DIN 3570 Pipe U-Bolts
DIN 3570 form A · DN 15 – DN 500 · M10 – M24Round-bend U-bolts sized to metric pipe ODs, for pipe racks, pipe bridges and plant supports.
DIN 3570 & MSS SP-58 Type 24 U Bolts: Manufacturer & Stockist
A U-bolt is a round rod bent into a U and threaded on both legs. It wraps around a pipe or section, its legs pass through the support, and nuts underneath clamp it down. It is the simplest pipe support there is.
Exotic Alloy manufactures U-bolts in Mumbai, India. Metric pipe U-bolts follow DIN 3570 form A, the round steel strap for pipes DN 15 to DN 500. Inch pipe U-bolts follow MSS SP-58 Type 24. Threads are rolled on straight bar before bending, so they are true and undamaged, and the bend is formed on a mandrel to the exact inside width. We stock and supply across India and export to Singapore, Southeast Asia, the Gulf and Africa.
Ready Stock, Custom Bends, Quick Delivery
DIN 3570 DN 15 to DN 150 in hot-dip galvanized steel, SS 304 and SS 316 ship from stock. Larger sizes, square bends, long legs, plastic coating and vehicle U-bolts are made to drawing.
DN 15 – DN 500
Round & square bends
M6 – M30 to drawing
HDG, SS 304, SS 316
Plastic-coated option
U bolt at a glance
- Form
- Round rod bent into a U, threaded on both legs
- Standards
- DIN 3570 form A (metric pipe), MSS SP-58 Type 24 (inch pipe)
- Key sizes
- Inside width A, thread d, thread length b, leg centres E
- Material
- S235JR, SS 304 (A2), SS 316 (A4), duplex, Grade 5 / 8
- Finish
- Plain, electro-galvanized, hot-dip galvanized, plastic coated
- Related
- J bolts, nuts, washers
U Bolt Specification
The range we manufacture and supply.
StandardsDIN 3570 form A round steel U-bolts for pipes; MSS SP-58 Type 24 U-bolts (inch pipe); vehicle U-bolts to OEM drawing
Size rangeDIN 3570 DN 15 to DN 500 (pipe OD 20 to 521 mm), M10 to M24; inch ½″ to 30″ pipe; custom M6 to M30 and ¼″ to 1¼″
ThreadMetric coarse 6g; UNC 2A; UNF or metric fine for vehicle U-bolts; rolled on straight bar before bending
BendRound (semicircular) for pipe; square or flat-top for sections and leaf springs; inside width and leg length to order
MaterialsS235JR (St37) carbon steel; ISO 898-1 4.6 / 5.6 / 8.8; SAE J429 Grade 5 / 8 for vehicles; SS 304 (A2), SS 316 (A4); duplex 2205
FinishPlain; electro-galvanized; hot-dip galvanized; passivated stainless; PVC / polyamide coated or EPDM-lined for pipe isolation
HardwareHex nuts and flat washers in matching material and finish, supplied on request (DIN 3570 U-bolts are normally sold without them)
CertificationMill certificate with heat number; EN 10204 3.1 with dimensions, coating thickness and material properties; PMI for stainless
IdentificationBagged or tagged by DN, thread, material and finish; heat number on the label
PackingCartons or wooden cases by size, with nuts and washers bagged separately or pre-assembled
Types of U Bolts We Manufacture
MSS SP-58 Type 24 U-Bolts
Inch pipe ½″ – 30″ · UNC threadsThe pipe-hanger industry's standard U-bolt for anchoring or guiding inch pipe on beams and stanchions, typically supplied with four hex nuts.
Square-Bend U-Bolts
Square or flat top · to drawingFor square and rectangular tubes, timber posts and channel sections, with corner radii to suit the section.
Leaf Spring U-Bolts
SAE J429 Gr 5 / 8 · 8.8 / 10.9 · fine threadFor clamping truck, trailer and bus leaf springs to axles, with round, square or semi-round bends to the OEM drawing.
Coated & Lined U-Bolts
PVC / polyamide coat · EPDM linerIsolate stainless, copper or plastic pipe from the bolt, damp vibration and protect the pipe surface.
Stainless & Duplex U-Bolts
SS 304 · SS 316 · duplex 2205For offshore, chemical, food and water treatment plants, as in the product photo.
