Most hose clamp mistakes are forgiving. A worm gear clamp that is a little too big still tightens, and one a little too small still goes on with some effort. A T-bolt hose clamp does not forgive anything. Its working range is a fraction of an inch, so you either order the right size or you end up with a clamp that bottoms out before it grips or will not close over the hose at all. That is why this guide starts from the catalogue. T-bolt and spring-loaded T-bolt clamps are the largest family in the OneTouch Exim clamp range, with 103 sizes, and the job here is to help you pick the right variant and the right part number on the first order.
Below: anatomy, the three OneTouch variants, measuring, a size table in inches and millimetres, applications beyond charge air, and installation. If your joint is on a turbo or intercooler, read this for sizing and variant choice, then use our guide to hose clamps for turbo and intercooler pipes for the boost-path detail, bead placement and V-band questions. We do not repeat that material here.
Anatomy of a T-bolt clamp
The solid band
The band is a plain strip of stainless steel with no slots punched in it. That single detail separates a T-bolt hose clamp from a worm gear clamp. A worm gear clamp needs perforations so the screw thread has something to engage. A T-bolt clamp is tightened by a bolt at one point, so the band can stay smooth all the way round. A smooth band presses the hose evenly and leaves nothing for soft rubber or silicone to squeeze into.
Band width and thickness vary by series and diameter. We are not going to quote a figure that applies to every part, because it does not. Check the band width on the product page for the exact OTE number you plan to order, and compare it with the space you have on the hose between the pipe bead and the hose end.
The trunnion and the T-bolt
One end of the band is formed into a loop that holds a trunnion, a short round cross-piece. The bolt passes through the trunnion. The other end of the band carries the bolt head, which is shaped like a T or sits in a formed loop, which is where the clamp gets its name. Tightening the nut draws the two band ends toward each other and shrinks the circle.
Because the trunnion can rotate slightly, the bolt stays in line with the band’s pull, so the clamp closes square instead of twisting on the hose.
The nut
T-bolt clamps use a real threaded bolt and nut, usually a locking nut so vibration does not back it off. You tighten it with a socket or a nut driver. It gives far more clamping force than a worm screw, which also makes it easy to over-tighten.
The bridge
When a T-bolt clamp is tightened, there is still a gap between the two band ends under the bolt. Without support, the hose could bulge into that gap and leak there. A bridge, a curved plate that sits under the band ends, spans the gap and keeps the hose surface supported right round the circle. This is the reason a T-bolt clamp gives close to a full 360° grip.
The spring-loaded variant
A spring-loaded T-bolt clamp adds a coil spring on the bolt, between the nut and the trunnion, usually with a cup or spacer to guide it. When you tighten the nut, the spring compresses and stores force. If the hose later shrinks, softens or slowly flows away from the band, the spring pushes the band closed and keeps the grip on. A plain T-bolt cannot do this. Once tightened, its diameter is fixed.
That slow flow of hose material under load is a form of creep, often called cold flow in the hose trade. It is the main reason a clamp that was tight at install feels loose a few months later.
Plain, spring-loaded or heavy-duty spring? Three variants compared
OneTouch lists three T-bolt variants. The part number prefix tells you which one you are looking at: OTE-4TB for the plain T-bolt, OTE-4ST…B for the spring-loaded T-bolt, and OTE-4ST…H for the heavy-duty spring-loaded T-bolt. The table compares them in practical terms.
| Variant | Plain T-bolt (OTE-4TB…) | Spring-loaded T-bolt (OTE-4ST…B) | HD spring-loaded T-bolt (OTE-4ST…H) |
|---|---|---|---|
| How it holds | Fixed diameter once the nut is tightened; solid band and bridge give an even grip | Same band and bridge, plus a coil spring that keeps pushing the band closed as the hose relaxes | Same spring principle in a heavier build for bigger, stiffer or harder-worked joints |
| Best for | Joints with steady temperature, rubber hose that holds its shape, ducts and pump hoses, places where a fixed grip is wanted | Silicone or rubber hoses that heat-cycle; charge air, intake and coolant joints on trucks and gensets | Large truck and off-road CAC hoses, high boost, heavy-wall reinforced silicone, joints with lots of engine movement |
| Range on the listed sizes | Mostly 0.31 in; smaller sizes 0.13–0.25 in | About 0.25–0.32 in | About 0.31–0.32 in |
| Size coverage listed here | 1.25 in to 8.81 in | 1.75 in to 7.81 in | 2.50 in to 8.63 in |
| Watch-outs | Loses grip if the hose cold-flows; no way to follow shrinkage between services | Needs spring travel left after tightening; tightening until the coils touch defeats the spring | Bulkier; check clearance to brackets, wiring and other hoses; fewer listed sizes, so some ODs fall between options |
| Typical choice | Default for fixed, stable joints | Default for heat-cycling hoses on medium pipes | Upgrade for the biggest and hardest-worked hoses |
The quick test: will the hose under the clamp change? If the joint sees large temperature swings, if the hose is silicone, or if you have had a hose loosen before, choose a spring-loaded T-bolt clamp. If the joint runs at a steady temperature and the hose is firm, a plain T-bolt is cheaper, more compact and does the job. Reach for the heavy-duty spring version when the hose is large and heavy-walled, the boost is high, or a standard spring clamp has already failed to hold.
