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2550: Solid Solution Nickel Alloy

Common Names:

SM2550, DMV2550, 2250, SM2250, 2050, SM2050, 2550E, 25 CR50 Ni, CRA2550E, CRA2550, M2550

Alloy Group

Solid Solution Nickel Alloy

Corrosion Resistance

Severe

Yield Strength

110

—

160

Wall Tolerance

0.875

Density

0.296

PREN

44.45

—

67.25

Additional Documentation

Alloy Details

Alloy 2550 (UNS N06255) is a cold-hardened nickel-based alloy designed for corrosion resistance in highly sour (H2S) environments with high chloride levels, offering high strength up to 400°F.

With its elevated nickel and molybdenum content, 2550 Alloy enhances the sour service performance of nickel alloys while providing superior protection against chlorides and dissolved oxygen. This makes it ideal for use in downhole tubular components, packers, and other subsurface equipment in severely sour wells under high-pressure, high-temperature (HPHT) conditions, as well as in saltwater injection wells and Acid Gas Injection (AGI) wells. However, careful consideration of all environmental factors, such as H2S, CO2, temperature, pH, and chloride concentration, is essential before selecting the final material.

For sour service applications, Alloy 2550 is categorized as a type 4d alloy in MR0175/ISO15156, with no limitations on H2S partial pressure below 300°F, and it can withstand 300 psi H2S at 425°F.

Solid Solution Nickel Alloy

Nickel-base alloys are primarily employed in environments where the partial pressure of H2S exceeds 3 psi. These alloys are enhanced with increased levels of Nickel, Molybdenum, and other elements to extend their performance in harsh conditions involving high temperatures, H2S, and chlorides. Nickel alloys are approved for highly sour environments in accordance with NACE MR0175/ISO 15156. In the annealed condition yield strengths may range from 30 to 55 ksi. Pipe is typically supplied in the cold-hardened condition with yield strength between 110 and 160 ksi.

Chemical Composition

C
6
Carbon
0.03%
Si
14
Silicon
1%
P
15
Phosphorus
0.03%
S
16
Sulfur
0.03%
Ti
22
Titanium
0.69%
Cr
24
Chromium
23%‒26%
Mn
25
Manganese
1%
Fe
26
Iron
6.02%‒24%
Ni
28
Nickel
47%‒52%
Cu
29
Copper
1.2%
Mo
42
Molybdenum
6%‒9%
W
74
Tungsten
3%

Specified Mechanical Properties

API 5CRA / ISO 13680 Group 4 Category 25-50-6
GradeYield
Strength
ksi		Tensile
Strength
ksi		Elongation
%		Hardness
HRC		NACE MR0175/ISO 15156
H2S Sour Service Limits
minmaxminminmax
1101101401251135Table A.14No limit ≤ 300°F,
Refer to table for temperatures up to 400°F
1251251501301037
140140160145938140 Grade not recommended for sour service

* NACE MR0175/ISO 15156 LIMITS YIELD STRENGTH TO 150 ksi, Non-standard mechanical properties and grades are made available upon agreement.

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