The Global Oil Duct Struct Market was valued at USD 71.50 Million in 2025 and is projected to reach USD 119 Million by 2034, growing at a Compound Annual Growth Rate (CAGR) of 7.7% during the forecast period. This sustained growth is primarily driven by global investments in power grid modernization, the rapid integration of renewable energy sources, and rising electricity demand due to industrial electrification trends.

As the power industry focuses on enhancing grid reliability and efficiency, the critical role of high-performance insulation components within transformers is increasingly recognized. In this blog, we profile the Top 10 Companies in the Oil Duct Struct Market—a mix of global material science leaders, specialized manufacturers, and regional powerhouses that are essential to the global energy infrastructure.

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🔟 1. Hitachi Energy

Headquarters: Zurich, Switzerland
Key Offering: Precision-machined axial strips, radial spacer strips, and complete insulation systems

Hitachi Energy (formerly Hitachi ABB Power Grids) is a global technology leader with a formidable presence in the transformer components sector. The company offers a comprehensive portfolio of oil duct structs, known for their exceptional dimensional stability and dielectric performance. Their components are integral to the power and distribution transformers they manufacture and supply to utilities worldwide.

Innovation Initiatives:

• Development of high-density, thermally stable pressboard materials
• Investment in automated, precision machining for tighter tolerances
• Integration of digital tools for component lifecycle management

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9️⃣ 2. Weidmann Electrical Technology

Headquarters: Rapperswil-Jona, Switzerland
Key Offering: WAPressboard-based axial and radial spacer strips, insulation components

Weidmann Electrical Technology is a premier global supplier of electrical insulation solutions, renowned for its high-quality cellulose-based products. The company’s oil duct structs are critical for maintaining cooling duct integrity in oil-immersed transformers. Their products are specified by leading transformer OEMs for demanding applications, including HVDC and large power transformers.

Innovation Initiatives:

• Pioneering research in cellulose and alternative insulation materials
• Focus on sustainability through responsible forestry and manufacturing
• Global supply chain with localized technical support

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8️⃣ 3. KREMPEL Group

Headquarters: Heilbronn, Germany
Key Offering: Insulation pressboards, laminated materials, custom-machined spacer strips

KREMPEL is a leading specialist in electrical insulation materials and systems. The company provides a wide range of oil duct struct solutions, from standard strips to complex, custom-machined components. With a strong focus on the European market, KREMPEL serves transformer manufacturers requiring high reliability and adherence to stringent international standards.

Innovation Initiatives:

• Development of composite and hybrid insulation materials
• Custom engineering services for complex transformer designs
• Commitment to quality certifications (ISO, VDE, UL)

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7️⃣ 4. Nantong Zhongling Electric Power Technology

Headquarters: Nantong, Jiangsu, China
Key Offering: Axial strips, radial spacers, transformer insulation components

Nantong Zhongling is a key Chinese manufacturer specializing in electrical insulation products for the power industry. The company has established itself as a reliable supplier of oil duct structs to both domestic and international transformer markets. Its competitive positioning is strengthened by cost-effective production and the ability to scale to meet large-volume orders.

Innovation Initiatives:

• Expansion of production capacity to serve growing Asian demand
• Investment in quality control systems to meet global standards
• Focus on serving the renewable energy transformer segment

Download FREE Sample Report: Oil Duct Struct Market – View in Detailed Research Report

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6️⃣ 5. Henan YAAN Electrical Insulation Plant

Headquarters: Hebi, Henan, China
Key Offering: Insulation presspaper, calibrated and milled spacer strips

Henan YAAN is a significant player in China’s electrical insulation sector, producing a variety of pressboard-based components, including oil duct structs. The company caters primarily to the vast domestic transformer industry, supplying components for power, distribution, and special application transformers. Its strength lies in its deep understanding of local market needs and cost competitiveness.

Innovation Initiatives:

• Modernization of manufacturing processes for improved precision
• Development of products suited for harsh operating environments
• Strengthening supply chain relationships within China

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5️⃣ 6. Von Roll Holding Ltd.

