Design Buckstay in the Steam Boiler

Fig. 1: Design Buckstay in the Steam Boiler

The furnace of steam boiler has internal pressure which is usually designed ±200 mm wg. The internal pressure is resisted by attaching buckstay in every approximately 2-3 m along the height of furnace wall. Buckstay is support that consist of four girder which be installed in the four sides of furnace wall; right side wall, left side wall, front side wall and rear side wall. At the corner design buckstay is hinged to permit expansion on the furnace wall of steam boiler.

Bucstay is designed to resist longitudinal load such as internal and external pressure, normal load such as internal pressure, moment bending because of support bracket of pressure part, and temporary load such as explosion, wind and seismic forces. Buckstay has important roles to keep the furnace remain in its position and no bending occurs when the steam boiler operates continuously.

Spacing of buckstay a long the height of furnace is calculated to avoid wall tubes deflection and prevent vibration on tubes which has same frequency same with natural frequency of furnace wall tubes. Deflection of buckstay is usually calculated as L/360.  At the time of application buckstay is attached to tie bar with slip connection to give limitation of deflection inward and outward of furnace wall tubes. Tie bar is rectangular bar and form continuous band around the furnace wall tubes (see figure 1).

For more details about calculation of design buckstay, please look this spreadsheet: "Calculation of Design Buckstay"