DIN 3570 U Bolt Dimensions
DIN 3570 form A, round steel U-bolts for pipes, in mm. The leg centre distance E always equals the inside width A plus the thread diameter, which is the spacing to drill in the support.
| DN NPS | Pipe OD mm | A inside width, mm | Thread d rod d2, mm | b thread length, mm | E leg centres, mm | H height, mm | Support holes ISO 273 medium, mm |
|---|---|---|---|---|---|---|---|
| DN 15 (½″) | 20–22 | 23 | M10 (8.9) | 30 | 33 | 60 | 2 × Ø11 at 33 c/c |
| DN 20 (¾″) | 25–27 | 30 | M10 (8.9) | 40 | 40 | 70 | 2 × Ø11 at 40 c/c |
| DN 25 (1″) | 30–34 | 38 | M10 (8.9) | 40 | 48 | 76 | 2 × Ø11 at 48 c/c |
| DN 32 (1¼″) | 38–43 | 46 | M10 (8.9) | 50 | 56 | 86 | 2 × Ø11 at 56 c/c |
| DN 40 (1½″) | 45–49 | 52 | M10 (8.9) | 50 | 62 | 92 | 2 × Ø11 at 62 c/c |
| DN 50 (2″) | 57–61 | 64 | M12 (10.7) | 50 | 76 | 109 | 2 × Ø13.5 at 76 c/c |
| DN 65 (2½″) | 77 | 82 | M12 (10.7) | 50 | 94 | 125 | 2 × Ø13.5 at 94 c/c |
| DN 80 (3″) | 89 | 94 | M12 (10.7) | 50 | 106 | 138 | 2 × Ø13.5 at 106 c/c |
| DN 100 (4″) | 108–115 | 120 | M16 (14.6) | 60 | 136 | 171 | 2 × Ø17.5 at 136 c/c |
| DN 125 (5″) | 133–140 | 148 | M16 (14.6) | 60 | 164 | 191 | 2 × Ø17.5 at 164 c/c |
| DN 150 (6″) | 159–169 | 176 | M16 (14.6) | 60 | 192 | 217 | 2 × Ø17.5 at 192 c/c |
| DN 175 (7″) | 191–194 | 202 | M16 (14.6) | 60 | 218 | 249 | 2 × Ø17.5 at 218 c/c |
| DN 200 (8″) | 216–220 | 228 | M20 (18.2) | 70 | 248 | 283 | 2 × Ø22 at 248 c/c |
| DN 250 (10″) | 267–273 | 282 | M20 (18.2) | 70 | 302 | 334 | 2 × Ø22 at 302 c/c |
| DN 300 (12″) | 318–324 | 332 | M20 (18.2) | 70 | 352 | 385 | 2 × Ø22 at 352 c/c |
| DN 350 (14″) | 356–368 | 378 | M24 (21.9) | 70 | 402 | 435 | 2 × Ø26 at 402 c/c |
| DN 400 (16″) | 407–419 | 428 | M24 (21.9) | 70 | 452 | 487 | 2 × Ø26 at 452 c/c |
| DN 500 (20″) | 508–521 | 530 | M24 (21.9) | 70 | 554 | 589 | 2 × Ø26 at 554 c/c |
Dimensions as published in a manufacturer's DIN 3570 form A datasheet (2026), cross-checked against the DIN 3570 table. The rod diameter d2 in brackets is the plain rod under the rolled thread. H is the height listed in the standard. Support holes are our suggestion, using ISO 273 medium clearance holes.
U Bolt Size Finder by Pipe OD
Enter the pipe outside diameter to get the DIN 3570 size, its dimensions and the holes to drill in the support.
Find my U-bolt
Matches the pipe OD to the DIN 3570 size ranges, allowing 1.5 mm either side. The leg yield load is a steel property of S235JR legs at the thread, not a safe working load: the pipe, the support and the nut usually govern.
DIN 3570 size
DN 50
nominal size
M12
thread
Inside width A:64 mm
Hole spacing E:76 mm
Holes in support:2 × Ø13.5 mm
Thread length b:50 mm
Yield, both legs (S235JR):39.6 kN
Installing Pipe U Bolts: Anchor or Guide?
The same U-bolt can hold a pipe rigidly or let it slide. The piping designer's support schedule says which, and the nuts are set accordingly.
