Externalspiral escape stairs are made of steel and for safety reasons around the ladder there is a steel frame and the protective mesh.
而外凸的旋转疏散楼梯采用钢制结构，为了安全起见，阶梯被一圈钢制框架包裹。
2
The temperature of the tube went up and then the expenditure of expensive alloy increased by using extern spiral finned tube, which enhanced the external heat transfer.
采用外螺旋肋片管实现高温侧强化传热后，再热器管壁温度升高，所需贵重金属耗量增加。
3
CONSTRUCTION: It is composed of an inner rubber protection layer, middle rubber layer, steel wire spiral layer and external rubber cover.