NAFCO | Choose the Right Material Valves According to Flow Media

NAFCO | Choose the Right Material Valves According to Flow Media
Time:2018-01-11 From: NAFCO- China Brass Valves and Brass Fittings China Manufacturers


Many flow media have a certain corrosive; the same medium with pressure, temperature and concentration changes of its corrosivity is also different. Therefore, the material should be based on corrosion resistance, choose the appropriate valve for the medium.

1, Stainless Steel Valves
Stainless steel valve resistance to atmospheric excellent, resistant to nitric acid and other oxidizing media, but also alkali, water, salt, organic acids and other organic compounds corrosion. But not resistant to sulfuric acid, hydrochloric acid and other non-oxidizing acid corrosion, nor resistant to dry hydrogen chloride, oxidative chloride and oxalic acid, lactic acid and other organic acids. Containing molybdenum 2% to 4% of stainless steel, such as Cr18Ni12Mo2Ti, its corrosion resistance than chromium-nickel stainless steel is more superior, its non-oxidizing acid and hot organic acids, chloride acid resistance better than chromium-nickel stainless steel, Pitting resistance is also good. Titanium or niobium stainless steel on the intergranular corrosion resistance. With high chromium, high nickel stainless steel, the corrosion resistance higher than ordinary stainless steel, can be used to deal with sulfuric acid, sulfuric acid, mixed acid, sulfurous acid, organic acids, alkali, salt solution, hydrogen sulfide, even at certain concentrations High temperature occasions. But not resistant to concentrated or hot hydrochloric acid, wet fluorine, chlorine, bromine, iodine, aqua regia and other corrosion.Stainless Steel Ball Valves China

NAFCO Stainless Steel Ball Valve, made of SUS304, SUS316.

 

2, Cast Iron Valves

⑴ gray cast iron valve
For water, steam, petroleum products, ammonia can work in the most corrosive media such as alcohols, aldehydes, ethers, ketones and lipids. It is not suitable for hydrochloric acid, nitric acid and other media. But can be used in concentrated sulfuric acid, because concentrated sulfuric acid can produce a layer of passive film on the metal surface. To prevent the concentrated sulfuric acid on the corrosion of cast iron.

⑵ Ductile Iron ValveS
Corrosion resistance stronger, in a certain concentration of sulfuric acid, nitric acid, sulfuric acid, acid salt work. But not resistant to fluoride, alkali, hydrochloric acid and ferric chloride hot solution of corrosion. Use to avoid sudden heat, rapid cooling, otherwise it will rupture.

⑶ Nickel cast iron valve
Alkali resistance than gray cast iron, ductile iron valve is strong; for dilute sulfuric acid, dilute hydrochloric acid and caustic, nickel cast iron is an ideal valve material.

 

3, Carbon Steel Valves
The corrosion resistance of carbon steel valves is similar to that of gray cast iron, slightly inferior to gray cast iron.

4, Brass Valves
Brass valves on water, sea water, a variety of salt solution, organic matter has good corrosion resistance. Right does not contain oxygen or oxidant sulfuric acid, phosphoric acid, acetic acid, dilute hydrochloric acid, etc. have good corrosion resistance, while good resistance to alkali. But not resistant to nitric acid, concentrated sulfuric acid and other oxidizing acid corrosion, nor molten metal, sulfur and sulfide corrosion. Avoid contact with ammonia, it can make copper and copper alloy stress corrosion cracking. Selection should be noted that the different grades of copper alloy, the corrosion resistance of a certain difference.Brass Ball Valves China

NAFCO Brass Ball Valve, made of HPb57-3, CW617N Brass.

 

5, Aluminum Valves
Strong oxidizing nitric acid corrosion resistance, resistant to organic acids and solvents. However, reducing media, strong acid, alkali corrosion is not. The higher the purity of aluminum, the better the corrosion resistance, but the lower the strength, only to be used as a very low pressure valve or valve lining.

6, Titanium Valves
Titanium is an active metal, at normal temperatures can generate a good corrosion resistance oxide film. It is resistant to seawater, various chlorides and hypochlorites, wet chlorine, oxidizing acids, organic acids, alkalis and the like. But it impatient purer reducing acids, such as sulfuric acid, hydrochloric acid corrosion, cut resistant to oxidation with nitric acid corrosion. Titanium valve on the pits have a good resistance. However, red smoke nitric acid, chloride, methanol and other media will have stress corrosion.

7, Zirconium Valves
Zirconium is also an active metal, it can form a close oxide film, it has good corrosion resistance to nitric acid, chromic acid, lye, melt, salt, urea, seawater, but not hydrofluoric acid, concentrated sulfuric acid , The corrosion of aqua regia, nor the corrosion of chloride and oxidative metal chlorides.

8, Ceramic Valves
Mainly made of silica fused sintering valve, such as zirconia, alumina, silicon nitride, etc., in addition to high wear resistance, temperature. Insulation performance, but also has a high corrosion resistance, in addition to the impatience of oxygen fluoride acid, fluoride and alkali alkali, heat-resistant concentrated nitric acid, sulfuric acid, hydrochloric acid, aqua regia, salt solution and organic solvents and other media. Such valves, such as the use of other materials, selection, should consider the corrosion resistance of other materials.

9, Glass Valves
Mainly made of silica fused sintered valve, the corrosion resistance and the same ceramic valve.

