Cast Iron Staves for Blast Furnaces

Cast iron staves by Primetals Technologies are a cooling solution that is exceptionally resistant to abrasion from unreduced burden materials as they descend the blast furnace. With over 40 years of experience as a leading supplier of blast furnace cast iron staves, Primetals Technologies provides innovative solutions tailored to match the varying conditions within the blast furnace. These solutions ensure long furnace campaigns and trouble-free operation.

Blast Furnace Cast Iron Stave Fixing Bolt Design

In recent years, several steelmakers have reported issues with their cast iron staves, often stemming from an inadequate design of the fixing between the cast iron staves and the blast furnace shell. This inadequate design can lead to stave failures, necessitating time-consuming and costly mid-campaign repairs.

Some cast-iron stave designs for blast furnaces utilize cast-in fasteners to secure the cast-iron staves to the furnace shell. These fasteners are difficult to position accurately during the casting process, and excessive stresses may cause them to be pulled out of the cold face of the staves. When this happens, the weight of the cast iron stave, often several tons, is transferred to the water pipes, which are not designed to bear such loads. Consequently, the pipes may fail, leading to water leaks into the blast furnace.

To prevent these failures, Primetals Technologies employs a larger-diameter fixing bolt design that secures the cast iron stave to the blast furnace shell, accommodating large tolerances during installation. This approach is crucial in blast furnace rebuild scenarios where the existing shell may have warped or distorted from its original position. The fixing bolts pass through oversized holes in the body of the cast iron staves, eliminating the need for a cast-in fastener. These bolts allow for thermal expansion of the cast iron staves during operation without compromising the integrity or failure of the fixing system.

Cast Iron Stave Piping

The design of cast iron stave piping is often a weak point in the blast furnace cooling system. Some designers limit the possible movement of cast iron staves by installing hard piping between them or rigid seal boxes around the pipes. Although cast iron staves do not expand as much as copper staves during operation, restricting this growth can lead to premature pipe failures.

To ensure sufficient flexibility in the cast iron stave and piping design, Primetals Technologies provides a fully fixed point on the center pipes at the bottom of the staves. This design allows any expansion of the cast iron staves to move upwards from this fixed point. The top pipes are attached to the blast furnace shell using compensators, which permit the cast iron staves to expand without inducing stress on the pipes. Any weld between the cast iron stave and the blast furnace shell is made to the protective shroud pipe, not the cooling water pipe. The welds between the shroud and process pipes of a blast furnace cast iron stave are completed at the manufacturer's workshop, ensuring a high-quality weld.

"We selected Primetals Technologies because their technical solution was one of the best, and the entire project could be successfully delivered at a competitive market price. Based on our past experience, Primetals Technologies is good at project execution.”

- China Steel Machinery Company