This is a balanced cost-effective price and corrosion resistance of austenitic stainless steel, good corrosion resistance, especially for sulfuric acid, phosphoric acid and halide (inclusive of Cl-, F-). Of Cr, Ni, Mo content is higher, it has good resistance to stress corrosion, pitting and crevice corrosion. The applicable conditions in the chlorine-containing medium.
Plate heat exchanger, heat exchanger: 254 the SMO high grade stainless steel timber -----------
By increasing the Mo on 316 improved ultra-low carbon grade stainless steel with excellent resistance to chloride pitting and crevice corrosion can not use the 316-containing brine, inorganic acid media.
Plate for heat exchanger materials: titanium -----------
Non-alloy titanium, light weight, density 4.51, naturally passive protective membrane (Ti2O3), and if it is damaged, has a "self-healing", so the corrosion resistance than stainless steel, is suitable for the chlorine-containing media (Cl - concentrations of> 200 mg / L, the temperature ≤ 130 ° C) typical material. Does not exceed 120 ° C seawater and other chloride (CaCl2) solution, and is virtually unaffected by corrosion. In general, can be used below 135 ℃ seawater and 165 ℃ following the concentration of salt (NaCl).
Titanium below the boiling point of organic acids (such as concentrated nitric acid, the concentration of carbonic acid, etc.) and in dilute alkali, corrosion resistance is also good.
The poor corrosion resistance of titanium in H2SO4, HCl, HF and aqua regia, etc.. Concentrated chloride solutions at high temperatures (120 ° C and above) (eg, pH> 7, the chloride concentration> 200 mg / L wastewater), may also cause crevice corrosion or stress corrosion. At this point, should be used in titanium - palladium alloy.
Plate for heat exchanger materials: titanium - palladium alloy -----------
This is the addition of palladium (0.12% ~ 0.25%), non-alloying of titanium, which significantly improved the titanium in acid media (especially the corrosion resistance in conditions less harsh conditions). For example, the concentration of 70% nitric acid containing oxidizing ions (such as Fe + and Cu +), hydrochloric acid and plating solutions, etc. have good corrosion resistance. In addition, can still be used for concentration ≤ 10%, temperature ≤ 70 ° C, dilute sulfuric acid.
Plate for heat exchanger material: Nickel 200-----------
This is a pure nickel plate, containing 99% nickel. Mainly used in high concentration (50% ~ 70%), high temperature (up to boiling point), caustic solution (NaOH, KOH, etc.). However, crevice corrosion caused by brackish water and other chloride sensitive.
Board for the heat exchanger material six: Hastelloy C-276 -----------
With good corrosion resistance: almost free from the influence of Cl-; various concentrations of sulfuric acid corrosion resistance, excellent, can be used for one of the hot concentrated sulfuric acid a few materials; widely used in organic acids (such as formic acid, acetic acid), high temperature HF acid and a certain concentration of hydrochloric acid (<40%), phosphoric acid (≤ 50%); chloride, fluoride and organic solvents (such as methanol, ethanol).
Board for the heat exchanger material seven: of Monel 400-----------
Ni (about 70%)-Cu (30%) of nickel-based alloys. Concentration of 80% at a temperature not higher than 50 ° C to 100 ° C non-inflatable sulfuric acid, concentration less than 50 percent of the temperature below 100 ℃ HF acid, acetic acid and caustic soda and other media, good corrosion resistance. Especially suitable for the acidic chloride solution and some of the conditions of the brackish water and saline; has good high temperature performance. However, does not apply to concentrated sulfuric acid, hydrochloric acid and nitric acid, but also very sensitive to the erosion of mercury (sometimes exist as an impurity).
Plate for the heat exchanger timber 8: Incoloy825 -----------
For various concentrations of sulfuric acid at low temperatures; at a concentration of 50% to 70% caustic soda (NaOH) solution, with good corrosion resistance, stress corrosion cracking. However, crevice corrosion caused by the chloride is very sensitive. In addition, the stamping performance is not good, it is not a slab of commonly used materials.