ASME SA249 TP316L BA Stainless Steel Welded Tube for Heat Exchangers

What Is ASME SA249 TP316L

ASME SA249 covers nominal-wall-thickness welded tubes and heavily cold-worked welded tubes of austenitic stainless steel, used primarily in boilers, heat exchangers, superheaters, and condensers. Grade TP316L is the low-carbon molybdenum-bearing version of 316, with carbon limited to 0.035 percent maximum, providing excellent corrosion resistance and resistance to sensitization in welded service.

Chemical Composition

For TP316L the limits are carbon 0.035 percent maximum, manganese 2.0 percent, phosphorus 0.045 percent, sulfur 0.030 percent, silicon 1.0 percent, chromium 16.0 to 18.0 percent, nickel 10.0 to 14.0 percent, and molybdenum 2.0 to 3.0 percent. The European equivalent is 1.4404, with carbon 0.030 percent, chromium 16.5 to 18.5 percent, nickel 10.0 to 13.0 percent, and molybdenum 2.0 to 2.5 percent.

Mechanical Properties

TP316L tubes have a minimum tensile strength of 485 MPa and a minimum yield strength of 170 MPa, with minimum elongation of 35 percent in 50 mm and 25 percent in 200 mm. The corresponding EN 1.4404 values are 490 to 690 MPa tensile and 190 MPa yield with 40 percent and 30 percent elongation.

Manufacturing and Finishes

Welded tubes are produced by automated welding processes such as tungsten inert gas, plasma arc, or laser welding without filler metal, then heat treated and pickled or bright annealed. The bright annealed finish, BA, is produced by annealing in a controlled atmosphere furnace, giving a smooth, clean surface suited to heat exchanger and condenser service.

Dimensional Tolerances

Outside diameter tolerances range from plus or minus 0.004 inch for tubes under 1 inch, through plus or minus 0.006 inch for 1 to 1.5 inches, up to plus or minus 0.015 inch for 3 to 4 inches, with wall thickness at plus or minus 10 percent for all sizes. Cut length tolerances are plus 1/8 inch or plus 3/16 inch depending on size.

Applications and Testing

TP316L heater and condenser tubes serve food preparation equipment in chloride environments, heat exchangers, coastal architectural railings and trim, boat fittings, springs, threaded fasteners, and chemical containers including transport. Testing options include eddy current, hydrostatic, radiography, corrosion, micro and macro examination, intergranular corrosion testing, ultrasonic, and liquid penetrant examination.

Frequently Asked Questions

Q: What standard covers SA249 TP316L?

A: ASME SA249, welded austenitic stainless boiler and heat exchanger tubes.

Q: What is the carbon limit of TP316L?

A: 0.035 percent maximum.

Q: What finishes are available?

A: Annealing pickling, bright annealing, and polished.

Q: What is the tensile strength of TP316L tube?

A: 485 MPa minimum.

Q: What sizes are available?

A: Outer diameters from 6 mm up to 219.1 mm with walls from 0.5 to 8 mm.

Q: What applications use TP316L welded tube?

A: Heat exchangers, condensers, boilers, and chloride-exposed food equipment.

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