SY/T 0518-2002 Design specification for steel butt-welding fittings for oil and gas pipelines
Some standard content:
1 General Provisions
Petroleum and Natural Gas Industry Standard of the People's Republic of China Design Code for Steel Butt-Weld Pipe Fittings for Oil and Gas Pipelines Approval Department: National Economic and Trade Commission Approval Date: 2002-05-28
Implementation Date: 2002-08-01
SY/T 0518.---2002
Replaces SY/T0518--1992
1.0.1 This standard is formulated to improve the design level of steel butt-weld pipe fittings for oil and gas pipelines, to achieve advanced technology, economic rationality, safety and applicability, and to ensure quality.
1.0.2 This standard specifies the requirements and methods for the design and selection verification of steel butt-weld pipe fittings for oil and gas pipelines. When calculating the design of pipe fittings, only the effect of design pressure is considered. When other loads (such as thermal expansion thrust, bending moment, etc.) must be considered, they should be analyzed separately and are not within the scope of this standard.
1.0.3 This standard applies to steel butt-welded pipe fittings (pipe heads, reducers, elbows, bends and tees) in onshore oil and gas pipeline projects under the following conditions:
Design pressure p is not greater than 10MPa;
Nominal diameter DN is not greater than 1000mm;
Design temperature T is higher than -40℃ and not higher than 120℃; Note: The design temperature of pipe fittings should be within the allowable service temperature range of steel. 1.0.4 For steel pipe fittings that exceed the design range of this standard, the following methods can be used for design: 1 Stress analysis including finite element analysis;
2 Confirmatory experimental analysis (such as confirmatory burst test, experimental stress analysis). 1.0.5 In addition to complying with this standard, the design of pipe fittings should also comply with relevant laws, regulations and rules promulgated by the state. When the requirements of this standard are lower than those of relevant national standards, the requirements of national standards shall prevail. 1.0.6 The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All versions will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. GB150-1998 Steel pressure vessels
GB/T3274--1988 Carbon structural steel and low alloy structural steel hot rolled thick steel plates and steel strips GB3531-1996 Low alloy steel plates for low temperature pressure vessels GB6654-1996 Steel plates for pressure vessels
GB5310--1995 Seamless steel pipes for high pressure boilers GB6479-2000 Seamless steel pipes for high pressure fertilizer equipment GB/T8163-1999 Seamless steel pipes for conveying fluids GB9948--1988 Seamless steel pipes for petroleum cracking Technical delivery conditions for steel pipes Part 1: Grade A steel pipes GB/T 9711.1--1997 Petroleum and natural gas industry 9 Technical delivery conditions for steel pipes for petroleum and natural gas industries Part 2: Grade B steel pipes GB/T 9711, 2--1999
GB/T124591990 Steel butt-welding seamless pipe fittingsGB/T13401—1992 Steel plate butt-welding pipe fittingsGB50251--1994 Code for design of gas pipeline engineeringGB502531994 Code for design of oil pipeline engineeringJB4730—1994
Non-destructive testing of pressure vessels
SY/T0510-—1998 Steel butt-welding pipe fittings
SY/T5257--1991 Steel elbows
SY/T0599---1997 Requirements for metal materials resistant to sulfide stress cracking for natural gas surface facilities 2 Terms and symbols
2.1 Terms
2.1.1 Pressurepressure
Unless otherwise specified, pressure refers to gauge pressure. 2.1.2 Operating pressure Operating pressure refers to the highest pressure that a pipe fitting may reach under normal working conditions. 2.1.3 Design pressure SY/T 0518--2002
Design pressure refers to the pressure used to determine the calculated thickness of a pipe fitting under the corresponding design temperature, and its value shall not be lower than the operating pressure. 2.1.4 Design temperature Design temperature refers to the highest or lowest temperature that a pipe fitting metal may reach under normal working conditions (the average temperature along the metal cross section of the pipe fitting). The design temperature and design pressure are used together as design load conditions. 2.1.5 Calculated thickness Calculated thickness refers to the thickness calculated according to the given formulas in each chapter. 2.1.6 Design thickness Design thickness refers to the sum of calculated thickness and corrosion allowance. 2.1.7 Nominal thickness Nominal thickness refers to the thickness rounded up to the standard steel specification after adding the negative deviation of the steel (for mechanically formed pipe fittings other than welded pipe fittings, rounding up is not required), that is, the thickness marked on the drawing. The actual minimum thickness of the pipe fitting after forming shall not be less than the nominal thickness shown in the figure.
