Tank - Anchor Chair

A is a critical structural assembly used to secure vertical aboveground storage tanks to their foundations. Rather than simply bolting through the tank floor, these "chairs" are welded directly to the tank shell to distribute heavy loads and prevent structural failure under extreme conditions. How They Work

: Slotted holes in the chair's top plate accommodate the tank's natural radial growth and thermal expansion without snapping the bolts. Why They Are Essential tank anchor chair

| Feature | Anchor Chair | Standard Base Ring | |---------|--------------|--------------------| | Height above foundation | 150–600 mm | 0–50 mm (grout only) | | Overturning leverage | Higher (better moment resistance) | Lower | | Thermal movement | Slotted holes allow sliding | Fixed bolts can cause buckling | | Fabrication cost | Moderate to high | Low | | Inspection access | Easy (under chair accessible) | Difficult (hidden by tank) | | Typical tank diameter | > 3 m (10 ft) | Any | A is a critical structural assembly used to

| Failure Mode | Cause | Mitigation | |--------------|-------|-------------| | Shell buckling | Excessive compressive anchor load | Increase chair height or add stiffener rings | | Weld cracking | Fatigue or undercut | Use full-pen welds, post-weld heat treat if thick | | Bolt corrosion | Moisture in grout pocket | Seal with flexible sealant, use stainless bolts | | Grout crushing | Poor compressive strength or thin grout | Use epoxy grout with minimum 50 mm thickness | | Anchor pullout | Insufficient embedment or concrete blowout | Increase embedment, use headed anchors or anchor channels | Why They Are Essential | Feature | Anchor

Note: This report is a general engineering guideline. Always consult project-specific codes, geotechnical data, and a licensed professional engineer for actual tank anchor chair design.

: Provides the specific mathematical procedures and formulas for sizing chair components.