Tanks and pressure vessels store water and chemicals and house filtration media, resins and membranes. They are long-life assets, and mistakes in specification tend to show up years later as leaks, cracks or failed inspections.
Volume is only the starting point. What is stored, at what temperature and pressure, and under which design code, decides the construction.
What falls under this category
- Storage tanks
- Rotomoulded polyethylene, FRP/GRP, epoxy-coated or glass-fused steel, stainless steel, sectional panel tanks and concrete.
- Chemical storage and day tanks
- Tanks for acids, alkalis and other treatment chemicals, often with bunds and level instruments.
- Filter and softener vessels
- FRP composite or steel pressure vessels that hold media or ion-exchange resin.
- RO membrane pressure vessels
- FRP housings for spiral-wound elements, rated for brackish or seawater pressures and holding from one to several elements.
- Other pressure equipment
- Hydropneumatic tanks and compressed-air receivers.
Specifications to compare
- Design pressure, temperature and code
- Design and test pressure, design temperature, and the code the vessel is built to (for example ASME Section VIII or EN 13445 for steel; ASME Section X for FRP).
- Stored liquid and specific gravity
- Tank walls must be designed for the density of what is stored. A tank for concentrated sulphuric acid needs much heavier construction than a water tank of the same volume.
- RO vessel details
- Pressure rating, number of elements, end-port or side-port configuration and port sizes.
- Capacity and dimensions
- Nominal and usable volume, footprint, height and weight when full.
- Nozzles and fittings
- Size, position and type of inlet, outlet, vent, overflow, drain and instrument connections.
- Environmental resistance
- UV stabilisation for outdoor plastic tanks and chemical compatibility at storage temperature.
- Certification
- Hydrostatic test certificates, material certificates, drinking-water approvals and any regional marking (for example PED in the European Union).
Information to send suppliers with your enquiry
- The stored medium, its concentration and specific gravity.
- Operating and design temperature and pressure.
- Volume, available footprint and maximum height.
- Indoor or outdoor installation.
- A nozzle schedule, or a sketch showing required connections.
- Design code and certification required by your client or insurer.
- Delivery access, including door widths and crane availability.
Common sourcing mistakes
- Ordering chemical tanks by volume only, without stating specific gravity and temperature.
- Installing plastic tanks outdoors without UV protection.
- No secondary containment for chemicals. A bund sized to hold at least 110% of the largest tank is a common requirement, but check local rules.
- Pressure vessels delivered without code documentation, which can block insurance or statutory inspection.
- Tanks that cannot physically reach their final position. Sectional tanks solve this for tight sites.