TORQUE-FREE AXIAL TENSIONING
Elongates the bolt or stud by pulling it directly along its axis, without twisting it; the nut is then run down freely. Target pre-tension is applied repeatably and evenly, independent of friction and lubrication uncertainties.
Hydraulic bolt tensioning — also called stud tensioning — brings a bolt or stud to its target pre-load by pulling it along its axis with a hydraulic cylinder instead of turning it. While the stud is stretched the nut is run down by hand; once the pressure is released the load stays in the joint. Unlike torque tightening, the result does not depend on friction or lubrication. How it works, step by step →
Spring return, wide capacity range. Flange, turbine, press and foundation bolts with standard headroom.
The same force in a shorter body, for joints without enough headroom for a standard cylinder.
Permanent solutionReplaces the nut, tensions with pressure and holds with a mechanical lock. For joints that are checked often.
| Capacity (Tensioning Force) | 160 – 6,400 kN |
| Model Range | M20 to M150 across 11 different models |
| Stud Size Range | M20 – M150 |
| Hydraulic System | Spring-return, working pressure 1500 bar |
| Safety | Stroke overrun warning and protection system |
| Alignment | Automatic piston-jack self-alignment feature |
| Flange Compatibility | DIN-EN · ANSI B16.5 · BS1560 · API |
| Service | Warranty, service and spare parts |
11 models · M20–M150 studs · 160–6,400 kN. Click a model to view its full dimension table and technical diagram.
Stud size, nut wrench flat, thread pitch, and all body dimensions (A–G) for all 11 models. The same data as the "DETAIL" panel on the cards above, on a single page for search engines.
↓ Calculate the right model for your target preload: Model Selector and LTF Calculator
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M20 | 30 | 2.5 | 66 | 93 | 63 | 142 | 36 | 25 | 49.8 |
| M22 | 32 | 2.5 | 66 | 93 | 63 | 144 | 36 | 25 | 51 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 32 | 64 | 96 | 128 | 160 |
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M24 | 36 | 3 | 87 | 117 | 68 | 175 | 38 | 28 | 56.5 |
| M27 | 41 | 3 | 87 | 117 | 68 | 178 | 38 | 28 | 58.7 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 56 | 112 | 168 | 224 | 280 |
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M24 | 36 | 3 | 103 | 117 | 75 | 175 | 38 | 30 | 64.5 |
| M27 | 41 | 3 | 103 | 117 | 75 | 178 | 38 | 30 | 66 |
| M30 | 46 | 3 | 103 | 120 | 80 | 184 | 41 | 30 | 67.6 |
| M33 | 50 | 3.5 | 103 | 123 | 84 | 190 | 44 | 35 | 71.9 |
| M36 | 55 | 4 | 103 | 126 | 89 | 196 | 47 | 38 | 77 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 90 | 180 | 270 | 360 | 450 |
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M33 | 50 | 3.5 | 118 | 123 | 88 | 192 | 44 | 35 | 76.5 |
| M36 | 55 | 4 | 118 | 126 | 96 | 198 | 47 | 38 | 80.8 |
| M39 | 60 | 4 | 118 | 130 | 96 | 204 | 51 | 42 | 83.6 |
| M42 | 65 | 4.5 | 118 | 133 | 105 | 211 | 54 | 41 | 91 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 132 | 264 | 396 | 528 | 660 |
Calculated using the formula F = P × A_eff; intermediate pressure values yield proportional force. Full table (500–1500 bar, 41 points) →
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M39 | 60 | 4 | 140 | 132 | 112 | 212 | 51 | 42 | 91.6 |
| M42 | 65 | 4.5 | 140 | 135 | 114 | 218 | 54 | 45 | 95.5 |
| M45 | 70 | 4.5 | 140 | 139 | 118 | 225 | 57 | 52 | 100 |
