Most purchase orders for a 2 inch hose clamp go wrong on the same line. The description says “2 in hose clamp, stainless” and nothing else. The supplier picks a range, the cartons arrive, and half the clamps either bottom out before they seal or won’t open wide enough to get over the hose bead. Then someone raises a second PO.
This guide is for the person who writes that line: the maintenance buyer, the fleet parts manager, the plant storeroom lead who orders clamps by the hundred. We’ll go through a clamp spec sheet one field at a time, compare the clamp types that all claim to fit 2 inches, explain why a 2-inch hose almost never measures 2 inches on the outside, and finish with an RFQ template and a receiving checklist. Part numbers refer to the OneTouch Exim (OTE) catalogue, which lists 347 clamp sizes in six families and cross-references more than 3,000 OEM and interchange numbers.
One rule runs through everything below. A clamp is sized to the outside diameter of the hose as it sits on the fitting, and the right range puts that number near the middle of the clamp’s travel, not at either end of it.
Read a 2 inch hose clamp spec line by line
A clamp listing looks like a short block of numbers. Each field answers a practical question the technician will face at install time, and each one is worth copying into your PO rather than leaving to the supplier’s judgement. Here is what each field means and what to check.
Clamping range (minimum and maximum diameter)
The range is written as two numbers, for example 1.56–2.50 in. The smaller figure is the clamp’s diameter with the screw run fully in. The larger figure is the widest it opens while the band is still held in the housing. Neither number is a target size. They are the limits.
On a standard worm gear clamp the travel between those limits is a little under an inch. In the OTE perforated worm gear line, each step up in size moves the range by about a quarter of an inch, so neighbouring sizes overlap heavily. That overlap is useful to a buyer: for almost any hose OD there is a size that puts it comfortably mid-range.
Why the middle? Near the minimum end, the screw has very little thread left to take up hose compression or a later retightening. Near the maximum end, only a few band slots are engaged in the housing, the tail is short, and the band can twist or ride up as it’s tightened. A mid-range fit leaves margin in both directions.
If you are comparing against a 50mm hose clamp listed only in metric, convert first. One inch is 25.4 mm, so 1.56–2.50 in works out to roughly 40–64 mm, and a true 50 mm OD sits close to the middle of it.
Band width
OTE standard worm gear clamps use a 1/2 in (about 12.7 mm) band. Width does two jobs: it spreads clamping load over more hose, and it decides how much straight fitting you need. Before ordering, check that the hose end, the fitting and any bead leave room for the full band width behind the bead.
On short stubs, such as some water pump necks or turbo outlets, a wide band can end up half on the bead and half off it. That clamp will never seal evenly no matter how hard it’s tightened. Heavy-duty constant torque clamps, hi-torque clamps and T-bolts generally use a wider, heavier band, so read the listing for the exact part rather than assuming.
Band material: 301 stainless or something else
The band on OTE’s standard worm gear clamps is 301 stainless steel. It’s an austenitic grade that gains strength when cold worked, which is why it shows up in springs and clamp bands: it keeps its spring after forming and resists general under-hood and plant corrosion well.
If a competing quote says only “stainless,” ask which grade. 304 and 316 bands are common across the industry, and 316 adds molybdenum for better resistance to chlorides, which matters on marine equipment and trucks that see heavy road salt. Our comparison of 304 and 316 stainless steel covers the chemistry in detail.
The bigger risk is a band made from a 400-series ferritic grade sold simply as “stainless.” These grades are cheaper, strongly magnetic and generally less corrosion resistant than the 300 series. The article on 300 vs 400 series stainless explains why. One caution for receiving inspection: cold-worked 301 can pick up slight magnetism, so a faint pull from a magnet is not proof of a 400-series band. A strong, snapping pull is the warning sign.
Screw and housing material
This is the field buyers skip most often. OTE’s standard 4SC worm clamps pair the 301 stainless band with a zinc-plated carbon steel screw. That combination is normal for truck and industrial clamps: the carbon steel screw is strong, and the plating handles ordinary service.
Where the screw will sit in splash, salt spray, washdown or a damp pump room, a 2 inch stainless hose clamp needs a stainless screw too. That is the all-stainless 4SS series, with the same ranges and the same size numbering as the 4SC series. The 1.56–2.50 in all-stainless version is OTE-4SS0032. On a mixed-material clamp, the first rust almost always appears at the screw head, so if your old clamps show orange at the housing and clean bands, this is the line on the PO to change.
