Sergei Slovenija
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- Slovenija Ljubljana
At the time of the work, my experience in TIG welding of stainless steel was probably a couple of meters of welding seams. I started practicing this craft in August 2020.
In production, an acute problem arose with the chemical resistance of the liquid-ring vacuum pump housings. Corrosive gases and cavitation have eaten holes in the spheroidal cast iron.
The first repair option was to seal the holes with epoxy resin filled with metal dust.
The second option is lining with thin stainless steel (0.6 mm), welded by MIG welding (Oops). But it worked much longer.
Therefore, I thought over the option of manufacturing new pump casings and covers entirely from INOX 304. The sequence of operations consisted in prototyping, welding of parts made with allowance for subsequent turning and milling work from a third-party contractor. The original geometry has been simplified for the sake of manufacturability of the assembly. Some of the parts were modeled according to the remains of the original dimensions. Oddly enough, I don't see any traces of cavitation wear yet. And the power of the vacuum has increased slightly.
Fortunately, the pump impeller itself was from INOX and did not require replacement. But the previous 5 pumps had a brass impeller, and there was "paper" from it after half a year of work.
Collected 2 pumps at once. They work without remarks and wear, but even mechanical seals with VITON sealing require regular inspection and preventive replacement once a quarter.
I collected it with a standard 26 series hand torch and it was hell. Its dimensions are such that in some places I had to bend the tungsten electrode at an angle and hold the arc sideways. I threw away the 26 burner and now I work No. 9 and No. 17, with a homemade super-flexible cable.
Video, part 1, beginning (and further on the channel, who is interested)
If I remember well, a new pump, completely made of stainless steel (head), cost almost 3,500 euros and the delivery time was around 6 months. Which was not acceptable.
In production, an acute problem arose with the chemical resistance of the liquid-ring vacuum pump housings. Corrosive gases and cavitation have eaten holes in the spheroidal cast iron.
The first repair option was to seal the holes with epoxy resin filled with metal dust.
The second option is lining with thin stainless steel (0.6 mm), welded by MIG welding (Oops). But it worked much longer.
Therefore, I thought over the option of manufacturing new pump casings and covers entirely from INOX 304. The sequence of operations consisted in prototyping, welding of parts made with allowance for subsequent turning and milling work from a third-party contractor. The original geometry has been simplified for the sake of manufacturability of the assembly. Some of the parts were modeled according to the remains of the original dimensions. Oddly enough, I don't see any traces of cavitation wear yet. And the power of the vacuum has increased slightly.
Fortunately, the pump impeller itself was from INOX and did not require replacement. But the previous 5 pumps had a brass impeller, and there was "paper" from it after half a year of work.
Collected 2 pumps at once. They work without remarks and wear, but even mechanical seals with VITON sealing require regular inspection and preventive replacement once a quarter.
I collected it with a standard 26 series hand torch and it was hell. Its dimensions are such that in some places I had to bend the tungsten electrode at an angle and hold the arc sideways. I threw away the 26 burner and now I work No. 9 and No. 17, with a homemade super-flexible cable.
Video, part 1, beginning (and further on the channel, who is interested)
If I remember well, a new pump, completely made of stainless steel (head), cost almost 3,500 euros and the delivery time was around 6 months. Which was not acceptable.