🧩 PE-HD – High-Density Polyethylene
(Weldable rigid and highly resistant plastic, used in tanks, guards, covers, and technical parts exposed to high stress)
🔹 What is PE-HD
PE-HD (High-Density Polyethylene) is a high-density polyethylene with a linear and compact molecular structure that provides high hardness, excellent mechanical strength, and exceptional chemical stability.
It is one of the most durable plastics used in industry and automotive sectors, resistant to oils, fuels, water, acids, and mechanical shocks. In the automotive repair field, PE-HD is found in tanks, underbody protections, and thick technical parts where rigidity and leak-tightness are required.
🔧 Composition
- Ethylene (CH2) – polymerized under low pressure with catalysts
- Additives – UV stabilizers, antioxidants, anti-static agents, colorants
- Density: 0.94–0.97 g/cm³
- Melting point: ≈ 130–135 °C
🚗 Where PE-HD is used in the automotive industry
| Component | Example parts | Observations |
| Exterior | Mudguards, housings, lower guards | Impact and chemical resistant |
| Engine Compartment | Fluid tanks, battery cases | Thermally stable and impermeable |
| Technical Interior | Panels, thick covers, support parts | Hard but relatively lightweight |
| Aftermarket | Auxiliary tanks, boxes, liner protectors | Easy to weld and process |
🔧 Welding temperatures and methods
| Method | Optimal temperature | Observations |
| Hot air | 260 – 280 °C | Clean and controlled welding |
| Heat plate (mirror) | 250 – 270 °C | Recommended for flat joints |
| Manual extrusion | 240 – 260 °C | For high thicknesses or corners |
| Electrofusion | — | Ideal for pipes and thick tanks |
🔩 What to weld PE-HD with (Material compatibility)
The question “what to weld PE-HD with” frequently arises in repairs of tanks and technical covers. The material is fully compatible only with other types of polyethylene, especially of similar density.
✅ Compatible:
- PE-HD ↔ PE-HD – ideal combination (identical to original material)
- PE-HD ↔ PE-MD / PE-LLD – very good compatibility
- PE-HD ↔ PE-LD – partial compatibility (risk of shrinkage)
❌ Incompatible:
- PP, ABS, ASA, PC, PA, PVC – will not bond, different melting points
💡 ReplastMD Recommendation:
Use original PE-HD welding rods at a temperature of 270–280 °C. Clean the oxidized area (with a knife or fine sandpaper), degrease with isopropyl alcohol, and apply constant pressure for a full and watertight weld.
🏭 Manufacturers and trade names
- LyondellBasell: Lupolen® HD
- Borealis: Borstar® HD
- SABIC: HDPE Series
- ExxonMobil: Escorene® HD
🧠 How to identify PE-HD
- Engraved marking: >PE-HD<, >HDPE<, >PE High Density<
- Semi-glossy surface, hard, rigid
- Yellow-blue flame, paraffin smell
- Floats in water (density ≈ 0.95 g/cm³)
- Softens uniformly at 270 °C, without smoke or bubbles
🛠️ PE-HD Welding at ReplastMD:
At our service center in Chisinau (Ciocana sector), ReplastMD performs professional PE-HD welding for:
- tanks, covers, lower guards, and mudguards
- structural repairs, cracks, and broken corners
- consolidation for leak-tightness and rigidity
- matte, uniform finish with original strength restored