Headquarters: Zurich, Switzerland
Key Offering: High-performance insulation papers, composite materials, machined parts

Von Roll is a globally recognized manufacturer of electrical insulation systems. The company’s expertise in material science enables it to produce high-quality oil duct structs that meet the demanding requirements of modern transformers. Von Roll’s products are known for their reliability and are used in critical applications where failure is not an option.

Innovation Initiatives:

• Long-standing expertise in insulation chemistry and engineering
• Global production and R&D footprint
• Strong focus on reliability and long-term performance data

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4️⃣ 7. Shandong Jinbao Electrical Material Co., Ltd.

Headquarters: Linyi, Shandong, China
Key Offering: Transformer insulation components, pressboard strips, laminated wood

Shandong Jinbao is a prominent Chinese supplier of insulation materials. The company manufactures a range of oil duct structs that are essential for transformer cooling systems. Its strategic location within a major industrial hub in China allows it to efficiently serve the country’s extensive transformer manufacturing base.

Innovation Initiatives:

• Continuous improvement in product consistency and quality
• Expansion of product portfolio to include value-added services
• Adaptation to evolving transformer design trends

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3️⃣ 8. Shenyang Defeng Insulation Material Co., Ltd.

Headquarters: Shenyang, Liaoning, China
Key Offering: Electrical insulation pressboard, crepe paper, spacer strips

Shenyang Defeng is a well-established manufacturer of insulation materials in Northeast China. The company produces oil duct structs that are used in a variety of transformer applications. It has built a reputation for reliability and serves a customer base that includes both regional transformer builders and larger national players.

Innovation Initiatives:

• Focus on serving the industrial and rail traction transformer markets
• Investment in raw material quality control
• Development of cost-effective solutions for medium-voltage applications

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2️⃣ 9. Isovolta AG

Headquarters: Werndorf, Austria
Key Offering: Composite insulation materials, laminated plastics, custom components

Isovolta is a European specialist in composite materials for technical applications, including electrical insulation. The company offers high-performance solutions that can be used as oil duct structs, particularly in applications requiring enhanced mechanical strength or specific dielectric properties. Their expertise lies in material compounding and lamination.

Innovation Initiatives:

• Expertise in thermoset and thermoplastic composites
• Customization capabilities for specialty transformers
• Strong focus on European automotive and industrial sectors

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1️⃣ 10. Miki Tokushu Paper Mfg. Co., Ltd.

Headquarters: Kōchi, Kōchi Prefecture, Japan
Key Offering: Electrical insulating papers, Nomex®-based products, pressboard components

Miki Tokushu Paper is a Japanese leader in the production of specialty papers, including those for electrical insulation. While traditionally strong in insulating papers, the company’s expertise extends to components like oil duct structs, especially for the high-quality transformer market in Japan and other advanced economies. They are known for their meticulous attention to quality.

Innovation Initiatives:

• Development and supply of aramid-based (Nomex) insulation solutions
• High-precision slitting and machining capabilities
• Focus on miniaturization and high-reliability applications

Get Full Report Here: Oil Duct Struct Market – View in Detailed Research Report

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🔧 Outlook: The Future of Oil Duct Structs is Smarter and More Precise

The oil duct struct market is evolving from a commodity component business to a value-added, precision-engineering sector. While traditional cellulose-based strips remain the foundation, the industry is investing in advanced manufacturing, new materials, and digital integration to meet the demands of next-generation transformers.

📈 Key Trends Shaping the Market:

• Increasing demand for precision-machined components with tight tolerances for enhanced thermal performance
• R&D into advanced materials like nanocellulose and high-density composites for superior dielectric and mechanical properties
• Growing importance of supply chain reliability and qualification processes as transformer OEMs seek to mitigate risks
• Rising demand driven by HVDC transmission projects and the global renewable energy build-out

Get Full Report Here: Oil Duct Struct Market – View in Detailed Research Report

The companies listed above are not only supplying critical components—they are enabling the reliability and efficiency of the world’s expanding electrical grids.