Wind Tower Manufacturing: The Ultimate FAQ Guide

Wind tower manufacturing involves various production and welding processes. It all starts with the manufacturing of steel plates by the steel industry. The steel plates are processed into strong tower sections and shipped to wind tower manufacturers.

Let’s understand how the wind tower sections are fabricated, the type of machinery used in the fabrication, and how welding automation can improve the production processes.

What is a Wind Turbine Tower?

The wind turbine tower is the main supporting structure of a wind energy system. It is a tall, slender structure that supports the machinery on the top of the tower. Wind turbine towers are composed of multiple sections. Once joined together, they provide the required height for the turbine to operate effectively.

Wind turbine towers are not just long, slender sections of steel. They must be adequately designed to have sufficient strength, stiffness, and stability. This helps them resist buckling under various wind loads and vibrations.

Two basic types of towers used for wind turbines are conical and cylindrical towers. These steel towers are manufactured using strong steel plates that are designed based on the required height, diameter, wall thicknesses, and project specifications.

Nowadays, wind tower manufacturing processes include accurate cutting, plate rolling, welding, fit-up, surface preparation, and painting. These can be precisely controlled with the help of welding automation equipment to improve the overall quality of the final product.

What is the Structure of a Wind Turbine Tower?

Owing to the great height of wind towers, they are constructed with multiple sections during fabrication. Sections are shipped to the project site and are connected on site to assemble the tower. Each of the tower sections is fabricated to have flanges on both ends, enabling them to be joined to adjacent tower sections and bolted together.

The longitudinal seams of the tower sections are welded during manufacturing. The individual sections are also connected through circular seam welding during the production process. After welding is done, each tower section is protected from corrosion with the help of surface treatments before transportation.

Wind turbine tower sections can house a variety of systems and components that allow maintenance personnel to access and work on the wind turbine system. Systems and components can include ladders, platforms, doors, power cables and controls, cable trays, and other electrical and mechanical systems.

How Many Types of Wind Turbine Towers Are There?

Wind turbine towers may be classified by the materials and methods used in their construction. The major classifications are steel, concrete, and hybrid towers.

1. Steel Wind Turbine Tower

You can spot steel towers widely, as they can easily be transported and installed. Steel towers can be sectionalized for transportation and assembled on-site. The assembly of steel towers can be accomplished with the aid of automated equipment. The towers can be designed and fabricated for a variety of uses and construction environments.

2. Concrete Wind Turbine Tower

Concrete towers can be constructed to provide thicker wall sections. These are mainly used for onshore projects. Compared to steel towers, concrete towers require more time for construction. These may utilize more complex construction methods as well.

3. Concrete and Steel Hybrid Wind Turbine Tower

A combination of steel and concrete sections in a single tower can be used to achieve greater heights. These can be used for taller onshore wind turbines where different structural materials are required. The other factors to consider when choosing an appropriate tower type include project requirements, the location, tower height, means of transportation, and methods of construction.

What is the Wind Tower Manufacturing Production Line?

A wind tower manufacturing production line assembles wind towers using a series of machines that convert steel plates into finished sections.

These processes include:

• CNC cutting
• Edge work and bevelling
• Rolling plates
• Welding (fit-up and longitudinal)
• Circular seam welding
• Polishing and grinding
• Sandblasting
• Painting

According to SENLISWELD, the major element of the wind tower production line is welding. This involves joining multiple cylindrical sections that form the main body of the tower. The types of equipment needed and the choice of layout of the production line depend on the size of the towers produced as well as the level of production.

● CNC Cutting Machine

First, large steel plates are cut to the right size. Flame or plasma cutting can be done by a CNC to enhance accuracy and speed. These machines can be used to provide uniform dimensions to the plates before the material moves to the next production stage. Our company uses CNC plasma and flame cutting machines to help us complete the first step in the production process of our heavy-duty towers.

