Type 316L Capillary Tube Coil For Downhole Application

Type 316L, Chemical composition

Application: Standard oil and gas CRA (corrosion resistant alloy)
Tensile strength, min.: 70ksi (485MPa)
Yield strength, min.: 25ksi (170MPa)
Elongation in 2 in., min.: 35%

Application (seamless tubing)
Alloy 316L seamless pressure tubing in the heat treated condition is typically used in oil and natural gas wells for applications including hydraulically-actuated surface-controlled subsurface safety valves, chemical injection, and instrumentation. In such applications, it is commonly referred to as control line tubing. The tubing is generally deployed by strapping it to the outside of the production casing. It may be encapsulated and can be included along with other pressure or TEC and mechanical components, such as bumpers, within a flatpack. The tubing is frequently supplied as 5,000 to 35,000 ft. coils on a wooden or steel reel, depending on size.

Description
Alloy 316L is a chromium - nickel austenitic stainless steel with an addition of molybdenum and reduced carbon content. The addition of molybdenum provides improved resistance to pitting and crevice corrosion in environments containing halides such as chlorides when compared to so-called conventional 18 chromium 8 nickel austenitic stainless steels such as 304L. The reduced carbon content minimizes harmful chromium carbide precipitation during welding and thereby improves resistance to intergranular corrosion. Austenitic stainless steels such as 316L are susceptible to stress corrosion cracking (SCC) in environments containing chlorides and other halides. Alloy 316L is generally used in oil and gas production environments which do not contain oxygen and have limited amounts of chlorides and hydrogen sulfide. Consult ISO 15156-3, Table A.2 for the limits regarding alloy 316L in hydrogen sulfide containing environments for oil and gas production.

Manufacturing Process and Resultant Properties
Seamless extruded tube hollows are drawn or drawn / sunk to final size to produce seamless tubing coils 500 to 2,000 ft. long, depending upon the size. The tubing is heat treated and joined by orbital welding to achieve the desired length. The final material condition of the tubing is heat treated.

Nondestructive Testing (NDT)
Eddy current testing (ECT) is performed at final size in the heat treated condition. Radiographic testing is performed on all orbital welds. 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
ASTM A269, Standard Specification for Seamless and Welded Austenitic Stainless Steel Tubing for General Service

Meets the material limits for 316L austenitic stainless steel listed in ISO 15156-3, Table A.2.

Coiled Tubing Size

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