| M48 | 75 | 5 | 140 | 142 | 114 | 231 | 60 | 51 | 101.3 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 200 | 400 | 600 | 800 | 1000 |
Calculated using the formula F = P × A_eff; intermediate pressure values yield proportional force. Full table (500–1500 bar, 41 points) →
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M52 | 80 | 5 | 175 | 148 | 120 | 248 | 63 | 52 | 115 |
| M56 | 85 | 5.5 | 175 | 154 | 138 | 258 | 70 | 58 | 119 |
| M60 | 90 | 5.5 | 175 | 161 | 138 | 262 | 70 | 58 | 122 |
| M64 | 95 | 6 | 175 | 161 | 153 | 283 | 76 | 63 | 132 |
| M68 | 100 | 6 | 175 | 161 | 153 | 283 | 76 | 63 | 135 |
| M70 | 103 | 6 | 175 | 161 | 153 | 287 | 76 | 63 | 135 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 300 | 600 | 900 | 1200 | 1500 |
Calculated using the formula F = P × A_eff; intermediate pressure values yield proportional force. Full table (500–1500 bar, 41 points) →
→ HRT6 detail page: specifications, applications and FAQ
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M72 | 105 | 6 | 219 | 167 | 157 | 297 | 82 | 72 | 146 |
| M76 | 110 | 6 | 219 | 174 | 182 | 308 | 89 | 80 | 155 |
| M80 | 115 | 6 | 219 | 174 | 182 | 312 | 89 | 80 | 158 |
| M85 | 120 | 6 | 219 | 180 | 190 | 323 | 95 | 84 | 165 |
| M90 | 130 | 6 | 219 | 186 | 205 | 334 | 101 | 88 | 179 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 500 | 1000 | 1500 | 2000 | 2500 |
Calculated using the formula F = P × A_eff; intermediate pressure values yield proportional force. Full table (500–1500 bar, 41 points) →
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M90 | 130 | 6 | 252 | 186 | 200 | 341 | 101 | 88 | 176 |
| M95 | 135 | 6 | 252 | 186 | 200 | 346 | 101 | 88 | 179 |
| M100 | 145 | 6 | 252 | 192 | 200 | 356 | 107 | 94 | 185 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 640 | 1280 | 1920 | 2560 | 3200 |
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M105 | 150 | 6 | 282 | 199 | 210 | 378 | 114 | 114 | 195 |
| M110 | 155 | 6 | 282 | 199 | 210 | 383 | 114 | 114 | 197 |
| M115 | 165 | 6 | 282 | 205 | 224 | 394 | 120 | 114 | 208 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 820 | 1640 | 2460 | 3280 | 4100 |
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M120 | 170 | 6 | 323 | 212 | 230 | 405 | 125 | 135 | 215 |
| M125 | 180 | 6 | 323 | 215 | 230 | 418 | 128 | 135 | 226 |
| M130 | 185 | 6 | 323 | 219 | 240 | 425 | 133 | 135 | 238 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 1040 | 2080 | 3120 | 4160 | 5200 |
Calculated using the formula F = P × A_eff; intermediate pressure values yield proportional force. Full table (500–1500 bar, 41 points) →
| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|---|---|---|---|---|---|---|---|---|
| M135 | 190 | 6 | 368 | 223 | 248 | 432 | 137 | 145 | 245 |
| M140 | 195 | 6 | 368 | 227 | 262 | 440 | 142 | 145 | 253 |
| M150 | 200 | 6 | 368 | 231 | 278 | 451 | 146 | 145 | 265 |
| Pressure (bar) | 300 | 600 | 900 | 1200 | 1500 |
|---|---|---|---|---|---|
| Force (kN) | 1280 | 2560 | 3840 | 5120 | 6400 |
Calculated using the formula F = P × A_eff; intermediate pressure values yield proportional force. Full table (500–1500 bar, 41 points) →
Hydraulic tensioning force increases in direct proportion to pump pressure (F = P × A_eff / 100). The table below shows the tensioning force (kN) each of the 11 HRT models can produce at different pump pressures — useful for system/pump selection and staged (25%/50%/100%) tensioning planning. The 1500 bar column is the model's nominal maximum capacity.