If you are still weighing whether you need a T-bolt at all or whether a hi-torque or heavy-duty constant torque clamp would do, our guide on how to choose a heavy duty hose clamp sets out that decision across the whole heavy-duty range.
T-bolt ranges are narrow: size it precisely
Look at the OTE plain T-bolt hose clamp sizes and a pattern jumps out. From 1.88 in upward, every listed plain T-bolt covers 0.31 in, for example 3.00–3.31 in or 6.00–6.31 in. The three smallest sizes are narrower still: 1.25–1.44 in covers 0.19 in, 1.38–1.56 in covers 0.18 in, and 1.50–1.63 in covers just 0.13 in. The 1.63–1.88 in and 1.75–2.00 in sizes cover 0.25 in. The spring-loaded versions cover a similar 0.25–0.32 in.
A worm gear clamp typically covers the best part of an inch and can absorb a quarter-inch measuring error. A T-bolt clamp cannot.
Why the range is so short
The bolt has a fixed length and the bridge has a fixed span. The clamp can close only until the band ends meet the bridge limits, and it can open only as far as the bolt will still catch the nut. The design trades range for strength and even pressure, a good trade only when the hose OD is known.
How to measure for a T-bolt clamp
Measure the outside diameter of the hose as it sits on the pipe or fitting. Not the pipe size, not the hose ID printed on the box, not the OD of the hose lying loose on the bench. Pushing a hose over a pipe stretches it, and the installed OD is what the band has to close on.
- Fit the hose fully onto the pipe, past any bead, as it will be in service.
- Measure where the clamp will actually sit, not at the hose end, which can flare slightly.
- Use calipers across the hose at two positions 90° apart and average them. Hoses are rarely perfectly round on a pipe.
- On large hoses where calipers will not reach, use a pi tape (a diameter tape that reads OD directly), or wrap a thin paper strip once round the hose, mark the overlap, lay it flat, measure the length and divide by 3.1416.
- Write the result to two decimal places in inches, or to the nearest millimetre. Rounding to the nearest quarter inch is not good enough for a T-bolt clamp.
Wall thickness varies widely with hose construction, so two hoses for the same pipe can differ by a full T-bolt size on the outside. A pipe size is never enough information.
The mid-range rule
Pick the size that puts your measured OD in the middle half of its range. For a 0.31 in range, that means the OD should sit roughly 0.08 in or more inside each end. Two OTE sizes often overlap your number, because the plain T-bolt steps are about 0.13 in apart in many places. When they do, choose the one where you sit closer to the centre.
Example: you measure 3.18 in. OTE-4TB0288 (2.88–3.19 in) technically covers it, but you are at the very top. OTE-4TB0300 (3.00–3.31 in) puts you near the middle, and OTE-4TB0313 (3.13–3.44 in) would put you near its bottom. The 4TB0300 is the right pick.
What happens at the ends of the range
- At the minimum: the clamp closes until its parts meet and stops. If the hose is still not compressed enough, you cannot go further. On a spring-loaded T-bolt clamp, a clamp near its minimum also tends to run out of spring travel early, so it cannot follow shrinkage.
- At the maximum: the band barely reaches round the hose, little bolt thread engages the nut, and the bridge may not fully cover the gap between band ends. You get a weak spot right under the bolt.
- In the middle: full thread engagement, full bridge support, and room to re-tighten after the first heat cycles.
For converting a measurement between inches and millimetres and checking it against every clamp family at once, the hose clamp size chart in mm and inches is the hub for the whole series.
