Valve material suitable for working temperature and working conditions (Tech Center of Shanghai HY Industry Co., Ltd)

Valve design and material selection must focus on one of the issues is the valve working temperature. In order to regulate the appropriate working temperature of the valve body material, from various types of valves with steel and alloy grades of material properties of China’s petrochemical, chemical, fertilizer, electric power and metallurgical industries with the appropriate working temperature of the valve body material and related requirements to make clear provisions for valve product design, manufacturing and inspection. In addition, from the technical management and production management and material procurement considerations, for each type of steel should be selected for good overall performance, should not choose too many steel and alloy grades to prevent confusion.

1,Overview

• Valve design and selection of materials must focus on one of the issues is the working temperature of the valve. In order to regulate the appropriate working temperature of valve materials, from various types of valves with steel and alloy grades of material properties of China’s petrochemical, chemical, fertilizer, power and metallurgical industries with the valve body materials and the appropriate working temperature and related requirements to make clear provisions for valve product design, manufacturing and inspection. In addition, from the technical management and production management and material procurement considerations, for each type of steel should be selected for good overall performance, should not choose too many steel and alloy grades to prevent confusion.

2, low-temperature working conditions

2.1 Ultra-low temperature valve materials

• Ultra-low temperature valve materials [-254 (liquid hydrogen) ~ -101 ℃ (ethylene)] must be used face-centered cubic lattice austenitic stainless steel, copper alloys or aluminum alloys, the low-temperature mechanical properties after heat treatment, especially low-temperature impact toughness must meet the standard requirements.

• The following austenitic stainless steels can be used for the manufacture of ultra-low temperature valves. ASTMA351CF8M, CF3M, CF8 and CF3, ASTMA182F316, F316L, F304 and F304L, ASTMA433316, 316L, 304, 304L and CF8D (Lanzhou High Pressure Valve Factory design, factory standard code GFQ81-93 ). Ultra-low temperature valve body, bonnet, gate or valve flap, etc. before finishing, must be deep-cooled in liquid nitrogen (-196 ℃).

2.2 Low temperature

• Applicable to low-temperature valves (-100 ~ -30 ℃) of the main body materials are low-temperature austenitic stainless steel and low-temperature pressure-bearing parts with ferritic and martensitic steel.

• Low-temperature austenitic stainless steel ASTMA351CF8M, CF3M, CF8 and CF3, ASTMA182F316, F316L, F304 and F304L, ASTMA433316, 316L, 304, 304L and CF8D.

• Ferritic and martensitic steels for low-temperature pressure-bearing parts are ASTMA352LCA (-32°C), LCB, LCC (-46°C), LC1 (-59°C), LC2, LC211 (-73°C), and LC3 (-100°C).

• The material in ASTMA352 standard is less expensive at the primary level, but its chemical composition must have reliable and very strict internal factory control standards when smelting. Its heat treatment process is complex, requiring several times for the tempering treatment, in order to meet the standard requirements of low-temperature impact toughness requirements, long production cycle. Low-temperature impact toughness does not meet the standard requirements, not allowed to feed for low-temperature steel use. Therefore, only in the production of large quantities, and can be smelted into the furnace is used, and in general the choice of austenitic stainless steel.

3, non-corrosive working conditions

• Valve working medium for water, steam, air and oil and other non-corrosive substances, generally using carbon steel. Valve with carbon steel refers to the ASTMA216 standard WCB, WCC cast steel and ASTMA105 forged steel. Valve with carbon steel suitable for working temperature of -29 ~ 425 ℃. However, in order to safety, taking into account the working temperature of the medium may fluctuate, therefore, the general use of carbon steel temperature should not exceed 400 ℃.

4,Corrosion conditions

4.1 Chromium-Molybdenum high temperature steel

• Valve materials selected Cr-Mo high temperature cast steel is mainly used in the ASTMA217 standard WC6, WC9 and C5 (ZG1Cr5Mo), its corresponding rolling stock are F11, F22 and F5 in ASTMA182.

1.  Low chromium grade chromium-molybdenum steel：Low chromium-grade chromium-molybdenum steel has WC6, WC9, F11 and F22, its applicable working medium is water, steam and hydrogen, should not be used for sulfur-containing oil. WC6 and F11 suitable working temperature is -29 ~ 540 ℃, WC9 and F22 suitable working temperature is -29 ~ 570 ℃.

2. chromium five molybdenum high temperature steel：Chromium five molybdenum high temperature steel C5 (ZG1Cr5Mo) and F5, its suitable working medium for water, steam, hydrogen and sulfur-containing oils, etc..

