HOT BLAST STOVE
METALLIC BELLOWS

For a steel plant in Germany, Belman designed and manufactured 13 Expansion Joints ranging in size from DN 1600 to DN 2600, along with four additional Expansion Joints sized DN 400. These Metallic Bellows are to be installed in a new hot blast stove, which is part of a major investment at the client’s plant aimed at improving energy efficiency and advancing greener steel production. The investment project includes the construction of a new heater system integrated with a heat recovery solution, supporting the steel plant’s transition towards more sustainable operations.

 

CLIENT ISSUE
The steel plant needed a substantial quantity of large-dimension Expansion Bellows for its new hot blast stove. For this investment project the client needed 17 Metallic Bellows, all in different dimensions and designs. The client was looking for a supplier with the capacity to design and produce this many different and large-sized Expansion Joints in their facilities, all while maintaining exceptional quality standards. In particular, the client needed a partner known for expert welding, high-end production and the ability to carry out comprehensive and advanced quality procedures. It therefore turned to Belman.

 

The steel plant has invested in energy efficiency improvements to reduce environmental impact
This project is supplied for a larger investment project at the client’s facilities. To enhance energy efficiency and reduce the environmental impact at its steel plant, the client is undertaking a significant modernisation project. The project involves the construction of a new hot blast stove for one of its blast furnaces. These upgrades are designed to improve energy efficiency, reduce CO₂ emissions and increase the use of secondary raw materials, among other things. A key component of this modernisation project is the implementation of a system that utilises waste heat from blast furnaces, effectively recovering energy that would otherwise be lost.

As with many other steel plants worldwide, this plant also has a broader strategy to transition towards more sustainable steel production methods, aligning with industry trends and regulatory requirements aimed at reducing the environmental footprint of steel manufacturing.

 

BELMAN SOLUTION – Hot blast stove Metallic Bellows
The 17 Expansion Joints – compromising 5 x DN 400, 3 x DN 1600 and 9 x DN 2000–DN 2600 – were all custom-designed with variations in design, number of convolutions, materials and built-in lengths. The differences reflect the specific requirements of their installation points within the hot blast stove, including:

• Hot blast lines
• Cold blast lines
• Combustion gas mains
• Combustion air mains

Each of these locations has different pipeline dimensions, which is why different sizes are needed. Furthermore, the movements that occur on the different locations in the pipelines vary, which explains the design of the Metallic Bellows and their function as well. On some locations, both axial and lateral movements occur which require Universal Expansion Joints, while on other locations only axial movement occurs, requiring Axial Expansion Joints. The Lateral Expansion Joint will handle lateral movements only.

Different coating systems applied
Different coating systems and coating colours were applied to all 17 Expansion Joints. Therefore, the Expansion Joints do not have the same colour – some are yellow, some are grey and some are aluminium-coloured. The reason for the different colours and coating systems is that the Expansion Joints are installed in different locations at the plant – some are installed inside the plant, while others are installed outside the plant. Furthermore, some Expansion Joints need to work at elevated temperatures. All the operating parameters set special requirements for the composition of the coating systems applied.

Quality assurance of the Metallic Bellows
The Expansion Joints had full traceability and were supported by an ITP and a Manufacturing Data Book (MDB). Nine of the Expansion Joints are PED Cat. III Expansion Joints witnessed by DNV. The rest of the Expansion Joints were covered by 3.1 certificates. For all Expansion Bellows, the following tests were carried out:

• Visual test (VT)
• Penetrant test (PT)
• Radiographic test (RT)
• Leak test
• Magnetic test (some of the Expansion Joints only)
• Ultrasonic test (some of the Expansion Joints only)
• Pressure test (some of the Expansion Joints only)
• Heat and hardness test (a small few of the Expansion Joints only)
• Coating report (Different coating systems and colours were applied to the Expansion Joints as per client specifications)

The reason for the different quality requirements is the location of the Expansion Joints on the steel plant and the different operating parameters.

All Metallic Bellows were third-party approved, and the client also did final inspections as well as inspections during the process. Belman is always happy to welcome clients and inspectors at our facilities.

 

Belman – experts in large-sized Expansion Joint for steel plants
Belman has a proven track record of delivering high-performance Expansion Joints for steel plants across the world. With over 30 years of experience in designing and manufacturing Expansion Joints, Belman has expertly designed, manufactured and supplied many large-dimension Expansion Joints. Having the facilities, capabilities, know-how and experienced staff has ensured clients successful deliveries of large-dimension Expansion Joints on many occasions. A standout example through the many years is  a 10-metre-long, DN 2800 Expansion Joint for a steel plant weighing in at 40 tonnes.