As an anchor (clamp)
- Drill holes at spacing E, square to the pipe
- Fit a washer under each nut
- Tighten both nuts evenly, a little at a time, so the bend sits centred
- Stop when the pipe is held: do not crush thin-wall or plastic pipe
As a guide (sliding)
- Leave a small gap between the bend and the pipe
- Use two nuts per leg, one above and one below the flange, locked against each other
- Let the pipe move along its axis with thermal expansion
- Add a slide plate or pipe shoe where the pipe would wear
Mixed metals corrode. A bare carbon steel U-bolt on stainless or copper pipe in wet conditions sets up galvanic corrosion and rust staining. Use stainless, plastic-coated or EPDM-lined U-bolts on those pipes.
U Bolt Grades & Finishes
| Material / grade | Standard | Min. yield | Typical use |
|---|---|---|---|
| S235JR (St37) | EN 10025-2 | 235 MPa to 16 mm, 225 MPa over 16 mm | DIN 3570 pipe U-bolts, general supports |
| Property class 4.6 / 5.6 | ISO 898-1 | 240 / 300 MPa | Metric U-bolts specified by class |
| Property class 8.8 | ISO 898-1 | 640 MPa (≤ M16), 660 MPa (> M16) | Heavy supports, machinery |
| SAE J429 Grade 5 / Grade 8 | SAE J429 | 92 / 130 ksi (634 / 896 MPa) | Truck and trailer spring U-bolts |
| SS 304 (A2) / SS 316 (A4) | ISO 3506-1 or bar specification | Per class or bar condition | Corrosive, hygienic and marine service |
| Finish | Specification | Notes |
|---|---|---|
| Plain (raw) | – | For U-bolts that are painted with the steelwork |
| Electro-galvanized | ISO 4042 / ASTM F1941 | Indoor and dry plant areas |
| Hot-dip galvanized | ISO 10684 / ASTM F2329 | Outdoor pipe racks; galvanized after threading and bending, nuts over-tapped |
| PVC / polyamide coated | To order | Isolates the pipe and reduces noise and vibration |
| Passivated stainless | ASTM A967 / A380 | SS 304, SS 316 and duplex U-bolts |
U Bolt Materials
Every grade links to its datasheet on this site.
Special alloy U-bolts: minimum properties of the bar we make them from
| Alloy | UNS | Condition supplied | Tensile min MPa | Yield 0.2 % min MPa | Elongation % | Why it is chosen for hex bolts |
|---|---|---|---|---|---|---|
| Inconel 625 | N06625 | Solution annealed (Grade 1) | 827 | 414 | 30 | Seawater, sour gas, cryogenic to 980 °C oxidation; subsea flange bolting |
| Inconel 718 | N07718 | Solution treated + aged (AMS 5662) | 1240 | 1035 | 12 | Highest strength to 650 °C; turbine and wellhead bolting |
| Monel 400 | N04400 | Hot-finished annealed | 517 | 207 | 35 | Seawater, hydrofluoric acid, no chloride SCC; marine and valve bolting |
| Monel K-500 | N05500 | Age hardened (AMS 4676) | 960 | 690 | 18 | Monel 400 corrosion resistance with three times the yield; pump shafts, subsea |
| Hastelloy C-276 | N10276 | Solution annealed (ASTM B574) | 690 | 283 | 40 | Wet chlorine, hot acids, mixed oxidising / reducing media; chemical reactors |
| Incoloy 825 | N08825 | Annealed (ASTM B425) | 586 | 241 | 30 | Sulphuric and phosphoric acid, sour gas (NACE MR0175); pickling plant |
| Duplex 2205 | S32205 | Solution annealed | 655 | 450 | 25 | Twice the yield of 316 with chloride SCC resistance; offshore topsides |
| Super Duplex 2507 | S32750 | Solution annealed | 750 | 550 | 15 | PREN > 40; seawater and desalination bolting |
| Titanium Grade 5 | R56400 | Annealed (ASTM B348) | 895 | 828 | 10 | Half the weight of steel, immune to seawater; aerospace and chemical |
| A-286 | S66286 | Solution treated + aged | — | — | — | Iron-base superalloy for 650 °C bolting; on request with certified values |
Bar minimums from the linked datasheets for the supply condition shown.
How Our U Bolts Are Made
1
Cut to developed length
Certified round bar cut to the developed length of the legs plus the bend.