C5 (ZG1Cr5Mo) if used for water steam, its high working temperature is 600 ℃. When used in working media such as sulfur-containing oil, its high working temperature is 550℃. Therefore, the working temperature of C5 (ZG1Cr5Mo) is specified as ≤ 550 ℃.

4.2 Stainless acid-resistant steel

• Stainless acid-resistant steel is used in petrochemical and chemical, fertilizer industry to resist nitric acid, sulfuric acid, acetic acid and organic acids and other corrosion-resistant chromium-nickel or chromium-nickel-molybdenum stainless acid-resistant steel. Stainless acid resistant steel cast steel is mainly used in ASTMA743 or ASTMA744 standard CF8, CF8M, CF3, CF3M, CF8C, CD-4MCu and CN7M, etc. The corresponding rolled materials are F304, F316, F304L, F316L, F347, F53 in ASTMA182 standard and US UNSN08020.

(1) Cr-Ni stainless steel：Cr-Ni class stainless acid-resistant steel CF8, CF3, F304, F304L, CF8C and F347, which is suitable for working medium for nitric acid and other oxidizing acids. Its high working temperature ≤ 200 ℃.

(2) Cr-Ni-Mo stainless steel：Cr-Ni-Mo stainless acid-resistant steel CF8M, CF3M, F316 and F316L, which is suitable for working medium for acetic acid and other reducing acids.

CF8M, CF3M, etc. can replace CF8 and CF3, but CF8, CF3 can not replace CF8M and CF3M. so, the United States and other countries stainless acid-resistant steel valves mainly with CF8M, CF3M, its high working temperature ≤ 200 ℃.

(3) CN7M alloy：CN7M alloy has better overall corrosion resistance, it is widely used in harsh corrosive conditions, including sulfuric acid, nitric acid, hydrofluoric acid and dilute hydrochloric acid, caustic soda, seawater and hot chloride salt solutions, etc., especially can be used in a variety of concentrations and temperatures ≤ 70 ℃ range of sulfuric acid. CN7M and UNSN08020 alloy use temperature of -29 ~ 450 ℃.

(4) Duplex stainless steel：Duplex stainless corrosion-resistant steel (Table 1) for precipitation hardening stainless steel, they are in the matrix of ferrite containing 35% to 40% austenite, its yield strength of about 19Cr-9Ni austenitic stainless steel, and has high hardness and good plasticity and impact toughness. Especially suitable for use in both abrasive and scouring corrosive working conditions, and thus widely used in oxidation and reduction of strong acid working conditions, in the environment with chlorine has a special resistance to stress corrosion cracking performance. CD-4MCu, CD3MN, CE3MN and F53 duplex stainless steel use temperature of -29 ~ 316 ℃.

4.3 Corrosion-resistant nickel-based alloys

Corrosion-resistant nickel-based alloy valves are mainly used in the ASTMA494 standard casting monel alloy (M35-1), cast nickel alloy (CZ-100), Inconel alloy (CY-40), Hastelloy B (N-12MV, N-7M) and Hastelloy C (CW-12MW, CW-7M, CW-6MC, CW-2M).

Monel alloys used for corrosion-resistant Monel valves are mainly UNSN04400 (Monel400) and UNSN05500 (MonelK500). There is no corresponding rolled material for cast nickel alloys, and the rolled materials for Inconel alloys are Inconel600 and Inconel625, etc.

(1) Monel alloy：Monel alloy has high strength and toughness, especially excellent corrosion resistance to reducing acids and strong alkali media and seawater, etc.. Therefore, it is usually used to manufacture equipment and valves for conveying hydrofluoric acid, brine, neutral media, alkali salts and reducing acids, etc. It is also suitable for dry chlorine gas, hydrogen chloride gas, high temperature chlorine gas at 425℃ and high temperature hydrogen chloride gas at 450℃, etc. But it is not resistant to the corrosion of sulfur-containing media and oxidizing media (such as nitric acid and media with high oxygen content). The overall is Monel alloy code MM, the inner parts are Monel alloy valve, the shell for carbon steel era number C / M, shell for CF8 era number P / M, shell for CF8M era number R / M. Monel alloy M35-1, Monel400 and MonelK500 alloy suitable working temperature of -29 ~ 480 ℃.

