Does Grade 321 Sanitary Pipe Need Annealing?

2021-11-04 14:22:28

Sanitary stainless steel pipe is a hollow strip of steel, a large number of pipeline used for conveying fluid, such as oil, natural gas, water, gas, steam, in addition, bending, torsion strength at the same time, lighter weight, so also widely used in manufacturing machinery parts and engineering structure.  Also commonly used for the production of conventional weapons, gun barrels, shells and so on.  

Factors affecting bright annealing of stainless steel sanitary tube the brightness of stainless steel tube after annealing determines the quality of the product.  There are many influencing factors, this paper lists about 5 important factors for reference. 

1.Annealing temperature is up to the specified temperature.  Stainless steel heat treatment is generally to take solution heat treatment, that is, people usually so-called “annealing”, the temperature range is 1040~1120℃ (Japanese standard).  You can also observe through the annealing furnace observation hole, the stainless steel tube in the annealing area should be incandescent, but there is no softening sag.  

2.Annealing atmosphere.  Generally, pure hydrogen is used as the annealing atmosphere. The purity of the atmosphere is better than 99.99%. If the other part of the atmosphere is inert gas, the purity can also be lower, but it must not contain too much oxygen and water vapor.  3. Sealing of furnace body.  The bright annealing furnace shall be enclosed and isolated from the outside air;  With hydrogen as a guard gas, only one vent is open (to ignite the vented hydrogen).  The method of inspection can be used to wipe the cracks of each joint in the annealing furnace with soap and water to see whether the air runs away;  One of the most easy to run out of air is the annealing furnace into the pipe place and out of the pipe place, the sealing ring in this place is particularly easy to wear, often check and change.  Stainless steel sanitary pipe  

3.protect the gas pressure.  In order to prevent micro-leakage, the protective gas in the furnace should maintain a certain positive pressure. If it is hydrogen protective gas, it is generally required to be above 20kBar.  

4. Water vapor in furnace.  On the one hand, check whether the furnace body material is dry, the furnace body material must be dried;  The second is whether the stainless steel sanitary tube into the furnace remains too much water stains, especially if there are holes in the tube, do not leak in, or the furnace atmosphere will be destroyed.  Should pay attention to is basically these, normal words, after opening the furnace should be back about 20 meters of stainless steel pipe will begin to shine, bright reflective of the kind  

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