Abstract: In this paper, the definition and classification of high temperature valve, commonly used high temperature valve type, design points and material selection to do an introduction.
Key words: high-temperature valve; design; material DOI: 10.16640 / j.cnki.37-1222 / t.2017.06.045
In recent decades, with the development of modern science and technology, there is an increasing demand for high-temperature valves in engineering projects. High temperature valve in petrochemical, chemical, power and other industries have applications. Due to the effect of long-term high temperature on the physical properties and mechanical properties of the metal materials, it is necessary to focus on the influence of high temperature on the relevant factors when designing and selecting high-temperature valves.
1 high temperature valve definition and grading In the general information on the valve operating temperature t> 450 ℃ valve called high temperature valve. The division of high temperature valve temperature level, there is no uniform standard. Literature [1] based on decades of experience in the production of high temperature valve will be classified as high temperature level five. Namely the valve working temperature t> 425-550 ℃ for the PI level, the working temperature t> 550 ~ 650 ℃ for the PII level, the working temperature t> 650 ~ 730 ℃ for the PIII level, the working temperature t> 730 ~ 816 ℃ for the PIV level, Operating temperature t> 816 ℃ for the PV level. Among them, PI ~ PIV-class valves rely mainly on the choice of suitable materials to ensure its performance, PV-class valves in addition to material selection is more important is the use of special design tools, such as liner thermal lining or take cooling measures. As described in the literature [2], the ultra-high temperature pneumatic angular stop valve is equipped with 5 sets of cooling structures to ensure the normal operation of the valve under the working medium temperature of 2 000 ℃.
2 commonly used high temperature valve type High temperature valve including high temperature valve , high temperature stop valve, high temperature check valve , high temperature ball valve , high temperature butterfly valve , high temperature needle valve, high temperature throttle , high temperature valve . Among them, the more commonly used for the gate valve, globe valve, check valve, ball valve and butterfly valve.
3 high temperature valve design points High-temperature valve design, pay special attention to the amount of thermal expansion, thermal change and mechanical properties of materials. Due to the material's thermal expansion coefficient, the difference between the parts subjected to heat load and the like, even if the valve seat and the valve core are heated at almost the same time, the performance such as expansion at high temperature is also different. In order to effectively reduce the stuck or rubbed Injury should be appropriate to increase the working gap between the valve parts, the increase in the gap should be based on the material's thermal expansion coefficient, stress and the actual use of temperature to determine [3]. High-temperature thermal change will result in loosening of the connection between the valve seat and the guide sleeve, exacerbating the fatigue aging valve parts, etc., in the design to take appropriate measures according to the specific circumstances, such as the sealing structure priority elastic seat. High temperature will significantly affect the mechanical properties of the material, the material temperature at different temperatures, hardness, plasticity, modulus of elasticity and Bonhams will also be different in the design should take full account of these factors on valve performance.
4 high temperature valve material selection 4.1 High temperature valve materials and their maximum temperature High temperature valve design process should be noted that the use of temperature shall not exceed the maximum allowable temperature of the material. According to ASME B31.3 high temperature valve materials commonly used in the highest temperature shown in Table 1. Special note is that in the actual valve design must also consider the media, such as corrosion and stress levels and other factors, the valve material to allow the actual temperature lower than the median value.
4.2 Corrosion conditions of high temperature valve materials commonly used 4.2.1 Hydrogen conditions Carbon steel and alloy steel pipes in hydrogen conditions, under the specific conditions prone to hydrogen embrittlement. According to the different sources of hydrogen in the metal, often divided into internal hydrogen embrittlement, electrochemical hydrogen embrittlement and environmental hydrogen embrittlement. We usually say hydrogen embrittlement, generally refers to the environment is also commonly known as hydrogen embrittlement hydrogen embrittlement. Hydrogen erosion and temperature, pressure and hydrogen solubility in the steel size.
Hydrogen conditions of material selection, should be based on the maximum operating temperature of the pipeline plus 20 ℃ ~ 40 ℃ margin and the partial pressure of hydrogen in the medium according to Nelson curve to select the appropriate hydrogen-resistant steel, high temperature is often selected Cr-Mo steel. In addition, since austenitic stainless steels do not decarburize at any temperature or under partial pressure of hydrogen, austenitic stainless steels can also be used, taking into account material cost considerations.