| Model | Stud | 500 bar | 750 bar | 1000 bar | 1250 bar | 1500 bar (max.) |
|---|---|---|---|---|---|---|
| HRT0 | M20–M22 | 53.3 | 80.0 | 106.7 | 133.3 | 160.0 |
| HRT1 | M24–M27 | 93.3 | 140.0 | 186.7 | 233.3 | 280.0 |
| HRT2 | M24–M36 | 150.0 | 225.0 | 300.0 | 375.0 | 450.0 |
| HRT3 | M33–M42 | 220.0 | 330.0 | 440.0 | 550.0 | 660.0 |
| HRT4 | M39–M48 | 333.3 | 500.0 | 666.7 | 833.3 | 1,000.0 |
| HRT5 | M52–M70 | 500.0 | 750.0 | 1,000.0 | 1,250.0 | 1,500.0 |
| HRT6 | M72–M90 | 833.3 | 1,250.0 | 1,666.7 | 2,083.3 | 2,500.0 |
| HRT7 | M90–M100 | 1,066.7 | 1,600.0 | 2,133.3 | 2,666.7 | 3,200.0 |
| HRT8 | M105–M115 | 1,366.7 | 2,050.0 | 2,733.3 | 3,416.7 | 4,100.0 |
| HRT9 | M120–M130 | 1,733.3 | 2,600.0 | 3,466.7 | 4,333.3 | 5,200.0 |
| HRT10 | M135–M150 | 2,133.3 | 3,200.0 | 4,266.7 | 5,333.3 | 6,400.0 |
When hydraulically tensioning a stud, not all of the force applied by the cylinder remains as permanent preload: some loss occurs due to nut embedment, friction, and elastic spring-back. Load Transfer Factor (LTF) is a widely used industry rule-of-thumb coefficient that shows how much hydraulic force above the target preload must be applied to compensate for this loss.
LTF is a design/selection tool used for the more consistent preload control that hydraulic tensioning offers compared to the torque method; it is not a precise measurement method (see the "Limits of LTF" section).
Enter your target preload, stud diameter, and grip length; calculate the required hydraulic force, the recommended HRT model, and the working pressure.
Enter your target preload (R), your stud's nominal diameter (D), and grip length (G) values into the calculator.
The tool calculates the coefficient using the formula LTF = 1.01 + D/G, and the hydraulic force (kN) to apply using F = R × LTF.
Based on the calculated force, the smallest HRT model satisfying F ≤ Capacity is shown along with the required working pressure (bar) for that model; a warning is given if the 1500 bar limit is exceeded.
LTF is a theoretical design coefficient used for selecting the appropriate tensioner and pressure; it does not measure the loss in a specific joint with millimeter precision. Because friction, surface roughness, nut embedment, and material tolerances can vary from joint to joint, the actual preload may deviate from the value calculated with LTF.
For critical applications (high-pressure equipment, safety-sensitive flanges, etc.) verifying the calculated value with physical methods is recommended:
This calculator is intended for preliminary selection and pre-order comparison; for the final pressure and model decision, we recommend contacting us via the quote form along with your project's technical data.
Load Transfer Factor (LTF) is a coefficient that shows how much hydraulic force above the target preload must be applied to compensate for losses such as nut embedment, friction, and elastic spring-back during hydraulic tensioning (LTF = 1.01 + D/G). If pressure equal to only the target preload is applied without using this coefficient, the actual preload in the joint may end up lower than intended.
The calculator uses the values you enter to calculate the required hydraulic force (F = R × LTF) and recommends the HRT model with the smallest (and therefore most economical) capacity that can meet this force. The recommendation is based on the model's published capacity at 1500 bar; we also recommend separately checking whether your stud diameter falls within the recommended model's size range.
No. LTF is a widely used industry theoretical design/selection coefficient; it is not a substitute for precise measurement. For critical applications, physical verification methods such as elongation measurement with a dial indicator or ultrasonic measurement are recommended (see the "Limits of LTF" section above).
In this case the calculator shows a warning; you should move to a higher-capacity HRT model, or share your target preload/grip length values along with your project's engineering data with us. The entire HRT series is sized according to the standard 1500 bar working pressure.
D is the nominal diameter of the stud — for example, D=72 mm for an M72 stud. G is the free grip length of the section being tensioned; it is generally found by adding up the flange thickness, nut height, and any additional elements, and should be confirmed from the project's technical drawing or the stud manufacturer's data.
The same load is achieved repeatedly within a ±5–10% band; far more consistent than torque-based methods.
On flanges and covers, all studs are drawn to the same tension; the joint runs leak-free and lasts longer.
In the torque method, variable lubrication throws off pre-tension; with tensioning, the load is applied directly.
The stud is not twisted; thread galling and embedment losses are significantly reduced.
In tight spaces and closely spaced bolt arrangements, multiple (cascade) or simultaneous tensioning can be applied.
Reduces the need for high-torque wrenches, operator effort, and noise.
