The other photo shows some of the new crown stays prior to fitting. As a result of the round topped nature of the boiler over the firebox, stays of three different lengths are required. Nuts and copper washers, shown here on one stay, are fitted to the protruding thread of the stay in the firebox to protect the end of the stay from burning in the intense heat. If they waste too much in use they would need to be replaced.
Credit: Dick Bellchambers, 22 February 2006