4.2.2 H2S corrosion conditions Petrochemical projects often exist H2S corrosion conditions, this time if the choice of ordinary valve will not be able to meet the safety requirements. From the literature [4] shows that the temperature t ≤ 120 ℃ and the presence of water, easy to cause steel stress corrosion cracking; temperature t ≤ 240 ℃ and no water, no corrosion; temperature t ≥ 240 ℃ corrosion increased, can cause Corrosion of steel rapidly and uniformly, and when hydrogen and hydrogen sulfide coexist, the corrosion rate is accelerated. Hydrogen sulfide corrosion conditions valve material selection and requirements can refer to JB / T "high-pressure hydrogenation valve with the technical specifications" implementation.
4.2.3 Other corrosion conditions Other corrosion conditions, high temperature valve material can be selected according to the media and temperature conditions such as stainless steel, nickel-based alloys, titanium and so on. Such as Inconel alloy for high concentration of chloride medium, fertilizer plant with Inco nel 600 or Inconel625 alloy manufacturing high-pressure high-concentration oxygen valve [5].
5 Conclusion In order to meet the requirements of the valve at high temperatures, high temperature valve design and material selection has some common features and ordinary valves, special attention needs to be paid to ensure its safe and normal use.
references:
[1] Le essence. High-temperature valve temperature and the main material grade [J]. Valve, 2003 (06): 10-11.
[2] Yang Rongshui, Huang Meilin et al .. Ultra-high temperature pneumatic angular stop valve [J]. Valve, 2014, (02): 26-27.
[3] Chen Li. High temperature valve design of the technology research [J]. Technology Innovation, 2014 (28): 19.
[4] Le Essence, Li Xiaogang. Analysis of the Industry Standard "Technical Specification for Valves for High Pressure Hydrogenation Unit" (JB / T11484-2013) [J]. Valve, 2014 (06): 39-41.
[5] Yu Wen Yu, Le essence. Valve body parts steel and alloy suitable working temperature [J]. Valve, 2008 (01): 28.
About the Author: Cui Li, an engineer, is mainly engaged in the design of pipes and pipes for petrochemical and chemical installations.
Key words: high-temperature valve; design; material DOI: 10.16640 / j.cnki.37-1222 / t.2017.06.045
In recent decades, with the development of modern science and technology, there is an increasing demand for high-temperature valves in engineering projects. High temperature valve in petrochemical, chemical, power and other industries have applications. Due to the effect of long-term high temperature on the physical properties and mechanical properties of the metal materials, it is necessary to focus on the influence of high temperature on the relevant factors when designing and selecting high-temperature valves.
1 high temperature valve definition and grading In the general information on the valve operating temperature t> 450 ℃ valve called high temperature valve. The division of high temperature valve temperature level, there is no uniform standard. Literature [1] based on decades of experience in the production of high temperature valve will be classified as high temperature level five. Namely the valve working temperature t> 425-550 ℃ for the PI level, the working temperature t> 550 ~ 650 ℃ for the PII level, the working temperature t> 650 ~ 730 ℃ for the PIII level, the working temperature t> 730 ~ 816 ℃ for the PIV level, Operating temperature t> 816 ℃ for the PV level. Among them, PI ~ PIV-class valves rely mainly on the choice of suitable materials to ensure its performance, PV-class valves in addition to material selection is more important is the use of special design tools, such as liner thermal lining or take cooling measures. As described in the literature [2], the ultra-high temperature pneumatic angular stop valve is equipped with 5 sets of cooling structures to ensure the normal operation of the valve under the working medium temperature of 2 000 ℃.
2 commonly used high temperature valve type High temperature valve including high temperature valve , high temperature stop valve, high temperature check valve , high temperature ball valve , high temperature butterfly valve , high temperature needle valve, high temperature throttle , high temperature valve . Among them, the more commonly used for the gate valve, globe valve, check valve, ball valve and butterfly valve.
