28CR Seamless Pipe | Corrosion Resistant Alloys

28 Chrome

UNS N08028 / W.Nr 1.4563

COMMON TRADE NAMES: Alloy 28, 28Cr, Sanicro 28™, SAF 28®, VM® 28, Nic28, NiCro 31/27

28 Chrome, or Alloy 28, is a cold hardened austenitic stainless steel intended for highly corrosive environments. It is resistant to strong acids, pitting corrosion, crevice corrosion, and stress corrosion cracking. Alloy 28 is commonly referred to by the tradename Sanicro® 28, 28 Chrome, and the universal designation of UNS N08028.

Characteristics

Corrosion Resistance

Alloy 28 has excellent resistance to strong acids, including phosphoric, hydrochloric, nitric, formic, and sulfuric acids. Its resistance to pitting and corrosion resistance makes it suitable for seawater piping and heat exchangers.

Elevated Temperature Resistance

Alloy 28 should not be exposed to temperatures exceeding 1100°F (593°C) for prolonged periods as this may result in embrittlement.

Mechanical Properties

In the annealed condition, Alloy 28 has a minimum yield strength of 32 ksi. However, it may also be provided in the cold-worked condition with yield strength exceeding 125 ksi. It maintains excellent toughness at cryogenic temperatures.

Applications

28 Chrome is used in severely corrosive conditions high in chlorides, such as marine applications and oil and gas production. In upstream oil and gas, 28 Chrome’s increased resistance to the effects of H2S relative to stainless steels allows its use as downhole tubular components, packers, and other subsurface equipment in sour wells with high-pressure and high-temperature (HPHT) conditions and Acid Gas Injection (AGI) wells. CRA offers specialty alloy 28 Chrome seamless pipe & tube for use in multiple industries and applications, including:

As tubing, casing, and liners in oil and gas wells with high-pressure, high-temperature (HPHT) sour environments

Oil & Gas Production
Marine Industry
Nuclear Industry
Chemical Processing
Geothermal Wells
Base Pipe for Sand Screens
Pipe for VIT
Acid Gas Injection Wells
Carbon Capture and Sequestration (CCS)

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Alloy 28 Chemical Composition

C	Cr	Ni	Fe	Mn	Si	Mo	Cu	P	S
≤ 0.03	26 - 28	29.5 - 32.5	BAL	≤ 2.5	≤ 1	3 - 4	0.6 - 1.4	≤ 0.03	≤ 0.03

(mass %)

Specified Mechanical Properties

API 5CRA / ISO 13680 Group 3 Category 27-31-4

Grade	Yield Strength ksi		Tensile Strength ksi	Elongation %	Hardness HRC	NACE MR0175/ISO 15156 H₂S Sour Service Limits
Grade	min	max	min	min	max	NACE MR0175/ISO 15156 H₂S Sour Service Limits
110	110	140	115	11	33	Table A.14 Type 4c	No limit ≤ 270°F, Refer to table for temperatures up to 450°F
125	125	150	130	10	35	Table A.14 Type 4c
140	140	160	145	9	38	140 Grade not recommended for sour service

*Non-standard mechanical properties and grades are made available upon agreement.

Specified Mechanical Properties in Annealed Condition
Per ASTM B668

Tensile Strength	Yield Strength	Elongation
minimum, ksi	minimum, ksi	minimum, %
73	31	40

*Higher strength properties can be provided in the cold hardened condition.

Typical Physical Properties

		70°F	200°F	400°F	600°F	800°F
Density	lbs/in³	0.29	-	-	-	-
Thermal Expansion	X10^-6/°F	-	8	8.5	9	9
Elastic Modulus	10³ ksi	28.3	27.6	26.3	25.1	23.8
Poisson Ratio	-	0.3	-	-	-	-
Thermal Conductivity	Btu-in/h·ft²·°F	66	84	102	114	132
Specific Heat	Btu/lb·°F	0.11	0.12	0.12	0.12	0.13
Yield Strength	ksi	31	28	23	22	19
Tensile Strength	ksi	73	74	64	57	53

Manufacturing Process

PROCESS	DESCRIPTION
Steel Making	Electric Arc Furnace followed by Vacuum Oxygen Decarburization (VOD) or Argon Oxygen Decarburization (AOD).
Pipe Making	Conventional Seamless Cold Finished Pipe and Tube Manufacturing Processes.
Heat Treatment	Cannot be hardened by heat treatment. May be provided in the annealed or cold hardened condition.