Wind power generation is a new renewable energy source, with approximately 1.3 trillion kilowatts of wind energy available globally. Developing and utilizing wind energy can effectively reduce carbon dioxide emissions. Wind turbine towers play a role in supporting and absorbing vibrations for generator sets. Tower structures mainly come in forms such as conical and cylindrical, with roughly 4 to 6 sections and a total height of about 90 to 140 meters. Wind turbine towers are typically manufactured using rolled low-alloy steel, effectively ensuring the tower’s fatigue strength for long-term use. Additionally, the roundness, straightness, and flatness of the tower body are important technical indicators, controlled by rigorously managing process parameters during construction.

Step 1#: Specific Manufacturing Scheme for Wind Turbine Towers

Material Procurement and Inspection

Steel and flanges are important externally sourced materials for tower fabrication. Upon arrival, materials must undergo careful inspection of their properties and thickness. Simplified, door frame, and flange materials should be tranquilized steel, with all performance indicators meeting the requirements of GB/T 1591. For forged flanges, Q355NE is used, and post-forging, it should meet the Z35 performance level requirements of GB/T 5313.

After passing visual inspection, personnel should conduct ultrasonic testing (UT) on 10% of the incoming batch to check the internal quality of the steel plates and flanges, meeting the NB/T47013-2015 Grade I requirements for flange flaw detection and NB/T47013-2015 Grade T1 requirements for steel plate flaw detection.

To ensure precise steel plate cutting, numerical control cutting machines are utilized. Deviations in cutting dimensions are controlled within reasonable limits, with width errors ≤±2mm and diagonal deviations ≤3mm. Simultaneously, to facilitate later grouping and assembly, the cylinder is divided into four equal parts along its length, with assembly baseline markings. Steel plate information is transferred to ensure material traceability, ensuring consistency between the cylinder’s longitudinal and circumferential seam bevel forms and bevel angles with processing requirements. Additionally, the bevels surrounding a 50mm range are polished before grouping.

Rolling and Circularizing

A 1.2m-long arc-shaped template is prepared before plate rolling, checking the curvature to ensure uniform gaps ≤2mm between the cylinder’s inner diameter and the template. After rolling, positioning welding is conducted, and misalignment is controlled reasonably. Gas shielded welding is used to fix the outer side of the cylinder’s bevel, and arc starting and arc extinguishing plates are assembled. Welding test plates are installed for designated batches and plate thicknesses. Rational welding parameters are used for longitudinal seam welding to effectively control welding line energy input and prevent welding deformation. After longitudinal seam welding, the cylinder is circularized to ensure the cylinder’s roundness is less than 0.5%. Diagrams for rolling and circularizing are shown in Figure 1.

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Longitudinal Seam Welding

Skilled welders first weld the internal seams of the cylinder section. After completing the internal seam welding, they clean the root of the seam and remove any oxide buildup before welding the back seam. During welding, it’s crucial to ensure that the gap between the longitudinal seams does not exceed 1mm and the misalignment does not exceed 2mm. Gas shielded welding is used as a base, with a wire diameter of φ1.6mm. The filler material used is submerged arc welding wire, with the grade being H10Mn2+SJ101. During welding operations, the interlayer temperature should be controlled between 100°C to 250°C, and the line energy should not exceed 40kJ/cm to ensure that the deposited metal can withstand -40°C impact. After welding, the welds undergo ultrasonic testing to meet the Grade B qualification level of GB/T5817. The appearance and quality of the welds are inspected for any issues such as undercutting, and internal quality is assessed using UT testing. Once the quality of longitudinal seam welding meets the requirements, the arc extinguishing plate and arc starting plate are removed. Welding is typically conducted using welding fixtures as shown in Figure 2 to improve welding quality.

Assembly

Flange assembly for wind turbine towers is completed on a high-precision platform. Before starting work, the circumference of the flange and the length of the cylinder pipe mouth are measured, and the misalignment is calculated. During assembly, the flange is first placed on the platform with the pipe mouth facing upwards, and then the cylinder is lowered onto the flange, with the longitudinal seam positioned between the two flange holes. After flange assembly, major sections of the cylinder are paired, with adjacent cylinder sections having longitudinal seams offset by 180°. Currently, there are two forms of cylinder pairing: outer diameter alignment and middle diameter alignment. Regardless of the alignment method, once the entire cylinder section is paired, quadrant lines are marked at the upper and lower flange ports, and the tower door installation centerline is identified. After meeting assembly standards, the welds are sealed. Flange assembly is illustrated in Figure 3.

