Transformer Oil Tank

Transformer Oil Tank Manufacturer - Custom Fabrication and OEM Enclosures

We manufacture structural oil tanks for power transformers, distribution transformers, and special industrial transformers. We build directly from your engineering drawings, ensuring leak-free performance, accurate dimensions, and C4/C5 corrosion protection.

Product Range

Corrugated Oil Tanks

Designed for distribution transformers up to 33 kV. Automated corrugated fins expand and contract with oil temperature changes, eliminating the need for a top conservator.

Power Transformer Tanks

Heavy steel plate enclosures with welded flange interfaces. Built to connect directly to external cooling radiators for substation transformers.

Bell-Type Tanks

Features a split top and bottom flange joined by high-strength bolts. Allows engineers to lift off the upper body without disturbing the core assembly inside.

Conservator Tanks

Auxiliary oil expansion units equipped with internal rubber bags, moisture breathers, and oil level gauge brackets.

Technical Specifications

Parameter	Manufacturing Capability
Steel Materials	Carbon Steel (S235JR, S355J2+N, ASTM A36, Q235B, Q355B); Stainless Steel (304, 304L, 316, 316L)
Plate Thickness	Wall Plates: 5 mm - 12 mm / Bottom Base and Flanges: 12 mm - 40 mm
Welding Standards	AWS D1.1, EN ISO 9606-1, ASME Section IX
Welding Methods	MIG/MAG Welding, Submerged Arc Welding (SAW), TIG Welding
Testing Methods	Air Bubble Test, Hydraulic Pressure Test (100 kPa), Vacuum Test (-0.09 MPa for 24 hours), Hot Oil Test (70 deg C for 8 hours)
Surface Treatment	Shot Blasting to ISO 8501-1 Sa 2.5; Internal dust lower than 150 mg/sqm
Paint Protection	Epoxy and Polyurethane coatings (180 um to 350 um dry film thickness); C4/C5 grade
Dimensions Tolerance	ISO 2768-m; Flange flatness within 1.0 mm per meter

110-220KV Power Transformer Oil Tank suppliers

Custom Manufacturing Process

We transform your 2D and 3D CAD drawings into finished steel structures.

Drawing Review: Our engineers check your CAD files for weld positions, stress points on lifting lugs, and flange alignment before cutting metal.

CNC Steel Cutting: High-power laser and plasma cutters slice steel plates and bevel edge angles for deep weld joints.

Bending and Forming: CNC bending machines form corrugated fins. Hydraulic presses shape heavy wall plates and stiffener channels.

Fit-Up and Welding: Certified welders assemble the main body. Submerged arc welding machines complete long straight seams to prevent oil leaks.

Flange Machining: Large CNC gantry milling machines flat-mill top flanges after welding. This removes heat warping and ensures a tight gasket seal.

Manufacturing Quality Control

Each transformer tank passes four inspection stages before shipment: material verification, weld inspection, pressure and leak testing, and coating inspection. This process checks material thickness, weld integrity, sealing performance, paint thickness, and coating adhesion to ensure consistent quality and reliable field performance.

Internal Cleanliness

We shot-blast the inside, vacuum all steel grit, and wipe internal surfaces with lint-free cloths. This prevents tiny iron particles from polluting transformer oil.

Non-Destructive Testing

ISO 9712 Level II inspectors check 100% of lifting lug welds and main seams using Ultrasonic and Dye Penetrant testing.

Leak Testing

Every tank undergoes a positive air pressure test under water or a 24-hour hot oil pressure test before painting.

Common Applications

Substation Transformers

Heavy-duty steel tanks built for 110 kV to 500 kV grid power transformers.

Commercial Distribution

Compact corrugated tanks designed for pole-mounted or pad-mounted transformers.

Solar and Wind Farms

Weatherproof enclosures built to withstand high salt, high humidity, and outdoor UV exposure.

Industrial Plants

Extra-thick steel tanks built to absorb physical shock and vibration in steel mills and mining equipment.

Packaging and Shipping

Inside Surface

Sprayed with rust-preventive oil compatible with transformer oil, then packed with desiccant bags to absorb moisture.

Outside Surfaces

All machined flanges, pipe ports, and bushing holes are covered with thick plastic blind plates and rubber gaskets.

Container Loading

Tanks are secured inside open-top or standard containers using custom steel frames and heavy-duty wire tie-downs.

Quality Documents

Material test reports, NDT weld reports, paint thickness certificates, and pressure test logs ship inside a waterproof folder with your order.

Honor Certificates

FAQ

Q: What welding qualifications do your workers have?

A: Our welders are certified under AWS D1.1 and EN ISO 9606-1 standards. We provide official Welding Procedure Specifications (WPS) and Procedure Qualification Records (PQR) with your quality documentation package.

Q:How do you test for oil leaks before shipping?

A: We test every tank using two methods. First, we test welds with dye penetrant liquid and pressurized air. Second, we fill or pressurized the tank with hot transformer oil at 50 kPa to 100 kPa for up to 24 hours to guarantee zero leaks.

Q: What paint options are available for coastal environments?

A: For severe marine environments (C5 category), we shot-blast steel to Sa 2.5 grade, then apply three paint layers: zinc-rich epoxy primer, intermediate epoxy barrier coat, and polyurethane topcoat. Total dry film thickness reaches 320 um or higher.

Q: How do you stop steel flanges from warping during welding?

A: We machine main cover flanges on a large CNC gantry mill after all heavy welding is complete. Machining after welding removes thermal stress and keeps flange surfaces flat within 0.5 mm to 1.0 mm, preventing oil leaks at gasket joints.

Q: What is your maximum tank manufacturing capacity?

A: Our factory lifts and welds single structures up to 60 metric tons. Our maximum transportable tank size is 12 meters long, 4.5 meters wide, and 4.2 meters high.

Q: How do you clean the inside of the tank before shipping?

A: After shot-blasting, our workers clean the interior using industrial vacuums and solvent wipes under bright LED lights. We keep total internal dust below 150 mg/sqm, then spray a protective oil coating and seal all openings with gasketed transport covers.

As one of the most professional transformer oil tank manufacturers and suppliers in China, we're featured by quality products and low price. Please rest assured to wholesale cheap transformer oil tank made in China here from our factory. Customized orders are welcome.