A transformer manufacturer in Tunisia required a customized 1000 kVA 11 kV 3-phase oil-immersed transformer tank together with a removable panel-type radiator cooling system.
Instead of purchasing a complete transformer, the customer required the tank and radiator assembly only, allowing its engineering team to complete the active-part assembly, electrical components and final transformer production locally.
The key procurement requirements were not limited to tank dimensions. The customer also needed to verify steel material, plate thickness, welding quality, radiator construction, oil-tightness, surface treatment, testing and mechanical interfaces before production.
The final solution was therefore developed around the customer’s approved transformer drawings and the relevant IEC 60076 requirements.
| Item | Project Requirement |
|---|---|
| Project Location | Tunisia |
| Equipment | Oil-Immersed Transformer Tank |
| Transformer Capacity | 1000 kVA |
| Phase | 3 Phase |
| Rated Voltage | 11 kV |
| Cooling Method | ONAN |
| Radiator Type | Removable Panel-Type Radiator |
| Tank Material | Welded Carbon Steel Plate |
| Plate Thickness | According to approved GA / tank design |
| Radiator Material | Steel |
| Radiator Connection | Removable Flange Connection |
| Welding | Continuous / qualified welding process |
| Leak Tightness | Oil leakage / pressure testing |
| Surface Treatment | Cleaning + anti-corrosion coating |
| Installation | Outdoor / Indoor |
| Standard Basis | IEC 60076 series |
| Supply Scope | Transformer Tank + Radiators |
| Customization | OEM according to customer drawings |
Engineering note: Tank plate thickness, radiator dimensions, flange dimensions, oil volume and reinforcement structure should be confirmed according to the customer’s approved GA drawing and mechanical design rather than using one standard thickness for every 1000 kVA transformer.
For transformer manufacturers, purchasing a transformer tank is different from purchasing a standard fabricated steel box.
The tank directly affects:
Mechanical strength → Oil tightness → Radiator connection → Cooling performance → Transportation → Final transformer assembly
Therefore, the purchasing team focused on several key points.
The tank body was manufactured from weldable structural carbon steel plate suitable for transformer tank fabrication.
The material selection needs to consider:
For OEM projects, the exact steel grade should be confirmed against the customer’s approved specification.
The tank plate thickness is an important purchasing parameter because it affects:
Rather than specifying one universal thickness, the tank body, cover, bottom plate and reinforcement structures should be designed according to the tank dimensions, oil volume, lifting loads and customer’s mechanical requirements.
The final production drawing can specify:
| Component | Procurement Requirement |
|---|---|
| Tank Side Plate | According to approved drawing |
| Tank Bottom Plate | According to mechanical design |
| Tank Cover | According to approved drawing |
| Reinforcement | Customized |
| Lifting Lugs | Customized |
| Radiator Flanges | Customized |
| Valve Interfaces | Customized |
This approach is more appropriate for OEM transformer tank procurement because a 1000 kVA tank does not necessarily have identical dimensions or steel thickness across different transformer designs.
Welding quality was one of the key manufacturing requirements.
The tank needs to maintain its mechanical integrity and prevent transformer oil leakage during long-term operation.
The manufacturing process therefore focuses on:
Particular attention should be paid to:
Tank corners + bottom seams + radiator connection areas + lifting structures + cover joints
These are important areas for mechanical strength and sealing performance.
For an oil-immersed transformer, the tank must provide reliable containment of insulating oil.
The completed tank assembly can be inspected and tested for leakage before shipment.
Typical quality-control procedures may include:
Checking:
The tank is checked for potential oil leakage around:
The appropriate test method and pressure should be determined according to the approved design, applicable standard and customer’s technical specification.
This is particularly important because oil leakage after the transformer has been assembled can result in significant rework costs.
The transformer tank was equipped with removable panel-type radiators for ONAN cooling.
The radiator assembly consists of multiple steel cooling panels connected to the upper and lower tank connections.
The main procurement points include:
The radiator configuration should be calculated according to the required transformer heat dissipation rather than simply selecting a radiator based on transformer capacity.
For an OEM transformer manufacturer, mechanical interface accuracy can be more important than appearance.
The radiator must correctly match the transformer tank.
The supplier therefore needs to control:
Incorrect flange dimensions can create problems during final transformer assembly.
For this reason, the radiator interface should be manufactured according to the customer’s approved GA drawing.
Because the transformer may be installed outdoors, surface protection is an important procurement consideration.
The tank and radiators should undergo an appropriate surface preparation and coating process.