Circumferential Seam Welding

Layer/Lane	Welding Method	Trademark	Diameter	Type/Polarity	Current (A)	Arc Voltage (V)	Welding speed (cm/min)	Notes
1	SAW	H10Mn2	Φ4.0	DC/ ~	560 ~ 680	25 ~ 34	40 ~ 45
2	SAW	H10Mn2	Φ4.0	DC/ ~	580 ~ 700	30 ~ 35	40 ~ 45	Welding After Root Cleaning
3	SAW	H10Mn2	Φ4.0	DC/ ~	560 ~ 680	30 ~ 35	40 ~ 45

Circumferential seam welding follows the same sequence as longitudinal seam welding, with welding parameters as referenced in the table below. During welding, ensure that non-welded areas of the cylinder are not grounded, and use dedicated grounding cables. Welding materials should be dried before use. Preheating is performed, and prior layer welds are cleaned. No more than two repair operations should be conducted at the same location, and there should be no weld seam joints within 300mm of a T-joint. Control the inclination angle during flange section welding, use aluminum profiles to secure the flange face, and adjust welding sequences based on specific conditions.

Step 2#: Coating

Before coating, the tower cylinder is sandblasted to remove rust, and surface roughness is inspected to ensure it meets the requirements of SA2.5. Additionally, soluble salt tests are conducted on the base material, and environmental conditions such as temperature and humidity are monitored. Each sandblasting operation should not exceed 2 hours, and after sandblasting, the base material is inspected, and paint film thickness is measured upon completion of coating. To improve coating quality, the following requirements should be met:

Single-coat preparation follows the requirements of the corresponding test standard, or GB/T 1727 if no specific standard exists;
For composite coatings, the dry film thickness is based on the requirements of each coating system, measured according to GBT 13452.2, with the exceedance not exceeding 20% of the design value. Each coating layer is sprayed at intervals of 24 hours, with a curing time of at least 7 days.

Step 3#: Installation of Internal Components

During the installation of internal components, personnel must control deviations. Upon arrival of externally purchased components, they should be checked against the inventory to ensure no missing or damaged parts. During the installation of internal components, the installation environment must meet standards. After completing the installation work, a final inspection is conducted.

Step 4#: Reinspection of Wind Turbine Tower Materials

For the cylinder steel plates, ultrasonic reinspection should be conducted on 10% of the total quantity of goods, following the technical standards specified in JB/T4730.3 at Level II. If any steel plate fails to meet the ultrasonic inspection standards, personnel must thoroughly inspect the quality of each plate. Mechanical performance sampling should be carried out based on the chemical composition and batch number of the furnace. The sampling rate should reach 100%. Each steel plate should be documented with information such as furnace batch number, part number, material, and quality grade.

For forged flanges, magnetic particle inspection should be conducted according to Level I requirements specified in JB/T 4730.4. Ultrasonic testing of forged flanges should be performed on 10% of the total quantity. The furnace batch number of forged flanges should also undergo effective reinspection based on their respective chemical composition and mechanical properties. Only after all products meet the quality standards can they be put into formal use.

All welding materials, including welding rods, gas shielded welding wires, and submerged arc welding wires, should meet the quality requirements specified for their respective batches. Quality certificates, material data sheets, and mechanical performance reports should be provided.

Step 5#: Storage and Transportation

Storage and shipping personnel should possess necessary knowledge. End caps should be used for storing tower sections to prevent contamination by other substances. Before installing the end caps, ensure the integrity of the coating. Flange bolts should be protected from rain and sun exposure. Tower sections and foundation segments should be labeled with installation drawing numbers, and bolts should be marked with product models. Warehouse staff should keep records of stored tower sections and components and conduct regular inspections to prevent degradation of stored items’ performance. During shipping, tower sections and components should be carefully inspected, and a shipping inspection report should be issued. When packaging tower sections, diagonal braces should be used to secure the flanges and tightened with bolts to prevent deformation during transportation. Tower sections should be securely bundled to avoid damage to the corrosion-resistant coating.

Conclusion

In conclusion, with the continuous development of wind turbine tower manufacturing technology, quality control of tower manufacturing technology is crucial. This article has analyzed the manufacturing process of tower sections and considered how to effectively control their production quality. It is hoped that this will improve the economic benefits of wind power generation and promote the development of wind power generation.