Nut & Ferrule Sets, 316 Stainless, 1/4" to 3/4", Swagelok Compatible
ABOUT THIS PART
316 stainless nut and ferrule sets for two ferrule compression tube fittings, in 1/4, 3/8, 1/2, 5/8 and 3/4 in. A set is one nut, one front ferrule and one back ferrule, from $7.95. Nuts and ferrule sets also sold on their own, from $3.95, because they do not wear out at the same rate. These are Superlok, and they interchange with Swagelok.
You need one set per end. A valve or a union with two tube connections takes two sets. That is the part people forget when they order a valve, and it is why a parts order arrives and cannot be installed the same day.
Prices
| Tube OD | Nut and ferrule set | Nut only | Ferrule set only |
|---|---|---|---|
| 1/4 in | $7.95 | $4.25 | $3.95 |
| 3/8 in | $12.95 | $6.25 | $6.95 |
| 1/2 in | $22.45 | $11.95 | $10.95 |
| 5/8 in | $24.55 | $13.55 | $11.55 |
| 3/4 in | $32.65 | $18.45 | $14.95 |
- Complete set is one nut, one front ferrule, one back ferrule, and it is the cheapest route in every size
- Nut only, for a galled or cross threaded nut where the ferrules already swaged on the tube are still good
- Ferrule set only, front and back, for remaking a joint onto fresh tube when the nut is fine
- Order by tube outside diameter. Wall thickness does not change the ferrule, it changes the pressure rating of the tube
Swagelok compatibility, plainly
| Question | Answer |
|---|---|
| Will these fit a Swagelok body? | Yes. Superlok is built to the same dimensional specification and sold by its manufacturer as a drop in replacement: thread form to ASME B1.1 Unified Inch, tube engagement and ferrule compression geometry, sealing surface finish, mechanical tolerances and 316 stainless grade |
| Do you run them that way? | Yes, on Swagelok bodies on our own builds, and have for years |
| What does Swagelok say? | Swagelok does not endorse mixing and will not warrant an assembly containing another manufacturer's parts. That is a warranty position, not a dimensional one |
| The rule that matters | Use a complete set from one brand on any given joint. Never pair one brand's front ferrule with another brand's back ferrule. The two ferrules are engineered as a pair, and that pairing is where small differences between manufacturers land |
Making the joint up
- Slide on the nut, then the back ferrule, then the front ferrule. Both ferrules taper toward the fitting body. A reversed back ferrule will not seal and is the most common field mistake on two ferrule fittings
- Bottom the tube in the fitting and finger tighten the nut
- Turn it one and a quarter turns past finger tight, for 1/4 in through 1 in. Same on both brands. Mark the nut first so you can see the turn
- Once made up, the ferrules are swaged onto that tube and stay there. The same joint breaks and remakes many times, snug plus a little each time. Used ferrules do not move to new tube
What these are not
- No pressure rating of their own. A two ferrule joint is rated by the tube and the fitting body. If you are filling a permit file, that number comes off the tube wall and the body, not off this page
- Not NPT and not tri clamp. They do not thread into a pipe port
- For rigid 316 stainless tube, not plastic tube or air line
- They do not include the fitting body, union, elbow, tee or valve
- Parts that need these and do not ship with them: the 1/2 in needle valve, the quick connect stems and bodies, the Superlok ball valves, the Superlok adjustable relief valves, the 3/8 in tube stub on the compound gauge and every tube stub version of the push-on hose adapters
Shipping from Bend, Oregon. These stay buyable whether or not the shelf count is exact, because our distributor restocks in a couple of days. Email info@nboler.com if you need a quantity confirmed before you order.
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 is in a set?
One nut, one front ferrule and one back ferrule, all 316 stainless. That is everything you need on one end of a tube fitting joint.
How many do I need?
One set per end. A valve or a union with two tube connections takes two sets. This is the part people forget when they order a valve, and then the order shows up and cannot be installed.
Can I buy just the nut?
Yes. $4.25 for 1/4 in, $6.25 for 3/8 in, $11.95 for 1/2 in, $13.55 for 5/8 in, $18.45 for 3/4 in. Buy the nut on its own when you have galled or cross threaded one and the ferrules already on the tube are still good.
Can I buy just the ferrules?
Yes. The front and back ferrule pair is $3.95 for 1/4 in, $6.95 for 3/8 in, $10.95 for 1/2 in, $11.55 for 5/8 in, $14.95 for 3/4 in. Buy ferrules on their own when you are re making a joint onto fresh tube and the nut is fine.
Is the complete set cheaper than buying the pieces separately?
Yes, in every size.
Do you stock 5/8 in?
Yes. The 5/8 in complete set is $24.55, the nut on its own is $13.55 and the ferrule set is $11.55. Six of each on the shelf, and they restock in a couple of days like the rest.
Will these work on Swagelok fittings?
Yes. These are Superlok, which is built to the same dimensional specification as Swagelok and sold by its manufacturer as a drop in replacement, matched on thread form to ASME B1.1, on ferrule compression geometry, on sealing surface finish and on 316 stainless material grade. We run them on Swagelok bodies on our own builds. Swagelok does not endorse mixing and will not warrant an assembly containing another manufacturer's parts, which is a warranty position rather than a dimensional one, and worth knowing before you decide.
Can I mix a Swagelok ferrule with a Superlok ferrule?
No. Use a complete set from one brand on a given joint. The front and back ferrules are engineered as a pair, and that pairing is where small differences between manufacturers show up.
Does tube wall thickness change which ferrule I need?
No. Order by tube outside diameter. A 1/2 in ferrule set fits 1/2 in tube whether the wall is 0.035 or 0.065, because the ferrule grips the outside. Wall thickness changes the pressure rating of the tube, not the ferrule.
What size do I order?
The outside diameter of your tube. 1/4 in tube takes the 1/4 in set. If you are matching a fitting instead of tube, the fitting size and the tube OD are the same number.
How do I make the joint up?
Slide on the nut, then the back ferrule, then the front ferrule, with both ferrules tapering toward the fitting body. Bottom the tube in the fitting, finger tighten, then turn one and a quarter turns past finger tight. Mark the nut first so you can see the turn.
Which way do the ferrules face?
Both taper toward the fitting body. A reversed back ferrule is the most common field mistake on two ferrule fittings and it will not seal.
Can I reuse ferrules?
On the same joint, yes. Once made up, the ferrules are swaged onto that tube and stay there, and that joint can be broken and re made many times, snug plus a little each time. Do not move used ferrules to a new piece of tube.
What pressure are these rated for?
They carry no rating of their own. A two ferrule compression joint is rated by the tube and the fitting body. If you need a number for a permit or a certification file, it comes off the tube wall and the body, not off the nut and ferrule.
Are these NPT?
No. They are compression tube fittings. They do not thread into a pipe port, and they are not tri-clamp.
What are they made of?
316 stainless steel, the nut and both ferrules.
Are they in stock?
They stay buyable, and our distributor restocks in a couple of days. Email info@nboler.com if you need a quantity confirmed before you order.