and 4 inch.
Why is the nut brass and not stainless?
Stainless threaded into stainless galls and seizes. Brass gives up first, which is the point, because the nut is cheap and the bolt thread is not.