Case Study: Solving Seat Deformation in Large-Diameter Butterfly Valves Under High-Temperature Conditions

Content Menu

● Project Background (Typical OEM Scenario)

● Problem Analysis

>> 1. Thermal Expansion of Rubber Seat

>> 2. Uneven Compression in Large Sizes

>> 3. Inadequate Pre-Compression Design

● Our Engineering Adjustment Strategy

>> ✔ Material Upgrade

>> ✔ Compression Ratio Optimization

>> ✔ Rubber Molding Control

>> ✔ 100% Pressure Testing at Elevated Temperature Simulation

● Results

● Technical Insight

● Conclusion

In recent OEM cooperation projects, we frequently encounter one recurring issue in municipal and industrial hot water systems:

Seat deformation in large-diameter resilient seated butterfly valves under elevated temperature conditions (100–120°C).

Although resilient seated butterfly valves are commonly used in water systems, temperature above standard room conditions significantly affects rubber performance — especially in sizes above DN800.

Project Background (Typical OEM Scenario)

◆ Valve Type: Resilient Seated Butterfly Valve

◆ Size: DN1000 – DN1400

◆ Medium: Hot Water

◆ Working Temperature: 110–120°C

◆ Pressure: PN10 / PN16

◆ Installation: Horizontal pipeline in municipal heating system

The client initially experienced minor internal leakage after several months of operation.

Problem Analysis

Through structural evaluation and material assessment, we identified three key risk factors:

1. Thermal Expansion of Rubber Seat

Standard EPDM seat material begins to soften under continuous high temperature exposure.

In large diameters, the compression ratio between disc and seat becomes more sensitive.
Even a small change in rubber elasticity can reduce sealing performance.

2. Uneven Compression in Large Sizes

For DN1000+ valves, if the rubber thickness distribution is not precisely controlled,
local deformation may occur due to:

Gravity effect on large discs

Uneven torque during operation

Flange tightening imbalance

3. Inadequate Pre-Compression Design

Many standard designs do not optimize pre-compression specifically for high-temperature environments.

Our Engineering Adjustment Strategy

Based on repeated OEM production experience, we applied the following improvements:

✔ Material Upgrade

Switched from standard EPDM to high-temperature resistant EPDM compound

Improved rubber cross-linking density to reduce thermal softening

✔ Compression Ratio Optimization

Increased seat pre-compression by approximately 3–5%

Recalculated torque to ensure operability remains within actuator limits

✔ Rubber Molding Control

Improved vulcanization uniformity

Controlled rubber thickness tolerance within stricter range

✔ 100% Pressure Testing at Elevated Temperature Simulation

Instead of only ambient hydrostatic testing, we simulated elevated temperature conditions during internal quality verification.

Results

After structural adjustment:

• No internal leakage observed during extended testing

• Stable torque performance

• Improved long-term sealing stability

• Reduced maintenance frequency reported by OEM partners

Technical Insight

In large-diameter butterfly valves,
sealing performance is not determined only by material type —

It depends on:

• Rubber formulation

• Structural compression design

• Manufacturing precision

• Real-condition testing

This is especially critical for DN800–DN2400 sizes, where dimensional tolerance becomes more sensitive.

Conclusion

For high-temperature applications, simply selecting “EPDM” is not enough.

Engineering optimization must consider:

• Diameter scaling effect

• Thermal behavior

• Structural tolerance

• Installation conditions

With over 10 years of OEM manufacturing experience,
we continuously refine our structural design for resilient seated butterfly valves in demanding environments.