(2) Cast nickel alloy：Chemical composition of cast nickel alloy (CZ-100) is 95% Ni and 1.00% C. There is no corresponding rolling material for it. When CZ-100 is used in high temperature and high concentration or anhydrous alkali solutions, it has excellent corrosion resistance. CZ-100 is commonly used in the production of chlor-alkali in high corrosion concentration (including molten anhydrous caustic soda) and for applications where there cannot be metal contaminated products such as copper and iron. Cast nickel alloy CZ-100 valve material code for Ni. CZ-100 alloy suitable for working temperature of -29 ~ 316 ℃.

(3) Inconel alloy:Inconel alloy CY-40 and Inconel600 (ASTM B564/N06600) are mainly used to resist stress corrosion, especially for high concentrations of chloride media, when the Ni content ≥ 45%, the chloride stress corrosion has an “immune” effect. In addition, it can also resist boiling concentrated nitric acid, fuming nitric acid, high temperature gases containing sulfur and vanadium and the corrosion of combustion materials.

Inconel alloy has been widely used in the manufacture of components for boiler feedwater systems in nuclear power plants because it is safer than stainless steel. It is also used in industrial production where high corrosion resistance is required for high strength, high pressure seals, and resistance to mechanical wear and oxidation at high temperatures. Such as large chemical fertilizer plants with Inconel600 or Inconel625 alloy (for Hastelloy CW-6MC rolling grade) to manufacture high-pressure (600 ~ 1500 LB) high concentration of oxygen valves, etc. CY-40 and Inconel600 alloy valve material code In. suitable for working temperature of -29 ~ 650 ℃.

(4) Hastelloy:Hastelloy is the commercial name, it includes a series of alloy grades, used on corrosion-resistant valves are mainly Hastelloy B (HastelloyB) and Hastelloy C (HastelloyC) these two categories.

• HastelloyB casting alloy grades in the ASTMA494 standard N-12MV (N-12M-1) and N-7M (some information called N-12M-2, also called it Chlorimet2 alloy), its rolled grades for the ASTMB335 standard UNSN10665. HastelloyB to various concentrations of hydrochloric acid are corrosion-resistant, non-oxidizing salts and acids are also resistant to corrosion. It is also resistant to non-oxidizing salts and acids. Hastelloy B corrosion-resistant valves, from corrosion resistance and resistance to intergranular corrosion should be selected from low-carbon grade Hastelloy B (N-7M). Hastelloy material code valve industry is not yet specified, Hastelloy B valve material code, can be used directly with its casting alloy grade to indicate. Hastelloy B suitable working temperature of -29 ℃ ~ 425 ℃.

• HastelloyC casting alloy grades for CW-12MW (some information called CW-12M-1) and CW-7M (CW-12M-2, also called it Chlorimet3 alloy) and HastelloyC-276 alloy, its casting alloy grades for CW-6MC and HastelloyC-4 alloy, its casting alloy grades Cast Hastelloy CW-7M, CW-12MW, CW-6MC and CW-2M have corresponding rolled grades UNSN10001, UNSN10003, UNSN10276 and UNSN06455. Hastelloy C is resistant to oxidizing solvents, low concentrations of hydrochloric and nitric acids at room temperature.

• The first generation HastelloyC (0Cr16Ni60Mo16W4) is characterized by excellent corrosion resistance in strongly corrosive oxidizing and reducing acid media, but the high nickel corrosion-resistant alloy is austenitic in organization because Ni reduces the solid solution degree of C in austenite, among other reasons. Therefore, Ni-Mo system HastelloyB and Ni-Mo-Cr system HastelloyC alloy are more serious intergranular corrosion tendency or susceptibility, at high temperatures will also lead to stress corrosion and crevice corrosion. In order to overcome intergranular corrosion, so the introduction of the second generation of HastelloyC,HastelloyC-276 (C from 0.03% reduced to 0.02%) and the third generation of HastelloyC,HastelloyC-4, which is characterized by low Si (Si ≤ 0.08%) and ultra-micro C (C ≤ 0.015%), and reduce the content of Fe and W, the addition of stabilized alloy elements such as Ti.

• Hastelloy C corrosion-resistant valves, from corrosion resistance and resistance to intergranular corrosion considerations, it is appropriate to use Hastelloy C-276 (CW-6MC) and Hastelloy C-4 (CW-2M). Hastelloy C valve material code more, and performance and working temperature differences, so CW-12MW, CW-7M, CW-6MC and CW-2M with HC-12, HC-7, HC-276 and HC-4, respectively, or directly with its casting alloy grades to indicate.

