Electropolishing of Large Vessels
Electropolishing the interior surfaces of tanks, mixers, and other large
pieces of equipment requires the use of special equipment and techniques
depending upon the product to be polished and the finish specifications.
Sometimes the tank can be filled with solution and used as its own vessel
for polishing; in other cases, the tank is partially filled with solution
and is rotated around a stationary cathode to achieve the desired finish.
Internal tank finishes in the range of 0.5 RMS units are reportedly produced
in this manner.
| |
|
|
| |
The photo above shows a steam-jacketed vessel of 10,000 gallon capacity
being electropolished to pharmaceutical specifications on the interior
surfaces. |
|
| An
investment of $25,000-$100,000 is typically required to establish
the capability to electropolish tanks; the cost varies with the
size of the tanks and the production volume. |
Electropolishing of Pipe & Tubing
Manual
or automatic machines are available for electropolishing the inside
surface of stainless steel pipe. Lengths of pipe or tubing up to
30' are handled in production volumes using such machines.
The principle involves pumping electropolishing solution through
the pipe and using either stationary or moveable interior cathodes
which distribute the current along the length of the pipe during
the electropolishing cycle. The equipment can be designed to polish
up to 20 lengths of pipe or tubing simultaneously. Machines have
been built to process tube diameters ranging from ¼" to 6". Finishes
in the range of 3-5 microinches are achieved by these methods.
The typical investment for a semi-automated machine to electropolish
tubing in the range of ¼" to 2" in diameter varies from $80,000
to $200,000 depending on the number of different diameters to be
electropolished and the production volume. |
| |
|
|
| |
The electropolishing machine above is designed for simultaneous
ID electropolishing of ten tubes, 20 feet in length. The capability
of the machine includes selected tube diameters from ¼” to 1”. Typical
production rates are about 2000 feet of tubing per shift. Finishes
in the range of 3-5 Ra are routinely achieved. Machines have also
been designed for larger size pipes up to about 6” in diameter. |
|
|
