Customer case

Pneumatic pipe bridge using weather-resistant steels

April 17, 2023 6 min read

Case details

Product Hollow sections – build a stronger future with less steel

Country Finland

Company SSAB Europe Oy

Industry Raw material handling

A new research center and office will be built at SSAB Europe Oy Raahe mill. The new two-story research center and office building is scheduled to be in use in 2024. In connection with the project, a new pneumatic pipe bridge will be built. The mail pipe will transport samples from the smelter and blast furnace to the new research center. About six kilometers of the new pneumatic mail pipe will be built and the old one will be upgraded. Work on construction of the pneumatic mail pipe foundation and workshop connecting the research center and the mill began in 2022 and will complete this spring.

Case details

Product Hollow sections – build a stronger future with less steel

Country Finland

Company SSAB Europe Oy

Industry Raw material handling

Pneumatic pipe bridge to the new research center.

The new pneumatic mail pipe at the Raahe steel mill is built on SSAB weather-resistant structural hollow sections. The original plan was to use painted structural steel tubes to build the required steel structure. However, the plans changed as the project progressed. The steel structure needed to be maintenance-free, and weather-resistant steel is more in architectural harmony with the new research center. Raahe steel mill's new research center will make extensive use of the mill's own weather-resistant steels.

The advantages of weather-resistant steel include freedom from maintenance. The oxide layer that transforms into a patina behaves as if it was a color coating. It seals-off the steel surface from the atmosphere and prevents corrosion. This allows for applications in non-painted condition, leading to considerable maintenance cost savings. The oxide-to-patina process takes place under normal atmospheric conditions, on rainy, snowy and sunny days. No anti-corrosion treatment is needed, which lowers overall costs.

The new pneumatic mail tube at the Raahe steel mill makes extensive use of different-sized weather-resistant tubes and is scheduled to complete in March 2023. The largest tubes are 300x300x10 mm and can be found in the bridge pillars. The smallest tubes are 60x60x4 mm and have been used in pipeline supports. The weather-resistant steel tubes used in the structure are manufactured at SSAB's Pulkkila and Hämeenlinna tube mills, from where they were shipped to Estonia, where the blocks needed for the bridge were manufactured. The finished bridge blocks were transported as elements to Raahe.

When using weather-resistant steel, there is no need to worry about possible transport damages. The advantage of weather-resistant steel is that it repairs itself and a new patina layer seals-off the point of damage to protect the steel from corrosion. Any future drilling or welding does not pose a corrosion risk.

The production process at the Raahe steel mill will change when SSAB starts producing fossil-free steel. The future production process will be built on the current site of SSAB’s Raahe mill and may result in changes to existing structures.

Installation of a weather-resistant pneumatic pipe bridge.

One of the two sample receiving units.

Hot samples from the smelter and the blast furnace are packed in a steel capsule and are transported in a 20 m/s pressurized pipeline. When the samples reach the research center, they are analyzed in two fully-automated research units. The maximum response time for samples from the smelter is 15 min and for samples from the blast furnace 30 min. The research laboratory works 24/7, just like the steel mill. The smooth operation of the research laboratory is an important part of ensuring quality at the Raahe steel mill. In a worst-case scenario, a delay in analyzing the sample could ruin an entire 120-tonne melting.