● Edge Milling Machine

Following the cutting of the steel plates, their edges may require beveling in order to prepare for welding. An edge milling or beveling machine achieves the desired bevel on a plate and prepares it for welding. When properly prepared, a suitable joint can be created. Edge milling is essential for successful welding and enhances the quality of the weld.

● Plate Rolling Machine

After edge milling, plate rolling can be done to shape the steel plate into a cylinder or cone. Prior to closing the longitudinal seam by welding, the plate rolling machine helps shape the steel plate into the desired tower section. The degree of automation of the plate rolling process mainly depends on the requirements of the production.

● Single Pipe Welding

Following rolling, the longitudinal seam of the cylindrical section must be welded to close the can. A SENLISWELD system allows you to position the welding head along with the workpiece using a welding manipulator and welding rotator. For longitudinal seam welding, the SENLISWELD system can employ single-wire or tandem SAW welding processes and even GMAW/STT for backing welding.

● Fit-Up Welding

After the completion of an individual can, a number of cans are aligned and fixed before they are welded to form a larger unit. The fit-up welding station helps ensure alignment by connecting two cylindrical sections together. Fit-up welding of two workpieces can be accomplished using Hydraulic fit-up welding rotators and column-and-boom welding manipulators.

● Several Pipes Welding

Longer tower sections are produced from a number of shorter sections. Each of the sections is aligned and positioned, and the circular seams of the sections are welded. The inner and outer circular seams are both welded. A SENLISWELD multiple-pipe welding station allows the circular seams of the pipe sections to be welded using welding rotators and manipulators.

● Polishing and Grinding

Burrs and other imperfections can be ground or polished off after welding. Grinding the welded seam helps eliminate irregularities and allows the next step in the process to be started. Prior to the final surface treatment, the polished or ground finish improves the appearance of the surface. It allows a more even distribution during sandblasting and painting.

● Sandblasting

Sandblasting removes irregularities and contaminants from the steel surface. It helps prep the surface for painting, allowing good adhesion of the coating. The SENLISWELD process of sandblasting uses turning rolls to aid and support the workpiece. This reduces the risk of damage during surface preparation.

● Painting

Painting steel provides a protective barrier for the tower against corrosion of its surface. The color and coating system vary based on the requirements of the project. During the painting process, SENLISWELD utilises temporary or “fake” flanges at both ends of the pipe to help maintain the quality and integrity of the coating.

What Are the Manufacturing Requirements of a Wind Tower?

The sections of wind towers are large, heavy, and difficult to handle. Hence, the manufacturing of these towers can only be automated using robust machinery.

Several factors will influence the design of your production line, including:

• The thickness of the steel plates
• The length and diameter of the towers
• Annual production targets
• The available space in your workshop
• The level of automation required
• The concerns with transportation of the completed towers

The actual size and weight of your tower sections will influence the design of your production line. SENLISWELD has the technical know-how. Hence, their consultation will assist you with equipment design and fabrication for your project. Your employees need to be trained to safely operate the automated machinery and perform quality control during the welding process.

Where Does Welding Automation Fit into Wind Tower Fabrication?

Welding manipulator + Conventional rotator

Welding is an essential part of wind tower manufacturing. Manually moving and positioning large and heavy sections of a wind tower significantly hinders the tower’s assembly. In the welding process, the use of a rotator helps rotate large cylindrical workpieces. This is useful when access to the joint is obstructed. Also, the use of a welding manipulator helps in positioning the welding head to the desired location.

The welding of large diameter sections is done by a welding manipulator, which helps in performing longitudinal or circumferential welds. Heavy-duty tower welding can be done by a process called submerged arc welding (SAW). For large diameter sections, a single wire welding system can be used, while for small diameter sections, a tandem welding system can be used.

Automation of long and circular welds helps improve control of the welding process and reduces the fatigue of the operators. For larger wind towers and thicker steel sections, this is a major advantage.

