Temperature Application Notes for Wafer & Flange Butterfly Valves

Key Premise: **Connection type (wafer/flange) does not determine the maximum temperature resistance; temperature rating depends on sealing and body materials.**

Flange-type valves have higher rigidity and are more suitable for long-term high-temperature and fluctuating-temperature conditions. Wafer-type valves, limited by the long bolt clamping structure, offer lower stability at high temperatures.

I. Soft-Sealed Butterfly Valves

(Centric with rubber/PTFE lining; temperature ranges apply to both connection types)

1. Standard Rubber (EPDM/NBR)

For water supply, HVAC and cold water systems

Continuous service: -20℃～120℃

Short-term low-pressure steam: up to 140℃

Exceeding 120℃ may cause aging, cracking and loss of elasticity.

Wafer type: Long bolts elongate at high temperatures, leading to gasket loosening and leakage.

Flange type: Secured with short bolts, lower risk of thermal expansion leakage.

2. PTFE Lining

For chemical acidic and alkaline media

Continuous service: -40℃～180℃

Short-term peak: 200℃

Cryogenic service down to -196℃.

3. Fluorine Rubber (FKM)

-30℃～200℃, resistant to oil and medium-temperature steam.

II. Metal Hard-Sealed Butterfly Valves

(Eccentric design; for high temperature and steam service)

1. Carbon Steel (WCB) Body

Continuous stable service: -40℃～425℃

Suitable for high-temperature water, saturated steam and hot oil pipelines.

2. Stainless Steel (304/316) Body

-196℃～450℃

For high-temperature corrosive flue gas and chemical media.

3. High-Temperature Alloy / Hard Alloy Sealing

Up to 550～600℃

Mainly used in power plant flue gas and high-temperature heat transfer oil systems.

III. Temperature Performance Differences Between Connection Types

1. Wafer Butterfly Valves

Recommended for **ambient temperature, low fluctuation, ≤120℃** soft-sealed applications (municipal water supply, cooling water).

Not recommended above 180℃:

Clamped by long bolts, which elongate and deform at high temperatures, causing external leakage.

Rarely used for large-bore, high-temperature pipelines.

2. Flange Butterfly Valves

Suitable for full temperature ranges: cryogenic, medium and high temperature.

Integral flange with short bolts provides high rigidity and stability.

Preferred for steam above 150℃, hot oil and frequently fluctuating process lines.

IV. Quick Selection Summary

- Water ≤120℃ / general water systems: wafer or flange soft-sealed; wafer for lower cost.

- 120℃～200℃ hot water, strong acids/alkalis: PTFE-lined, preferably flange type.

- Steam, flue gas, hot oil above 200℃: flange-type metal hard-sealed only; wafer not recommended.

- Cryogenic media (refrigerant, liquid nitrogen): PTFE-lined or stainless steel hard-sealed, flange structure preferred for stable sealing.