Anchoring: the invisible part of the lining that determines service life

When a lining fails prematurely, the refractory material is rarely to blame — the anchoring behind it is. During a boiler overhaul on a grate firing system we found exactly that picture: the right material, clean workmanship, but scale-corroded and partly cracked anchors from the previous lining. The lining was held by friction, not by design.

Five rules for anchoring

• Anchor material to suit the operating temperature: at 900–1,100 °C, heat-resistant steels such as 1.4828 or 1.4841 — structural steel simply scales away.
• Anchor spacing matched to the layer thickness, typically 200–300 mm; closer on the roof and arch than on the wall.
• Expansion compensation at the anchor heads so that the steel can move without blowing off the material.
• Anchors are wearing parts — renew them consistently at every repair relining.
• Record the material and the spacing in the as-built documentation. That saves time and money at the next overhaul.