Product Overview
PP duct elbow manufactured by one-piece injection molding — 45deg and 90deg direction-change fittings for industrial ventilation, exhaust, and process piping systems. Unlike fabricated elbows made by cutting and welding pipe segments, injection-molded elbows are produced as a single seamless piece with uniform wall thickness throughout the bend — no weld lines at the tangent points, no thinning at the extrados, no wrinkles at the intrados. Available in PP, PVC, and PPS materials for diameters from 15 mm to custom sizes.
| Application | Direction change in ventilation ductwork, exhaust systems, process piping, chemical drain lines, laboratory fume hood ducting |
| Material | PP (standard corrosion), PVC (rigid/UV), PPS (flame retardant / 200degC) |
| Angle | 45deg and 90deg standard; custom angles available |
| Diameter range | 15 mm to 500 mm (injection molded); larger sizes fabricated from PP/PVC/PPS sheet |
| Wall thickness | 2.5 mm to 8 mm depending on diameter |
| Connection | Butt-weld ends (standard); flanged ends (optional); socket ends (small diameters) |
| Color | Beige / Dark Grey / White |
| Lead time | 5-15 days standard; 15-20 days custom |
Why Injection-Molded Elbows Beat Fabricated
Fabricated elbows are made by miter-cutting pipe sections at an angle and welding them together. Each weld is a potential leak point. Each mitered joint creates a sharp internal edge that disturbs flow and increases pressure drop. Injection-molded elbows eliminate these problems:
- Smooth internal radius — no miter joints. A fabricated 90deg elbow typically uses three mitered segments (two 45deg cuts) with internal weld beads at each joint. These beads create turbulence, increase pressure drop, and trap debris. An injection-molded elbow has a continuous smooth internal radius from inlet to outlet — lower pressure drop, no debris traps, clean airflow.
- Uniform wall thickness around the bend. When a straight pipe is bent, the outer radius (extrados) thins and the inner radius (intrados) thickens or wrinkles. Fabricated elbows from cut-and-welded segments avoid this but introduce welds. Injection-molded elbows are formed with the bend geometry built into the mold — wall thickness is consistent at every point, verified by the mold design, not dependent on bending technique.
- No weld at the tangent. The tangent point where the bend meets the straight pipe is the highest-stress location in an elbow — thermal cycling and system vibration concentrate there. In a fabricated elbow, this is exactly where the weld sits. An injection-molded elbow has no weld at this critical location. This is particularly important for exhaust systems operating under negative pressure where weld failure means system leakage, directly relevant to EU Industrial Emissions Directive ductwork integrity requirements.
Why Xicheng
16 years, 2600+ systems shipped worldwide. Elbows seem simple but are one of the most failure-prone components in a duct system — the flow disturbance, pressure pulsation, and vibration all concentrate at direction changes:
- 45deg and 90deg from the same mold family. Our injection molds produce both angles in matching material, wall thickness, and dimensional tolerance — 45deg for gradual direction changes and vertical offsets, 90deg for sharp turns at risers, drops, and equipment connections. Both angles connect seamlessly to our straight pipe and duct sections with identical material properties.
- Round and square elbows available. Round elbows for circular duct systems (15-custom sizes). Square elbows for rectangular duct systems — injection molded for standard profiles, fabricated for custom cross-sections. Square-to-round elbow transitions for connecting rectangular branch ducts to round main ducts.
- Flanged or weld-end connection. Butt-weld ends for permanent installations where joint integrity is critical. Flanged ends for sections requiring periodic disassembly — equipment connections, clean-out access, future expansion points. Socket ends for small-diameter (under 200 mm) slip-fit assembly.
Send your duct layout showing direction changes to xicheng023@outlook.com. We’ll specify elbow angles, connection types, and provide a complete fittings schedule.
Core Advantages
- One-Piece Injection Molded Bend: Smooth internal radius — no miter joints, no internal weld beads, no debris traps, lower pressure drop than fabricated elbows.
- No Weld at the Tangent Point: The highest-stress location is solid, continuous material — not a weld seam vulnerable to thermal cycling and vibration.
- 45deg and 90deg, Round and Square: Full range of angles and cross-sections from a single manufacturer — matching material and dimensions to your straight duct.
- Three Material Options: PP for general corrosion, PVC for rigid UV-stable, PPS for fire-rated and high-temperature to 200degC.
- Flanged or Weld-End: Connection type matched to your installation method — permanent welded or serviceable flanged.
Key Specifications
| Material | PP / PVC / PPS — virgin resin, injection molded |
| Angle | 45deg and 90deg standard |
| Diameter Range | 15 mm – 500 mm (injection molded); fabricated larger (injection molded); larger sizes fabricated |
| Wall Thickness | 2.5 – 8 mm |
| Connection Type | Butt-weld, flanged, or socket |
| Operating Temperature | PP: -10 to 80degC | PVC: 0 to 60degC | PPS: up to 200degC |
| Service Life | 10-15 Years |
| Brand / Origin | Xicheng / China |
Certifications and Compliance
- CE Certified – PP Elbow, Duct, Fittings
- RoHS Compliant – All materials
- ISO 9001 – Quality Management System
- ISO 14001 – Environmental Management System
- SGS Tested – PP material properties, weld integrity, dimensional accuracy
- Design Compliance – Fittings designed to meet EU Industrial Emissions Directive (2010/75/EU) for leak-tight industrial exhaust ductwork systems
How to Order
- You send – Elbow angle (45deg/90deg), diameter, material preference, connection type, quantity
- We confirm – Diameter within mold range, material availability, lead time, and pricing
- We produce – 5-15 days. Injection molded, dimensional inspection before shipment
Contact xicheng023@outlook.com or WhatsApp +86 18927456906 — quotation within 24 hours.
Complete Your System
- PP Industrial Pipe – Straight pipe sections for your system
- PP Round Duct – Round ventilation duct
- PP Duct Tee – Tee fittings for duct branching
- PP Duct Reducer – Diameter transition fittings
FAQ
45deg or 90deg elbow — which should I use?
Use 45deg elbows where space allows — they have roughly half the pressure drop of a 90deg elbow. For a 90deg direction change, two 45deg elbows with a short straight section between them is more efficient than a single 90deg elbow, though it requires more space. Use single 90deg elbows where space is tight — at risers, drops, and equipment connections where a sharp turn is unavoidable.
Are injection-molded elbows compatible with extruded pipe?
Yes — the outside diameter and wall thickness of our injection-molded elbows match standard pipe dimensions. Butt-weld connection to extruded or injection-molded straight pipe is straightforward. If connecting to another manufacturer’s pipe, confirm the OD and wall thickness match before ordering.
Do you make custom angle elbows?
Yes — 30deg, 60deg, and other angles are available as fabricated elbows from PP/PVC/PPS sheet with full-penetration welding. For non-standard angles at small quantities, fabrication is more cost-effective than building a dedicated injection mold.
