A pipeline was constructed of a pipe with inside diameter 101 mm and outside diameter 114 mm. On examination it was found that the wall thickness had been reduced by corrosion to about half the original value in 3.25 years. i) Estimate the rate of corrosion in mm per year. A decision has to be made on what material to use to replace the pipe. Three suggestions have been made: ii) Replace with the same schedule carbon steel pipe and accept renewal at 3-year intervals. iii) Replace with a schedule 80 pipe, outside diameter 113 mm, inside diameter 97 mm. iv) Use stainless steel pipe, which will not corrode. The estimated cost of the pipes, per unit length is schedule 40 carbon steel $6, schedule 80 carbon steel $8, stainless steel (304) schedule 40 $26. Installation and fittings for all the materials adds $17.5 per unit length. The downtime required to replace the pipe does not result in a loss of production. If the expected future life of the plant is 8 years, recommend which pipe to use.
A pipeline was constructed of a pipe with inside diameter 101 mm and outside diameter 114
mm. On examination it was found that the wall thickness had been reduced by corrosion to about
half the original value in 3.25 years.
i) Estimate the rate of corrosion in mm per year. A decision has to be made on what material to
use to replace the pipe. Three suggestions have been made:
ii) Replace with the same schedule carbon steel pipe and accept renewal at 3-year intervals.
iii) Replace with a schedule 80 pipe, outside diameter 113 mm, inside diameter 97 mm.
iv) Use stainless steel pipe, which will not corrode.
The estimated cost of the pipes, per unit length is schedule 40 carbon steel $6, schedule 80 carbon
steel $8, stainless steel (304) schedule 40 $26. Installation and fittings for all the materials adds
$17.5 per unit length.
The downtime required to replace the pipe does not result in a loss of production. If the expected
future life of the plant is 8 years, recommend which pipe to use.
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