Abstract: This paper mainly introduces the design of HV 20,000 PSI valve for shale gas pressure cracking. It expounds the design points from design standards, product application and theoretical calculations, so that relevant designers have a certain understanding of product design and provide them with Design reference.
Key words: shale gas; valve; 20000 PSI; design calculation CLC number: TE37 Document code: A Article ID: 2095-2945(2018)29-0100-02
Abstract: This paper mainly introduces the design of super high pressure 20000PSI valve for shale gas pressure crack, and expounds the main points of design step by step from the design standard, product application and theoretical calculation, so that the related designers have a certain understanding Of the product design and provide the design reference for it.
Keywords: shale gas; valve, 20000PSI; design calculation
The ultra-high pressure large-diameter valve is applied to the wellhead device of shale gas pressure cracking construction. The main function is to connect the fracturing tubing head with the fracturing horn head. Compared with the common API 6A valve, it has large diameter, high pressure resistance and sealing. Reliable features. The specific specifications on the relevant industry specifications API 6A and GB 25513 are limited, which is not enough to guide the actual design of the product. This article focuses on the structure, materials and calculations.
1 The internal and external structure of the structural valve is shown in Figure 1. The installation position of the well site is shown in Figure 2:
1. hydraulic cylinder; 2. bonnet; 3. valve stem; 4. support plate; 5. valve body;
7. Valve plate; 8. Tail cap; 9. Tail bar 2 Materials According to API 6A "Code for Wellhead Device and Tree Equipment", the material of the hanger needs to meet the specifications, see Figure 1, for DD/EE/FF/level When selecting the material of the hanger, it must be considered whether the material meets the requirements of NACE MR0175. For carbon steel and low alloy steel, the hardness requirement should be considered. The stainless steel needs to consider the partial pressure of H2S. For example: AISI 4140 110K low alloy steel can not be used for DD grade, hardness Exceeded HRC22; 17-4PH stainless steel material can not be used in EE grade, H2S partial pressure exceeds 1.5 psi.
In addition to the standard, acidification is usually required during fracturing operations. The strong acid operation does not belong to the above standards. According to the field experience and in order to enhance the service life, the material selection is modified to: the nickel-based Inconel 625 anti-corrosion alloy is deposited on the key sealing part of the body, and the metal sealing surface of the valve plate and the valve seat is supersonic spraying. Tungsten carbide hard alloy, and surface polishing; stem and tail rods use 318 duplex stainless steel to ensure strength while ensuring strong corrosion resistance.
3 Design and calculate 5-1/8′′ 20000PSI (138Mpa) hydraulic slab gate valve for ultra-high pressure shale gas pressure cracking. The main materials are: shell material AISI 4130, yield strength 75K; valve plate material is Markov Stainless steel AISI 410ss, yield strength 75K.
The design of the valve, the most important are the following:
(1) Confirmation of the sealing surface width;
(2) Check the thickness of the valve plate;
(3) Checking the strength of the valve body;
(4) Calculation of the effective diameter of the valve stem;
(5) valve stem thread check;
(6) Strength check of valve plate and stem nut T-joint;
(7) Check valve slenderness ratio check;
(8) Check the inner diameter and strength of the hydraulic cylinder;
(9) Calculation of cylinder head thickness and connection stud strength check;
(10) Medium flange bolt strength check;
(11) Check the thickness of the bonnet.
This article only selects the thickness of the valve plate and the strength of the valve body for calculation and display. The specific calculation steps are as follows:
3.1 Valve plate thickness calculation The valve plate is made of AISI 410, and the metal sealing surface is sprayed with tungsten carbide. The structure is a parallel sealing surface. Tensile strength is:滓b?åŸ655MPa; yield strength is:?滓s?åŸ517MPa; cloth hardness: HB: 207～235
The calculated thickness of the valve plate is:
DMP: the average diameter of the sealing surface, taken 162.98mm, given by design; From: Poisson's ratio, AISI 410 is 0.28 for material properties; P: working pressure, 138 MPa (20000 Psi);滓W>: Allow bending stress <?滓W>==344.67Mpa; C: Corrosion allowance, take 1mm
The actual thickness SB of the valve plate is 88.9 mm, and the calculated thickness S/B is large, that is, the thickness of the valve plate meets the requirements.