Hex size
OTE worm gear clamps use a 5/16 in hex head, the usual size for this clamp class. A technician with one 5/16 nut driver should be able to service every worm clamp on the vehicle. If a substitute clamp arrives with a 7 mm or 8 mm head, it still works, but it’s a tool change on every job and an invitation to round off heads with the wrong socket. If your shops standardise on a driver, write the hex size on the PO.
Torque rating
OneTouch Exim lists a 45 in-lbs torque rating (about 5.1 N·m) for its standard worm gear clamps. Treat that as the most the clamp is rated to take, not as the number every hose needs. Soft silicone or thin-wall hose may seal at less and can be cut or extruded if you go all the way. Where the hose or equipment maker publishes an installation torque, use it.
Two practical points for buyers. First, don’t copy 45 in-lbs across to constant torque, hi-torque or T-bolt clamps; their ratings differ, so check each listing. Second, if your shops use impact drivers on worm clamps, no torque rating on a spec sheet will protect the hose.
SAE number
The SAE number is a size code, not a quality grade. On OTE worm gear part numbers the SAE size is the last digits, so OTE-4SC0032 is SAE 32 and OTE-4SC0028 is SAE 28. SAE J1508 is the hose clamp specification that much of the industry references for sizes and performance types.
When a mechanic asks for an SAE 32 hose clamp, in this catalogue that is the 1.56–2.50 in range. Brands that use the same SAE number land on close but not always identical ranges, so the safe habit is to write the inch range next to the number every time. “SAE 32” alone on a PO is half a specification.
Liner
A liner is a smooth strip under the perforated band that bridges the slots. Without it, the slot edges press into soft hose, and as the screw is tightened the band can pinch or push rubber and silicone up through the perforations. On silicone coolant or charge-air hose, a liner is worth specifying every time.
OTE offers lined versions within the worm gear family (for example OTE-4SCH032, 1.56–2.50 in) and a separate range of lined hose clamps such as OTE-4CL0032, with all-stainless options. If the spec line has no liner field, assume there isn’t one.
Spring element
Some clamps add a spring. Constant torque clamps use a stack of Belleville washers on the screw. Spring-loaded T-bolts use a coil spring on the bolt. The purpose is the same: rubber and silicone slowly relax under clamp load, a behaviour known as creep or cold flow, and hoses shrink when the engine cools overnight. A rigid clamp loses grip as that happens. A sprung clamp keeps pushing, which is why constant torque clamps are the standard fix for coolant that seeps on a cold start and stops once the engine warms.
Four clamp types that all “fit” 2 inches, and how they differ
Ask a catalogue for the right 2″ hose clamp size and you’ll get several answers, because more than one 2 inch hose clamp design covers that diameter. Every row in the table below includes 2.00 inches somewhere in its range. What separates them is where 2.00 falls within the clamp’s travel and what the clamp is built to handle.
To read the position columns: 0% means the clamp is fully closed (its minimum diameter) and 100% means fully open (its maximum). Somewhere between about 30% and 70% is the comfortable zone. We’ve added a second position column for a 2.30 in OD, because that is a realistic figure for a hose sold as 2-inch, as the next section explains.
| OTE part | Type | Range (in / approx. mm) | Position at 2.00 in OD | Position at 2.30 in OD | Best use |
|---|---|---|---|---|---|
| OTE-4SC0028 | Worm gear, SAE 28 | 1.31–2.25 / 33–57 | 73% | Out of range | Hoses measuring under about 1.95 in OD; tight on a true 2.00 |
| OTE-4SC0032 | Worm gear, SAE 32 | 1.56–2.50 / 40–64 | 47% | 79% | General-purpose pick for a measured OD near 2.00 |
| OTE-4CT0028 | Constant torque | 1.31–2.25 / 33–57 | 73% | Out of range | Coolant hose with cold-start seep, OD below 2.00 |
| OTE-4CT200L | HD constant torque | 1.25–2.13 / 32–54 | 85% | Out of range | Heavy-duty coolant joints around 1.6–1.8 in OD |
| OTE-4TB0188 | T-bolt | 1.88–2.19 / 48–56 | 39% | Out of range | Large-bore coolant or air hose with an OD of 1.95–2.10 |
| OTE-4TB0200 | T-bolt | 2.00–2.31 / 51–59 | 0% (fully closed) | 97% | Only for ODs of about 2.10–2.25 |
| OTE-4ST200B | Spring-loaded T-bolt | 2.00–2.31 / 51–59 | 0% (fully closed) | 97% | Charge-air and boost hose with an OD of about 2.10–2.25 |
Worm gear: SAE 28 or SAE 32
Both sizes “cover” 2 inches, but SAE 28 puts a 2.00 in OD at nearly three-quarters of its travel, with little left before it runs out. SAE 32 puts the same hose almost dead centre. If someone in your shop has been buying SAE 28 for 2-inch work and complaining that clamps are hard to start over the bead, this is the reason. For a measured OD between about 1.95 and 2.15 in, OTE-4SC0032 is the default. If the screw needs to be stainless, order the same range as OTE-4SS0032.
