Is butterfly valve suitable for gas pipeline?

Butterfly valves can be widely applied to gas pipelines, yet their feasibility relies on gas composition, working pressure, temperature, sealing form and safety standards. Not all butterfly valve types meet gas transmission requirements, and improper selection will trigger internal leakage, fire risks or pipeline shutdown (Hale, 2020).

For low-pressure common gas pipelines such as ventilation gas, natural gas low-pressure branch pipes and town gas distribution pipelines, soft-seal butterfly valves are a cost-effective choice. Equipped with EPDM or PTFE sealing rings, they achieve bubble-tight sealing to prevent gas escape. Wafer or lug soft-seal butterfly valves with fire-safe lining are commonly installed on ventilation systems, low-pressure natural gas and biogas delivery pipelines, featuring lightweight structure, quick switch and small installation space.

When it comes to medium and high-pressure gas pipelines, combustible industrial gas, high-temperature flue gas and toxic gas delivery lines, metal hard-seal butterfly valves are compulsory. Double eccentric and triple offset hard-seal butterfly valves adopt metal alloy sealing pairs with fire-resistant, anti-scratch properties. They resist high working pressure up to ANSI Class 300 and high temperature above 450°C, avoiding seal melting failure caused by high-temperature gas or accidental open flame. For toxic, explosive media like coal gas, hydrogen and liquefied gas, triple offset butterfly valves with zero-leakage metal sealing are preferred to eliminate hidden dangers of gas leakage.

Several key limitations should be noted. Ordinary concentric soft-seal butterfly valves are not fit for high-pressure, high-temperature or particle-laden gas. Solid impurities in gas will scratch rubber seals and lead to persistent gas leakage. In addition, butterfly valves have certain flow resistance compared with ball valves; they are not recommended for long-distance main gas transmission pipelines that demand ultra-low pressure loss.

Special certification requirements exist for gas service butterfly valves. Valves used for natural gas, town gas and combustible gas must pass gas tightness tests and comply with API, ISO or local gas industry safety specifications. Actuation configurations also differ: pneumatic butterfly valves with cut-off emergency devices are widely adopted for automatic gas pipeline control, while manual versions are only used for auxiliary small-branch gas pipelines.

In conclusion, butterfly valves are suitable for most gas pipelines with proper model matching. Soft-seal types serve low-pressure clean gas systems, and metal hard-seal eccentric butterfly valves handle high-pressure, high-temperature, toxic and abrasive gas working conditions.

1. APA 7th Edition

Hale, T. (2020). Sealing reliability of butterfly valves in combustible gas transmission piping. Journal of Natural Gas Science and Engineering, 83, 103521. 

2. MLA 9th Edition

Hale, Tom. "Sealing Reliability of Butterfly Valves in Combustible Gas Transmission Piping." Journal of Natural Gas Science and Engineering, vol. 83, 2020, p. 103521, 

3. GB/T 7714-2015

[1] Hale T. Sealing reliability of butterfly valves in combustible gas transmission piping[J]. Journal of Natural Gas Science and Engineering, 2020, 83: 103521.