10, Enamel Valves
Mainly to the melting of silica and burning enamel in the black metal products, the corrosion resistance and the same ceramic valve.

11, Glass Steel Valves
FRP corrosion resistance, with its adhesive varies. Epoxy FRP can be used in hydrochloric acid, phosphoric acid, dilute sulfuric acid and some organic acids; phenolic FRP corrosion resistance is better; furan FRP has good alkali, acid and corrosion resistance.

12, Plastic Valves
Plastic has a certain corrosion resistance, with the different types of plastics, their corrosion resistance vary greatly.

⑴ nylon
Also known as polyamide, it is a thermoplastic, has good corrosion resistance. Can be resistant to dilute acid, salt, alkali corrosion. On hydrocarbons, ketones, ether, grease, oil has good corrosion resistance. But not resistant to acid, oxidizing acid, phenol and formic acid corrosion.

⑵ polyvinyl chloride
PVC is a thermoplastic that has good corrosion resistance. Acid, alkali, salt, organic matter. Impatience concentrated nitric acid, fuming sulfuric acid, acetic anhydride, ketones, halogenated, aromatic and other corrosion.

⑶ polyethylene
Polyethylene has excellent corrosion resistance, its hydrochloric acid, sulfuric acid, hydrofluoric acid and other non-oxidizing acid and dilute nitric acid, alkali, salt solution and at room temperature have good corrosion resistance of organic solvents. But not resistant to concentrated nitric acid, concentrated sulfuric acid and other strong oxidants corrosion.

⑷ polypropylene
Polypropylene is a thermoplastic with similar corrosion resistance as polyethylene, slightly better than polyethylene. It is resistant to most organic acids, inorganic acids, bases, salts. However, strong nitric acid, fuming sulfuric acid, chlorosulfonic acid and other strong oxidizing corrosion resistance is poor.

⑸ phenolic plastic
Can be resistant to hydrochloric acid, sulfuric acid, phosphoric acid and other non-oxidizing acid, salt solution corrosion. But not resistant to nitric acid, chromic acid and other strong acid, alkali and some organic solvents corrosion.

⑹ chlorinated polyether
Also known as polyether, is a linear, high degree of crystallinity of the thermoplastic. It has excellent corrosion resistance, second only to fluorine plastic. It is resistant to acids, alkalis, salts and most organic solvents other than concentrated sulfuric acid and concentrated nitric acid but not to liquid chlorine, fluorine and bromine.

⑺ poly chlorotrifluoroethylene
Like other fluoroplastics, it has excellent corrosion resistance and other properties, corrosion resistance slightly lower than PTFE. It has good corrosion resistance to organic acids, inorganic acids, alkalis, salts and many kinds of organic solvents. Some solvents that contain halogen and oxygen at high temperatures swell. It is not high temperature fluoride, fluoride, alkali, concentrated nitric acid, aromatics, fuming nitric acid, molten alkali metals.

⑻ polytetrafluoroethylene
PTFE has a very good corrosion resistance, it is almost molten metal lithium, potassium, sodium, chlorine trifluoride, high temperature trifluoride oxygen, high-velocity liquid oxygen, almost all chemical media corrosion.

⑼ Plastic lining valve
Due to the low strength of plastic, many valves are made of metal lined outer shell, made of plastic lining. Plastic lining valves, with the lining of different plastics, its corrosion resistance is not the same. The corrosion resistance of the plastic lining is the same as the corresponding plastic in the plastic valve described above. However, when used, consider the corrosion resistance of other materials used in plastic lined valves.

⑽ Rubber lined valve
Rubber is softer, so many valves are lined with rubber to improve the valve's corrosion resistance and sealing performance. With the different types of rubber, the corrosion resistance is quite different. The vulcanized natural rubber is resistant to the oxidation of non-oxidizing acids, alkalis and salts, but is not resistant to aggressive oxidants such as nitric acid, chromic acid, concentrated sulfuric acid and to petroleum products and certain organic solvents. Therefore, the natural rubber is gradually replaced by synthetic rubber. The nitrile rubber in synthetic rubber has good oil resistance but is not resistant to strong solvents such as oxidizing acids, aromatics, lipids, ketones and ethers. The fluorine rubber has excellent corrosion resistance and can withstand various types of acids, alkalis, salt and petroleum products, Hydrocarbons, but less than the solvent resistance of fluoroplastic; polyether rubber can be used for water, oil, ammonia, alkali and other media.

⑾ lead-lined valve
Lead is an active metal, but because of soft materials, often used as a special valve lining. Lead corrosion product film is a strong protective layer, it is well-known sulfuric acid-resistant materials, in the phosphoric acid, chromic acid, carbonic acid and neutral solution, seawater and other media with high corrosion resistance, but not alkali, hydrochloric acid Nor are they suitable for working in their corrosive products.

 

Ningbo Acro Fluid Control Co., Ltd. (NAFCO) is a professional brass valve manufacturers in China for floor heating manifolds, such as brass ball valves China, Brass radiator valves, brass gate valves, brass angle valves, brass check valves, brass float valves, radiator valves China, thermostatic radiator valves, brass fittings China.

In case of futher questions, please feel free to contact NAFCO at www.acrofluid.com, or send emails to support@acrofluid.com.

 

 

 

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