Most procurement specifications for wind turbine hydraulic and pitch-control piping reference "DIN 3015" without specifying which part — yet Part 1 and Part 2 carry significantly different load ratings and fastening geometries. Selecting the wrong series does not cause immediate failure under normal conditions; it causes failure during a pressure surge or vibration event, when it is too late to retrofit.
§ 01 What DIN 3015 covers
DIN 3015 is a German standard specifying pipe clamps for hydraulic and pneumatic systems. It defines clamp geometry, dimensional tolerances, bolt patterns and material options for securing single pipelines to a structural support surface — typically a steel rail, Unistrut channel or welded bracket inside a wind turbine tower.
The standard is divided into three parts, each addressing a distinct function:
- Part 1 — single-bolt clamp bodies (light series, LS)
- Part 2 — twin-bolt clamp bodies (heavy series, HS)
- Part 3 — cushion insert elements that fit inside Part 1 or Part 2 bodies
Parts 1 and 2 are interchangeable on the same mounting rail — they share the same base flange geometry — which means you can mix series on a single cable tray without changing the rail. Part 3 inserts are sized to match the pipe OD and are selected independently of the clamp body series.
§ 02 Part 1 — Light series (single bolt)
Light Series — Single Central Bolt
LSThe Part 1 body uses a single M8 or M10 bolt on the centreline of the clamp. The two halves of the body are hinged or separated and drawn together by this single fastener. The geometry is compact and the installed weight is low — important in areas of the tower where multiple small-bore lines run in dense parallel groups.
Suited for:- Hydraulic control and pilot lines (low to medium flow rates)
- Pitch-control hydraulic circuits where pipe OD is typically 6–42 mm
- Instrumentation and sensing lines throughout the nacelle and tower
- Locations where weight and compactness outweigh maximum load capacity
- Main hydraulic supply and return lines at operating pressures above ~200 bar on larger bore pipes
- High-vibration zones adjacent to pumps or actuators without supplementary damping
§ 03 Part 2 — Heavy series (twin bolt)
Heavy Series — Two Flanking Bolts
HSThe Part 2 body places two M8 or M10 bolts symmetrically on either side of the pipe rather than on the centreline. This arrangement produces higher and more uniform clamping force around the pipe circumference, significantly increasing resistance to both axial displacement and vibration-induced fatigue loosening.
The two-bolt geometry also distributes the load across a larger footprint of the mounting rail, reducing point stress on the rail and the clamp base. For pipes carrying high-pressure fluid with pulsating flow — as in most wind turbine main hydraulic circuits — the Part 2 body is the standard choice.
Suited for:- Main hydraulic supply and return lines (160–250 bar operating pressure in wind turbine towers)
- All pipe runs adjacent to hydraulic pump units and proportional valve manifolds
- Larger bore pipes (OD > 42 mm) where clamping force from a single bolt is insufficient
- Any line where flow pulsation or pump-induced vibration is present
- Extremely space-constrained installations where Part 1 compactness is required
§ 04 Part 3 — Cushion insert elements
Part 3 of DIN 3015 does not define a clamp body. It defines the cushion insert — the elastomeric lining element that sits between the metal or engineering-polymer clamp body and the outside surface of the pipe.
The insert performs three functions simultaneously:
- Vibration isolation — the elastomeric material absorbs high-frequency vibration transmitted from pump pulsation into the pipe wall, preventing fatigue cracking at the clamp contact points;
- Galvanic separation — an EPDM or neoprene insert electrically isolates a carbon-steel pipe from a stainless-steel or aluminium clamp body, eliminating the bimetallic corrosion cell;
- Surface protection — prevents fretting wear and coating damage on coated or lined pipes under dynamic load.
Inserts are sized to the pipe OD independently of the body series. A Part 3 insert sized for 42 mm OD fits equally into a Part 1 or Part 2 body of the matching bore. The insert material must be specified separately: EPDM for general and offshore use, NBR where petroleum-based hydraulic fluid contact is possible, silicone for high-temperature zones above 100 °C.
§ 05 Part 1 vs. Part 2 — the decision rules
The two most common specification errors are: using Part 1 where Part 2 is required (under-specification), and specifying Part 2 everywhere to avoid thinking about it (over-specification that adds weight and cost without benefit). The correct approach uses four decision criteria:
| Criterion | Use Part 1 (LS) | Use Part 2 (HS) |
|---|---|---|
| Operating pressure | Control / pilot lines, ≤ 100 bar on small bore | Main circuits, 160–250 bar, any bore |
| Pipe OD | Typically ≤ 42 mm | ≥ 42 mm, or any OD with pulsating flow |
| Vibration environment | Low — remote from pumps and actuators | Moderate to high — pump room, valve manifolds |
| Space constraint | Dense multi-pipe runs, limited rail width | Standard rail spacing available |
When in doubt, Part 2 is the conservative choice. The cost premium over Part 1 is modest; the cost of an in-service failure due to under-specification is not.
§ 06 Material grades across both series
Both Part 1 and Part 2 bodies are available in the same three material grades. The standard does not mandate a material — it specifies geometry. The grade selection follows the installation environment:
- Engineering nylon (PA66-GF) — glass-fibre reinforced polyamide; standard grade for onshore towers where temperature is below 80 °C and corrosion category is C3 or lower. Non-metallic, lightweight, non-magnetic by nature;
- Aluminium alloy — significantly higher mechanical strength than nylon; suited to C3–C4 onshore environments, all large-bore hydraulic lines, and any location where temperature may exceed the nylon limit;
- 316L stainless steel — mandatory for offshore (C5-M) and coastal installations; the molybdenum content provides chloride-pitting resistance that aluminium alloy cannot match in sustained marine exposure. All fasteners should match: A4-80 grade.
The insert material is independent of the body grade. A 316L stainless body with an EPDM Part 3 insert is the standard specification for offshore wind hydraulic lines.
§ 07 Quick reference
Part 2 (HS) → twin flanking bolts · high clamping force · main circuits · pulsating flow
Part 3 → insert element only · vibration isolation + galvanic separation + surface protection
Material → nylon (C1–C3 onshore) / aluminium (C3–C4) / 316L SS (offshore C5-M)
Rail compatibility → Part 1 and Part 2 share the same base flange — mix freely on one rail
For the full six-parameter selection framework that integrates DIN 3015 series choice with kA withstand rating, installation spacing and environment, see Cable Cleat Selection Parameters.