2.1.8 Effective thickness Effective thickness refers to the nominal thickness minus the corrosion allowance and the negative deviation of steel thickness. 2.1.9 Nominal thickness at bevel ends The nominal thickness at bevel ends refers to the thickness at the bevel of the pipe end, which is the thickness that identifies the pressure grade of the pipe. When the standard yield strength of the pipe material is greater than or equal to the corresponding pipe line, it is generally equal to the wall thickness of the corresponding pipe line. 2.1.10 Nominal diameter Nominal diameter is the nominal diameter. There are two series of steel pipe outer diameters corresponding to the nominal diameter: Series I (A series) and Series II (B series). When marking, for series I (A series) pipe fittings, \A may not be added after the nominal diameter DN; for series II (B series) pipe fittings, \B should be added after the nominal diameter DN. The nominal true diameter and its corresponding outer diameter are shown in Table 2.1.10. 277
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Nominal diameter
2.2 Symbol
Series I (A)
Design pressure (MPa);
Table 2. 1.10 Correspondence table between nominal diameter of steel pipe and outer diameter of steel pipe Series I (B)
Nominal diameter
Allowable working pressure of tee calculated by pressure reduction coefficient method (MPa); Design temperature (℃);
.-Nominal thickness of pipe end of fittings (mm);-Calculated thickness of fittings (mm);
Calculated wall thickness of tee main pipe (mm);
Calculated wall thickness of tee branch pipe (mm);
Design thickness of fittings (mm);
Nominal thickness of fittings (mm);
Effective thickness of fittings (mm);
Tee main pipe Effective wall thickness (mm),
Effective wall thickness of tee branch pipe (mm);
Series I (A)
Series II (B)
Wall thickness of branch pipe after removing corrosion allowance at the flange of drawn or extruded tee shoulder (measured at a height equal to R from the outer diameter of the main pipe) (mm);
Allowable stress of steel for pipe fittings (MPa); Strength design factor;
-Standard yield strength lower limit of steel for pipe fittings (MPa); g
.-Welding joint coefficient;
D--Outer diameter of pipe fittings (for reducers, it is the outer diameter of the large end, for tees, it is the outer diameter of the main pipe ) (mm); d----·For reducers, it is the outer diameter of the small end; for tees, it is the outer diameter of the branch pipe (mm); d
Inner diameter of the tee branch pipe after removing the corrosion allowance (mm); Length of the reducer (mm);
C-the distance from the center of the tee to the end of the main pipe (i.e. the half length of the tee) (mm); M-the distance from the center of the tee to the end of the branch pipe (mm); Ak-the required reinforcement cross-sectional area of the tee opening (mm); Ae-the sum of the reinforcement areas (mm2);
H-the height of the effective reinforcement area of the tee branch pipe (mm), W-half the width of the effective reinforcement area of the tee main pipe (mm); SY/T0518 --2002
f.-Strength reduction coefficient, equal to the ratio of the lower limit of the standard service strength of the branch pipe material to the main pipe material. When the ratio is greater than 1.0, take f,=1.0;
n—pressure reduction coefficient;
DN——nominal diameter of the pipe fitting.
