Crack in the body of the acid return pipe
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Since the factory was established in 2008, at least 5 acid return pipes for the wash tower have been replaced. The first time this problem occurred, I thought it was caused by thermal expansion and contraction due to rainwater, so I built an additional shelter; that didn’t work either, and eventually at least 4 more poles had to be removed. The pipeline is made of cast iron, with dimensions of 1500*350, and it is also supported by vertical posts at its lower part. The acid temperature is controlled at 65 degrees upon entry into the tower, and around 80 degrees when returning to the tower. This phenomenon has never occurred with drying and double absorption.
It’s easier to use a better material; aren’t you tired from keeping changing it?
I agree with you; it is recommended to replace the material as soon as possible, using stainless steel 304L or 316L in place of the anode protection, or opting for valves made of alloy, which is also a good option
Cast iron pipes inherently have defects during the production process; it is recommended to use alternative materials – 316L with anodic protection or Xunda XDS specialty stainless steel would also be good options
What acid is it? The material should be selected based on the medium, pressure, and temperature
It would be helpful to provide more detailed information on the site conditions and the process media, so that everyone can discuss them.
This post was last edited by Linyi Qianda Zhu Guangqian on 2016-1-17 at 21:47. You produce concentrated sulfuric acid; the acid temperature is normal. There have been multiple problems with the acid return pipeline during the first absorption process, while there have been no issues with the same cast-iron acid return pipelines during the second absorption and drying processes. You can increase the wall thickness of the DN350, L=1500mm pipe to 20mm, or replace it with a thick-walled stainless steel pipe. The standard wall thickness for DN350 pipes is 14mm, which allows them to withstand a pressure of 10 Kg; by increasing the thickness, they can withstand a pressure of 16 Kg. When pumps are started or stopped, sudden pressure changes can cause cast iron pipes to suffer from brittle fracture, so it’s important to check the pressure levels in each section of the pipe.
Our pump outlet pressure is 0.2 MPa, which is equivalent to 2 kilograms. After starting the pump, open the outlet valve; the pressure should not exceed 1 MPa, right?
Cast iron pipes have been used since the plant was established, and this phenomenon has not occurred elsewhere.
The acid is 98% absorption acid, the pump outlet pressure is 0.2 MPa, and the pipe diameter is 250 MM. The tower is about 5 meters tall. The pressure has not been measured on the acid return pipeline; its diameter is 350 MM. For drying, the first suction and the second suction follow the same design; the only difference is that the drying acid has a concentration of 93%. It only appears with one inhalation (it’s always this part every time).