HDG pressed steel water tank
An HDG pressed steel water tank is a bolted sectional tank assembled from mild steel panels that are hydraulically pressed into a ribbed, flanged shape and then hot-dip galvanised. In Singapore it is the standard choice for non-potable fire water storage: sprinkler tanks, hosereel tanks, wet riser tanks and general fire reserve.
Waves Fluid Engineering Pte Ltd supplies, installs, replaces and repairs HDG pressed steel tanks across Singapore. We hold the sole dealership for tanks manufactured by Dezhou Yigao New Material Co., Ltd, which lets us quote competitively and keep lead times predictable, and we also replace leaking, broken or rusted panels on existing tanks whoever originally installed them.
What does HDG mean on a water tank?
HDG stands for hot-dip galvanised. The fabricated steel panels and fittings are dipped in molten zinc after pressing, so the zinc coats the faces, the folded edges and the bolt holes rather than just being sprayed on the surface. That is what lets the tank stand up to Singapore's humidity and sun in an outdoor or rooftop installation.
Also known as: HDG tank, galvanised water tank, pressed steel sectional tank, panel bolted steel tank, GI water tank and sectional steel water tank. All describe the same bolted panel tank.
Pressed steel and HDG are two different things
The two terms get used interchangeably, but they describe different stages. Pressed steel is the forming process: flat mild steel plate is pressed under hydraulic force into a ribbed panel with flanged edges, which gives the panel its stiffness without needing a welded frame. HDG is the protection applied afterwards: the finished panels, stays, bolts and cleats are hot-dip galvanised. An HDG pressed steel tank is both, which is why you see the terms together.
What HDG tanks are used for
HDG tanks hold non-potable water. In Singapore they are specified almost entirely for fire protection storage, because the duty suits a large, outdoor, structurally strong tank that is not used for drinking water.
Sprinkler water tank
Dedicated storage feeding the automatic sprinkler system and its pumps.
Hosereel water tank
Fire water reserve for the hose reels. See our hosereel water tank page for the SCDF capacity requirements.
Wet riser water tank
Fire water storage serving the wet riser system in multi-storey and high-rise buildings.
Industrial non-potable storage
Cooling tower make-up, process water and general building service water where the finish is confirmed.
Not for drinking water. HDG pressed steel tanks are non-potable. For potable and domestic water storage in Singapore, use an FRP / GRP tank to SS 245:2014, or an SS316 stainless steel tank for food-grade and higher-specification duties.
Standards and compliance
Two separate things are often collapsed into one sentence, so it is worth separating them. SS 22:1979 Pressed steel sectional rectangular tanks is the Singapore Standard that the tank itself is built to. SCDF's Fire Code is what requires your building to have fire water storage in the first place, and sets the system requirements. The tank is supplied to SS 22; the fire protection system is designed to the Fire Code by your QP or fire safety engineer.
Is SS 22 still used? Yes. SS 22:1979 remains listed on the Singapore Standards eShop, where it carries an obsolescent note, and it continues to be referenced in Singapore fire protection specifications for pressed steel sectional tanks. If your consultant specifies a different design or plate thickness schedule, send us the specification and we will quote against it.
Panel sizes
The tank is built up from modular panels, which is what lets us match the capacity to an awkward plant room and carry the panels in through a normal doorway. We supply HDG panels in three sizes:
1m x 1m (H)
Standard panel
1m x 0.5m (H)
Height adjustment
0.5m x 0.5m (H)
Fine adjustment
Mixing the three sizes gives a wide choice of tank dimensions, so the stored volume can be matched closely to the design requirement rather than rounded up to the nearest whole module. Individual panels are also replaceable, which matters later: a single cracked or rusted panel can be changed without rebuilding the tank.
Design and installation requirements
Most problems that show up years later start at installation. These are the points we check and get right on every HDG tank:
1m c/c
Plinth spacing
1m centre-to-centre is the standard plinth spacing. Where 2m centre-to-centre is used, an I-beam skid base is required to carry the load properly.
1 per cell
Air vents
Each compartment normally has one air vent, though a consultant may specify more than one per compartment.
3m +
Safety features
Tanks 3m or higher require a perimeter guard rail on the roof panels and a safety cage on the external ladder.
No limit
Tank height
There is no fixed height restriction on an HDG tank, because it is non-potable. The 4m restriction applies to potable water tanks.
Standard fittings
- Lockable manhole cover for access and tank security
- Insect-proof air vent to each compartment
- Galvanised internal and external ladders
- Flanged inlet, outlet, overflow and drain nozzles
- Internal stays and cleats, hot-dip galvanised
- Water level indicator and ball float valve on request
HDG compared with other tank materials
Tank material is chosen by what the water is used for and the standard the installation must meet, not by price alone.
| Tank type | Water | Typical use | Standard |
|---|---|---|---|
| HDG pressed steel | Non-potable | Sprinkler, hosereel, wet riser, fire reserve. Suits outdoor and rooftop. | SS 22 |
| Bitumen painted steel | Non-potable | The same fire duties, but specified for indoor plant rooms and tank rooms. | SS 22 |
| FRP / GRP | Potable | Domestic and potable storage, NEWater, cooling tower, rainwater. | SS 245:2014 |
| SS304 stainless | Non-potable | Fire, chemical and treated water where longer service life is wanted. | Grade 304 |
| SS316 stainless | Potable | Drinking water and food processing, higher corrosion resistance. | Grade 316 |
Recent installations
Our services for HDG tanks
New tank
Supply and installation
- Size the tank from your requirement, or work from the consultant's drawing and capacity schedule.
