Patent ID: 8365687

Claim:
A tube shield having a cylindrical shape and adapted to be attached with refractory cement (R) around an outer peripheral surface of a boiler tube (T), the tube shield, comprising: at least first and second shield parts for surrounding the boiler tube (T), the first and second shield parts having complimentary parting surfaces for defining a gap between abutting complimentary parting surfaces of adjacent shield parts when the first and second shield parts are attached with refractory cement (R) around the boiler tube (T); each shield part enclosing 140-220° of a total circumference of the boiler tube (T), each complimentary parting surface being configured in a continuous dovetail form, a dovetail protrusion (DP) in in the first shield part with a dovetail protrusion base (DPB) having a first dimension and a dovetail protrusion top (DPT) having a second dimension, the dovetail protrusion (DP) extending in a circumferential direction, a corresponding dovetail slot (DS) in the second shield part with a dovetail slot base (DSB) having a third dimension and a dovetail slot top (DST) having a fourth dimension, the dovetail slot (DS) extending in the circumferential direction; the first dimension of the dovetail protrusion base (DPB) of the dovetail protrusion (DP) being equal or less than the fourth dimension of the dovetail slot top (DST) of the dovetail slot, means for assembling the first and second shield parts together to form a gap between the dovetail protrusion (DP) and dovetail slots (DS), and means for filling the gap with refractory cement (R) such that the first shield part is locking into the second shield part with a multitude of dovetail protrusions (DP) located in a corresponding multitude of dovetail slots (DS) in the second shield part.