What is the best material for corrosion resistance of double suction pump body?

Double suction pump pump body corrosion resistance material selection needs to be combined with the corrosive properties of the medium (such as acid, alkali, salt concentration, chloride ion content, etc.), temperature and pressure conditions, the following are excellent corrosion-resistant materials and applicable scenarios:
I.Stainless steel: the first choice for comprehensive corrosion resistance
1. Austenitic stainless steel (316L, 904L)
Features:
316L: containing molybdenum (Mo) elements, better than 304 chloride ion (Cl-) corrosion resistance, resistance to intergranular corrosion (due to carbon content ≤ 0.03%), suitable for medium concentration of acids, alkalis, salt solutions (such as phosphoric acid, acetic acid, sulfate).
904L: high nickel (Ni), molybdenum (Mo), copper (Cu) alloy stainless steel, non-oxidising acids (such as sulphuric acid, hydrochloric acid) and chloride ions corrosion resistance is very strong, can be resistant to 80 ℃, 5% concentration of sulphuric acid.
Application scenarios: chemical and pharmaceutical (acid and alkali solution), seawater desalination, food processing (need to sanitary corrosion resistance).
2. Duplex stainless steel (2205, 2507)
Features:
Austenitic + ferrite duplex organisation, strength is 2 times that of 316L, resistance to chloride stress corrosion (such as seawater, Cl-containing chemical media) and pitting corrosion ability is outstanding, temperature resistance up to 250 ℃.
Application scenarios: marine engineering (seawater pumps), petrochemical (Cl-containing crude oil transport), hydrometallurgy (acidic slurry).
II.High-alloy materials: extreme corrosion conditions
1. Hastelloy (C-276, B-3)
Features:
C-276: containing tungsten (W), molybdenum (Mo), nickel (Ni), resistant to strong oxidising / non-oxidising acids (such as nitric, hydrochloric and sulphuric acids), chlorine solutions and high-temperature corrosion, resistant to hydrochloric acid up to 120 degrees Celsius, any concentration.
B-3: High nickel-molybdenum alloy, excellent corrosion resistance to hydrochloric acid and hydrofluoric acid, and excellent performance in reducing acid environment.
Application Scenario: Chemical reactor, pharmaceutical autoclave, pickling equipment (strong corrosion + high temperature).
2. titanium and titanium alloy (TA2, TC4)
Features:
Resistant to seawater, wet chlorine gas, nitric acid, organic acid corrosion ability is very strong, low density (light weight), but high cost, temperature ≤ 300 ℃.
Application Scenario: Ship seawater pump, chlor-alkali industry (wet chlorine gas transmission), desalination equipment.
III. Engineering plastics: non-metallic corrosion-resistant programme
1. Polyvinylidene fluoride (PVDF)
Features:
Resistant to strong acid and alkali (such as 90% sulphuric acid, 40% sodium hydroxide), strong weather resistance, temperature resistance - 40 ℃ ~ 150 ℃, but the strength is low, need to be used with metal skeleton.
Application scenario: electroplating industry (hydrofluoric acid, chromic acid solution), chemical waste gas treatment (acidic liquid).
2. Polypropylene (PP)
Features:
Resistant to inorganic acids, alkalis, salt solutions (such as hydrochloric acid, phosphoric acid), low cost, but temperature resistance ≤ 90 ℃, poor resistance to oxidising acids (such as nitric acid).
Application scenarios: sewage treatment (neutral or weakly acidic wastewater), food processing (non-toxicity requirements).