求翻译：12. The larger diameter cover felt disks for 13” furnaces consists of 13 individually cut disks at 35” diameter. The smaller diameter cover felt disks for 13” furnaces are cut to 24” diameter. To conserve felt, these pieces can be cut down from the larger pieces to the correct diameter (if in good shape, not hard or holes greatly enlarged). The number of 24” diameter pieces shall depend upon the distance between the top of the heat zone cover plate and the top of the split ring.是什么意思？

待解决 悬赏分：1 - 离问题结束还有