What Equipment Is Used in Wind Tower Manufacturing?

There are many pieces of equipment that help streamline the wind tower production line.

1. CNC Cutting Machine

Prior to forming, CNC plasma or flame cutting machines can accurately cut steel plates to size.

2. Edge Milling Machine

Edge milling machines make bevels on the edges of steel plates for better preparation for welding.

3. Plate Rolling Machine

Plate rolling machines shape steel plates into different cylindrical and conical sections.

4. Welding Rotator

A welding rotator holds and rotates a tower section for welding. Depending on your workpiece, you can benefit from conventional rotators, self-aligning rotators, hydraulic fit-up rotators, and even other customized turning solutions.

5. Welding Manipulator

A welding manipulator is a system that holds the welding head in a desired position. You can use it for both longitudinal and circular seam welding.

6. Fit-Up Welding Station

A fit-up welding station helps to align two or more tower sections before they are welded. Hydraulic fit-up welding rotators can be used to adjust and align large cylindrical sections during the joining process.

7. Auxiliary Hydraulic Support

Large-diameter tower sections may require additional hydraulic supports. Auxiliary hydraulic support helps ensure stability, especially when dealing with large and heavy workpieces.

8. Sandblasting and Painting Equipment

For surface treatment, painting and sandblasting, you must prep the surface with the help of turning rolls and other support equipment.

What Are the Main Stages of Wind Tower Welding?

Wind tower section fabrication consists of the following processes:

● Longitudinal Seam Welding

In this process, rolled steel plates are welded along their length to produce cylindrical or conical sections.  To produce an airtight tower section, GMAW/STT can be used for backing welding. This can be followed by single-wire or tandem SAW depending on the production line.

● Fit-Up Welding

This process involves the alignment of individual conical or cylindrical can sections before welding of adjacent sections is done to build up the height of the tower.

● Circular Seam Welding

The aligned tower sections are welded around their circumference to build the tower. If the length of the sections to be welded is too large to be handled manually, the tower section is supported by a column and boom welding manipulator and rotated using a welding rotator.

● Final Surface Treatment

Upon completion of welding of the tower sections, the welded areas are polished and ground. The towers are then moved to the painting shed for sandblasting and painting.

How Can Welding Automation Improve Wind Tower Production?

By automating the welding process, you can easily handle large and heavy tower sections.

Here is how an appropriate automated system can benefit you:

• Enhance welding consistency
• Minimise the need for manual handling.
• Make production more efficient.
• Hold the workpiece in the proper position.
• Eradicate operator fatigue
• Withstand high-volume production requirements.
• Give you better control over welding operations.

With the help of welding rotators, you can keep large cylindrical workpieces moving at a controlled speed. On the other hand, welding manipulators assist in positioning the welding head properly.

A complete production line is made by combining welding rotators, welding manipulators, fit-up stations, hydraulic supports, and other equipment depending on your production specifications.

How Many Tower Internals Are Present Inside a Wind Tower?

There are many internal components in a wind turbine tower that support its operation, inspection, and maintenance. These are divided into two categories:

1. Electrical tower internals
2. Infrastructure tower internals

1. Electrical Wind Tower Internals

Electrical components are mainly lights, cables, cable trays, and junction boxes.

● Wind Turbine Tower Lights

You need adequate lighting inside the tower as there is minimal to no natural light. Hence, different lighting systems are used based on the tower design and project requirements.

● Wind Turbine Tower Cables

There are power and control cables installed inside the tower which connect to various parts of the wind turbine system. Data and monitoring cables are also installed to assist in communication and system monitoring.

To keep all these cables organised and protected, there are cable trays which make future maintenance easier.

2. Infrastructure Internals of a Wind Turbine Tower

Internal infrastructure components assist workers in accessing and maintaining the equipment within the tower.

● Wind Turbine Tower Door

The tower door allows you to access the inside of the tower. It is made of steel and aluminium, depending on the project requirements.

