Oleum storage and handling

Any storage tank must be designed so that branches below the liquid level are kept to a minimum. These will normally be limited to a bottom outlet line and consideration should be given to providing an internal plug valve. An isolation valve should be bolted directly on to the tank branch with an automatic valve in the outlet line. 

All storage vessels must be provided with a system of heating which will maintain the contents at 20 - 25 C (65% oleum). Inside coils should never be used because of the possibility of steam leakage. Outside coils can be used, but should not be in direct contact with the tank surface to avoid the possibility of accelerated corrosion at hot spots. A high standard of maintenance will be required to avoid steam or condensate leaks under the lagging. The upper part of all 65% storage vessels above the maximum liquid level should be heated to about 90 C to prevent 

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Du Pont Chemicals. 1988. Sulfur Trioxide and Oleum Storage and Handling. 

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