DIN 3015 divides pipe clamps into two series: Part 1 (light, single clamp) for standard mounting and Part 2 (heavy, double clamp) for high-load and high-vibration locations. Selecting the wrong series or bolt size for a given pipe OD is one of the most common specification errors on wind turbine projects. This table covers the full OD range used in wind turbine hydraulic, cooling, and pneumatic circuits.
§ 01 How to Read the Sizing Tables
DIN 3015 clamp sizes are designated by the nominal pipe outside diameter (OD) they grip. The clamp designation is typically written as DIN 3015-1 – [OD] (e.g., DIN 3015-1 – 28 for a 28 mm pipe). The tables below give, for each nominal OD:
- OD range — the actual pipe OD range the clamp accommodates (clamps grip a range, not a single diameter)
- Bolt size — the fastener thread diameter used to torque the clamp halves together
- Indicative torque — installation torque for standard steel body with EPDM or NBR insert, zinc-plated bolt, property class 8.8
- Typical wind turbine application — which circuit or location this OD range commonly serves
Zone badges: Nacelle = hydraulic / gear oil / cooling circuits inside nacelle; Tower = tower interior lines; Offshore = exposed marine environment, requires A4 hardware.
§ 02 DIN 3015 Part 1 — Light Series (Single Clamp)
Part 1 is the standard selection for most wind turbine pipe runs. It uses a single-piece clamp body with one insert and two bolts (or a U-bolt on smaller sizes). Suitable for static and moderate-vibration service up to the load ratings in the manufacturer's data sheet.
| Nom. OD (mm) | OD Range (mm) | Bolt Size | Torque (N·m, indicative) | Typical Wind Application |
|---|---|---|---|---|
| Small bore — pneumatic, pilot lines, instrument tubing | ||||
| 6 | 5.5 – 6.5 | M6 | 4 – 6 | Pneumatic pilot lines Nacelle |
| 8 | 7.5 – 8.5 | M6 | 4 – 6 | Pneumatic, instrument lines Nacelle |
| 10 | 9.5 – 10.5 | M6 | 5 – 7 | Hydraulic drain, pilot Nacelle |
| 12 | 11.5 – 12.5 | M6 | 5 – 7 | Hydraulic case drain Nacelle |
| Medium bore — main hydraulic pressure and return lines | ||||
| 14 | 13.5 – 14.5 | M8 | 10 – 14 | Hydraulic pressure line Nacelle |
| 16 | 15.5 – 16.5 | M8 | 10 – 14 | Hydraulic pressure / return Nacelle |
| 18 | 17.5 – 18.5 | M8 | 10 – 14 | Hydraulic return line Nacelle |
| 20 | 19.5 – 20.5 | M8 | 12 – 16 | Hydraulic return / tower pitch Nacelle Tower |
| 22 | 21.5 – 22.5 | M8 | 12 – 16 | Pitch hydraulic line Tower |
| 25 | 24.5 – 25.5 | M8 | 12 – 16 | Pitch hydraulic line Tower |
| 28 | 27.5 – 28.5 | M8 | 14 – 18 | Pitch / cooling line Tower |
| Large bore — cooling water, gearbox oil, tower conduit | ||||
| 32 | 31.5 – 32.5 | M10 | 22 – 28 | Gearbox cooling supply Nacelle |
| 38 | 37.5 – 38.5 | M10 | 22 – 28 | Gearbox cooling, water cooling Nacelle |
| 42 | 41.5 – 42.5 | M10 | 24 – 30 | Main cooling circuit Nacelle Tower |
| 48 | 47.5 – 48.5 | M10 | 24 – 30 | Cooling water tower supply Tower |
| 54 | 53.5 – 54.5 | M12 | 38 – 46 | Cooling main riser Tower |
| 60 | 59.5 – 60.5 | M12 | 38 – 46 | Cooling main riser Tower |
| 70 | 69.5 – 70.5 | M12 | 40 – 50 | Large cooling / conduit Tower Offshore |
| 76 | 75.5 – 76.5 | M12 | 40 – 50 | Conduit, fire suppression Tower Offshore |
| 89 | 88.5 – 89.5 | M12 | 44 – 54 | Large conduit / scour protection Offshore |
§ 03 DIN 3015 Part 2 — Heavy Series (Double Clamp)
