High-Quality PP Coated Backing Ring Flange for Electrofusion Pipe Fittings

Product Description

Product Description

Polypropylene Bolted Flange PP Coated Acid & Alkali Resistant, Ideal for Chemical and Water Treatment Piping

Zhejiang Fengfeng pipe's PP Coated Flange features a carbon steel/iron steel core fully encapsulated by a polypropylene (PP) coating. The coating uniformly covers the sealing face, bolt holes, and all external surfaces, ensuring zero metal exposure to corrosive environments. Allowing direct replacement of uncoated flanges without system modification. The PP Coated Flange is specifically designed for pipeline systems handling corrosive media. It is widely used in: Chemical plants (acid/alkali transfer lines) Water and wastewater treatment facilities Electroplating and metal finishing operations Pharmaceutical and food grade processing Marine and offshore saltwater systems Mining and metallurgical slurry pipelines By replacing standard uncoated flanges with PP coated flanges, users significantly extend pipeline service life and reduce maintenance costs associated with corrosion-related leaks and flange failures. No exposed metal, perfect for corrosive media like acids and alkalis. Used in chemical, water treatment, and electroplating pipelines. Standard size, direct replacement for uncoated flanges. Temp range -20°C to +120°C.

How to Install a PP Backing Ring Flange (PP Coated Flange)

1.Preparation Before Installation
Before installation, make sure all parts are clean and undamaged.
Check the following:
PP backing ring flange / Stub end / flange adapter / Gasket (if required) / Bolts, nuts, and washers / Pipe alignment
Important:
The flange sealing surface must be smooth and clean.
Remove dust, oil, or debris before assembly.
Ensure the pipe ends are aligned correctly to avoid leakage or stress.
2.Insert the Flange onto the Pipe
First, slide the PP backing ring flange onto the pipe.
Then:
Weld or connect the stub end/flange adapter to the pipe according to the pipe connection method:
Butt fusion / Electrofusion / Socket fusion / Compression connection
After welding, allow the joint to cool completely.
3. Position the Gasket
Place the gasket between the two flange faces if the system design requires one.
Requirements:
The gasket must be centered properly.
Do not allow the gasket to protrude into the pipeline.
Use suitable gasket material according to the working pressure and medium.
4. Align the Two Flanges
Bring the two flanges together carefully.
Ensure:
Bolt holes are aligned correctly.
The flange faces are parallel.
No excessive force is used to pull pipes into alignment.
Misalignment may cause:
Leakage
Uneven pressure
Damage to the flange or gasket
5. Install Bolts and Nuts
Insert all bolts through the flange holes.
Then:
Install washers and nuts.
Hand-tighten all bolts first.
Important:
Use appropriate bolt material for the application environment.
6. Tighten the Bolts in a Cross Pattern
Tighten the bolts gradually using a diagonal (cross) sequence.
This ensures even pressure distribution on the gasket.
Recommendations:
Tighten in 3–4 stages.
Do not fully tighten one bolt at a time.
Use a torque wrench when possible.
7. Final Inspection
After installation, inspect the system carefully.
Check:
Bolt tightness,Flange alignment,Gasket position,Possible leakage points
Then perform:
Hydrostatic pressure test
Leak test according to pipeline standards

Product Parameters

TECHNICAL PARAMETERS
Product Name	PP coated Backing Ring Flange (PP Coated Flange)
Function	flange
Main Materials	Iron ,Polypropylene(PP)
Application areas	Chemical, water treatment, electroplating, pharmaceutical, marine industries
Advantages	Compared to uncoated flanges, PP coated flanges provide excellent corrosion resistance (acids, alkalis, salts), lower lifecycle maintenance costs, more reliable sealing, and suitability for chemical, electroplating, wastewater, marine, and food/pharma applications. The initial cost is slightly higher, but the long-term savings are significant.
key features	Rust-free / Non-corrosive,Acid-proof / Alkali-resistant,Reliable sealing,Low maintenance,Long service life
Durability & Maintenance	Bolt with soft gasket, tighten in star pattern using torque wrench.

