1. Titanium material
 
Titanium itself is a very active metal and can even replace hydrogen from water.Titanium is widely used as an anti-corrosion material because it is easy to passivate.It is easy to form a dense oxide layer on its surface for passivation. Among all metals, titanium has the largest passivation coefficient, up to 2.44.This passivation film can protect titanium metal from corrosion under various media conditions.
 
2. Carbon steel and stainless steel

Carbon steel heater is only suitable for chemical or electrolytic oil removal, zincate galvanizing solution and hot water tank heating.
 
3. Non metallic material

1) Glass

Fluorine free pure reducing medium can be used as straight tube vertical electric heater with glass tube shell.Ordinary glass tube is easy to crack and is not applicable. 95 heat-resistant glass or quartz glass tube should be used, which is very expensive.The glass heating pipe is easy to be damaged, so it can be protected by PP pipe whose inner diameter is about 5mm larger than the outer diameter of the glass pipe.Glass cannot be used as a cooling pipe.
 
2) Polytetrafluoroethylene

The heating and cooling of fluorine-containing solution can only be made of polytetrafluoroethylene, and pure reducing medium can also be used for heating and cooling.
When steam heating or water cooling, multiple fine Teflon tubes can be used as bundle tube heat exchangers in the solution, but it takes up a large space, so the plating bath should be designed wider.
If the electric heating pipe is directly threaded with electric heating wire in the Teflon pipe, the pipe should be thick with sufficient mechanical strength, but the thermal conductivity is poor.Most metal electric heaters are coated with thin Teflon tubes for corrosion protection.If the sleeve is too tight, the plastic pipe is easy to crack due to the large difference in the coefficient of thermal expansion between the metal pipe and the plastic pipe. If the gap is too large, the thermal conductivity will decline again.When the outer layer is damaged due to aging, it shall be replaced in time.