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PP-STEEL Flange

Corrosion-Resistant Backing Ring for HDPE and PP Flange Connections

PP-Coated Steel Backing Flange, also known as PP-Steel Backing Ring or PP-Coated Steel Flange, is designed for detachable flange connections in HDPE and PP piping systems.

The product combines the mechanical strength of a carbon-steel core with the corrosion resistance of a polypropylene coating. It is used together with an HDPE or PP stub end, flange adaptor, gasket and bolting set to connect plastic pipelines to valves, pumps, tanks, steel pipes, ductile iron pipes and other flanged equipment.

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Core Parameters

  • Raw Materials – PP, carbon steel

    Diameter:  DN15-630mm (1/2 inch-24 inch)

    Pressure Rating:PN10, PN16,ASME B16.5 Class150

    Supply capacity: 3 × 40 feet per week container.

    Standards:GB/9119-2010; ISO 7005-1:1992; DIN 2501; DIN 2576

    The steel core carries the bolt load, while the PP coating isolates the steel from moisture, soil and many corrosive environments. This makes the backing flange a practical solution for water supply, irrigation, chemical processing, mining and industrial pipeline systems.


    Available from DN15 to DN630 mm, with PN10, PN16 and ANSI/ASME B16.5 Class 150 drilling patterns. Customized dimensions, hole patterns, coating options and markings are available on request.

    Factory pricing. Global compliance. Ready to supply. Get your quote.

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  • A PP-Coated Steel Backing Flange is a loose mechanical support ring used in HDPE and PP flange assemblies. It slides over the plastic pipe before the stub end or flange adaptor is welded to the pipe.


    After the welded joint has cooled, the backing flange is moved behind the stub-end collar. A compatible gasket is placed between the two flange faces, and bolts are tightened evenly to connect the HDPE or PP pipeline to a mating flange.


    The backing flange does not provide the seal by itself. Its main function is to distribute bolt loads around the stub-end collar and provide the correct bolt-hole pattern for the mating flange. The PP coating helps protect the steel core from corrosion in demanding environments.

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Product Features

    • ✅Steel-core backing flange with polypropylene protective coating
    • ✅Designed for HDPE and PP stub ends or flange adaptors
    • ✅Provides mechanical support for bolted flange joints
    • ✅PP coating improves corrosion and chemical resistance
    • ✅Available in PN10, PN16 and ANSI/ASME B16.5 Class 150 patterns
    • ✅Standard size range from DN15 to DN630 mm
    • ✅Suitable for detachable pipe-to-equipment connections
    • ✅Compatible with pumps, valves, tanks and metal pipe systems
    • ✅Customized drilling standards and dimensions available
    • ✅Suitable for water, irrigation, mining and industrial applications

Please send your request to the email address:sales@mfgpipe.com (We will respond to you within 24 hours).

Technical Specifications

Item Specification
Product name PP-Coated Steel Backing Flange
Alternative name PP-Steel Backing Ring / PP-Coated Steel Flange
Application For HDPE or PP stub ends and flange adaptors
Size range DN15–630 mm / 1/2 inch–24 inch
Core material Carbon steel
Surface coating Polypropylene (PP) coating
Optional coating Glass-fibre-reinforced PP coating, subject to confirmation
Pressure patterns PN10, PN16, ANSI/ASME B16.5 Class 150
Metric standards EN 1092-1, ISO 7005-1, DIN 2501, DIN 2576, GB/T 9119, or customized
ANSI standard ANSI/ASME B16.5 Class 150
Connection method Bolted flange connection
Compatible components HDPE/PP stub end, flange adaptor, gasket, bolts, nuts and washers
Customization Size, bore, thickness, hole pattern, coating, labels and packaging
Sample Available on request

Typical Size Combinations

SIZE DN K n D B d h
1/2" 20 60 4 98 32 16 14
3/4" 25 70 4 108 37 16 14
1" 32 79 4 120 44 16 14
11/4" 40 89 4 140 52 16 16
11/2" 50 98 4 150 63 16 16
2" 63 121 4 165 78 20 20
21/2" 75 140 4 185 92 20 20
3" 90 152 4 200 108 20 22
4" 110 191 8 230 128 20 22
[4"] 125B 191 8 230 140 20 22
5" 125 216 8 260 140 23 24
[5"] 140 216 8 260 158 23 24
6" 160 241 8 286 178 23 26
[6"] 180 241 8 286 195 23 26
8" 200 298 8 345 235 23 28
[8"] 225 298 8 345 240 23 28
10" 250 362 12 410 288 26 30
[10"] 280 362 12 410 294 26 30
12" 315 432 12 485 345 26 35
14" 355 476 12 535 376 30 40
16" 400 540 16 600 430 30 40
18" 450 578 16 640 470 32 45
20" 500 635 20 700 533 32 45
22" 560 692 20 760 590 35 50
24" 630 749 20 820 645 35 50