Detailed Photos

Product Structure

Key Properties

Core material:Carbon steel or ductile iron
Coating material:Polypropylene (PP)
Coating coverage:Fully encapsulated – sealing face, bolt holes, all external surfaces
Coating thickness:0.3mm – 1.5mm (coating) or 2mm – 5mm (full lining)
Face types:RF (Raised Face), FF (Flat Face), MFM, etc.
Standards:DIN, ANSI, JIS, GOST

Corrosion resistance:Resists acids, alkalis, salts, and chemical solvents
Temperature range:-20°C to +120°C
Pressure rating:PN10 / PN16 / Class 150
Rust-proof:PP coating prevents rust completely
Smooth surface:Non-stick, easy to clean
Electrical insulation:PP provides electrical isolation
Durable:Long service life in corrosive environments

Installation Method

Application

1. Inspection:Check PP coating for any damage before installation
2. Gasket:Use soft gasket (EPDM, NBR, or PTFE) – no metal gaskets
3. Bolt:Use stainless steel bolts to prevent galvanic corrosion
4. Tightening:Tighten in star/cross pattern using a torque wrench
5. Caution:Do not over-tighten – PP coating may crack

Chemical plants:Acid and alkali transfer pipelines
Water treatment:Wastewater and chemical dosing lines
Electroplating:Corrosive bath solution handling
Food & pharmaceutical:Food-grade PP for hygienic processing
Marine:Saltwater and offshore pipelines
Mining:Slurry and chemical processing

FAQ

1. Why choose us?
Factory Direct Pricing, Large Stock, Quality!
(1).Manufactuer: Fittings 20mm-1400mm, rated PN10-PN25.
(2).Custom branding & products, backed by three plants.
(3).Large inventory
(4).Competitive pricing with strict in-house quality control.
(5).Rapidly source and consolidate piping products.

2.What are common uses of HDPE/PE/PPR/PERT II pipe & fittings?
Zhejiang Fengfeng Pipe Industry's HDPE/PE/PPR/PERT II pipes & fittings are essential from construction materials to household products and agriculture. Their strength, durability, and versatility make them invaluable across industries. Used in urban and rural drinking water projects, sewage and wastewater systems, domestic and industrial wastewater pipelines, drainage and storm-water management, underground firewater pipelines, infrastructure, airports, ports, railways, highway drainage, sports venues, landscape irrigation, geothermal heating/cooling, solar/wind farm water piping, residential, commercial, municipal water networks, agricultural irrigation, greenhouse watering, gas distribution, low/medium-pressure natural gas pipelines, industrial piping, corrosion-resistant chemical processing, mining for slurry/water transport, power plants, and cooling systems.

3.What are the key benefits of Electrofusion Fitting?
Zhejiang Fengfeng Pipe Industry's electrofusion fittings form a zero-leakage, permanent joint through a precisely controlled process creating a homogeneous molecular bond. This is a fusion of materials into a single entity, not just a mechanical seal.

Detailed breakdown of the process and principles ensuring a leak-proof connection:

(1).Core Principle: Molecular Diffusion & Interfusion:
Thermal fusion with HDPE/PPR material at melt temperature (~200-220°C) transitions to a viscous state. Under pressure, polymer chains interdiffuse and entangle, forming a seamless material upon cooling.

(2).Step-by-Step Process to Ensure Zero Leakage

(3).The Role of "Smart" Technology in Guaranteeing Integrity:
Modern electrofusion involves stored data in fittings, read by intelligent welding units ensuring a leak-proof process:
Barcode/Data Matrix: Stores fitting-specific welding parameters (voltage, time, cool time).
Automatic Process Control: Welder reads code, executing cycle automatically, avoiding human errors.
Real-Time Monitoring & Rejection: Welder monitors parameters, aborting cycle if deviations occur, preventing defective joints.
Data Logging: Digital record (date, time, location, parameters) for traceability and proof of leak-proof installation.

(4).Comparison: Why Mechanical Fittings Can Leak:Electrofusion offers superior, permanent, leak-free performance:Feature Electrofusion Joint.Mechanical/Gasketed Joint.Sealing Mechanism Homogeneous molecular bond (pipe and fitting unite). Compression of elastomeric seal against pipe surface.Inherent Weakness None, if procedure followed correctly. Seal aging, hardening, and creep over time. Vibration and thermal cycling sensitivity causing bolts to loosen.Long-Term Performance Static or improves with crystallization. Lifetime equal to the pipe (50+ years). Degrades over time. Requires re-torquing and seal replacement.

Conclusion: The Guarantee of Zero Leakage
Zhejiang Fengfeng Pipe Industry's electrofusion joint is leak-proof, eliminating the potential leakage interface. It combines material science, precision engineering, and process intelligence for a joint that is intrinsically permanent, used in gas distribution, potable water mains, and chemical pipelines.