Constant torque: match the range before the feature
Buyers often reach for a constant torque clamp because it fixes cold seep, then pick whichever range mentions 2 inches. OTE-4CT0028 and the heavy-duty OTE-4CT200L both include 2.00, but both put it high in their travel. For a 2.00 in OD, the 1.56–2.50 in constant torque size (OTE-4CT0032) lands at the same 47% as the worm gear SAE 32, and the heavy-duty 1.75–2.63 in size (OTE-4CT250L) lands near 28%. The Belleville stack also needs a little travel to work, so a clamp near the top of its range is a poor home for one.
T-bolt and spring T-bolt: narrow ranges, no guessing
A 2 inch T-bolt clamp has a solid band and a bolt that pulls it evenly around the full circumference. The grip is better than a worm clamp’s, especially under pressure and vibration, but the range is only about 0.31 in. That’s why ordering a T-bolt “for a 2-inch hose” is risky. OTE-4TB0200 is labelled 2.00–2.31 in, yet a hose that truly measured 2.00 OD would have it fully closed with nothing left to tighten. OTE-4TB0188 suits that hose far better.
The spring-loaded OTE-4ST200B has the same 2.00–2.31 in range plus a coil spring to follow the hose as it relaxes. It’s the clamp of choice for turbocharger charge-air hoses running through the intercooler circuit, where heat cycling and boost pressure loosen rigid clamps. With T-bolts of either kind, measure the OD on the fitting and buy to that number. There is no slack for an estimate.
Why a 2-inch hose almost never measures 2 inches outside
Hose is named by its inside diameter, because that’s what has to match the fitting. The clamp sits on the outside, so it sees the ID plus two wall thicknesses. A hose with a 2.00 in ID and a 0.20 in wall has a 2.40 in OD before it’s even fitted. Pushed over a 2.00 in tube, the hose stretches slightly and the OD grows a little more.
Wall thickness varies widely by construction. A single-ply rubber hose, a multi-ply reinforced silicone hose and a wire-reinforced suction hose can all be sold as 2-inch and still differ in OD by a quarter of an inch or more. As simple arithmetic, a wall anywhere from 1/8 in to 5/16 in gives an OD between 2.25 and about 2.63 in. That’s why the correct 2 inch hose clamp for a hose sold as 2-inch is very often an SAE 36 or a 2.13–2.44 in T-bolt, not an SAE 32.
“2 inch” is also ambiguous when the clamp sits on pipe. A 2-inch nominal pipe size has an outside diameter of 2.375 in, not 2.00. Charge-air and coolant tubes on trucks, by contrast, are usually specified by their actual OD. Make sure you know which kind of “2 inch” is on the drawing.
How to measure the OD before you order
- Measure on the fitting, where the clamp will actually sit, not on a loose length of hose from the shelf.
- Use calipers and take two readings at 90 degrees to each other. Use the larger one; hoses go oval.
- No calipers? Wrap a strip of paper around the hose, mark the overlap, lay it flat and measure. Divide that length by 3.1416. A wrap of 7.38 in gives an OD of about 2.35 in.
- Write the result on the PO with two decimals and the unit. “2.35 in OD on fitting” removes most of the guesswork from a quote.
