Boiler Overhaul and Modernisation at a Waste-to-Energy Plant in Vienna

Vienna, Austria 

• Team size: 36 people
• Project duration: 3 weeks
• Project scope: Overhaul of two boiler line

A 36-person PRO-Welding team carried out extensive overhaul and modernisation work on two boiler lines at a waste-to-energy plant in Vienna. The project lasted three weeks, with teams working in two shifts. The scope included the replacement of economiser coil assemblies, repairs to the combustion grate systems, and the overhaul of valves and associated pipework.

Economiser Coil Replacement and Boiler Casing Repairs

The main scope of work involved the complete replacement of economiser coil assemblies on both boiler lines. This included removing the worn components, transporting and installing the new assemblies, and completing the required welded connections.

In parallel, repairs were carried out on the economiser casing walls. Damaged areas were repaired using weld build-up techniques, followed by grinding to achieve a smooth surface and restore the required minimum material thickness. All deteriorated suspension components supporting the coil assemblies were also replaced.

Given the size of the components and the limited working space, careful planning of the dismantling and transport operations was essential. Access openings were prepared in the boiler casing, and dedicated transport routes were established to allow the safe movement of both removed and replacement components.

Electric hoists, suspended lifting systems and a specially designed transport trolley were used to handle the assemblies. These arrangements enabled efficient movement of the economiser coils between the boiler interior and the external vertical lifting system.

All welded connections were completed using the TIG (141) process. Due to restricted access, every joint required mirror welding in challenging positions. Despite these conditions, all welds selected for radiographic testing (RT) and penetrant testing (PT) passed inspection. Visual testing (VT) of all welds also produced satisfactory results.

The work was successfully completed with a positive pressure test, and the economiser coil replacement was finished ahead of schedule. The quality of workmanship received positive feedback from both the client and the external inspection body responsible for the final acceptance.

Overhaul and Modernisation of Combustion Grate Systems

The second major work package involved the overhaul and modernisation of worn components within the combustion grate systems of both incineration lines.

The scope included replacing worn grate beams, shafts and grate bars, along with bearings, bushings and other mechanical components requiring repair or replacement.

Due to the considerable size and weight of certain components, the dismantling and installation sequence had to be carefully planned. Parts suitable for continued operation were serviced, refurbished where necessary and reinstalled.

Valve and Boiler Pipework Modernisation

The third work package focused on the extensive overhaul and modernisation of valves and associated pipework across both boiler lines.

A total of 250 valves were replaced, along with deteriorated pipe sections and various piping components, including flanges, reducers, elbows and tees.

Where required, new pipework sections were fabricated and installed to accommodate the necessary modifications. All assembly and welding activities were carried out in accordance with the technical requirements and the scope agreed with the client.

Project Execution and Results

The three-week project required close coordination of a 36-person team, divided into three groups working simultaneously on the different areas of the overhaul.

Working in two shifts, the teams maintained the required quality standards while meeting the project schedule. The main challenges included handling large components inside the boilers, installing heavy assemblies and carrying out precision welding in confined spaces.

The completed overhaul helped prepare both boiler lines for the next operating season.

This project further demonstrates PRO-Welding’s experience in delivering complex industrial maintenance, installation and welding services, particularly in power generation facilities and waste-to-energy plants.