● Wind Turbine Tower Entrance Stairway

The entrance stairway makes it easier to access the tower entrance where required. Materials and designs often vary depending on the project.

● Wind Turbine Tower Ladder

To move vertically, there are ladders that help technicians during inspection and maintenance. These are installed on tower sections during the manufacturing process. They can be assembled with the sections at the project site.

● Wind Turbine Tower Platform

Platforms help create a safe working environment for technicians inside the tower. These can be installed at intervals during the welding process to make construction and future maintenance easier.

How Are Wind Tower Flanges Used?

The entire wind turbine tower system may be very high, and therefore transport of a fully assembled tower is challenging. Hence, the tower is divided into sections. These are fitted with flanges at each end to facilitate their transportation separately. These are bolted together at the installation site.

A wind tower flange is a large, circular piece of metal that has a number of small holes in it, arranged in a regular pattern. It is the link for the tower sections. Flange alignment and controlled welding are critical because there are risks of flange distortion, which can impact the tower sections’ connection.

What Should You Consider When Choosing Wind Tower Welding Equipment?

When deciding on the equipment that you will use for your wind tower manufacturing line, you must consider more than the price.

Important factors to look for include:

• Maximum workpiece weight
• Tower diameter
• Tower length
• Steel thickness
• Annual production output
• Welding method
• Workshop layout
• Required automation level
• Operator safety
• Technical support
• Maintenance and after-sales service

Your equipment supplier should also be familiar with how each of the machines is integrated into the production line.

What are the Technical Elements of Chinese Wind Turbine Materials?

Wind turbine steels are reduced alloy, super strength framework steels. China’s reduced alloy super-strength steel manufacturing technology is established. As a result, Q345 steel is not the only steel grade available for wind turbine construction.

Aside from Q345 steel, there are other reduced alloy super-strength steel types that are ideal for the manufacture of wind turbine towers. Wind farm owners may pick the most cost-effective wind turbine components for their own.

Metal mechanical property research is strictly governed by Chinese GB requirements. The standard test sample for steel plates with thicknesses greater than 12mm is 10mm 10mm 55mm; for steel plates with thicknesses less than 12mm, the standard test sample is 10mm 7.5mm 55mm.

Each research category has three lab tests, and the mean value is used to determine the test results.

If anyone’s test value goes below 70% of the norm, the test personnel must take another three tests from the same steel bar and take the average of the six variables.

What are the Analogous Steel Grades in Foreign Steel Regulations?

Below there is a related metal grades comparison chart with various steel levels for international wind farm owners who may not be acquainted with Chinese steel grades. The comparison table will assist you in choosing the right steel content for your wind turbine welding.

Why Choose SENLISWELD for Wind Tower Manufacturing?

SENLISWELD has been in the welding automation manufacturing industry for over 20 years. They offer wind tower production line solutions according to the requirements of your project. The company offers technical advice, design and OEM support, quality control, and one-year warranty service for wind tower welding automation machines.

Support can also be provided depending on your tower sizes, annual production capacity, and workshop layout. Then, the production line can be designed around your real manufacturing needs, rather than using a one-size-fits-all solution. SENLISWELD offers equipment like welding rotators, welding manipulators, fit-up rotators, CNC cutting machines, and other machinery for wind tower manufacturing.

Conclusion

Once you understand the manufacturing of wind towers, you will be able to appreciate how steel plates are transformed into solid tower sections for installation. This process involves CNC cutting, edge milling, plate rolling, longitudinal seam welding, fit-up, circular seam welding, polishing, sandblasting, and painting.

Appropriate welding rotators, welding manipulators, and fit-up stations can help improve production efficiency, welding consistency, and operator safety. SENLISWELD offers wind tower manufacturing solutions and welding automation solutions according to the tower size, annual production volume, and workshop space.

For those who require a production line, they can also collaborate with a professional technical team to create equipment suitable for their project and production process.