Part 2 uses a heavier body wall, a backing plate, and (on the double-clamp variant) a second clamp body for mounting two parallel pipes simultaneously. The bolt size steps up by one grade versus Part 1 for the same OD, and the load rating is significantly higher. Specify Part 2 for:
- High-vibration nacelle locations (gear-mesh frequency clamps, generator outlet)
- High-pressure hydraulic lines ≥ 200 bar where pipe reaction forces are significant
- Structural support clamps where the clamp also carries the weight of the pipe run
- Offshore locations where inspection intervals are long and a higher safety margin is required
| Nom. OD (mm) | OD Range (mm) | Bolt Size | Torque (N·m, indicative) | vs Part 1 |
|---|---|---|---|---|
| 6 – 12 | 5.5 – 12.5 | M8 | 10 – 14 | One bolt grade up; heavier body |
| 14 – 28 | 13.5 – 28.5 | M10 | 22 – 28 | Higher clamping force; backing plate |
| 32 – 54 | 31.5 – 54.5 | M12 | 38 – 50 | Structural-grade; double-clamp option |
| 60 – 89 | 59.5 – 89.5 | M14 | 55 – 70 | Large-bore structural; offshore spec |
§ 04 Common Wind Turbine Pipe OD Reference
A quick field reference: the pipe ODs most commonly encountered on wind turbine projects by circuit type. Actual ODs depend on the OEM specification and turbine rating.
| Circuit | Typical OD Range (mm) | DIN 3015 Part | Insert | Notes |
|---|---|---|---|---|
| Hydraulic pilot / drain | 6 – 12 | Part 1 or 2 | NBR | Use Part 2 near gear-mesh excitation |
| Hydraulic pressure (pitch) | 14 – 28 | Part 1 or 2 | NBR | 250 bar systems → Part 2 + M10 min. |
| Hydraulic return | 18 – 38 | Part 1 | NBR | Low pressure; Part 1 adequate |
| Gearbox cooling oil | 32 – 54 | Part 1 | NBR | Verify oil compatibility with compound |
| Water / glycol cooling | 28 – 76 | Part 1 | EPDM | EPDM mandatory — not NBR |
| Pneumatic control | 6 – 25 | Part 1 | EPDM | No oil contact; EPDM preferred |
| Tower cable conduit | 50 – 89 | Part 1 | EPDM | UV/ozone exposure → EPDM only |
| Offshore large bore | 60 – 89 | Part 2 | EPDM | A4 stainless bolts; verify ozone rating |
§ 05 Part 1 vs Part 2: Decision Logic
The two series are not interchangeable — Part 2 is not simply "better" than Part 1. Over-specifying Part 2 where Part 1 is sufficient adds cost and weight without benefit. The decision tree:
- Static load, standard vibration, non-structural → Part 1
- High vibration (nacelle gear-mesh, generator harmonics) → Part 2
- Hydraulic pressure ≥ 200 bar, OD ≥ 14 mm → Part 2
- Structural: clamp carries weight of pipe run → Part 2 with backing plate
- Offshore, long inspection interval → Part 2, A4 stainless hardware
- Two parallel pipes, same OD → Part 2 double-clamp variant
§ 06 Installation Torque Notes
The indicative torques in the tables above assume:
- Bolt property class 8.8, zinc-phosphate or zinc-plated finish (dry torque)
- Standard steel clamp body with EPDM or NBR insert, 60–70 Shore A
- No lubrication on bolt threads unless otherwise specified
Torque deviates in the following common situations:
- Stainless (A4-70) bolts — use anti-seize compound; reduce torque by ~10–15% or apply the value in the stainless supplier's table to achieve the same clamp force
- Harder insert (75+ Shore A) — torque may need to increase 10–20% to achieve the same radial grip; confirm with manufacturer
- Hot-dip galvanised bolts — thread interference from zinc build-up; use manufacturer's torque table for HDG fasteners
- Re-torquing after thermal cycling — initial torque loss of 10–25% (indicative) is normal after the first heat cycle as insert and plating relax; re-torque after first service interval