Class 150 Ductile Iron Backing Flange for HDPE and PP Pipe Systems
Ductile Iron Backing Flange, also known as a ductile iron backing ring or backup ring, is used with HDPE or PP stub ends and flange adaptors to create strong, detachable bolted pipeline connections.
WhatsApp: 8615515833787 WeChat: 15515833787Size – DN75-630mm (Can Be Customized)
Pressure rating : SDR11-PN16 Bar, SDR13.6-PN12.5 Bar, SDR17-PN10 Bar, SDR21-PN6 Bar, SDR26-PN6 Bar
Raw materials:High Quality PE80 Or PE100 Raw Materials
Supply capacity: 3 × 40 feet per week container.
Certificate:ISO 14001, ISO 9001, OHSAS 18001, CE BS EN 12001 Certification
The backing flange slides over the pipe before the HDPE or PP stub end is fused to the pipe. Once the fusion joint has cooled, the ductile iron ring is positioned behind the stub end collar. Bolts then connect the assembly to a mating flange on a valve, pump, tank, steel pipe or other flanged equipment.
Made from ductile iron and available with painted or fusion-bonded epoxy coating, our backing flanges provide reliable mechanical support for HDPE and PP piping systems.
Standard ANSI/ASME B16.5 Class 150 drilling patterns are available from 1 inch to 24 inches, with customized dimensions and standards available on request.
Factory pricing. Global compliance. Ready to supply. Get your quote.
A Ductile Iron Backing Flange is a loose mechanical support ring used in HDPE and PP flange assemblies. It provides the bolt-hole pattern and load-bearing structure required to connect a thermoplastic pipeline to flanged equipment.
During installation, the backing flange is first placed over the pipe. The HDPE or PP stub end is then butt-fused to the pipe. After cooling, the backing flange is moved into position behind the stub end collar. A suitable gasket is placed between the mating flange faces, and the bolts are tightened evenly to form the connection.
The ductile iron backing flange distributes bolt loads around the stub end collar and helps prevent excessive local stress on the thermoplastic component. It does not itself create the seal; correct gasket selection, flange alignment and bolt tightening are essential.
| Item | Specification |
| Product name | Ductile Iron Backing Flange |
| Alternative name | Ductile Iron Backing Ring / Backup Ring |
| Application | For HDPE or PP stub ends and flange adaptors |
| Size range | 1 inch–24 inches |
| Material | Ductile iron, ASTM A536 grade subject to confirmation |
| Standard drilling pattern | ANSI/ASME B16.5 Class 150 |
| Optional drilling patterns | ANSI/ASME B16.47, AWWA C207, EN 1092-1, AS 4087, JIS or customized |
| Surface finish | Painted, fusion-bonded epoxy coated or customized coating |
| Connection method | Bolted flange connection |
| Compatible components | HDPE/PP stub end, flange adaptor, gasket, bolts, nuts and washers |
| Customization | Bore size, thickness, drilling pattern, coating, marking and packaging |
| Sample | Available on request |
| Size | Pressure | SDR | Type | OD | ID | T | Bolt No. | Bolt Hole Dia | Bolt Hole Circle |
| B.D. | B.C. | ||||||||
| 1" | 267 PSI | 7 | C | 4.25 | 1.38 | 0.56 | 4 | 0.63 | 3.12 |
