Special Alloy Valves: Duplex, Nickel Alloys and Titanium

Vannes industrielles

When carbon steel and 316 stainless steel are no longer adequate in seawater, chloride, acid, high-temperature or abrasive service, valve bodies and internals are produced in special alloys. We supply special alloy valves, including ball, gate, globe, check and butterfly valves, in duplex and super duplex, nickel alloys (Inconel, Monel, Hastelloy), titanium, zirconium and nickel-aluminum bronze (NAB) on a project basis.
Duplex F51Super duplex F53 / F55Alloy 625Alloy C-276Titanium Gr. 2
Duplex · Ni alloysSpecial alloy valves for corrosive service

Gamme de produits

Alloy groups and typical service

GroupTypical gradesService typique
Duplex / super duplexF51, F53, F55; cast ASTM A995 4A, 5A, 6ASeawater, chloride-bearing process water, offshore, lines requiring high strength
Nickel-chromium alloysAlloy 600, Alloy 625 (Inconel)High temperature, oxidizing and chloride environments
Nickel-copper alloysAlloy 400, K-500 (Monel)Hydrofluoric acid, seawater, alkaline environments
Nickel-molybdenum-chromiumAlloy C-276 (Hastelloy)Strong acids, chlorine and mixed chemical environments
Pure nickelNickel 200Caustic (sodium hydroxide) service
TitaniumGr. 2, Gr. 3, Gr. 5, Gr. 7, Gr. 12Seawater, chlorine dioxide, oxidizing acids
ZirconiumZirconium alloysHot acids (e.g. sulfuric and hydrochloric at certain concentrations)
Nickel-aluminum bronzeC95800Seawater cooling and firewater systems
High-temperature steelsWC1, WC6, WC9, C5, C12ASteam, superheated steam and high-temperature process lines
Low-temperature steelsLCB, LCC, LC1, LC2, LC3, LF2, LF3Sub-zero service (not cryogenic)
Other stainless steels321, 310, 904LHigh-temperature oxidation, sulfuric acid environments

For duplex grades see duplex and super duplex valves; for nickel alloys see nickel alloy valves.

Quality control for special alloy valves

  • 100% PMI (positive material identification) to verify the alloy of every part
  • EN 10204 3.1 certificates; 3.2 with independent inspection on request
  • Ferrite content measurement and ASTM G48 pitting corrosion testing for duplex materials
  • NACE MR0175 / ISO 15156 hardness and material compliance where the service requires it
  • Non-destructive examination such as radiography (RT) and liquid penetrant testing (PT); the scope is stated in the offer

See our guides to EN 10204 3.1 and 3.2 material certificates et NACE MR0175 sour service.

Typical special alloy valves

Examples include Alloy 600 globe valves, Alloy 400 gate valves, Alloy C-276 knife gate and globe valves, NAB C95800 gate valves and Alloy 625 triple-offset butterfly valves, sourced through our manufacturer network. Depending on the fluid and service, the whole valve can be made in the alloy, only the wetted parts (ball, disc, seat, stem) can be alloyed, or a carbon steel body can be overlaid with the alloy; the choice weighs corrosion rate, safety and cost.

At a glance

Valve typesBall, gate, globe, check, butterfly and knife gate valves
Alloy groupsDuplex and super duplex, super austenitic (6Mo), Alloy 20, nickel alloys, titanium, zirconium, nickel-aluminum bronze
Product formsCast or forged body, bonnet and internals; alloy wetted parts or overlay as an option
Inspection100% PMI; EN 10204 3.1, 3.2 on request; ferrite measurement and ASTM G48 for duplex
Sour serviceNACE MR0175 / ISO 15156 where required

Material program

Body, bonnet and internal parts can be produced as castings or forgings in the alloys below. Material is selected by fluid, concentration, temperature and chloride content; for alloy materials, 100% PMI and EN 10204 3.1 certificates are standard.