2
Thread rolling
Both ends thread-rolled while the bar is straight, giving a full, accurate thread right to the start.
3
Bending
Bent on a mandrel to the inside width A, with legs parallel and of equal length; square bends on a two-corner former.
4
Heat treatment
Grade 8 / 10.9 vehicle U-bolts quenched and tempered after bending, and hardness checked.
5
Finishing
Galvanizing, plating, coating or passivation, then thread check with ring gauges.
6
Fixture check
Inside width, leg centres and leg length checked in a go fixture, and nuts run on both legs.
Where Our U Bolts Are Used
Pipe racks & pipe bridges
Holding process and utility pipes on steel beams in refineries and plants.
Building services
Water, fire-fighting and HVAC pipework on strut and steel supports.
Trucks & trailers
Leaf spring U-bolts clamping spring packs to axles.
Marine & offshore
Stainless and duplex U-bolts for deck pipework, rails and antenna masts.
Telecom & signs
Fixing antennas, brackets and signs to round poles.
Solar & agriculture
Galvanized U-bolts on solar trackers, irrigation lines and farm structures.
U Bolt Inspection & Certification
| Check | Method | Applied to |
|---|---|---|
| Material | Mill certificate; PMI on stainless | Every heat |
| Inside width & leg centres | Go fixture and callipers against A and E | Every lot |
| Leg length & thread length | Measured against b and H | Every lot |
| Thread | Ring gauges, after coating | Every lot |
| Coating | Magnetic thickness gauge | Galvanized and plated lots |
| Hardness / tensile | Rockwell; tensile on bar | Heat-treated vehicle U-bolts |
Every shipment includes
- Mill certificate with heat number
- Dimensional report against DIN 3570 or drawing
- Coating thickness report
- Packing list by DN and finish
On request
- EN 10204 3.1 / 3.2 certificates
- Salt spray test report
- Third-party inspection
U Bolt Questions, Answered
A U bolt is a rod bent into a U with a thread on each leg. It wraps around a pipe, tube or bar, and the two legs pass through holes in a support, where nuts and washers clamp it in place. Round-bend U-bolts hold pipes, square-bend U-bolts hold square sections, and vehicle U-bolts clamp leaf springs to the axle.
Give the bend shape (round or square), the inside width A, which must clear the pipe or section, the thread size, the thread length b, the overall height or leg length, the material and finish, and whether nuts and washers are needed. For pipes, quote the pipe outside diameter or nominal size and the standard, for example DIN 3570 DN 50 for a 60.3 mm pipe.
DIN 3570 steps the thread with pipe size: M10 for DN 15 to DN 40, M12 for DN 50 to DN 80, M16 for DN 100 to DN 175, M20 for DN 200 to DN 300 and M24 for DN 350 to DN 500. For example, the DN 50 U-bolt for 57 to 61 mm pipe has an inside width of 64 mm, M12 threads 50 mm long and legs 76 mm apart.
Drill the holes at the leg centre distance E. For DIN 3570 this is the inside width A plus the thread diameter, for example 76 mm for the DN 50 size with M12 threads. Use a clearance hole such as ISO 273 medium, 13.5 mm for M12, and keep the support flat so that both legs are loaded equally.
DIN 3570 U-bolts are commonly sold without nuts and washers. We supply matching hex nuts and washers in the same material and finish on request, and recommend two nuts per leg where the U-bolt must be locked in a set position, for example when it acts as a pipe guide.
It depends on the support's job. As an anchor, the U-bolt is tightened to clamp the pipe. As a guide, it is set with a small clearance and locked with double nuts so that the pipe can move along its axis with thermal expansion. Over-tightening a U-bolt on a thin-walled or plastic pipe can dent it, so follow the piping designer's support schedule.
Use stainless steel U-bolts, or plastic-coated or sleeved U-bolts, so that dissimilar metals are not in direct contact. A bare carbon steel U-bolt on a stainless or copper pipe in wet conditions can cause galvanic corrosion and staining. Stainless 316 is preferred in coastal and chemical plants.
Yes, to the vehicle maker's drawing, usually with round or square bends, fine threads and SAE J429 Grade 5 or Grade 8 or ISO 8.8 or 10.9 steel. Spring U-bolts stretch in service, so vehicle makers generally call for new U-bolts when springs are replaced and for re-tightening to their torque after the first loaded run.