Once you have the number, the table below maps it to a part. If your OD comes in under about 1.85 in, you’re really in 1.5-inch territory; our 1.5 inch hose clamp size guide picks up from there. If it’s above about 2.60 in, the 3 inch hose clamp guide covers the next band of sizes.
| Measured OD on fitting | Approx. mm | Worm gear first choice (position in travel) | T-bolt option |
|---|---|---|---|
| 1.85–1.95 in | 47–50 | OTE-4SC0028, SAE 28 (57–68%) | OTE-4TB0175 (1.75–2.00 in) |
| 1.95–2.10 in | 50–53 | OTE-4SC0032, SAE 32 (41–57%) | OTE-4TB0188 (1.88–2.19 in) |
| 2.10–2.25 in | 53–57 | OTE-4SC0032 (57–73%) or OTE-4SC0036 (31–47%) | OTE-4TB0200 or spring OTE-4ST200B (2.00–2.31 in) |
| 2.25–2.40 in | 57–61 | OTE-4SC0036, SAE 36 (47–63%) | OTE-4TB0213 (2.13–2.44 in) |
| 2.40–2.60 in | 61–66 | OTE-4SC0040, SAE 40 (36–57%) | OTE-4TB0225 (2.25–2.56 in) for ODs up to about 2.50 |
Writing the RFQ: what to send so the quote comes back right
A good request for quote answers the supplier’s questions before they’re asked. Every missing item becomes an email round trip or, worse, an assumption. For 2-inch clamps, these are the details that change the answer:
- Measured OD on the fitting, with two decimals and how you measured it. If you have several hose brands on the same joint across the fleet, give the smallest and largest readings.
- Media: coolant, charge air, fuel, oil, water, suction, washdown chemicals. It points to the hose material and whether a liner or all-stainless clamp makes sense.
- Operating temperature, including how cold the joint gets at rest. Big swings are the case for a spring element.
- Pressure in psi or bar, and whether it pulses (boost) or is steady. High or pulsing pressure moves you toward a T-bolt.
- Environment: road salt, marine, washdown, outdoor storage. This decides between a plated screw and an all-stainless clamp.
- Quantity and packing: single units for a trial, or full export cartons for stock.
- Existing part number: the OEM or competitor number on the clamp you’re replacing. OneTouch Exim’s clamp cross-reference database covers more than 3,000 interchange numbers, so this is often the fastest route to the right range. Manufacturer names and numbers are used for reference and interchange only.
- Destination and need-by date: city, country and delivery address or port, so freight can be quoted with the parts.
Sample RFQ line list
Here is how a fleet buyer might lay out a 2-inch clamp request. The values are examples; replace them with your own measurements.
- OTE-4SC0032 worm gear hose clamp, 1.56–2.50 in (40–64 mm), SAE 32, 301 SS band, 1/2 in band width, 5/16 in hex. Application: radiator lower hose, rubber, measured OD 2.05 in on fitting. Qty 500, export cartons.
- OTE-4SS0036 all-stainless worm gear clamp, 1.81–2.75 in (46–70 mm), SAE 36. Application: washdown water line, measured OD 2.32 in. Qty 200.
- OTE-4ST200B spring-loaded T-bolt clamp, 2.00–2.31 in (51–59 mm). Application: charge-air hose, silicone, measured OD 2.18 in, pulsing boost. Qty 100.
- OTE-4CT0032 constant torque clamp, 1.56–2.50 in. Application: heater and bypass hose with cold-start seep, measured OD 2.00 in. Qty 150.
- Cross-reference request: OEM clamp number [your number], fitted on [engine or equipment model]. Please confirm the OTE equivalent and its range. Qty 300.
- Ship to: [city, country]. Need-by date: [date]. Packing: cartons labelled with OTE part number and quantity.
Notice what isn’t on that list: “or equivalent” with no range attached. If you’ll accept substitutes, say what has to match: range, band material, screw material, hex size, liner or spring. Anything you don’t write down is something the supplier is free to change. You can send the list through the OneTouch Exim quote request form, or by WhatsApp or phone on +91-7838759114.
Receiving inspection: checks before clamps go on the shelf
A ten-minute check on every 2 inch hose clamp delivery saves a roadside failure later. You don’t need a lab. Pull a few clamps from each carton and work through these points, then record what you found against the PO line.
Dimensions
Run the screw fully in and measure the inside diameter with calipers. Then open it to the point where the band is still captured and measure again. Both readings should match the stated range within whatever tolerance you agreed on the PO. If you didn’t agree one, this is the shipment that teaches you to.