| 1 1/4" | 267 PSI | 7 | C | 4.62 | 1.72 | 0.63 | 4 | 0.63 | 3.5 |
| 1 1/2" | 267 PSI | 7 | C | 5 | 1.97 | 0.69 | 4 | 0.63 | 3.88 |
| 2" | 267 PSI | 7 | C | 6 | 2.46 | 0.75 | 4 | 0.75 | 4.75 |
| 2 1/2" | 267 PSI | 7 | C | 7 | 2.97 | 0.88 | 4 | 0.75 | 5.5 |
| 3" | 267 PSI | 7 | C | 7.5 | 3.6 | 0.94 | 4 | 0.75 | 6 |
| 4" | 267 PSI | 7 | C | 9 | 4.6 | 0.94 | 8 | 0.75 | 7.5 |
| 5" | 267 PSI | 7 | C | 10 | 5.69 | 0.94 | 8 | 0.88 | 8.5 |
| 6" | 267 PSI | 7 | C | 11 | 6.75 | 1 | 8 | 0.88 | 9.5 |
| 8" | 267 PSI | 7 | C | 13.5 | 8.75 | 1.12 | 8 | 0.88 | 11.75 |
| 10" | 267 PSI | 7 | C | 16 | 10.92 | 1.19 | 12 | 1 | 14.25 |
| 12" | 267 PSI | 7 | C | 19 | 12.92 | 1.5 | 12 | 1 | 17 |
| Size | Pressure | SDR | Type | OD | ID | T | Bolt No. | Bolt Hole Dia | Bolt Hole Circle |
| B.D. | B.C. | ||||||||
| 2" | 160PSI | 11 | B | 6 | 2.64 | 0.51 | 4 | 0.75 | 4.75 |
| 3" | 160PSI | 11 | B | 7.5 | 3.75 | 0.53 | 4 | 0.75 | 6 |
| 4" | 160PSI | 11 | B | 9 | 4.8 | 0.55 | 8 | 0.75 | 7.5 |
| 6" | 160PSI | 11 | B | 11 | 6.9 | 0.63 | 8 | 0.88 | 9.5 |
| 8" | 160PSI | 11 | B | 13.5 | 8.9 | 0.87 | 8 | 0.88 | 11.75 |
| 10" | 160PSI | 11 | B | 16 | 11 | 0.98 | 12 | 1 | 14.25 |
| 12" | 160PSI | 11 | B | 19 | 13.15 | 1.26 | 12 | 1.13 | 18.75 |
| 14" | 160PSI | 11 | B | 21 | 14.4 | 1.38 | 12 | 1.13 | 21.25 |
| 16" | 160PSI | 11 | B | 23.5 | 16.4 | 1.65 | 16 | 1.13 | 21.25 |
| 18" | 160PSI | 11 | B | 25 | 18.4 | 1.69 | 16 | 1.25 | 22.75 |
| 20" | 160PSI | 11 | B | 27.5 | 20.5 | 1.81 | 20 | 1.25 | 25 |
| 22" | 160PSI | 11 | B | 29.5 | 22.5 | 2.01 | 20 | 1.38 | 27.25 |
| 24" | 160PSI | 11 | B | 32 | 24.5 | 2.17 | 20 | 1.38 | 29.5 |
| Size | Pressure | SDR | Type | OD | ID | T | Bolt No. | Bolt Hole Dia | Bolt Hole Circle |
| B.D. | B.C. | ||||||||
| 2" | 267 PSI | 7 | B | 6 | 2.63 | 0.75 | 4 | 0.75 | 4.75 |
| 3" | 267 PSI | 7 | B | 7.5 | 3.75 | 0.94 | 4 | 0.75 | 6 |
| 4" | 267 PSI | 7 | B | 9 | 4.75 | 0.94 | 8 | 0.75 | 7.5 |
| 6" | 267 PSI | 7 | B | 11 | 6.88 | 1 | 8 | 0.88 | 9.5 |
| 8" | 267 PSI | 7 | B | 13.5 | 8.88 | 1.12 | 8 | 0.88 | 11.75 |
| 10" | 267 PSI | 7 | B | 16 | 11 | 1.19 | 12 | 1 | 14.25 |
| 12" | 267 PSI | 7 | B | 19 | 13.13 | 1.5 | 12 | 1 | 17 |
Note: Special specifications are available upon request. Please contact us for further product information and pricing.
Ductile Iron Backing Flanges are suitable for:
A typical HDPE or PP flange connection includes:
It is used with an HDPE or PP stub end or flange adaptor to create a detachable bolted connection to a valve, pump, tank or other flanged equipment.
No. The seal is created by the stub-end sealing face and a compatible gasket. The backing flange provides mechanical support and bolt-hole alignment.
Ductile iron generally provides better toughness and impact resistance than gray cast iron, making it suitable for mechanically loaded flange assemblies.
It may be reused if it is free from cracks, corrosion, deformation and damaged bolt holes. Inspect it before reinstallation.
Yes. Customized ANSI, AWWA, EN, AS and JIS drilling patterns can be supplied according to drawings or project requirements.
Please provide the following details:
Contact us today for drawings, samples, technical information and pricing.