3 high temperature valve design points High-temperature valve design, pay special attention to the amount of thermal expansion, thermal change and mechanical properties of materials. Due to the material's thermal expansion coefficient, the difference between the parts subjected to heat load and the like, even if the valve seat and the valve core are heated at almost the same time, the performance such as expansion at high temperature is also different. In order to effectively reduce the stuck or rubbed Injury should be appropriate to increase the working gap between the valve parts, the increase in the gap should be based on the material's thermal expansion coefficient, stress and the actual use of temperature to determine [3]. High-temperature thermal change will result in loosening of the connection between the valve seat and the guide sleeve, exacerbating the fatigue aging valve parts, etc., in the design to take appropriate measures according to the specific circumstances, such as the sealing structure priority elastic seat. High temperature will significantly affect the mechanical properties of the material, the material temperature at different temperatures, hardness, plasticity, modulus of elasticity and Bonhams will also be different in the design should take full account of these factors on valve performance.
4 high temperature valve material selection 4.1 High temperature valve materials and their maximum temperature High temperature valve design process should be noted that the use of temperature shall not exceed the maximum allowable temperature of the material. According to ASME B31.3 high temperature valve materials commonly used in the highest temperature shown in Table 1. Special note is that in the actual valve design must also consider the media, such as corrosion and stress levels and other factors, the valve material to allow the actual temperature lower than the median value.
4.2 Corrosion conditions of high temperature valve materials commonly used 4.2.1 Hydrogen conditions Carbon steel and alloy steel pipes in hydrogen conditions, under the specific conditions prone to hydrogen embrittlement. According to the different sources of hydrogen in the metal, often divided into internal hydrogen embrittlement, electrochemical hydrogen embrittlement and environmental hydrogen embrittlement. We usually say hydrogen embrittlement, generally refers to the environment is also commonly known as hydrogen embrittlement hydrogen embrittlement. Hydrogen erosion and temperature, pressure and hydrogen solubility in the steel size.
Hydrogen conditions of material selection, should be based on the maximum operating temperature of the pipeline plus 20 ℃ ~ 40 ℃ margin and the partial pressure of hydrogen in the medium according to Nelson curve to select the appropriate hydrogen-resistant steel, high temperature is often selected Cr-Mo steel. In addition, since austenitic stainless steels do not decarburize at any temperature or under partial pressure of hydrogen, austenitic stainless steels can also be used, taking into account material cost considerations.
4.2.2 H2S corrosion conditions Petrochemical projects often exist H2S corrosion conditions, this time if the choice of ordinary valve will not be able to meet the safety requirements. From the literature [4] shows that the temperature t ≤ 120 ℃ and the presence of water, easy to cause steel stress corrosion cracking; temperature t ≤ 240 ℃ and no water, no corrosion; temperature t ≥ 240 ℃ corrosion increased, can cause Corrosion of steel rapidly and uniformly, and when hydrogen and hydrogen sulfide coexist, the corrosion rate is accelerated. Hydrogen sulfide corrosion conditions valve material selection and requirements can refer to JB / T "high-pressure hydrogenation valve with the technical specifications" implementation.
4.2.3 Other corrosion conditions Other corrosion conditions, high temperature valve material can be selected according to the media and temperature conditions such as stainless steel, nickel-based alloys, titanium and so on. Such as Inconel alloy for high concentration of chloride medium, fertilizer plant with Inco nel 600 or Inconel625 alloy manufacturing high-pressure high-concentration oxygen valve [5].
5 Conclusion In order to meet the requirements of the valve at high temperatures, high temperature valve design and material selection has some common features and ordinary valves, special attention needs to be paid to ensure its safe and normal use.
references:
[1] Le essence. High-temperature valve temperature and the main material grade [J]. Valve, 2003 (06): 10-11.
[2] Yang Rongshui, Huang Meilin et al .. Ultra-high temperature pneumatic angular stop valve [J]. Valve, 2014, (02): 26-27.
[3] Chen Li. High temperature valve design of the technology research [J]. Technology Innovation, 2014 (28): 19.
[4] Le Essence, Li Xiaogang. Analysis of the Industry Standard "Technical Specification for Valves for High Pressure Hydrogenation Unit" (JB / T11484-2013) [J]. Valve, 2014 (06): 39-41.
[5] Yu Wen Yu, Le essence. Valve body parts steel and alloy suitable working temperature [J]. Valve, 2008 (01): 28.
About the Author: Cui Li, an engineer, is mainly engaged in the design of pipes and pipes for petrochemical and chemical installations.
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