TEGA

A Major Innovation in the Piping Industry: TEGA PE100 Gate Valve

Gate valves are vital for potable water networks. Traditional flanged cast iron valves are commonly used but compromise safety when integrated with polyethylene systems. Polyethylene gate valves with PE outlets allow for direct electrofusion or butt fusion, significantly enhancing network safety, reducing water loss, and minimizing leaks.

Fig 1 – Cast Iron Gate Valve.
Fig 2 – Connection pieces for Cast Iron Gate Valve

 

Fig 3 – TEGA PE100 Gate Valve

Disadvantages of Cast Iron Valves
The key drawbacks of cast iron valves include:
•Corrosion susceptibility
•Cracking due to freezing
•Need for extra components like steel flanges, PE flange adaptors, bolts, nuts, and gaskets for connection to PE pipelines
•Challenging installation and susceptibility to water leaks

Polyethylene gate valve bodies address these issues, but earlier attempts in Europe to produce fully PE gate valves failed due to the mechanical limitations of plastic.

Challenges with PE Gate Valves
Gate valves use a wedge principle for sealing, requiring a V-shaped body with minimal flex.

Fig 4

However, polyethylene’s low modulus of elasticity and high expansion coefficient make it prone to significant deformation under pressure, leading to sealing issues. Stress analysis using ANSYS software demonstrated excessive deformation in all-PE valves compared to cast iron valves.

The behavior under pressure of a DN100 cast iron valve and a D110 polyethylene valve was analyzed using the ANSYS software in a simulated environment. The results are as follows.

Fig 5 Cast Gate Valve ANYSIS Stress Analysis

 

Fig 6 PE Gate Valve ANYSIS Stress Analysis Result

During the design studies, stress and deformation under pressure were evaluated by applying internal pressure to valves made from three different materials (cast iron, polyethylene, and composite body PE), with valve ends closed. The study included DN100 cast iron, D110 polyethylene, and composite body PE gate valves, all subjected to an internal pressure of 2.4 MPa.

As shown in Table 3, Fully PE valves deform nearly 10 times more than cast iron valves. This excessive deformation causes significant expansion of the valve body, leading to sealing failure.

As a result, a gate valve made entirely of polyethylene cannot operate efficiently. However, after years of R&D and numerous unsuccessful prototypes, a major breakthrough has been achieved.

Solution: Composite Body Design
After extensive R&D, the problem was resolved by using a composite material within the polyethylene valve body. This innovation minimizes deformation while preserving corrosion resistance. The composite body retains the benefits of plastic and eliminates the need for flanged connections, enabling direct electrofusion or butt welding.

Conclusion
TEGA’s Composite Body PE Gate Valve addresses the limitations of both cast iron and fully PE valves. Unlike cast iron, it resists cracking, freezing, and corrosion. While slightly more deformable than cast iron, the composite body strikes the right balance of flexibility and rigidity. The valve complies with international standards, offering a superior, durable, and efficient solution for modern potable water systems.

Table 1: Casting and Plastic Material Specifications
Table 2: Stress Analysis with ANYSIS Software
Table 3: Deformation Analysis Results Using ANSYS Software

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