If the spiral steel pipe for water transportation is used to transport tap water or drinking water, the inner wall is usually made of IPN8710 non-toxic anti-corrosion coating, and the outer wall is made of epoxy coal tar pitch for anti-corrosion. Of course, it can also be used for inner and outer plastic-coated anti-corrosion or tpep anti-corrosion. These can be applied to drinking water pipes, without changing the water quality.
If the spiral steel pipe for water transportation is used to transport sewage or industrial water, the inner and outer walls only need to be anti-corrosion epoxy coal tar pitch. It is cheap, easy to construct, and has a strong waterproof and moisture-resistant effect. Of course, if you don't mind the cost, you can also use plastic-coated anti-corrosion or tpep anti-corrosion.