Alloy 2550

Alloy 2550

UNS N06255

COMMON TRADE NAMES: CRA 2550E, CRA2550, 25%CR50%Ni, SM2550®

2550 Applicable EnvironmentsAlloy 2550 (UNS N06255) is a cold hardened nickel-based alloy intended for corrosion resistance to highly sour (H2S) environments with high chloride content, requiring high strength up to 400°F.

The high nickel and molybdenum content of 2550 extends the sour service limits of nickel alloys while also providing excellent resistance to chlorides and dissolved oxygen. Therefore, it is commonly used for downhole tubular components, packers, and other subsurface equipment in severely sour wells with high-pressure and high-temperature (HPHT) conditions, saltwater injection wells, and Acid Gas Injection (AGI) wells. However, all environmental factors, including H2S, CO2 , temperature, pH, and chloride concentration, should be considered before final material selection.

For sour service applications, 2550 is classified in MR0175/ISO15156 as a type 4d alloy, with no restrictions to a partial pressure of H2S below 300°F and resistant to 300 psi H2S at 425°F.

CRA 2550E

CRA 2550E (UNS N06255) is a premium, electro-slag re-melted version of alloy 2550. The performance and consistency are enhanced through tightly controlled compositional limits and microstructural cleanliness. CRA 2550E has excellent hydrogen embrittlement resistance at all standard strength levels.

Applications in Upstream Oil & Gas

  • Corrosive environments containing high levels of CO2 , H2S, and chlorides
  • Salt water disposal (SWD) wells containing dissolved oxygen
  • Tubing
  • Casing
  • Liners
  • Base Pipe for Sand Screens
  • Expandables
  • Perforating Guns
  • Landing Joints
  • Extensions
  • Shrouds
  • Maker Joints
  • Pipe for VIT
  • Swell Packers
  • Geothermal
  • Carbon Capture and Sequestration (CCS)
  • Water alternating gas wells

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Chemical Composition

≤ 0.0323 - 2647 - 52BAL≤ 1≤ 16 - 9≤ 1.2≤ 0.03≤ 0.03≤ 0.69≤ 3
(mass %)

Manufacturing Process

Steel MakingMade by electric furnace process or blast furnace followed by Vacuum Oxygen Decarburization (VOD) process or Argon Oxygen Decarburization (AOD) Process
Pipe MakingManufactured by traditional tube manufacturing processes, High strength tubulars should be furnished in cold worked condition
Heat TreatmentSolution Annealing Process before final cold drawing

Specified Mechanical Properties

API 5CRA / ISO 13680 Group 4 Category 25-50-6

NACE MR0175/ISO 15156
H2S Sour Service Limits
1101101401251135Table A.14No limit ≤ 300°F,
Refer to table for temperatures up to 400°F
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.

Typical Physical Properties

Thermal ExpansionX10-6/°F7.27.47.7
Elastic Moduluspsi x 10628.527.927.827.6
Poisson Ratio0.
Thermal ConductivityW/ft h °F1.51.822.2
Specific HeatBtu/lb °F0.

Frequently Asked Questions

What are the advantages of utilizing cold-working for alloys?

Superior dimensional control, better surface finish, and the ability to achieve high strength in alloys which cannot be achieved by heat treatment alone.

What is the recommended PREN for saltwater injections?

It is recommended that materials have a PREN > 40 for seawater injection applications.

Product Availability

MIN OD: 2-1/16″ (2.0625″)
MAX OD: 10-3/4″ (10.750”)
LENGTHS: Up to 70′ (840”) – R1, R2, R3

END FINISH: Plain end, Premium threads, & API threads

Standard & Non-Standard Sizes Available.

Manufactured Material Available as Quickly as 1 Week.

Non-Standard Mill Quantities Accommodated