The HRT tensioner doesn't work alone — it operates as part of a complete system. Without the right pressure, the right distribution, and the right connection, the target preload cannot be achieved.
| HRT Tensioner | Based on the model selected (HRT0–HRT10) |
| 1500 Bar Hydraulic Pump | Electric or pneumatic drive |
| High Pressure Hose | Rated for 1500 bar, length to suit your needs |
| Distribution Manifold | Designed by number of lines for multiple (simultaneous) tensioning |
| Pressure Gauge | Real-time pressure monitoring |
| Connection Fittings | Adapters, T-pieces, quick couplings |
The tensioner is threaded onto the pulling washer/puller nut at the end of the stud; the bridge seats against the part.
Hydraulic pressure from the pump acts on the cylinder's piston area, pulling and elongating the stud axially with a force of F = P × A_eff.
As the stud elongates, the main nut is run down by hand, friction-free, onto the joint face.
Once pressure is released, the stud springs back elastically and the pre-tension is locked into the nut.
P: bar / MPa pressure · A_eff: effective piston area · E: material modulus of elasticity · ΔL: elastic elongation
Manufactured with CNC precision at İvedik OSB, Ankara; not dependent on imported parts.
11 models covering most stud sizes from a single manufacturer.
Custom design is available for non-standard studs or flanges.
The right model is determined based on your stud size and target preload, together with the pressure calculation.
Critical parts are kept in stock, with service support provided.
One supplier for everything from the tensioner to the pump, manifold, hoses and gauges.
Hydro Bard designs and manufactures its hydraulic bolting tools at its own plant in İvedik OIZ, Ankara, Türkiye, and supplies them directly to industrial customers outside Türkiye.
Our tools are designed, machined, assembled and pressure tested under one roof. We are not the local agent of a foreign brand.
Our CNC machining capabilities cover turning up to Ø320 mm and milling up to 800 × 400 × 500 mm on our own machine park, so non-catalogue sizes do not wait on an outside supplier.
Every tool is assembled, filled with oil and pressure tested before it leaves the plant.
Send your stud size, target preload and joint details; our engineers reply in English with a calculated model proposal.
The HRT series covers stud sizes from M20 to M150 across 11 models (from HRT0 at M20–M22 up to HRT10 at M135–M150), delivering tensioning forces from 160 kN to 6,400 kN. You can identify the right model from the model table based on your stud size, target pre-tension and flange standard, or send us your specifications through the quote form.
In the torque method, wrench torque is converted into nut load through friction and lubrication, so the actual clamping force stays uncertain. In bolt tensioning, the hydraulic cylinder pulls the stud directly along its axis (F = P × A_eff) and the nut is simply run down by hand, friction-free. This makes pre-tension repeatable within a ±5–10% band and avoids torsion and thread damage on the stud.
The HRT series is a spring-return hydraulic system rated for a maximum working pressure of 1500 bar. Capacity ranges from 160 kN (HRT0) to 6,400 kN (HRT10) depending on the model; each model's effective piston area (cm²) and weight are listed in the model table.
The HRT series is manufactured in dimensions compatible with DIN-EN, ANSI B16.5, BS1560 and API flange standards, and includes a stroke-overrun warning/protection system along with automatic piston-jack self-alignment.
Yes. HRT tensioners have a compact body designed for multiple (cascade) or simultaneous tensioning in confined spaces and closely spaced stud patterns, reducing the need for high-torque wrenches, operator effort and noise.
Yes. We handle maintenance and repair for HRT series tensioners in-house — send us your unit and we'll inspect it and manage the repair process. We also manufacture original spare parts (pistons, seals, etc.) on request for the models we produce; we don't maintain a separate parts catalog, but you can contact us directly for the part you need.
Yes. We manufacture in Ankara, Türkiye, and supply industrial customers abroad directly. Quotations are prepared in English.
Delivery time depends on the model, size and quantity, and whether the size is a catalogue or a custom design. We confirm it in writing with each quotation.
Related: What is bolt tensioning? Torque or tensioning? HRT pressure–force tables Complete system solutions System selector
Send us your stud size, target pre-tension and working environment details; we'll send back a calculated model recommendation along with its technical documentation.
Technical Quote Form →| Stud | Nut A/F | Thread Pitch | A | B | C | D | E | F | G (mm) |
|---|