Flange Plate — PP and PVC Duct Flange Disc
A flange plate is the simplest component in any duct connection system: a flat PP or PVC disc with a center bore sized to the duct diameter and a ring of bolt holes on a specified circle. It is welded to the end of a duct section and provides the sealing face that mates with an identical flange on the adjacent section. No weld neck. No socket. Just the plate.
Xicheng manufactures flange plates in polypropylene and PVC. Standard diameters with ANSI, DIN, or JIS bolt circles up to 500 millimeters are injection-molded — the center bore, bolt holes, and both sealing faces formed in one mold cycle. Custom diameters, non-standard bolt patterns, and rectangular flange plates for square ductwork are fabricated from PP or PVC sheet.
When you need to add a flanged connection to the end of a straight duct section, this is the fitting. Weld it on. Bolt it up. The gasket does the rest.
The Simplest Part That Can Fail an Entire System
A flange plate has three features: a flat face, a center hole, and a bolt circle. If the face is not flat, the gasket compression is uneven and the joint leaks at the low spot. If the center hole diameter is incorrect, the duct will not fit. If any bolt hole is mispositioned by more than a millimeter, the bolt will not pass through both mating flanges simultaneously.
An injection-molded flange plate eliminates these variables for standard sizes. The bolt circle is formed by fixed pins in the mold — identical on every part. The sealing faces are formed by the mold surfaces — flat within 0.2 millimeters with no post-molding facing required. The center bore is concentric with the bolt circle because both are formed in the same tooling.
For non-standard diameters or bolt patterns, fabricated flange plates are cut from PP or PVC sheet, the center bore is cut out, and bolt holes are drilled to the customer’s pattern. The plate is then welded to the duct end by the installer or — if specified — pre-welded to a duct stub at the factory.
Technical Specifications
| Parameter | Specification |
|---|---|
| Material | Virgin-grade PP (Polypropylene), PVC |
| Type | Flat flange plate — weld-on |
| Round — Standard | ANSI 150, DIN, JIS bolt patterns |
| Round — Injection-Molded | Single-piece, up to 500mm |
| Rectangular | Fabricated to customer dimensions |
| Density (PP) | 0.90 to 0.91 g/cm3 |
| Operating Temperature (PP) | -10-degrees-Celsius to 90-degrees-Celsius |
| Operating Temperature (PVC) | 0-degrees-Celsius to 60-degrees-Celsius |
| Certifications | ISO 9001, ISO 14001; SGS tested |
| Custom | Non-standard diameters, bolt patterns, rectangular plates |
Frequently Asked Questions
Q: How is a flange plate different from a weld neck flange?
A: A flange plate is a flat disc with a center bore — no integral pipe stub. You weld it directly to the end of your duct. A weld neck flange has an integral stub that butt-welds to the duct, providing a stronger connection. Flange plates are simpler and lower cost. Weld neck flanges are preferred for larger diameters and higher loads.
Q: Can you produce a rectangular flange plate for square duct?
A: Yes. Send us the duct internal cross-section, wall thickness, and desired bolt spacing. We fabricate a rectangular flange plate to your dimensions.
Q: What is the lead time?
A: Standard injection-molded flange plates ship within 5 to 7 working days. Fabricated plates require 7 to 14 working days.
Send us the duct diameter, drilling standard, and exhaust gas composition. You will have a quotation within 48 hours.
Contact Xicheng Environmental Today.
- 🎯 Address: No.34 Zhenxing Road (Shengtaian Heavy Industrial Park B), Loucun, Guangming New Dist, Shenzhen, Guangdong, China
- ☎️ Phone/WhatsApp: +86 18126478161
- 🗺️ Email: fanalax@gmail.com
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