A typical process may include:
Steel surface preparation → Cleaning → Primer → Intermediate coating → Top coating
The final coating system can be customized according to:
For projects in coastal or high-humidity environments, the customer may require a more stringent anti-corrosion coating system.
For this type of OEM project, quality documentation is an important part of the purchase decision.
A typical inspection plan can include:
| Inspection / Test | Procurement Purpose |
|---|---|
| Raw Material Inspection | Verify steel material |
| Material Certificate | Traceability |
| Dimensional Inspection | Verify GA drawing |
| Welding Inspection | Check fabrication quality |
| Visual Inspection | Surface and weld quality |
| Flange Inspection | Verify radiator interfaces |
| Leakage Test | Check oil-tightness |
| Pressure / Tightness Test | Verify tank sealing |
| Coating Inspection | Verify surface protection |
| Final Dimensional Check | Confirm shipment condition |
| Packing Inspection | Prevent transportation damage |
The final inspection and documentation package can be customized according to the customer’s purchase order and inspection requirements.
For buyers purchasing transformer tanks from overseas suppliers, the following checklist can be used before production approval.
| Parameter | Specification |
|---|---|
| Transformer Rating | 1000 kVA |
| Voltage | 11 kV |
| Phase | 3 Phase |
| Transformer Type | Oil-Immersed |
| Cooling | ONAN |
| Tank Construction | Welded Steel |
| Tank Plate | Customized |
| Steel Grade | According to approved specification |
| Plate Thickness | According to approved mechanical design |
| Radiator Type | Removable Panel |
| Radiator Material | Steel |
| Radiator Thickness | According to thermal/mechanical design |
| Radiator Connection | Flanged |
| Oil Circulation | Natural |
| Air Cooling | Natural |
| Welding | Controlled / Qualified Process |
| Leakage Testing | Required |
| Surface Treatment | Anti-Corrosion Coating |
| Dimensional Inspection | Required |
| Material Certificate | Available according to order |
| Final Inspection | Before Shipment |
| Standard Basis | IEC 60076 Series |
| Customization | OEM / Customer Drawing |
The customer was not simply looking for a 1000 kVA steel tank.
Its actual requirement was an OEM-ready tank and radiator assembly that could be integrated into its own transformer production process.
The supplied solution therefore focused on five procurement priorities:
Tank and radiator dimensions were based on the customer’s transformer design.
The tank structure, reinforcement and lifting points were designed according to the required mechanical loads.
Welding and sealing areas were controlled to reduce the risk of oil leakage.
The removable radiator configuration was designed for the required ONAN cooling arrangement.
Material, dimensional, welding, leakage and final inspection records can be provided according to the agreed inspection plan.
For transformer manufacturers, a customized tank provides greater flexibility.
A supplier can manufacture the tank according to:
This is particularly useful when the transformer manufacturer performs the active-part assembly and final electrical configuration locally.
For the Tunisia project, the supplier delivered a customized mechanical solution consisting of:
1000 kVA 3-phase oil-immersed transformer tank
11 kV transformer application
Removable panel-type radiators
ONAN cooling configuration
Customized mechanical interfaces
Welding, leakage and dimensional quality control
The solution enabled the Tunisian transformer manufacturer to integrate the tank and radiator assembly into its own production process while maintaining control over the transformer core, winding, electrical accessories and final configuration.
Transformer tanks are generally fabricated from weldable steel plates selected according to the mechanical design, welding requirements and customer’s specification. The exact steel grade should be confirmed before production.
There is no single universal thickness for every 1000 kVA transformer tank. Tank plate thickness depends on dimensions, oil volume, mechanical loads, vacuum/pressure requirements and the customer’s approved design.
The completed tank can undergo visual welding inspection and an appropriate leakage or pressure/tightness test according to the approved design, applicable standards and customer’s inspection specification.
Yes. Removable panel-type radiators can be detached from the transformer tank, making transportation, installation, inspection and maintenance easier.
Yes. Transformer tanks can be manufactured according to customer-approved GA drawings, radiator drawings, flange dimensions and mechanical specifications.
Yes. Radiator height, number of elements, connection dimensions, flange arrangement and other mechanical parameters can be customized according to the required transformer cooling design.
Buyers should consider requesting material certificates, approved drawings, dimensional inspection reports, welding inspection records, leakage/tightness test reports and final inspection documentation.
The IEC 60076 series covers requirements for power transformers and related aspects. IEC 60076-22-2 specifically addresses removable radiators for liquid-immersed transformers.
