Valve Material Reference
ASTM A995 CD4MCu / A890 4A Valve
Duplex SS Cast (CD4MCu)ASTM A995 CD4MCu (also referred to as A890 Grade 4A) is the cast duplex stainless steel specification equivalent to UNS S31803 / S32205 (Duplex 2205).
Form
Cast
Max Temp
+300°C (austenite-ferrite ratio changes above this)
Min Temp
−40°C
Category
Duplex
Chemical Composition — ASTM A995 CD4MCu / A890 4A
Temperature Range
−40°C to +300°C (limited by embrittlement above 300°C)
Maximum Temperature
+300°C (austenite-ferrite ratio changes above this)
Minimum Temperature
−40°C
Equivalent Grades — ASTM A995 CD4MCu / A890 4A
| Standard | Equivalent Grade |
|---|---|
| ASTM wrought equiv. | A182 F51 / A276 S31803 (Duplex 2205) |
| EN | 1.4470 / X2CrNiMoN22-5-3 |
| ISO | 22-5-3N |
Suitable Services
Seawater systems — offshore platforms, FPSO, desalination
High-chloride brine and produced water
HCl service (limited concentrations)
Sour gas service per NACE MR0175
Phosphoric acid service
Pulp and paper bleaching chemicals (chlorine dioxide)
Not Suitable For
Temperatures above +300°C (embrittlement risk)
Temperatures below −40°C (limited toughness)
Cryogenic service (use SS 316L / CF3M)
Concentrated nitric acid (use SS 304L/317L)
Valve Body Applications
Seawater valve bodies (offshore, FPSO, desalination)
Chemical process valve bodies (HCl service, phosphoric acid)
Oil field production valve bodies (NACE service)
Desalination plant valve bodies
Trim Applications
Duplex valve trim for seawater service
Hard-facing (Stellite) on seating faces recommended for gate/globe
Typical Valve Types in ASTM A995 CD4MCu / A890 4A
Gate, globe, ball, check valves: Class 150–900 per ASME B16.34
Subsea gate valves: NACE MR0175 compliant
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