UK Water Treatment Custom FRP Flange/Tee/Elbow Case Study

Project Overview

Client Background & Needs

The client is a global water treatment engineering company with operations in the UK, South Africa, the US and beyond. Its projects span municipal water supply, sewage treatment and industrial water systems, where pipe connectors demand high corrosion resistance, pressure capacity and dimensional accuracy.

The client sought a China supplier able to build to drawing glass-reinforced plastic (FRP) flanges, double-flange tees and double-flange elbows. The parts had to withstand high-pressure conditions (1.2 MPa to 3 MPa), and some flanges needed a threaded port to connect hoses or instruments on site.

Custom Metal Molds: From Drawing to Tooling

Because the specifications were non-standard, the client commissioned us to build dedicated metal molds. Rather than simply copying the drawings, we reviewed the actual installation environment, medium flow rate and bolt pre-tension, then proposed optimizations for neck thickness, sealing-face angle and stiffener layout before finalizing the tooling.

The custom metal flange mold being machined to ensure cavity precision

Finished metal mold, ready for volume production of custom FRP flanges

Product Solution: Threaded Flanges & Double-Flange Fittings

Based on the client’s drawings and our optimized scheme, we supplied the following FRP pipe connectors:

• Threaded flange: one side carries a threaded port for direct hose or instrument connection, enabling fast on-site assembly.
• Double-flange tee: three flanged ends for main-pipe branching, with even pressure distribution and reliable sealing.
• Double-flange elbow: two flanged ends to change pipeline direction, suited to corners in water treatment layouts.

Finished custom FRP flange featuring a threaded port design

Custom FRP flanges with double-flange tee and elbow for high-pressure water lines

Material & Pressure Rating

The products use a vinyl ester resin FRP system. Compared with ordinary unsaturated polyester resin, vinyl ester offers superior resistance to acids, alkalis and chloride ions — ideal for water treatment and chemical environments. By controlling fiber lay-up angle and wall thickness, the pressure capability covers 1.2 MPa to 3 MPa.

Hydrostatic pressure test validating high-pressure sealing performance

Production & Quality Control

Each part is molded in the metal tool by hand lay-up or filament winding, then after cure and demolding goes through surface finishing, dimensional inspection, gel-coat spraying and hydrostatic testing — ensuring every shipment meets drawings and service requirements.

FRP tee production — flange face formed in one shot

Gel-coat spraying improves corrosion resistance and surface finish

Worker verifies flange dimensions with calipers to control tolerance

Production Video

The following is the real production process of FRP flanges and fittings, covering molding, finishing and surface treatment.

Packing & Shipping

Finished parts are protected with bubble columns and stretch wrap before being packed into cartons, preventing transit damage to sealing faces and threaded ports so they arrive intact at overseas project sites.

Flanges and fittings packed with bubble protection

Results

• The client placed three sample orders upfront and was satisfied with both quality and pricing;
• Beyond building to drawing, we proposed drawing optimizations based on the actual use case;
• After sample validation, the client moved into formal volume procurement;
• The parts are already running stably in water treatment projects across the UK, South Africa and the US.