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Alloy 20 – material overview

Looking for a valve in this exotic alloy? Find it in the following configurations: BallButterflyCastCheckControlCryogenicCustom madeFootForgedGateGlobeNeedlePlug, and Safety relief, as well as Strainers.

Alloy Valve Stockist generally supplies Alloy 20 valves, otherwise known as Carpenter 20, which can be found in cast grade A351 CN7M, often referred to as simply “A20” and specified under the universal code UNS 08020 ¡. We stock and distribute gate, globe, check, ball, butterfly, plug, needle and custom made valves.

As a valve stockist, we stock, supply and distribute valves in exotic materials such as titanium, hastelloy, duplex, super duplex, monel, incoloy, inconel, alloy 20, 254 SMO, 6 Moly,tantalum, zirconium, uranus, 904L both in stock and can also deliver against tight lead times.

Alloy 20 is a nickel-chromium-molybdenum stainless steel alloy developed for applications involving sulphuric acid. Its corrosion resistance also finds other uses in the chemical, food, pharmaceutical, and plastics industries. Alloy 20 resists pitting and chloride ion corrosion and its copper content protects it from sulphuric acid. It is also known as Carpenter 20. Cast versions are designated CN7M.


. Nickel, 32.5-35%

. Chromium, 19-21%

. Carbon, 0.06% maximum

. Copper, 3-4%

. Molybdenum, 2-3%

. Manganese, 2% maximum

. Silicon, 1% maximum

. Columbium, 1% maximum

. Iron, 31-44% (balance)

Other Names

  • UNS N08020
  • DIN 2.4660
  • CN7M
  • Carpenter 20 CB 3 TM
  • AL 20 TM
  • Carlson Alloy C20 TM
  • Nickelvac 23 TM
  • Nicrofer 3620 Nb TM


ASTM B729, B464, B366, B473, B462

ASME SB729, SB464, SB366, SB473, SB462

ANSI / ASTM A555-79