| 摘要 |
<p>Removable roof made of three parts (a,b,c), and used on a pit heating or holding furnace. Part (a) consists of five girders forming an upper, main frame; whereas part (b) consists of a seal formed by girders; part (c) is a roof suspended from frame (a). The three parts (a,b,c,) are pref. not rigidly connected to each other; and the first girder is a T-beam with its bottom end not in contact with the roof to avoid longitudinal thermal expansion of the beam. Part (b) is pref. bolted onto part (a) by a thermally insulating mat; and the roof is joined to seal (b) via a second insulating mat. Heat resisting castings are pref. used to form girder, which dips into a sand gutter on the top of the furnace wall to make a seal. The three parts forming the roof are free to expand and contract with changes in temp. so the proof does not distort.</p> |