3.2 Body strength calculation The material of the valve body is AISI 4130, and the tensile strength is:滓b?åŸ655MPa; yield strength is:?滓s?åŸ517MPa; cloth hardness: HB: 207 ~ 235; rated working pressure: 138Mpa; strength test pressure: 207Mpa;
According to API 6A, Code for Wellhead and Tree Equipment, the maximum primary film stress intensity St during hydrostatic testing is:
St=?滓y=×517=430.83MPa
According to API 6A "Code for Wellhead Installation and Tree Equipment", the design of the primary film stress intensity Sm at rated working pressure is:
St=?滓y=×517=344.67MPa
According to ASME VIII, Pressure Vessel Construction Rules, the overall primary film stress intensity is:
S/t=+=+=256.43 where: P is the strength test pressure, taking 207Mpa, given for design; R is the inner radius of the dangerous section, taking 157.4mm, given for design; t is the shell at dangerous section Thickness, take 213.05mm, given for design.
The ratio of the outer radius of the dangerous section: Y===2.35
According to ASME VIII, Pressure Vessel Construction Rules, the maximum stress strength at rated pressure is:
The overall calculated stress at the primary film and the maximum stress strength at the rated pressure are less than the values ​​specified in the API6A specification, and the housing design meets the requirements.
4 Conclusion UHV large-diameter gate valve is an indispensable equipment in shale gas pressure cracking construction. When the shale gas pressure cracking operation, the different construction methods have different requirements for the valve. For example, when the acidizing operation, the acid resistance level of the valve needs to be improved; when the clumping operation is performed, the construction period is long, and the valve sealing grease should be selected high. Viscosity, frost resistance, etc. Through scientific and rational design, the products can better meet the requirements of on-site use.
references:
[1] Liu Honglin, Wang Li, Wang Hongyan, et al. Discussion on applicable technology of shale gas exploration and development in China [J]. Oil and Gas Well Testing, 2009, 08.
[2] Wu Hanchuan, Liu Boxiu. Development of fracturing equipment in unconventional natural gas exploration and development[J]. Journal of Oil and Gas, 2011, 06(33).
[3] Sun Xiaoying, Pan Wei, Li Shulin. Finite Element Analysis of Key Parts of Fracturing Equipment [J]. Science and Technology Innovation and Application, 2017, 24.
Key words: shale gas; valve; 20000 PSI; design calculation CLC number: TE37 Document code: A Article ID: 2095-2945(2018)29-0100-02
Abstract: This paper mainly introduces the design of super high pressure 20000PSI valve for shale gas pressure crack, and expounds the main points of design step by step from the design standard, product application and theoretical calculation, so that the related designers have a certain understanding Of the product design and provide the design reference for it.
Keywords: shale gas; valve, 20000PSI; design calculation
The ultra-high pressure large-diameter valve is applied to the wellhead device of shale gas pressure cracking construction. The main function is to connect the fracturing tubing head with the fracturing horn head. Compared with the common API 6A valve, it has large diameter, high pressure resistance and sealing. Reliable features. The specific specifications on the relevant industry specifications API 6A and GB 25513 are limited, which is not enough to guide the actual design of the product. This article focuses on the structure, materials and calculations.
1 The internal and external structure of the structural valve is shown in Figure 1. The installation position of the well site is shown in Figure 2:
1. hydraulic cylinder; 2. bonnet; 3. valve stem; 4. support plate; 5. valve body;
7. Valve plate; 8. Tail cap; 9. Tail bar 2 Materials According to API 6A "Code for Wellhead Device and Tree Equipment", the material of the hanger needs to meet the specifications, see Figure 1, for DD/EE/FF/level When selecting the material of the hanger, it must be considered whether the material meets the requirements of NACE MR0175. For carbon steel and low alloy steel, the hardness requirement should be considered. The stainless steel needs to consider the partial pressure of H2S. For example: AISI 4140 110K low alloy steel can not be used for DD grade, hardness Exceeded HRC22; 17-4PH stainless steel material can not be used in EE grade, H2S partial pressure exceeds 1.5 psi.
In addition to the standard, acidification is usually required during fracturing operations. The strong acid operation does not belong to the above standards. According to the field experience and in order to enhance the service life, the material selection is modified to: the nickel-based Inconel 625 anti-corrosion alloy is deposited on the key sealing part of the body, and the metal sealing surface of the valve plate and the valve seat is supersonic spraying. Tungsten carbide hard alloy, and surface polishing; stem and tail rods use 318 duplex stainless steel to ensure strength while ensuring strong corrosion resistance.