Band edges
Run a fingertip (carefully) or a cotton swab along both edges of the band. Burrs and sharp shear edges cut into hose as the clamp tightens and as the joint vibrates. Edges should be smooth or rolled. Look at the perforations too: they should be clean, evenly spaced and free of torn metal.
Screw engagement
Drive the screw from fully open to fully closed with a nut driver. It should feed smoothly with no skipping, ratcheting or binding. Then fit one clamp on a scrap of the real hose over a tube or mandrel and tighten it with a torque-limiting driver up to the listed rating. The screw should not jump slots, the housing shouldn’t spread, and the band shouldn’t twist.
Material and components
For lines ordered as all-stainless, confirm the screw is stainless too and not plated carbon steel; a quick magnet check on the screw helps here. On lined clamps, the liner should cover the slots fully across the clamping zone. On constant torque clamps, look at the Belleville washer stack for presence and consistent orientation. On spring T-bolts, the spring should be seated and intact.
Marking, labelling and count
Check that carton labels show the part number and quantity you ordered, and that cartons for different ranges aren’t mixed. Where clamps carry a band marking, it should match the label. Count one carton fully. If anything fails, quarantine the lot, photograph the issue next to the label and send it to the supplier with the PO line number.
For buyers who manage clamps for several hose sizes, the same spec-and-inspect routine works across the range. Our 1 inch hose clamp sizing guide applies it to smaller coolant and fuel lines.
2-inch clamp buying FAQ
Which hose clamp for 2 inch hose should I order?
It depends on the hose’s outside diameter, not its 2-inch inside diameter. Measure the OD on the fitting. If it reads 1.95 to 2.15 in, a 1.56–2.50 in worm clamp (SAE 32) sits mid-range. Many 2-inch hoses measure 2.25 to 2.60 in OD because of wall thickness, which calls for SAE 36 or SAE 40, or a T-bolt matched to the exact OD.
Is a 50mm hose clamp the same as a 2 inch hose clamp?
Not exactly. 50 mm is about 1.97 in, and either label only tells you one diameter. What matters is the clamp’s full range in the same unit as your measured hose OD. A 1.56–2.50 in clamp covers roughly 40 to 64 mm, so a 50 mm OD sits near its middle. Convert at 25.4 mm per inch before comparing metric and inch listings.
What range is an SAE 32 hose clamp?
In the OneTouch Exim catalogue, SAE 32 is the 1.56–2.50 in range (about 40–64 mm), sold as OTE-4SC0032 with a plated screw or OTE-4SS0032 in all-stainless. The SAE number is a size code, and other brands’ SAE 32 ranges can differ slightly. Always write the inch range on the purchase order next to the SAE number.
Do I need a 2 inch stainless hose clamp with a stainless screw?
Only where the screw will see corrosion. Standard OTE worm clamps use a 301 stainless band with a zinc-plated carbon steel screw, which suits normal engine-bay and plant service. For road salt, marine use, washdown or damp outdoor equipment, order the all-stainless 4SS series. It uses the same ranges and SAE numbers, so switching doesn’t change your sizing.
When is a 2 inch T-bolt clamp worth the extra cost?
Choose a T-bolt where pressure, vibration or heat cycling defeat worm clamps: turbo charge-air hoses, large coolant connections on heavy equipment and pressurised air lines. The solid band grips evenly all the way round. The trade-off is a narrow range of about 0.31 in, so you must measure the OD accurately. For boost hoses, a spring-loaded T-bolt also follows hose relaxation.
Can I stock one clamp size for every 2-inch hose in the fleet?
Usually not safely. Hoses from different makers and constructions vary in OD, so one range can be mid-travel on one truck and nearly bottomed out on another. A practical approach is to measure each joint type once, then stock two worm gear ranges, typically SAE 32 and SAE 36, plus any T-bolt sizes your charge-air hoses need.
Get a quote on the right 2-inch range
Send OneTouch Exim your measured ODs, the application and quantities, or simply the OEM numbers on the clamps you’re replacing. We’ll match each line to a 2 inch hose clamp range that sits where it should, confirm band and screw materials, and quote single units or export cartons with freight to your destination. Prefer to talk it through? WhatsApp or call +91-7838759114.