• Suitable working temperature of Hastelloy CW-7M and UNSN10001 alloy is -29～425℃, the suitable working temperature of Hastelloy CW-12MW and UNS N10003 alloy is -29～700℃, the suitable working temperature of Hastelloy CW-6MC and UNSN10276 alloy is -29～676℃, the suitable working temperature of Hastelloy CW-2M and UNSN06455 alloy for the appropriate working temperature of -29 ~ 425 ℃.

4.4 Titanium alloys

• Titanium (Ti) has high strength, light weight, high enough thermal resistance and low temperature toughness and good processing properties and welding properties. Used in the production of valves are mainly cast pure titanium and forged pure titanium ZTA2.

• Titanium for corrosive media due to the temperature and other working conditions and performance of corrosion resistance, corrosion resistance and even fire, explosion, etc.. Therefore, the order and design selection should be used when the nature of the medium (concentration, temperature, etc.) to give clear provisions.

• Valves made of titanium have excellent corrosion resistance in a variety of oxidizing strong corrosive media and neutral media.

• Titanium has excellent corrosion resistance in nitric acid below the boiling point and concentration of ≤ 80%. In fuming nitric acid when the NO2 content exceeds 2% and the water content is not enough, titanium and fuming nitric acid reaction will explode, therefore, titanium is generally not used in high temperature nitric acid content of 80% or more.

• Titanium in sulfuric acid is not resistant to corrosion, titanium in hydrochloric acid with moderate corrosion resistance. It is generally believed that industrial pure titanium can be used in hydrochloric acid with a concentration of 7.5% at room temperature, 3% at 60°C and 0.5% at 100°C. Titanium can also be used in phosphoric acid with a concentration of 30% at 35°C, 10% at 60°C and 3% at 100°C.

• Titanium in HF (hydrofluoric acid) is not resistant to corrosion, titanium in acid fluoride solution is also not resistant to corrosion, titanium in boric acid and chromic acid corrosion resistance, in hydroiodic acid and hydrobromic acid can be used.

• Titanium can be used in mixed acid of 10% sulfuric acid and 90% nitric acid at 60℃, mixed acid of 1% hydrochloric acid and 5% nitric acid at boiling and aqua regia at room temperature (Note: aqua regia is a mixture of 3 volumes of concentrated hydrochloric acid and 1 volume of concentrated nitric acid).

• Titanium is completely resistant to corrosion in various concentrations of barium hydroxide, calcium hydroxide, magnesium hydroxide, sodium hydroxide and potassium hydroxide solutions at room temperature, but cannot be used in boiling sodium hydroxide and potassium hydroxide. The corrosion of titanium will be aggravated by the ammonia contained in the alkali.

• Titanium in tap water, river water and air in the high working temperature of 300 ℃. Titanium can be used in seawater with a high flow rate of up to 20m / s. Titanium has high corrosion resistance in seawater at temperatures ≤ 120 ℃, if the temperature is higher than 120 ℃, may produce pitting corrosion and crevice corrosion.

• Titanium in addition to anthranilic acid, oxalic acid and more concentrated citric acid (concentration ≥ 50%), titanium has excellent corrosion resistance to all organic acids, but the water content in organic acids is too low ( < 0.1%) when titanium prone to pitting corrosion.

• Titanium has excellent corrosion resistance in hydrocarbons and chlorinated hydrocarbons. Titanium in dry chlorine gas can react violently to form TiCl4 and there is a risk of fire, but titanium in wet chlorine (water content in 0.3 ~ 1.5%) has good corrosion resistance.

• Titanium is stable in dry HCl from 20 to 160°C, but hydrochloric acid in wet hydrogen chloride causes corrosion of titanium.

• Titanium in chloride solution pitting corrosion potential is higher than stainless steel, titanium resistance to chloride ion pitting corrosion performance than stainless steel, thus titanium in chloride solution has gained wide application.

• In the temperature ≤ 80 ℃ titanium generally does not produce pitting corrosion, but in high temperature medium concentration of chloride solutions (such as 100 ℃ of 25% aluminum chloride solution, 175 ℃ of 70% calcium chloride solution, 200 ℃ of 25% magnesium chloride solution and 200 ℃ of 75% zinc chloride solution) is more likely to pitting corrosion.

5,High temperature service

• High temperature service valves mainly refer to the high temperature valves used in oil refineries.

5.1 Sub-high temperature

• Sub-high temperature refers to the valve operating temperature in the region of 325 ~ 425 ℃. If the medium is water and steam, mainly with WCB, WCC, A105, WC6 and WC9. If the medium is sulfur-containing oil, mainly with C5, CF8, CF3, CF8M and CF3M with sulfide corrosion resistance. They are mostly used in the normal decompression device and delayed coking device in refineries, when the valves made of CF8, CF8M, CF3 and CF3M are not used to resist corrosion of acid solution, but used for sulfur-containing oil and oil and gas pipelines. In this working condition, the high working temperature of CF8, CF8M, CF3 and CF3M is 450℃ at the upper limit.