Alloy groupCast (ASTM)Forged / bar (UNS)Service typique
Duplex stainlessA995 4A (CD3MN)A182 F51 (S31803), F60 (S32205)Chloride-bearing water, sour service; seawater depending on conditions
Super duplexA995 5A (CE3MN), 6A (CD3MWCuN)A182 F53 (S32750), F55 (S32760)Seawater, high chloride, pressurized lines
Super austeniticA351 CK3MCuN (6Mo)S31254 (6Mo), N08904 (904L)Seawater, chloride-bearing process fluids
Alloy 20A351 CN7MB462 N08020Sulfuric acid
Ni-Cu (Monel 400 / K-500)A494 M35-1N04400, N05500Hydrofluoric acid, seawater, brine solutions
Ni-Cr-Mo (Inconel 625)A494 CW6MCN06625High temperature, chloride and acid mixtures
Ni-Mo-Cr (Hastelloy C-276 / C-22)A494 CW12MW, CX2MWN10276, N06022Wet chlorine, hypochlorite, mixed acids
Ni-Fe-Cr (Incoloy 800H / 825)n/aN08810, N08825High temperature, phosphoric and sulfuric acid
Pure nickeln/aNi 200 / 201 (N02200 / N02201)Caustic (NaOH) service
TitaniumB367 (Gr. C-2, C-3, C-5, C-12)Gr. 2, 3, 5, 7, 12 (B381 / B348)Seawater, chlorinated media, oxidizing acids
Zirconiumn/aZr 702, 705Hot acids (e.g. acetic and formic acid processes)
Nickel-aluminum bronzeB148 C95800n/aSeawater, shipboard systems

Standard materials

GroupCast (ASTM)Forged (ASTM)
acier au carboneA216 WCB, WCCA105N
Low temperatureA352 LCB, LCC, LC1, LC2, LC3A350 LF2, LF3
High temperature (Cr-Mo)A217 WC1, WC6, WC9, C5, C12AA182 F11, F22, F5, F9, F91
StainlessA351 CF8, CF8M, CF3, CF3M; A217 CA15 (13Cr martensitic)A182 F304, F316, F304L, F316L, F321; F6a (13Cr)

Documentation and testing

On industrial projects the documentation package matters as much as the valve. We confirm the certificate and test scope for every line item at quotation stage:

  • EN 10204 3.1 material certificates for pressure-retaining and wetted parts, traceable by heat number
  • EN 10204 3.2 with third-party inspection, on request
  • Pressure test reports to API 598 or EN 12266-1: shell, seat and, where specified, gas tests
  • Fire-test certificates (API 607 / ISO 10497) for fire-safe type-tested designs
  • PMI reports for alloy and stainless materials
  • Dimensional, visual and coating inspection records
  • PED 2014/68/EU CE declaration for equipment within its scope
  • NACE MR0175 / ISO 15156 compliance statement for sour (H₂S) service

Technical datasheets

Foire aux questions

When is a duplex stainless steel valve required?

In chloride-bearing water, 316 stainless steel can suffer pitting and stress corrosion cracking. Duplex (F51) and super duplex (F53 / F55) steels offer both higher corrosion resistance and roughly twice the yield strength, so they are preferred for brine and offshore applications, with super duplex the usual choice for seawater.

Why is PMI important for special alloy valves?

Alloys that look alike can be mixed up, and a mix-up can cause severe corrosion damage. PMI (positive material identification) uses a portable spectrometer to verify the actual composition of each part and compares it with the certificate.

What is the difference between Inconel, Monel and Hastelloy?

All three are nickel-based. Inconel (for example Alloy 625) is nickel-chromium based and performs well at high temperature and in oxidizing media. Monel (Alloy 400) is nickel-copper based and performs well in hydrofluoric acid and seawater. Hastelloy C-276 is nickel-molybdenum-chromium based and offers the broadest resistance of the three to strong acids and mixed chemicals.

Related categories

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