Inconel Alloy 625, Chemical composition
Description
Inconel Alloy 625 is an austenitic nickel / chromium / molybdenum / niobium alloy (see Table 1 on reverse). The high alloy content enables alloy 625 to withstand severe aqueous corrosion environments. High molybdenum content (8.0 to 10.0%) makes the alloy very resistant to chloride pitting and crevice corrosion. High nickel content (58.0% min.) provides relative freedom from chloride ion induced stress-corrosion cracking. Alloy 625 has shown excellent corrosion resistance in oil and gas production environments containing hydrogen sulfide, carbon dioxide and chlorides. Consult ISO 15156-3, Table A.14 for the limits regarding material type 4d in hydrogen sulfide containing environments for oil and gas production.
| Element | Composition, % |
| Chromium | 20.0-23.0 |
| Nickel | 58.0 min. |
| Ferrous | 5.0 max. |
| Molybdenum | 8.0-10.0 |
| Cb+Ta | 3.15-4.15 |
| Manganese | 0.50 max. |
| Silicon | 0.50 max. |
| Carbon | 0.100 max. |
| Phosphorus | 0.015 max. |
| Sulfur | 0.015 max. |
| Aluminum | 0.40 max. |
| Titanium | 0.40 max. |
| Cobalt | 1.0 max. |
Application: Nickel alloy with very good resistance to pitting, crevice corrosion & sour well environments.
Tensile strength, min.: 120000psi (827MPa)
Yield strength, min.: 60000psi (414MPa)
Elongation in 2 in., min.: 30%
Application
Inconel Alloy 625 seam welded pressure tubing in the heat treated and cold worked condition is typically used in oil and gas wells for chemical injection applications. In such applications, it is commonly referred to as capillary tubing and is free hanging (self-supporting) inside the production casing. The chemicals being injected are often used to enhance production flow rates, inhibit corrosion or scaling and/or de-water. The tubing is frequently supplied as 5,000 to 35,000 ft. coils on a wooden reel, depending on size.
Manufacturing Process and Resultant Properties
Strip splice welds join lengths of cold rolled strip to enable long lengths between orbital welds (greater than 14,500 ft between orbital welds is achievable). The strip is formed into a tubular cross section and longitudinally seam welded using the gas tungsten arc (GTAW) process. The tubing is first sunk to an intermediate outside diameter, heat treated, and make the same process to obtain the desired size.
Nondestructive Testing (NDT)
Eddy current testing (ECT) is performed on the longitudinally seamwelded tubing and strip splice welds at intermediate size in the as-heat treated condition. Those strip splice welds detected by ECT at intermediate size in the as-heat treated condition. Yield pressure hydrostatic testing is performed on the heat treated tubing at final size.
Quality Assurance
Eddy current test (ECT)
Ultrasonic test
Hydrostatic test
Chemical composition analysis
Tensile test
Hardness test
Dimension & visual inspect
Metallographic analysis
Standards and Specifications
Alloy 625 Tubing with Enhanced Properties
ASTM B704, Standard Specification for Welded UNS N06625, UNS N06219, and UNS N08825 Alloy Tubes, except in the as-cold worked condition
ASTM B444, Standard Specification for Alloy UNS N06625 Seamless Pipe And Tube
Meets the material limits for annealed and cold-worked, solid solution, nickel-based alloys listed in ISO 15156-3 for material type 4d in Table A.14.
Coiled Tubing Size
| Imperial size | Metric size |
| OD inch | WT inch | OD mm | WT mm |
| 1/8 (0.125) | 0.028 | 3.18 | 0.71 |
| | 0.035 | 3.18 | 0.89 |
| 3/16 (0.188) | 0.028 | 4.76 | 0.71 |
| | 0.035 | 4.76 | 0.89 |
| | 0.049 | 4.76 | 1.24 |
| 1/4 (0.250) | 0.035 | 6.35 | 0.89 |
| | 0.049 | 6.35 | 1.24 |
| | 0.065 | 6.35 | 1.65 |
| | 0.083 | 6.35 | 2.11 |
| 3/8 (0.375) | 0.035 | 9.53 | 0.89 |
| | 0.049 | 9.53 | 1.24 |
| | 0.065 | 9.53 | 1.65 |
| | 0.083 | 9.53 | 2.11 |
| 1/2 (0.500) | 0.035 | 12.7 | 0.89 |
| | 0.049 | 12.7 | 1.24 |
| | 0.065 | 12.7 | 1.65 |
| | 0.083 | 12.7 | 2.11 |
| 5/8 (0.625) | 0.049 | 15.88 | 1.24 |
| | 0.065 | 15.88 | 1.65 |
| | 0.083 | 15.88 | 2.11 |
| 3/4 (0.75) | 0.065 | 19.05 | 1.65 |
| | 0.083 | 19.05 | 2.11 |
| 1 | 0.065 | 25.4 | 1.65 |
| | 0.083 | 25.4 | 2.11 |
Tubing length up to 32,808 feet (10,000 m)
For control line, chemical injection line, umbilicals
Available materials
Austenitic: 316L
Duplex: S31803, S32205
Super Duplex: S32750
Nickel alloy: N06625, N08825
Norm Equivalence
| Grade | UNS No | Euro norm | Japanese |
| No | Name | JIS |
| Alloy | ASTM/ASME | EN10216-5 | EN10216-5 | JIS G3463 |
| 316L | S31603 | 1.4404, 1.4435 | X2CrNiMo17-12-2 | SUS316LTB |
| 2205 | S31803 | 1.4462 | X2CrNiMoN22-5-3 | SUS329J3LTB |
| 2507 | S32750 | 1.4410 | X2CrNiMoN25-7-4 | |
| 625 | N06625 | 2.4856 | NiCr22Mo9Nb | |
| 825 | N08825 | 2.4858 | NiCr21Mo | |
