ASSESSMENT AND REPAIR OF
COMPENSATOR RESULTING IN COST SAVINGS

For a long-standing client – a steel plant in Germany – Belman conducted an assessment followed by the repair of a DN 3000 Hot Stove Compensator. Although the Expansion Joint had reached the end of its service life, several components were identified to be in acceptable condition. Belman assisted the client with extending the service life of the Compensator through repair. This solution contributed to minimising the amount of scrap materials and supported the client’s objective of implementing more resource-efficient and environmentally friendly solutions.

 

CLIENT ISSUE
The client noticed that one of its Hot Stove Expansion Joints was approaching the end of its service life. By acting proactively and conducting timely due diligence, especially considering the demanding operating conditions, the client was able to address the issue before it developed into a critical failure. Rather than immediately replacing the entire Expansion Joint with a completely new one, the client sought to evaluate the feasibility of repairing the Expansion Joint, reusing as many components as possible. The objective was to minimise the amount of scrap materials, reduce overall consumption and pursue a more sustainable and cost-efficient solution – without compromising safety, operational reliability or compliance with applicable standards.

The client was already familiar with Belman’s capabilities in handling large and complex Expansion Joints, as well as its stellar reputation for high quality components, comprehensive experience and craftsmanship. This, combined with extensive experience in the refurbishment and repair of Expansion Joints alongside in-depth technical knowledge of wear mechanisms and lifetime extension, meant that Belman was a natural choice to carry out the assessment and repair.

 

BELMAN SOLUTION

Assessment and repair of the Compensator

The Compensator was dismantled on-site by the client, including removal of the refractory lining. The Expansion Joint was subsequently shipped to a sub-supplier for sandblasting, after which it was shipped to Belman. At Belman’s facilities, the Compensator was fully disassembled and subjected to a comprehensive technical evaluation to assess which parts could be re-used and which should be replaced.

The internal components – specifically the Bellows and inner sleeve construction – were found to be degraded beyond acceptable limits and were therefore designated for replacement. In contrast, the external hardware components were assessed to be in acceptable condition and were refurbished through sandblasting and surface treatment, enabling their reuse in the final assembly. Belman presented a full proposal and, as per agreement with the client, began work on repairing the Compensator. During disassembly, everything was carefully measured, inspected, analysed and evaluated. This process ensured that the final refurbished Expansion Joint would maintain compatibility with the existing system and operational requirements. Based on these findings, Belman developed and executed a repair solution that combined the replacement of critical components with the refurbishment of reusable parts. Throughout the process, care was taken to ensure that all interfaces, dimensions and functional characteristics remained consistent with the original design.

Material selection was a key aspect of the refurbishment. As the original Compensator had demonstrated reliable performance, it was essential that the same materials were used for the new parts (Bellows, inner sleeves etc.). Belman therefore carried out PMI (Positive Material Identification) testing on these existing components to verify material grades and ensure that newly manufactured parts matched the original specifications. However, as per agreement with the client, it was decided to change the material of the Bellows to 1.4835 (253 MA).

 

From Bellows with one convolution (Lens) to Bellows with four convolutions

The original Compensator had Bellows with one convolution (Lens). To achieve a more economical and flexible solution, Belman suggested replacing these with Bellows featuring multiple convolutions. After applying this Bellows design, the repaired Expansion Joint now has two Bellows each with four convolutions, as opposed to the old one, which had two Bellows, each with one convolution. This required special calculations to ensure the client had the same solution and movement absorption as in the original Compensator, as well as that everything fit as it should. Belman also adapted it according to our Welding Procedure Specifications (WPSs).

 

Special transport of the Expansion Joint

Once the repair was complete, Belman returned the Compensator to the steel plant for re-installation. The transport was arranged by Belman. Due to the large dimensions of the Compensator, special transport was required. The 8-tonne-heavy Expansion Joint was transported on a lowboy/low-bed trailer, positioned horizontally on the truck and securely fastened. Prior to sending the Expansion Joint to Belman, the client had removed the refractory lining. After receiving the repaired Compensator, the client will refit the refractory lining themselves before installing the Compensator in the blast stove.

 

What was Belman’s scope of supply for this Compensator repair?

• Disassembly of the Expansion Joint (cutting out the old inner sleeves and Bellows and making, sharpening and repairing cutting marks)
• Design and manufacture of new Bellows and inner sleeve construction
• Sandblasting and painting of carbon steel parts
• Assembling the Compensator
• Adding insulation and gaskets
• Tightness testing and visual testing
• Arranging shipment of the Expansion Joint back to the client

 

Belman – highly experienced in Compensator repair

With extensive experience in Expansion Joint repair projects since 1994, Belman is the first choice for Compensator renovations. An impressive track record assures clients the right solutions at the right cost, within the requested (and/or agreed) timeline. Leveraging extensive expertise, Belman accurately assesses which parts need replacement and which parts can be renovated and reused. Tailored advice is provided to clients, always considering both the project timeline and financial factors to ensure the best possible solution for the client. Belman carries out renovations of both Compensators originally produced by Belman as well as Expansion Joints manufactured by other brands