4.What is the Step of Process Purpose & Anti-Leak Mechanism?
Step 1: Surface Preparation Pipe end is scraped to reveal clean, virgin material, removing contamination that prevents molecular diffusion and weak bonds.

Step 2: Clamping & Alignment:
Pipe and fitting are clamped straight, aligned with a precise gap. Eliminates stress and misalignment that could cause voids or thin spots in the joint.

Step 3: Initiation & Heating:
Voltage is applied to the resistance wire coil in the fitting. Heats uniformly, melting both the fitting's inner surface and the pipe's outer surface. Creates a precise melt zone. Controlled heating prevents incomplete fusion and potential leaks.

Step 4: Melting & Interfusion:
Molten material merges under internal pressure from pipe expansion and fusion bead, ensuring intimate contact. Fusion bead fills gaps, compensating for surface irregularities, ensuring no voids.

Step 5: Controlled Cooling:
Power is cut. Joint cools naturally under restraint. Polymer chains solidify slowly, locking structure in place. Prevents stress cracks and maintains integrity under cyclic pressure and temperature changes.

5.What is HDPE?
High-Density Polyethylene (HDPE) is a thermoplastic from petroleum, known for its high strength-to-density ratio. Strong yet lightweight, HDPE is durable, impact-resistant, and withstands various conditions since the 1950s.
Using virgin HDPE raw materials from traceable sources is crucial for performance, safety, and value. For Zhejiang Fengfeng Pipe Industry, specifying prime resins from SHANGHAI JINFEI PETROCHEMICAL and ZHEJIANG PETROLEUM & CHEMICAL delivers measurable benefits.

(1).Guarantee of Core Performance & Long-Term Integrity
Virgin Material vs. Recycled/Off-Spec Material. Long-Term Hydrostatic Strength (LTHS) ensures fittings meet PE100/PE100RC classification, handling rated pressure for 50+ years. Recycled materials risk strength loss, test failures, and SCG, leading to bursts.

(2).Environmental Stress Crack Resistance (ESCR).Intact polymer structure offers superior chemical and stress resistance, extending lifespan in harsh environments. Low ESCR makes fittings weak, initiating cracks under stress.

(3).Consistent Electrofusion Quality Stable Melt Flow Rate (MFR) ensures uniform heating, inter-diffusion, and cooling during electrofusion, creating a strong bond. Contaminants cause uneven heating, poor fusion, and leaks.

(4).Dimensional Stability & Low-Temperature Toughness Predictable shrinkage for precise molding; retains impact resistance at -20°C, preventing brittle fracture. High warpage, poor tolerances, and brittleness lead to cracks during handling, installation, or freeze-thaw cycles.

6. Critical Value for Projects & Business:
(1).Risk Mitigation & Safety Assurance:
Role: In pipelines, a faulty fitting risks catastrophic failure. Virgin material is key to preventing systemic risks.
Value: Safeguards brand reputation, avoiding huge costs from liability claims, project failures, and environmental damage.

(2).Passport to International Certification & Markets:
Role: All top certifications (CE, ISO, WRAS) demand full traceability and certified raw material performance. Only virgin resin offers this.
Value: A prerequisite for entering regulated markets like the EU, Middle East, and North America.

(3)..Lowest Total Cost of Ownership:
Role: Though initial costs are higher, it ensures a maintenance-free, zero-replacement system for 50+ years.
Value: Dramatically reduces lifetime costs for owners and operators. A single repair (especially excavation) costs more than minor fitting price differences.

(4).Foundation for Credible Quality Commitment:
Role: Traceability to renowned petrochemical producers is a strong quality guarantee.
Value: Provides compelling technical proof in communications with engineers, contractors, and tender boards, significantly building trust and justifying a premium.

Conclusion: The Strategic Message
Using traceable, virgin raw materials sends a strong strategic message to clients, especially internationally:
Zhejiang Fengfeng Pipe Industry's reliability is molecularly engineered. We invest in higher material costs to protect your projects from decades of risk and potential catastrophic costs. This is a 50-year performance warranty.
This shifts the competitive narrative from price to value, responsibility, and risk management, establishing Zhejiang Fengfeng Pipe Industry as a critical infrastructure solutions provider, not just a commodity supplier.