Hi Friends,
Hence Nihard steel and High chromium steel (27% Cr) conforming to ASTM A532 are the best suited material for the equipment and facilities for red area of Alumina refinery. These materials gives reasonably high service life. To prevent the erosion in the shell of the ball mills / rod mills, high manganese steel liners of adequate thickness conforming to ASTM A128 or IS-276 are provided. The suction and discharge lines of pumps of red area handling slurry containing abrasive solids like bauxite and silica are provided with carbon steel pipes having higher schedule to take care of erosion and replaced periodically as and when required.
As a guideline, minimum plate thickness of the shell of Digesters and Flash tanks are kept as 20 mm and 16 mm respectively. However, the thickness of dished end portions are generally kept at around 24 mm and 22 mm respectively for digesters and flash tanks.
Trust, the above information gives fair idea for selecting the equipment and facilities with right material of construction to ensure uninterrupted operation of plant for longer duration with minimum downtime.
Please put your views / remarks / suggestions / comments, if any.
If you like this article, then please press your rating as +1 .
Thanks and regards.
Kunwar Rajendra
In earlier posts, we have already discussed about the material of construction for pressure vessels like digesters and flash tanks in Alumina refinery. In present post, we will discuss the preferred material of construction mainly for pumps, valves, pipe bends and inlet tee of flash tanks installed and operated in red area of Alumina refinery. As such, carbon steel (mild steel) is the most favorable material of construction for plant, equipment and facilities used in highly alkaline environment of Alumina refinery because of noncorrosive nature of sodium aluminate solution.
Bauxite grinding to security filtration comes under red area of Alumina refinery as the material like bauxite and residue having brick red colour are handled in this portion of the plant. Bauxite particles because of presence of silica is highly erosive in nature which erodes the pumps, pipeline, heater tubes, valves, bends and inlet tees of cyclones & flash tanks within very short duration. Thus it becomes essential to ensure suitable material of construction for manufacture for the components envisaged in direct contact of bauxite slurry.
Hence Nihard steel and High chromium steel (27% Cr) conforming to ASTM A532 are the best suited material for the equipment and facilities for red area of Alumina refinery. These materials gives reasonably high service life. To prevent the erosion in the shell of the ball mills / rod mills, high manganese steel liners of adequate thickness conforming to ASTM A128 or IS-276 are provided. The suction and discharge lines of pumps of red area handling slurry containing abrasive solids like bauxite and silica are provided with carbon steel pipes having higher schedule to take care of erosion and replaced periodically as and when required.
As a guideline, minimum plate thickness of the shell of Digesters and Flash tanks are kept as 20 mm and 16 mm respectively. However, the thickness of dished end portions are generally kept at around 24 mm and 22 mm respectively for digesters and flash tanks.
Trust, the above information gives fair idea for selecting the equipment and facilities with right material of construction to ensure uninterrupted operation of plant for longer duration with minimum downtime.
Please put your views / remarks / suggestions / comments, if any.
If you like this article, then please press your rating as +1 .
Thanks and regards.
Kunwar Rajendra
Dear Sir,
ReplyDeleteWe have worked with various metallurgy in form of sleeves at the inlet ports of Valves as this is the area where there is maximum erosion takes place. We have worked with high manganese Alloys, High Chrome Steels, Nickel Alloys depending on the applications.
These Valves which such Sleeves have been able to give exponentially higher lives for Valves as compared to conventional Valves.
But in extremely critical applications of Valves total wetted portion of the Valves being Nickel lined have been the best solution.
I think the same can be extended to other applications of Pumps, pipe bends etc as well.
Thank you for your e.mail expressing your views and suggestions.
ReplyDeleteI fully agree with you. Hope, I will continue to receive your valued advice.
Regards.
Kunwar Rajendra
what the best construction material for heat exchanger, flash tanks, tube digester, ball mills, mud settler, desilication, lime slaker
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