3 Design and calculate 5-1/8′′ 20000PSI (138Mpa) hydraulic slab gate valve for ultra-high pressure shale gas pressure cracking. The main materials are: shell material AISI 4130, yield strength 75K; valve plate material is Markov Stainless steel AISI 410ss, yield strength 75K.
The design of the valve, the most important are the following:
(1) Confirmation of the sealing surface width;
(2) Check the thickness of the valve plate;
(3) Checking the strength of the valve body;
(4) Calculation of the effective diameter of the valve stem;
(5) valve stem thread check;
(6) Strength check of valve plate and stem nut T-joint;
(7) Check valve slenderness ratio check;
(8) Check the inner diameter and strength of the hydraulic cylinder;
(9) Calculation of cylinder head thickness and connection stud strength check;
(10) Medium flange bolt strength check;
(11) Check the thickness of the bonnet.
This article only selects the thickness of the valve plate and the strength of the valve body for calculation and display. The specific calculation steps are as follows:
3.1 Valve plate thickness calculation The valve plate is made of AISI 410, and the metal sealing surface is sprayed with tungsten carbide. The structure is a parallel sealing surface. Tensile strength is:滓b?åŸ655MPa; yield strength is:?滓s?åŸ517MPa; cloth hardness: HB: 207～235
The calculated thickness of the valve plate is:
DMP: the average diameter of the sealing surface, taken 162.98mm, given by design; From: Poisson's ratio, AISI 410 is 0.28 for material properties; P: working pressure, 138 MPa (20000 Psi);滓W>: Allow bending stress <?滓W>==344.67Mpa; C: Corrosion allowance, take 1mm
The actual thickness SB of the valve plate is 88.9 mm, and the calculated thickness S/B is large, that is, the thickness of the valve plate meets the requirements.
3.2 Body strength calculation The material of the valve body is AISI 4130, and the tensile strength is:滓b?åŸ655MPa; yield strength is:?滓s?åŸ517MPa; cloth hardness: HB: 207 ~ 235; rated working pressure: 138Mpa; strength test pressure: 207Mpa;
According to API 6A, Code for Wellhead and Tree Equipment, the maximum primary film stress intensity St during hydrostatic testing is:
St=?滓y=×517=430.83MPa
According to API 6A "Code for Wellhead Installation and Tree Equipment", the design of the primary film stress intensity Sm at rated working pressure is:
St=?滓y=×517=344.67MPa
According to ASME VIII, Pressure Vessel Construction Rules, the overall primary film stress intensity is:
S/t=+=+=256.43 where: P is the strength test pressure, taking 207Mpa, given for design; R is the inner radius of the dangerous section, taking 157.4mm, given for design; t is the shell at dangerous section Thickness, take 213.05mm, given for design.
The ratio of the outer radius of the dangerous section: Y===2.35
According to ASME VIII, Pressure Vessel Construction Rules, the maximum stress strength at rated pressure is:
The overall calculated stress at the primary film and the maximum stress strength at the rated pressure are less than the values ​​specified in the API6A specification, and the housing design meets the requirements.
4 Conclusion UHV large-diameter gate valve is an indispensable equipment in shale gas pressure cracking construction. When the shale gas pressure cracking operation, the different construction methods have different requirements for the valve. For example, when the acidizing operation, the acid resistance level of the valve needs to be improved; when the clumping operation is performed, the construction period is long, and the valve sealing grease should be selected high. Viscosity, frost resistance, etc. Through scientific and rational design, the products can better meet the requirements of on-site use.
references:
[1] Liu Honglin, Wang Li, Wang Hongyan, et al. Discussion on applicable technology of shale gas exploration and development in China [J]. Oil and Gas Well Testing, 2009, 08.
[2] Wu Hanchuan, Liu Boxiu. Development of fracturing equipment in unconventional natural gas exploration and development[J]. Journal of Oil and Gas, 2011, 06(33).
[3] Sun Xiaoying, Pan Wei, Li Shulin. Finite Element Analysis of Key Parts of Fracturing Equipment [J]. Science and Technology Innovation and Application, 2017, 24.
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