Stainless Steel Bright Annealed Tube is manufactured as per ASTM A249/ASME SA249, ASTM A269, EN 10217-7 with a full line of grades, diameters and lengths, the standard stainless steels include 304/304L, 316/316L, 321 grade, Bright annealing finish has a bright, reflective appearance on stainless steel tube surface, that are free of heavy oxides or scales. Bright Annealing is now the standard method for annealing tubing. After bright annealing, the OD is often mechanically polished with a 180-240 grit to give the ideal finish.
Bright annealing (BA) refers to stainless steel material is heated in closed furnace in reducing atmosphere of inert gases, common Hydrogen gas, after fast annealing, rapid cooling, stainless steel has a protective layer on the outer surface, no reflect in open air environment, this layer can resist corrosion attack. In general, material surface is more smooth and brighter.
Welded Stainless Steel Bright Annealed Tube Manufacturing
Tube production is completed entirely inline, beginning with high quality strip material for rolling form, then TIG welding, tube enters the closed annealing chamber. In the closed annealing chamber the stainless tube is heated to high temperature by induction coils in reducing atmosphere of inert gases like Argon/Nitrogen and Hydrogen gas. After some time the red hot tube exits from the closed annealing chamber and is subjected to rapid cooling. After the tube exits the chamber it finally goes into the last stages of sizing and straightening. BA tubing requires the inner surface has a very good surface roughness and cleanliness, is a comprehensive consideration of organizational stability corrosion resistance and workability of the pipe.
Annealing and pickling finish is still the standard practice for many manufacturers.
Welded Bright Annealed Tube Specifications
- ASTM A249/SA249 Boiler / Heat Exchanger
- ASTM A268/SA268 Ferritic steel
- ASTM A269 General Services
- ASTM A270/SA270 Sanitary / Pharmaceutical Tubing
- ASTM A554 Ornamental and Mechanical Tubing
- ASTM A789/SA789 Duplex steel Tubing
Stainless Steel Grades
- Stainless:304, 304L, 316, 316L, 309, 309S, 310, 321, 347/147H
- Stainless 405, 409, 410, 430, 439
- Super Alloys 2205, S32750, S32760
Quality/Testing
Our tube mill operators complete all required ASTM and customer specifications testing, based on fabrication and surface finish requirements. Mechanical tests are performed at regular intervals, and all tubing is 100% eddy current tested.
- Quality Management System
- Eddy Current
- Expansion
- Flatten
- Tension
- Rockwell
- Metallurgical
- Dimensional
- Bend
- Flare
- Reverse Bend
- Flange
- Surface Roughness
- Surface Passivity
- Others Upon Request
Stainless Steel Bright Annealed Tube Sizes
| INCHES | MILLIMETERS | INCHES | MILLIMETERS |
|---|---|---|---|
| 0.375 | 9.525 | 2.312 | 58.725 |
| 0.500 | 12.700 | 2.362 | 60.000 |
| 0.625 | 15.875 | 2.375 | 60.325 |
| 0.675 | 17.145 | 2.382 | 60.503 |
| 0.750 | 19.050 | 2.500 | 63.500 |
| 0.840 | 21.336 | 2.625 | 66.675 |
| 0.875 | 22.225 | 2.750 | 69.850 |
| 1.000 | 25.400 | 2.875 | 73.025 |
| 1.062 | 26.975 | 3.000 | 76.200 |
| 1.125 | 28.575 | 3.250 | 82.550 |
| 1.250 | 31.750 | 3.500 | 88.900 |
| 1.315 | 33.401 | 3.613 | 91.770 |
| 1.375 | 34.925 | 3.750 | 95.250 |
| 1.500 | 38.100 | 4.000 | 101.600 |
| 1.625 | 41.275 | 4.138 | 105.105 |
| 1.681 | 42.698 | 4.378 | 111.201 |
| 1.750 | 44.450 | 4.500 | 114.300 |
| 1.770 | 44.958 | 4.760 | 120.900 |
| 1.875 | 47.625 | 4.934 | 125.324 |
| 1.900 | 48.260 | 5.000 | 127.000 |
| 1.913 | 48.590 | 5.370 | 136.400 |
| 1.969 | 50.001 | 5.500 | 139.700 |
| 2.000 | 50.800 | 6.000 | 152.400 |
| 2.125 | 53.975 | 8.000 | 203.200 |
| 2.250 | 57.150 |
Open Air Annealing VS. Bright Annealing
Open Air Annealing
Open Air Annealing is an annealing process performed with atmospheric oxygen. This exposure to atmospheric oxygen causes scaling on the surface. All relevant standards require that tubes be provided free of scale, so tubes are pickled to remove the layer of scale. Pickling uses a combination of nitric and hydrofluoric acid which chemically attacks the scale on the surface. This acid combination must be carefully removed from the tubing to prevent unintentional corrosion. This can be particularly challenging for small diameter tubes.
Bright Annealing
Bright annealing is an annealing process performed in a vacuum or a controlled atmosphere containing inert gases (such as hydrogen). This controlled atmosphere reduces the surface oxidation to a minimum which results in a brighter surface and a much thinner oxide layer. Pickling is not needed after bright annealing since the oxidation is minimal. Since there is no pickling, the surface is much smoother which results in better resistance to pitting corrosion.
Bright annealing is annealing in an oxygen-free environment. The gas that replaces oxygen is called the protective gas. The protective gases are generally: water vapor, ammonia, nitrogen and hydrogen. Among them, hydrogen is the most common protective gas. Because bright annealing has high requirements on the internal environment of the annealing furnace, the cost of this process is higher than that of ordinary annealing.
Grinding and Polishing
Our manufacturing process includes the capability to grind and polish tube. These processes yield a tube with a smooth weld seam area and consistent tube body appearance.