T-bolt size table: OTE plain sizes with spring and HD spring options
This T-bolt clamp size chart lists the OTE plain T-bolt sizes shown in our catalogue references, from 1.25 in to 8.81 in, with millimetre ranges rounded to the nearest whole millimetre. The last column names a spring-loaded or HD spring-loaded T-bolt listed at or near the same diameter, so you can see at a glance whether a spring version exists for your hose. Where a spring option only overlaps part of the plain range, the table says so.
| Plain T-bolt (OTE) | Range (in) | Range (mm) | Spring / HD spring option near this size |
|---|---|---|---|
| OTE-4TB0125 | 1.25–1.44 | 32–37 | None listed; plain only |
| OTE-4TB0138 | 1.38–1.56 | 35–40 | None listed; plain only |
| OTE-4TB0150 | 1.50–1.63 | 38–41 | None listed; plain only |
| OTE-4TB0163 | 1.63–1.88 | 41–48 | OTE-4ST175B (1.75–2.00) overlaps the top |
| OTE-4TB0175 | 1.75–2.00 | 44–51 | OTE-4ST175B spring (1.75–2.00), same range |
| OTE-4TB0188 | 1.88–2.19 | 48–56 | OTE-4ST175B (to 2.00) or OTE-4ST200B (from 2.00) |
| OTE-4TB0200 | 2.00–2.31 | 51–59 | OTE-4ST200B spring (2.00–2.31), same range |
| OTE-4TB0213 | 2.13–2.44 | 54–62 | OTE-4ST200B overlaps the lower part (to 2.31) |
| OTE-4TB0225 | 2.25–2.56 | 57–65 | None centred; OTE-4ST250B / 4ST250H start at 2.50 |
| Gap in plain sizes listed here: 2.56–2.75 in. Spring: OTE-4ST250B and HD OTE-4ST250H (2.50–2.81, 64–71 mm). | |||
| OTE-4TB0275 | 2.75–3.06 | 70–78 | OTE-4ST250B / 4ST250H overlap the bottom (to 2.81) |
| OTE-4TB0288 | 2.88–3.19 | 73–81 | HD OTE-4ST300H (from 3.00) or OTE-4ST306B (from 3.06) |
| OTE-4TB0300 | 3.00–3.31 | 76–84 | HD OTE-4ST300H (3.00–3.31), same range; OTE-4ST306B (3.06–3.38) |
| OTE-4TB0313 | 3.13–3.44 | 80–87 | OTE-4ST306B spring (3.06–3.38) |
| OTE-4TB0325 | 3.25–3.56 | 83–90 | OTE-4ST306B (to 3.38) or HD OTE-4ST350H (from 3.50) |
| OTE-4TB0350 | 3.50–3.81 | 89–97 | HD OTE-4ST350H (3.50–3.81), same range |
| OTE-4TB0375 | 3.75–4.06 | 95–103 | None centred; ask for options |
| OTE-4TB0400 | 4.00–4.31 | 102–109 | OTE-4ST406B spring or HD OTE-4ST406H (4.06–4.38) |
| OTE-4TB0425 | 4.25–4.56 | 108–116 | OTE-4ST406B / 4ST406H overlap the bottom (to 4.38) |
| OTE-4TB0450 | 4.50–4.81 | 114–122 | None listed; ask for options |
| Gap in plain sizes listed here: 4.81–5.75 in. Spring: HD OTE-4ST500H (5.00–5.31, 127–135 mm) and OTE-4ST525B (5.25–5.56, 133–141 mm). | |||
| OTE-4TB0575 | 5.75–6.06 | 146–154 | OTE-4ST575B spring (5.75–6.06), same range |
| OTE-4TB0600 | 6.00–6.31 | 152–160 | HD OTE-4ST600H (6.00–6.31), same range |
| OTE-4TB0625 | 6.25–6.56 | 159–167 | HD OTE-4ST600H overlaps the bottom (to 6.31) |
| OTE-4TB0700 | 7.00–7.31 | 178–186 | HD OTE-4ST725H (7.25–7.56) overlaps the top |
| Gap in plain sizes listed here: 7.31–8.00 in. Spring: HD OTE-4ST725H (7.25–7.56, 184–192 mm) and OTE-4ST750B (7.50–7.81, 190–198 mm). | |||
| OTE-4TB0800 | 8.00–8.31 | 203–211 | HD OTE-4ST831H (8.31–8.63) starts where this ends |
| OTE-4TB0850 | 8.50–8.81 | 216–224 | HD OTE-4ST831H overlaps the bottom (to 8.63) |
Three things to take from the table. First, a plain T-bolt exists at most diameters listed between 1.25 and 4.81 in, but spring versions are patchier, so check the spring column before you design a joint around one. Second, where a spring range only clips your plain range, measure carefully: your OD needs to sit in the middle of the spring clamp’s range, not just inside it. Third, the gaps above are gaps in this list, not necessarily in the catalogue. With 103 T-bolt and spring-loaded sizes in the family, there is a good chance a size we have not shown fits your hose. Browse the full T-bolt clamp category or send your measured OD for a match.
