Special Expansion Joints for Hot Blast Main Application

The designer of the blast furnace hot blast main faces several unique challenges. The hot blast main is typically a large diameter pipe subject to a number of thermal expansion components. The expansion joint system must be designed to accommodate thermal movements in the X, Y and Z directions of the stove branch connections, main and bustle pipe. Thermal movements are due to variations in skin temperature caused by the media as well as variations in the temperature of tie rods and structures due to changes in ambient conditions. Consideration must also be given to the forces and movements imposed on the stove connections and structures as well as stresses in the hot blast piping system. Finally, the expansion joints must operate over the lengthy blast furnace campaign with minimal maintenance required.

Senior Flexonics Pathway has pioneered the use of .125" thick, high nickel-alloy bellows over the last 12 years. The USS/ Kobe Steel Lorain Works #3 blast furnace expansion joints are an example of this bellows design.

These bellows type expansion joints can take movement in all directions while welded pipe type expansion joints could take only axial movement. The high nickel alloy bellows material offers superior resistance to chloride stress corrosion cracking. Additionally, the .125" bellows thickness allows relatively easy weld repair if necessary. A plan view of the hot blast main layout at the Lorain Works is shown on the back of this news release for reference.

Senior Flexonics Pathway is facilitated to provide the heavy wall bellows required for hot blast main service in all sizes. Senior Flexonics Pathway engineers can also provide pipe stress analysis and the engineering support required to locate and specify guide and anchor requirements for hot blast main applications. Our hot blast main customers include Bethlehem Steel, USS, LTV and many others. For more information about expansion joints for hot blast main applications, contact Senior Flexonics Pathway.