Lagging, corrosion under

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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