Overview of Bright Annealing Stainless Steel Tube
Bright annealing 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.
Specification of Bright Annealing Stainless Steel Tube
| Welded Tube | ASTM A249, A269, A789, EN10217-7 |
| Seamless Tube | ASTM A213, A269, A789 |
| Grade | 304, 304L, 316, 316L, 321, 4302205 Etc. |
| Finish | Bright Annealing |
| OD | 3 Mm – 80 Mm; |
| Thickness | 0.3 Mm – 8 Mm |
| Forms | Round, rectangular, square, hex,oval, etc |
| Application | Heat Exchanger, Boiler, Condenser, Cooler, Heater, Instrumentation Tubing |
Testing and Procedure of Bright Annealing Stainless Steel Tube
l Heat Treatment and Solution Annealing / Bright Annealing
l Cutting to required length and deburring,
l Chemical Composition Analysis Test With 100% PMI and One tube from each heat by Direct Reading Spectrometer
l Visual Test and Endoscope Test for Surface Quality Test
l 100% Hydrostatic Test and 100% Eddy Current Test
l Ultrasonic Test subject to the MPS (Material Purchase Specification)
l Mechanical Tests includes Tension Test, Flattening Test, Flaring Test, Hardness Test
l Impact Test subject to Standard request
l Grain Size Test and Intergranular Corrosion Test
l 10. Ultrasoic measuring of Wall Thickness
The monitoring of the tube temperature is essential for
l Effective Bright Surface Finish
l To strengthen and maintain a strong internal bond of the stainless tube.
l Heating as fast as possible .Slow heat results in oxidation at intermediate temperatures .Higher temperatures produce reducing condition which is very effective for the final brighter appearance of the tubes. The peak temperature maintained in the annealing chamber is around 1040°C.
Purpose And Advantages Of Bright Annealed
l Eliminate work hardening and obtain satisfactory metal lographic structure
l Obtain a bright, non-oxidizing surface with good corrosion resistance
l The bright treatment maintains the smoothness of the rolled surface, and the bright surface can be obtained without post-processing
l No pollution problems caused by common pickling methods
