The below is an excerpt from CIRIA publication W002 Chemical storage tank systems – good practice http://www.ciria.org and is reprinted here with kind permission.
Part 1 of this article was originally published in edition 40 of Port Technology International and is available for download at https://184.108.40.206 under journal archives.
Part 2 of this article continues the discussion on operation, inspection and maintenance of storage tank systems. The CIRIA guide aims to provide a general good practice guidance for the selection and design, manufacture, installation, operation and maintenance of chemical storage systems. It is intended for use by any sized company.
Cleaning of chemical storage systems can be a hazardous activity, and is important for the long life of a system. Some good practice guidance on cleaning of systems is given below:
• Depending on the nature and scale of cleaning, specialist contractors may be required. This is particularly true for inside tanks which are classed as confined spaces, thus special training and apparatus are required.
• Specialist cleaning machinery is available for certain cleaning tasks such as machines for lowering into tanks and wall climbers.
• Take great care when cleaning, access may be difficult and require specialist equipment such as scaffolding or access vehicles. Cleaning may also be awkward especially around pipes and connections.
• Ensure cleaning fluids used are compatible with the chemicals stored or spilled.
• Always wash down the area affected by a spill as soon as it has been cleared. Remember that the water used is likely to have
• Cleaned surfaces may be slip hazards whilst drying, particularly on impermeable surfaces such as in bunds. Clearly mark these with warning signage for other site operatives.
• As part of the cleaning programme include vents, meshes, grills, sumps etc. These can collect debris and become blocked, or their performance affected so should be cleared on a regular basis.
• Sand blasting or high pressure water jetting should only be undertaken from a stable platform, and only when tanks are empty. This will help to avoid loss from holes that may be punctured in the tank by point jetting.
• Great care should be taken when using steam or hot water for cleaning. After cleaning, cooling steam can create a vacuum in systems if vents are left shut, are blocked or do not have a vacuum break. Always ensure that a vacuum break system is operated before commencing steam cleaning.