If you are replacing a clamp from an OEM or another brand and have its part number, the clamp cross-reference is faster than measuring. Manufacturer names and part numbers are used for reference and interchange only; OneTouch Exim has no affiliation with them.
Applications beyond charge air
Charge air hoses made the T-bolt clamp famous, and they are covered in depth in our turbo and intercooler guide. But a heavy duty T-bolt hose clamp earns its place on plenty of other joints. The common thread is a large hose with a known OD, a need for even pressure, and enough load or vibration that a worm clamp struggles.
Engine air intake ducts
The air filter housing to turbo inlet run on trucks, buses and off-road machines uses big rubber elbows and ducts, often 4 in and larger. Pressure is low, but a leak lets unfiltered dust into the turbo. A plain T-bolt gives a reliable seal on the thick rubber and resists the engine shake that loosens worm clamps. Hi-torque clamps also work on these ducts and offer a wider range, which helps when the duct OD is uncertain. Pick the T-bolt when you know the OD and want the stronger, more even grip.
Large coolant hoses on gensets and big diesels
Standby and prime-power generator sets, marine propulsion engines and large stationary or rail diesels run radiator and coolant hoses well above the 2 in sizes found on most trucks. These hoses heat-cycle every time the set starts and stops, and a standby genset may sit cold for weeks and then go straight to full load. That temperature swing is exactly where a spring-loaded T-bolt clamp helps: it keeps pressure on the hose when it shrinks overnight, which stops the slow cold-start seep that leaves a crust of dried coolant on the joint.
On the smaller coolant hoses of the same engines, a constant torque clamp is usually the more compact choice.
Industrial blowers and pneumatic conveying
Positive displacement blowers, rotary lobe units and pneumatic conveying lines move air, and often abrasive powders, through flexible connectors and hose sections between rigid pipe. The connectors absorb vibration and thermal growth from the blower, and the air leaving a blower can be hot. A T-bolt clamp holds those connectors firmly without the band slots of a worm clamp cutting into the rubber as it flexes.
Marine wet exhaust (stainless)
On boats with water-cooled exhausts, raw water is injected into the exhaust gas and the mix travels through rubber exhaust hose to a muffler and out through the hull. A failed joint here can let water or exhaust gas into the boat, so builders treat these connections seriously. Large-bore wet exhaust hose is thick and stiff, and a stainless T-bolt clamp handles it better than a narrow worm clamp. Marine practice commonly calls for two clamps on each exhaust hose connection; check what your boat builder and the marine standard you work to require.
Salt water is hard on stainless steel, especially where water sits trapped under a band (our 304 vs 316 stainless steel guide explains why grade matters here). Ask about the band, bolt and nut grade for the exact part number before fitting T-bolts below the waterline or in the bilge.
Performance builds with silicone hose
Race and custom builds use silicone couplers everywhere. Silicone is soft and relaxes with heat more than rubber does. A perforated worm clamp can bite into it and cut the surface layer, while a T-bolt’s smooth band and bridge spread the load evenly. On joints that heat-cycle hard, use the spring-loaded version. On tight engine bays, check clearance around the bolt head and nut before you order, because a T-bolt sits taller than a worm clamp.
One caution for builders: if the joint you are looking at is two metal flanges meeting end to end, such as a turbine outlet or downpipe connection, you need a flange clamp, not a hose clamp. Our guide on how to choose a V-band clamp covers those joints.
Installing a T-bolt clamp
A T-bolt hose clamp is easy to fit, but its strong bolt makes it easy to fit badly. This sequence works for plain and spring-loaded versions on any of the applications above.
- Confirm the size before you start. Re-measure the hose OD on the pipe and check that it sits in the middle of the clamp’s printed range. If not, stop now rather than forcing it.
- Clean the joint. Wipe oil, coolant residue and old sealant off the pipe end and the inside of the hose. Do not use grease, soap or spray lubricant as an assembly aid on a pressurised joint.
- Open the clamp fully. Back the nut off enough to slide the clamp over the hose end, or open the band and wrap it round if the hose is already fitted at both ends. Do not bend the band to force it.
- Fit the hose fully home. Push it to its full engagement on the pipe, past any bead, and square to the pipe axis.
