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In industrial piping systems, the reliability of butterfly valves is directly related to production safety and operating costs. In the face of high-temperature steam, corrosive media, high abrasion slurry and other complex working conditions, how to choose the most suitable butterfly valve material? This article takes you to decipher the engineering logic behind the choice of materials, and helps enterprises realize cost reduction and efficiency.I. Material Mapping: Full Scenario Coverage from Normal Temperature to Extreme

I. Material Mapping: Full Scenario Coverage from Normal Temperature to Extreme

1、Valve body materials

(1) Cast iron butterfly valve: a classic choice for economy and universality

Material characteristics: GG25 gray cast iron (ASTM A48) or ductile iron (ASTM A536), tensile strength ≥ 200MPa, suitable for dry air, water, weak acids and alkalis and other media. Gray cast iron is low cost, but it is strictly prohibited to be used in steam system.

Mainly used in building water supply and drainage, heating systems, fire piping and other non-corrosive or slightly corrosive media environment.

Innovative breakthrough: through micro-alloying treatment to enhance the uniformity of graphite morphology of cast iron, so that the valve deformation resistance increased by 40%, especially suitable for municipal water supply, HVAC and other high-frequency opening and closing scenarios.

 

2、Stainless steel butterfly valve: “All-round defender” for corrosive working conditions.

304/316L austenitic steel (ASTM A351): can withstand chlorine ions, seawater and other media, widely used in such as food processing, pharmaceutical industry. 2205 duplex steel upgraded version (UNS S32205), seawater, weak acid resistant media, but the welding needs special technology.

 

3、Specialty alloys: Challenging extreme working conditions

Special stainless steel such as 1Cr18Ni9Ti and other high-performance alloys such as Hastelloy, titanium alloys, Inconel 625 nickel-based alloys, etc., resistance to extreme temperatures, high pressure and strong corrosion, mechanical strength and wear-resistant properties significantly better than traditional materials, not only improves the corrosion resistance of the product, abrasion resistance and life expectancy, but also promotes the technological innovation of the entire industry.

4、Sealing materials: the key to determine the leakage rate

 (1) Soft seal

EPDM rubber: weak acid/alkali resistance (pH 3-11), suitable for water treatment, EPDM rubber will swell and fail when encountering grease.

NBR rubber: good oil resistance, used for oil pipelines.

PTFE: the most chemically inert, but poor cold flow, need to be enhanced by metal skeleton, PTFE seal will be brittle at low temperature.

 

(2) Hard seal

Stainless steel + graphite: economic, for general industrial pipelines, with good corrosion resistance and moderate cost.

Alloy steel: high temperature wear resistance, applicable to high temperature and high pressure occasions.

Silicon carbide ceramic:: with very high hardness and temperature resistance, suitable for extreme wear conditions.

 

II. The selection of material misconceptions crack: avoid 90% of users stepped on the ‘pit’!

Mistake 1: Blindly pursuing high-grade materials: material costs increase, but the actual working conditions do not play the material advantages.

Misconception 2: Ignore the material process synergy: similar materials due to casting process differences, pressure resistance level may differ by 2 levels.