- Quote the tank, fittings and installation, with the panel arrangement confirmed.
- Deliver panels to site and assemble, bolt and seal in the plant room or on the roof.
- Fill, leak test, commission and hand over with warranty.
Repair
Panel replacement and repair
- Visit site and inspect the tank, the panels and the galvanising condition.
- Identify leaking, broken or rusted panels and failed joints.
- Give an obligation-free quotation for repair or full replacement.
- Carry out the works, replacing individual panels where the tank is otherwise sound.
Service life and maintenance
A well-installed HDG tank in Singapore conditions typically gives many years of service, but the galvanising is what you are protecting. Rust usually starts where water sits, where the coating has been damaged during installation, or around fittings and bolt holes. An annual visual inspection of the panels, bolts, stays and ladder, carried out at the same time as tank washing, catches it while a single panel swap is still the answer. Leaving it leads to a full tank replacement instead, which is a far bigger job on a live fire system. See our tank repair works for details.
Our certifications
BCA ME11
Mechanical Engineering, L1
BCA GB1
General Builder Class 1
bizSAFE Star
Workplace Safety & Health
ISO 9001:2015
Quality Management System
Warranty
Two-year warranty on new tanks
Newly installed HDG pressed steel water tanks come with a two-year warranty from the date of installation, subject to terms and conditions.
Related tanks & services
Water tank installation
Bitumen painted tank
Hosereel water tank
SS304 stainless steel tank
FRP / GRP water tank
Tank repair works
Tank washing (PUB)
Water pump systems
Frequently asked questions
What is an HDG pressed steel water tank?
It is a bolted sectional water tank built from mild steel panels that are hydraulically pressed into a ribbed, flanged shape and then hot-dip galvanised. The panels are delivered separately and assembled on site with sealed bolted joints, which is why the tank can be built inside a plant room that a one-piece tank could never be carried into.
What is the difference between pressed steel and HDG?
Pressed steel describes how the panel is formed: flat mild steel plate is pressed under hydraulic force into a ribbed panel with flanged edges. HDG describes the protection applied afterwards: the panels and steel fittings are dipped in molten zinc. An HDG pressed steel tank is both, so the terms appear together rather than being alternatives.
Can an HDG tank store drinking water?
No. HDG pressed steel tanks are for non-potable water, which in Singapore means fire protection storage and similar industrial duties. For potable and domestic water, use an FRP / GRP tank compliant with SS 245:2014, or an SS316 stainless steel tank where a higher specification is required.
Is SS 22:1979 still valid for pressed steel tanks?
SS 22:1979 Pressed steel sectional rectangular tanks remains listed on the Singapore Standards eShop, where it carries an obsolescent note, and it continues to be referenced in fire protection specifications in Singapore. It is a Singapore Standard covering the tank itself, not an SCDF certification: SCDF's Fire Code sets the requirement for the building's fire water storage, while the tank is supplied to SS 22. If your project specifies a different standard or plate thickness schedule, send it to us and we will quote against it.
What panel sizes are available?
We supply HDG panels in 1m x 1m (H), 1m x 0.5m (H) and 0.5m x 0.5m (H). Mixing the three gives a wide range of tank dimensions, so the capacity can be matched to the available space rather than rounded up to the nearest whole module.
Is there a height limit for an HDG tank?
There is no fixed height restriction on an HDG tank, because it holds non-potable water. The 4m maximum height applies to potable water tanks. Separately, any tank 3m or higher requires a perimeter guard rail on the roof panels and a safety cage on the external ladder.
What plinth does an HDG tank need?
The standard plinth spacing is 1m centre-to-centre. Where the design uses 2m centre-to-centre, an I-beam skid base is required to spread the load correctly. The plinth or base is normally prepared before the tank panels arrive on site.
Can a single leaking or rusted panel be replaced?
Yes, in most cases. Panel bolted tanks are modular, so an individual cracked, broken or rusted panel can be replaced and the joints resealed without dismantling the whole tank. We inspect the tank first and advise honestly whether panel replacement or full replacement is the better option, since repeated patch repairs on a tank at the end of its life are not good value.
Can an HDG tank be installed outdoors or on a roof?
Yes. Hot-dip galvanising is applied after the panels are formed, so the zinc covers the faces, folded edges and bolt holes, which is what allows the tank to handle Singapore's humidity, rain and sun. For indoor plant rooms, a bitumen painted pressed steel tank is the usual alternative.
How long does installation take?
It depends on the tank size, the access route into the plant room or onto the roof, and whether an existing tank has to be dismantled first. Because panels arrive as modular components, they can be carried through normal doorways and assembled in place. We confirm the programme in the quotation after a site visit.
Do you work from the consultant's drawing?
Yes. We regularly work from M&E consultants' and main contractors' drawings and capacity schedules, and we can also advise on tank sizing and the panel arrangement where the drawing leaves it open. Send us the drawing and we will quote against it.
What warranty do you give?
Newly installed HDG pressed steel water tanks come with a two-year warranty from the date of installation, subject to terms and conditions. Products and spare parts we supply are from recognised manufacturers, and we hold the sole dealership for the tanks we import.
Need an HDG tank supplied, installed or repaired?
Call or WhatsApp +65 9487 0446 or email sales@wavesfluid.com.sg for a site visit and quotation.
