Acid-tank design: why corrosion allowance is only one input
An acid tank cannot be specified safely by capacity and a generic corrosion allowance alone. Chemistry, concentration, temperature, contamination and operating practice can change material compatibility. This guide explains the questions an engineering team should resolve before a tank design is finalised.
Section 01Define the stored liquid accurately
Specify the acid, concentration range, temperature range and credible contaminants. Include startup, shutdown, dilution and upset conditions where relevant. A material suitable for one concentration and temperature may not be suitable across the complete operating envelope.
Use product and process information from the responsible operator and chemical specialists. Do not infer compatibility from the name “acid tank” or from a drawing of a tank used elsewhere.
Section 02Select materials with corrosion expertise
Material selection may require specialist corrosion review, documented compatibility information and service experience relevant to the actual chemistry. Coatings, linings and composites can introduce their own preparation, application and inspection requirements.
A corrosion allowance is an engineering input, not a universal protection strategy. It does not resolve incompatibility, localised attack, vulnerable weld details or damage to a lining. The design should define how deterioration will be detected and managed.
Section 03Confirm the structural and operating basis
Tank geometry, liquid density, pressure and vacuum limits, supports, site loads and design life influence structural checks. Confirm whether API 650 applies to the particular tank and service; using its name does not establish suitability for every chemical storage duty.
Coordinate normal and emergency venting, filling and withdrawal arrangements, foundation interfaces and operational controls with the responsible disciplines. Protecting against overpressure or vacuum involves the full system, not just shell thickness.
Section 04Pay attention to nozzles and maintainability
Nozzles, drains, manways and instrument connections are important interfaces between the tank and the process plant. Material compatibility, connection loads, inspection access and the ability to isolate or maintain equipment need consideration.
Maintenance planning should address inspection access, cleaning, lining repair where applicable and replacement of vulnerable components. These activities require site-specific procedures and must not be improvised from a general design article.
- Verified chemistry and material-compatibility basis.
- Defined pressure, temperature and density envelopes.
- Connection schedules and piping interfaces.
- Inspection, containment and maintenance responsibilities.
Section 05Separate the tank from the wider containment system
Spill containment, drainage, emergency response and environmental controls need coordinated site engineering. The tank design package should state where its scope ends and which interfaces require information or approval from others.
Namibian industrial and mining projects may have additional project, statutory and environmental requirements. The responsible team must identify those obligations; this article does not claim to provide a complete compliance checklist.
Section 06What experience contributes to the design conversation
My experience includes Bannerman acid tanks and sulphuric-acid tank design in Namibia, alongside API 650 storage tanks. The useful starting point for a new enquiry is a complete service description and a clear division of engineering responsibilities.
No material selection, corrosion rate, tank thickness or repair method should be adopted from this article. Final decisions require verified process inputs, the applicable standards and competent project-specific review.