Diesel Engine Power Packs for Water Pump Application-- / Deutz / Yuchai / Weichai

Anti-corrosion issue of industrial pump

Let us talk about in the following the key points of material selection for some common industrial medium:

1. As one of the highly corrosive mediums, sulfur is an important industrial material used in many fields. Sulfur with different concentration and different temperature corrodes the objects far differently. For example. Sulfur with concentration higher than 80% and temperature lower than 80℃ deals little corrosion to carbon steels and cast irons which are not fit with flowing sulfur, while it would be suggested to be the material of pump valves. Common stainless steels, say 30(OCr18Ni9) and 316(OCr18Ni12Mo2T i), are also hardly good for being sulfur medium. The pump valves for transporting sulfur are usually made of tantirons(very hard to be forged) and also highly alloyed stainless steels(20^th alloy). It is a more economical choice that we use fluorine-butterfly pump(F46) in that fluoroplastic has a quality of better corrosion resistance. Our company deals with these products applicable: IHF fluorine-butterfly pump, PF(FS) highly anti-corrosion centrifugal pump, CQB-F fluoroplastic magnetic drive pump etc.

2. Most of the metallic materials are not quite anti-corrosion when it comes to hydrochloric acid and, even high silicon cast irons with molybdenum can only make it with hydrochloric that is lower than 30% in concentration and 50℃ in temperature. On the contrary to metallic materials, most of the non-metallic materials have a better resistance of hydrochloric corrosion, therefore adding a rubber pump and plastic pump internally, such as polypropylene, fluoroplastic and so on, is the best choice for transporting hydrochloric. Products available: IHF fluorine-butterfly pump, PF(FS) highly anti-corrosion centrifugal pump, CQ polypropylene magnetic pump or fluoroplastic magnetic pump etc.

3. Most metals will be rapidly corroded when it comes to nitric acid, but stainless steel is the most widely-used anti-nitric materials given its good corrosion resistance for nitric acid with all range of concentration under normal temperature. However, it is worth mentioning that molybdenum stainless steel, such as 316 and 316L, does not have a better performance on anti-nitric corrosion than common stainless steel, such as 304 and 421. For nitric acid with high temperature, we usually use titanium or alloyed-titanium stainless steel as materials. Products available: DFL(W)H chemical pump, DFL(W)PH shielding chemical pump, DFCZ process pump, DFLZP self-inhaling chemical pump, IH chemical pump, CQB magnetic pump etc. And the material is 304.

4. Acetic acid is the strongest among other organic acids, in which ordinary steels will be heavily decayed under all range of concentration and temperature. Stainless steel is good acetic-proof material and moreover, molybdenum 316 stainless steel is also applicable to environment with high temperature and dilute acetic acid steam. For occasion with high temperature and high concentration acetic acid, other corroding medium or other rigor demand, it is suggested we choose alloyed stainless steel or fluoroplastic pumps.

5. Steels are widely used with sodium hydroxide under 80℃ of temperature and 30% concentration. Many factories still use ordinary steels even the temperature turns to 100℃ in spite of the increasing of the corrosion, but it is indeed an economical way. Compared to cast irons, there is no obvious advantage of ordinary stainless steel, so it is allowed that we take small portion of iron into the medium but, it is not expected to adopt stainless steels. Titanium or alloyed titanium stainless steels are often used for dealing with high temperature alkali liquid. Ordinary cast-iron pumps of our company are always capable of dealing with room temperature alkali liquid with low concentration, while we are also able to supply with you all types of stainless steel pumps or fluoroplastic pumps for special demands.

6. The corrosion of ammonia to most metals or non-metal objects is slim but, it is not suitable to use cuprum or copper alloy. Most of our products are capable of transporting ammonia or ammonia liquid.

7. The corrosion rate of saline water or sea water to ordinary steels is not so high, so we usually use coating for protection. The average corrosion rate to all types of stainless steels is rather low, but there might be partial corrosion because of chloridion, so 316 stainless steel is a better choice. Our company can supply all kinds of chemical pumps with 316 material setting.

8. Now let us talk about alcohol, ketone, ester and ether. Common alcohol: methyl alcohol, ethyl alcohol, glycol, propyl alcohol etc. Ketone: acetone, butanone and so on. Ester: methyl ester, ethyl ester and other esters. Ether: methyl ether, ethyl ether, butyl ether etc. All of the above do not have corrosion quality, applicable to common-use materials, but we still need to choose them appropriately in accordance with their qualities. Besides, it is worth mentioning that ketone, ester and ether have solubleness to many types of rubber, so we need to be careful while selecting sealing materials.