Note: Special specifications are available upon request. Please contact us for further product information and pricing.

Please send your request to the email address:sales@mfgpipe.com (We will respond to you within 24 hours).

Applications

PP-Coated Steel Backing Flanges are suitable for:

  • ✅HDPE and PP water-supply systems
  • ✅Irrigation and agricultural pipelines
  • ✅Water-treatment and wastewater-treatment plants
  • ✅Chemical and industrial fluid-transfer systems
  • ✅Mining and slurry pipelines
  • ✅Pump, valve and flow-meter connections
  • ✅Tank, vessel and manifold connections
  • ✅Plastic-to-metal pipeline transitions
  • ✅Underground and outdoor pipeline installations

 

Flange Assembly Components

 

  • A complete HDPE or PP flange connection usually includes:

    1. 1. HDPE or PP pipe
    2. 2. PP-coated steel backing flange
    3. 3. HDPE or PP stub end / flange adaptor
    4. 4. Compatible gasket
    5. 5. Mating flange, valve, pump, tank or equipment
    6. 6. Bolts, nuts and washers

 

Installation Guidelines

 

  • ✅Confirm the pipe size, flange standard, pressure class and bolt-hole pattern.
  • ✅Slide the PP-coated steel backing flange over the pipe before welding the stub end.
  • ✅Butt-fuse the HDPE or PP stub end to the pipe according to the approved fusion procedure.
  • ✅Allow the fusion joint to cool completely.
  • ✅Position the backing flange behind the stub-end collar.
  • ✅Place a compatible gasket between the flange sealing faces.
  • ✅Align the bolt holes with the mating flange.
  • ✅Insert bolts, washers and nuts.
  • ✅Tighten bolts gradually in a star pattern to ensure even gasket compression.
  • ✅Avoid excessive bolt torque, which may damage the gasket, PP coating or thermoplastic stub end.

 

Why Choose Our PP-Coated Steel Backing Flange?

  • ✅Combines steel strength with PP corrosion protection
  • ✅Supports detachable HDPE and PP pipeline connections
  • ✅Available in metric and ANSI drilling standards
  • ✅Suitable for PN10, PN16 and Class 150 applications
  • ✅More corrosion resistant than untreated carbon steel
  • ✅Flexible custom size, coating and hole-pattern service
  • ✅Suitable for valves, pumps, tanks and industrial equipment connections
  • ✅Export-ready packing and responsive quotation support

 

Frequently Asked Questions

 

What is a PP-coated steel backing flange?

It is a steel backing ring covered with polypropylene coating, used with an HDPE or PP stub end to create a detachable bolted flange connection.

 

Does the PP-coated backing flange provide the seal?

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.

 

What is the difference between PN10, PN16 and Class 150?

PN10 and PN16 are metric pressure classes with corresponding EN or ISO bolt patterns. Class 150 uses ANSI/ASME bolt patterns. Always confirm the required standard before ordering.

 

Can this product be used outdoors?

Yes, provided the selected PP coating, UV resistance, operating temperature and environmental conditions are suitable for the project.

 

Can you provide customized hole patterns?

Yes. EN, ISO, DIN, GB, ANSI and customized drilling patterns can be manufactured according to the project drawing or specification.

 

Request a Quote

 

Please provide:

  • ✅HDPE or PP pipe outside diameter
  • ✅Stub-end or flange-adaptor size
  • ✅Required standard: PN10, PN16 or Class 150
  • ✅Required bolt-hole pattern
  • ✅Application and operating medium
  • ✅Quantity and destination port
  • ✅Project drawing or technical specification, if available

Contact us today for drawings, samples, technical support and pricing.

Please send your request to the email address:sales@mfgpipe.com (We will respond to you within 24 hours).

 

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