- Position the clamp. Set it a short distance in from the hose end, fully on the hose, behind any bead, and square to the pipe. Make sure the bridge sits under the band ends, not off to one side.
- Turn the bolt to a reachable spot. Rotate the clamp so you can get a socket on the nut later and the bolt will not rub on a bracket, a wiring loom or another hose.
- Tighten evenly to the specified torque. Use a torque wrench or a calibrated nut driver and follow the OEM figure for the joint or the clamp maker’s instruction for that part. On a spring-loaded T-bolt, stop at the specified figure. Do not tighten until the spring coils touch, or there is no travel left for the spring to do its work. Our hose clamp torque chart explains where published figures come from and why a T-bolt is not a wheel nut.
- Re-check after the first heat cycle. Run the system to working temperature, let it cool, and check the nut again. Hoses relax most early in their life. Paint-mark the hose next to the clamp so movement shows at a glance during later inspections.
T-bolt clamp vs worm gear vs hi-torque
| Question | Worm gear | Hi-torque | T-bolt / spring T-bolt |
|---|---|---|---|
| Range per size | Wide | Wide, and very wide on the wide-range series | Narrow, about 0.13–0.32 in |
| Band | Perforated | Heavier band than a standard worm clamp | Solid, with a bridge under the bolt |
| Grip | Good on small hoses, uneven near the housing | Stronger, better on large firm hoses | Strongest and most even of the three |
| Follows hose shrinkage | No | No | Spring-loaded version does |
| Best fit | Small and general-purpose hoses | Large ducts and hoses with uncertain OD | Known-OD hoses under pressure, heat or vibration |
In the T-bolt clamp vs worm gear debate, range usually decides it. If you know the OD and the joint matters, fit a T-bolt. If you need one clamp to cover several possible hoses, or the joint is small and low-stress, a worm gear clamp is the practical answer. Hi-torque sits between them: more force than a worm clamp with a much wider range than a T-bolt, but no solid band and no spring.
T-bolt hose clamp FAQs
What size T-bolt clamp do I need for a 3 inch hose?
It depends on the hose OD on the pipe, not the 3 in label. A thin rubber coupler on a 3 in pipe might measure about 3.2 in, which suits OTE-4TB0300 (3.00–3.31 in) or OTE-4TB0313. A thick silicone hose might measure 3.4–3.5 in and need OTE-4TB0325 or 4TB0350. Measure with calipers and pick the range that centres your number.
Why does a T-bolt clamp have such a small size range?
The bolt length and the bridge span set how far the clamp can close and open. The design gives up range in exchange for a much stronger, more even grip than a worm gear clamp. Most OTE plain T-bolts cover 0.31 in, and the smallest sizes cover less, so accurate measurement of the installed hose OD is essential.
When is a spring loaded T-bolt clamp worth the extra cost?
Choose the spring version when the hose heat-cycles, is made of silicone, or has loosened under a plain clamp before. The coil spring keeps load on the band as the hose shrinks or cold-flows, so the joint stays tight between services. On a steady-temperature joint with firm rubber hose, a plain T-bolt is usually enough and is more compact.
What is the difference between OTE-4ST…B and OTE-4ST…H clamps?
Both are spring-loaded T-bolt clamps. The B series is the standard spring-loaded version. The H series is the heavy-duty spring-loaded version, built heavier for large, stiff or hard-worked hoses such as big truck charge air cooler connections. Check each product page for band width and hardware, and compare clearance before choosing the HD version.
Can I reuse a T-bolt clamp?
On a non-critical joint, a clean, undamaged clamp can often be refitted. On boost, coolant, exhaust or marine joints, fit a new one. A band that has been tightened and heat-cycled takes a set, the locking nut wears, and a spring may have lost some force. A new clamp costs far less than the downtime from a failed joint.
Are stainless T-bolt clamps suitable for marine use?
A stainless T-bolt clamp is a good choice for large marine hoses such as wet exhaust, but salt water attacks lower-grade stainless and any plated hardware. Confirm the band, bolt and nut grade for your part number before ordering, follow your boat builder’s requirements for double clamping, and inspect for rust staining at the bolt at every haul-out.
Order the right T-bolt size the first time
OneTouch Exim supplies plain, spring-loaded and heavy-duty spring-loaded T-bolt clamps across 103 sizes, quoted per order from single units to export cartons, with worldwide shipping. Send us your measured hose ODs to two decimal places, the hose material and the application, or an OEM part number from the old clamp, and we will match each joint to the right OTE T-bolt clamp. You can also reach the team on WhatsApp or phone at +91-7838759114.