5.2 High temperature Ⅰ

• Valve working temperature of 425 ~ 550 ℃ for high temperature Ⅰ (referred to as PI level). PI level valve body material for the ASTM A351 standard CF8 as the base form of “high temperature Ⅰ carbon chromium nickel rare earth titanium quality heat-resistant steel”. Because PI grade is a specific designation, the concept of high temperature stainless steel (P) is included here. Therefore, if the working medium is water or steam, although also available high-temperature steel WC6 (t ≤ 540 ℃) or WC9 (t ≤ 570 ℃), in the case of sulfur-containing oil, although also available high-temperature steel C5 (ZG1Cr5Mo), but here they can not be called PI grade.

5.3 high temperature Ⅱ grade

• The valve working temperature of 550 ~ 650 ℃, as high temperature Ⅱ (referred to as P Ⅱ level). P Ⅱ level high temperature valves are mainly used in refineries of heavy oil catalytic cracking device, which contains high temperature lining wear-resistant gate valve used in the three rotary nozzles and other parts. P Ⅱ level valve body material for the ASTMA351 standard CF8 as the base form of “high temperature Ⅱ carbon chromium-nickel Rare-earth titanium-tantalum reinforced heat-resistant steel”.

5.4 high temperature Ⅲ grade

• Valve operating temperature of 650 ~ 730 ℃, as high temperature Ⅲ level (referred to as P Ⅲ level). P Ⅲ level high temperature valves are mainly used in refineries on large heavy oil catalytic cracking device. p Ⅲ level high temperature valve body material for ASTM A351 standard CF8M as the base form of “high temperature Ⅲ level carbon chromium nickel molybdenum rare earth titanium tantalum reinforced heat-resistant steel “.

5.5 high temperature Ⅳ grade

• Valve operating temperature of 730 ~ 816 ℃, set as high temperature Ⅳ level (referred to as P Ⅳ level). The upper limit of the operating temperature of the P Ⅳ class valve is 816 ℃ because the valve design selected from the standard ASMEB16.34 pressure-temperature class provides a high temperature of 816 ℃ (1500°F). In addition, the working temperature exceeds 816 ℃, the steel is close to entering the forging temperature region, when the metal is in the plastic deformation zone, the plasticity of the metal is good, it is difficult to withstand high working pressure and impact without deformation. P Ⅳ valve body material for the ASTMA351 standard CF8M as the base form “high temperature Ⅳ carbon chromium nickel molybdenum rare earth titanium tantalum reinforced type heat-resistant steel. CK-20 and ASTMA182 standard F310 (C content ≥ 0.050%) and F310H and other heat-resistant stainless steel.

5.6 High temperature V

• Valve operating temperature > 816 ℃ or more, known as high temperature V (referred to as P V level). P V high-temperature valves (for cutting off the valve, but not the regulating butterfly valve type of valve) must use special design means, such as lining heat insulation lining or through the water or gas cooling, etc., in order to ensure the normal operation of the valve. Therefore, the upper limit of the working temperature of the P V class high-temperature valve is not specified, this is because the control of the valve’s working temperature is not based on the material alone, but with special design means to solve the problem, and the basic principle of the design means is the same. P V class high-temperature valve can be based on its working medium and working pressure and the use of special design methods, etc., the choice of reasonable, can meet the valve’s material. In the P V class high temperature valve, usually flue insert valve or butterfly valve insert or butterfly plate is often used in the ASTMA297 standard HK-30, HK-40 high temperature alloy, they can resist corrosion in the following 1150 ℃ oxidation and reducing gas, but can not withstand the impact and high pressure load.

6,Conclusion

• In today’s rapid development of technology, the main material of the valve is increasingly diversified, high parameterization. Valve materials corresponding to the working medium is also more complex, the working temperature requirements are higher. Understanding the performance of various types of valves with steel and alloys and their appropriate working temperature, is the design, manufacture, procurement and use of valves of the relevant scientific and technical personnel and operators must master the knowledge. In particular, the use of the material temperature can not exceed its appropriate working temperature, otherwise it will cause terrible and serious accidents.

Shanghai HY Industry Co., Ltd is qualified superalloy supplier.We have more than 20 years experience in kind of  Nickel alloy，Cobalt alloy，Titanium alloy.