What is the required sandblasting grade for steel-lined PE storage tanks before plastic lining?
Thread Content
Recently, we need to manufacture several horizontal storage tanks with a capacity of 80 cubic meters, using a steel-lined PE structure and the rotational molding process. Before lining the tanks with PE, sandblasting is required to remove rust, oil, impurities, etc. What level of surface treatment is needed for the inner wall of the carbon steel tank before lining? Is Sa2 level, Sa2.5 level, or Sa3 level required? Please help and give some advice, thank you!
It is generally required to be above 2.5. We do this often; it’s also related to the PE material chosen.
DL/T935-2005 specifies the technical requirements, which can be referred to. Technical requirements for manufacturing processes: a) Steel-plastic composite pipes and fittings should be manufactured using the tight-lining plastic coating method or the hot-rolling plastic coating method; the loose-lining plastic coating method shall not be used. b) Before lining, the inner and outer surfaces of all pipes and fittings shall be treated by sandblasting or shot blasting, and the quality of the treated surfaces shall meet the Sa2 grade requirements specified in the GB8923-1988 standard. ) c) After surface treatment, the dust and abrasives attached to the surface of the steel pipe or fittings should be removed, and lining should be applied immediately. The time interval from the completion of surface treatment to the completion of painting the outer surface should not exceed 24 hours at most. d) The substrate should be heated evenly in an automatic heating furnace; local heating using flames is not allowed during production. e) The workpieces after thermal rolling and plastic lining should undergo leveling treatment to ensure a uniform thickness and a dense structure of the plastic lining layer. f) The finished product shall not be subjected to further heat treatment, nor shall it be repaired by local flame heating.
It should be at least Sa3 grade; if sandblasting is not up to standard, it will directly affect the quality of the lining
The pretreatment of the metal substrate is carried out using surface treatment techniques. The sandblasting method is generally used, with a requirement to reach a certain level ； The plastic sheet lining must be polished, using tools such as wire brushes, flat shovels, or coarse sandpaper; however, the scratches caused must not exceed 0.5 mm. Finally, any dust particles on the surface should be removed.