4　Materials

4.1　Material Selection

4.1.1　The cost effectiveness shall be taken into account in material selection for the component parts of tray provided that the requirements defined in tower engineering drawing or tray datasheet are met.Materials for component parts of the tray are shown in Table 4.1.1.

Table 4.1.1　Materials matching relations

4.1.2　Unless otherwise specified，materials for component parts of the tray（e.g.，support ring，connecting bar and beam support）welded to the tower body shall be the same as or equivalent to those for shell（or cladding of shell）.

4.1.3　The corrosion resistant performance of the material for fasteners shall not be worse than that for tray floors.

4.1.4　The use of gaskets or seal strips made of asbestos or asbestos products shall not be permitted，while those made of graphite，ceramic fiber or other proper material which is reinforced by fiberglass or stainless steel wire shall be selected to avoid breakage and detachment of gaskets or seal strips during operation.