GRP water tank Internal Steel Structural Choose Stainless Steel or Galvanized Steel
For the internal accessories of a fiberglass-reinforced plastic (FRP) GRP water tank specifically the tie rods(lacing bar) and columns(steel support)—the selection is clear: for potable/drinking water, stainless steel (SS304/SS316) should be preferred; for fire protection or applications with less stringent water-quality requirements, hot-dip galvanized steel may be used, but its long-term corrosion risk under immersion must be considered. This judgment is supported by industry standards and practical cases.
Selection Summary
| Selection Recommendation Summary | ||
| Application | Recommended Material | Reason |
| Potable / drinking water | SUS304 stainless steel | High hygiene and safety requirements; prevents corrosion from contaminating water; common industry practice |
| Non-potable water, fire protection water, Industry water, cooling water, | Hot-dip galvanized steel (zinc layer 45-60 μm) | Less stringent water-quality requirements; cost-controllable; regular inspection of zinc layer condition required |
More Specific Guidance
If It Is a Drinking Water Tank
Choose stainless steel tie rods and steel support.
Because internal components are in direct contact with water, hot-dip galvanized steel may gradually lose its zinc coating and begin to rust after long-term immersion, creating potential water-quality risks. For drinking water tanks, internal components should generally be stainless steel, especially:
SUS304: commonly used for ordinary drinking water and domestic water tanks;
SUS316L: more suitable when water has higher chlorine content, stronger corrosivity, or stricter hygiene requirements.
If It Is a Fire-Protection Tank
Hot-dip galvanized steel can be selected.
Fire-protection tanks are normally not used for drinking water, so hot-dip galvanized tie rods and steel support offer a reasonable balance between corrosion protection and cost.
However, if the client, design drawings, or acceptance standards explicitly require stainless steel, the design requirements must be followed.
If It Is for Industrial Cooling Water, Circulating Water, or Non-Potable Storage
Hot-dip galvanized steel is usually acceptable.
However, if the water contains high levels of chloride ions, acidic/alkaline substances, or chemical additives — or if the tank environment is very humid and poorly ventilated — stainless steel should be prioritized.
Recommended Approach
Drinking water / domestic water tanks: choose stainless steel — preferably SUS304; choose SUS316L for higher requirements.
Fire-protection, cooling water, or non-potable tanks: hot-dip galvanized steel is acceptable.
If the budget allows and future maintenance should be minimized: prioritize stainless steel.
If the budget is limited, the use is non-potable, and the environment is ordinary: hot-dip galvanized steel offers better cost-effectiveness.
If the project is a domestic drinking water FRP tank, it is not advisable to choose hot-dip galvanized tie rods and columns just to save cost. If it is a fire-protection tank or non-potable water tank, hot-dip galvanized steel is a reasonable choice. The final decision should still follow the design drawings, tender documents, acceptance standards, or client technical requirements.
Is this project for a drinking water tank, fire-protection tank, or industrial water storage tank? The recommended solution may differ depending on the application.
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