The material selection for concentric butterfly valves in chemical applications depends mainly on the corrosiveness of the medium, operating temperature, and pressure. Below is a comprehensive summary commonly used in chemical plants, water treatment facilities, petrochemical systems, and general industrial processes.
1. Body Material Requirements
(1) Ductile Iron (DI / GJS400 / GGG40)
Suitable for weakly corrosive chemical media
Used for water, air, weak acids, weak alkalis
Cost-effective and widely used
Not recommended for strong acids or oxidizing media
(2) Stainless Steel 304 (CF8)
Medium corrosion resistance
Suitable for acetic acid, alcohols, ammonia, and some salt solutions
Better corrosion resistance than carbon steel or ductile iron
(3) Stainless Steel 316 (CF8M)
The most commonly used stainless steel for chemical applications
Suitable for acids, chlorides, seawater, and saline solutions
Excellent resistance to pitting and chemical attack
(4) Special Materials for Highly Corrosive Media
|
Material |
Application |
|
C95400 Aluminum Bronze |
Seawater and chloride environments |
|
CD4MCu / ASTM A890 Grade 1B |
Highly corrosive, chloride-rich media |
|
PP / PVDF / UPVC |
Strong acids and alkalis (non-high-temperature) |
|
PTFE-lined body |
Strong acids such as HCl, HF, high-concentration sulfuric acid |
2. Disc Material Requirements
The disc is directly exposed to the chemical medium; therefore, corrosion resistance is critical.
Common Disc Materials
(1) DI with Coating (Epoxy / Nylon / Rilsan)
Used for weakly corrosive media;Low cost but limited chemical resistance
(2) Stainless Steel CF8 / CF8M
Most widely used;Good corrosion resistance;Suitable for acids, alkalis, and neutral salt solutions
(3) Duplex / Super Duplex (2205 / 2507)
For chloride-rich chemical media;Resistant to seawater, brine, and aggressive chemical solutions
(4) PTFE-Lined Disc
Ideal for extremely corrosive chemicals;Recommended for HF, strong acids, and certain solvents
(5) Bronze / Aluminum Bronze (C95400, C95500)
Suitable for seawater and salt-related chemical industries
3. Seat Material Requirements
The seat (liner) determines the sealing performance and chemical compatibility.
Common Seat Materials
|
Seat Material |
Chemical Compatibility |
Notes |
|
EPDM |
Neutral chemical media, acids, alkalis, hot water |
Most universal elastomer |
|
NBR |
Oils, fuels, hydrocarbons, general liquids |
Excellent oil resistance |
|
FKM (Viton) |
Strongly corrosive chemical media |
Resistant to solvents and acids |
|
PTFE |
Strong acids, strong alkalis, high-corrosive media |
Best overall chemical stability |
|
Nylon |
Moderately corrosive media |
Often used as disc coating |
4. Shaft (Stem) Material Requirements
The shaft must balance corrosion resistance and mechanical strength.
Common Options
SS410 – General applications,SS420 – Medium corrosion resistance
SS316 – Widely used in chemical plants,17-4PH – High strength + corrosion resistance
Monel / Hastelloy – Highly corrosive and specialty chemical media
5. Recommended Material Combinations for Chemical Applications
General Chemical Service
Body: DI,Disc: SS304,Seat: EPDM,Shaft: SS420 / SS316
Medium Corrosive Media (Acids / Alkalis / Salts)
Body: CF8,Disc: CF8M,Seat: EPDM or FKM,Shaft: SS316
Highly Corrosive Media
Body: CF8M or CD4MCu,Disc: PTFE-lined,Seat: PTFE,Shaft: SS316 / Duplex
Chloride-Rich / Seawater-Based Chemical Media
Body: C95400 or CF8M,Disc: C95400 or Duplex,Seat: EPDM or FKM,Shaft: Duplex / 2507 / Monel
Post time: Nov-19-2025