3 Basic provisions
3.0.1 The design of pipe fittings must have the corresponding qualifications. 3.0.2 The design parameters (such as design pressure, allowable stress, design temperature, etc.), test pressure and corrosion allowance of pipe fittings should not be lower than the values of the corresponding pipe lines.
3.0.3 The thickness addition shall be calculated according to the formula (3.0.3) Calculation. C = C + Cz
Where: C----thickness addition (mm);
Ci—negative thickness deviation of steel for pipe fittings (mm): C2——corrosion allowance (mm).
The negative thickness deviation of steel plates or steel pipes shall comply with the provisions of the corresponding steel standards. When the negative thickness deviation of steel is not greater than 0.25mm and does not exceed 6% of the nominal thickness, the negative deviation can be ignored. The corrosion allowance of pipe fittings shall be determined based on the design life of the pipe fittings and the corrosion rate of the medium on the metal material, and its value shall not be less than the value of the corresponding pipe line.
3.0.4 The allowable stress of steel for pipe fittings shall be calculated according to formula (3.0.4). Ea]- Ko
3.0.5 The strength design factor refers to the coefficient used to determine the allowable stress of the material, which is related to the grade of the area where the pipe fittings are located and shall be selected in accordance with the provisions of GB50251 "Design Code for Gas Pipeline Engineering" or GB50253 "Design Code for Oil Pipeline Engineering". 3.0.6 The welded joints of pipe fittings shall be double-sided butt joints or full penetration butt joints equivalent to double-sided welding. 100% non-destructive testing: =1.0
3.0.7 The nominal thickness of pipe fittings shall not be less than the nominal thickness of the pipe end of the connected steel pipe (or pipe fitting). When the nominal thickness of the pipe fitting is large and the inner diameter cannot meet the requirements of pipeline cleaning, the outer diameter of the pipe fitting can be increased so that the minimum inner diameter of the pipe fitting can pass through the cleaning equipment smoothly. 3.0.8 The mechanical properties and chemical composition of the pipe fitting material shall be the same or similar to those of the connected steel pipe (or pipe fitting). 3.0.9 The groove type of the pipe fitting end shall comply with the provisions of Figure 3.0.9, and the inner end of the groove shall be aligned with the inner wall of the connected steel pipe: 279
SY/T 0518--2002
Maximum 30°
Minimum 15
Maximum 30°
Minimum 15
(a) Ordinary groove
Maximum 30°
Minimum 15°℃7
Maximum 30°
Minimum 15°
(b) Composite groove
Note: ① When the standard service strength lower limit of the pipe fitting material is the same as that of the pipe material, the minimum value of the inner cutting angle is not limited. ② If there is a special need, other groove forms are allowed. ③ In the figure, D is the outer diameter of the corresponding pipe line.
Figure 3.0.9 Groove type
3.0.10 Pipe fittings designed according to this standard shall be manufactured, inspected and accepted according to GB/T12459, GB/T13401, SY/T0510 or SY/T5257; all butt joints shall be 100% radiographically inspected according to JB4730, and qualified at Level II; all fillet welds shall be 100% magnetic particle or penetrant inspected according to JB4730, and qualified at Level I. 4 Materials
4.1 General provisions
4.1.1 Pipe fittings shall be made of seamless steel pipes, straight seam steel pipes or steel plates, and the steel shall have good toughness and weldability. 4.1.2 Steel for pipe fittings shall be smelted in electric furnaces or oxygen converters. The technical requirements of steel shall comply with the provisions of the corresponding national standards, industry standards or relevant technical conditions.
4.1.3 The steel used for pipe fittings shall be accompanied by the steel quality certificate of the steel production unit. The manufacturing unit shall inspect and accept the steel according to the quality certificate and re-inspect it if necessary.
4.1.4 The selection of steel for pipe fittings shall take into account the use conditions of the pipe fittings (such as design temperature, design pressure, medium characteristics) and the related pipe lines, the welding performance of the materials, the manufacturing process of the pipe fittings and the economic rationality. 4.1.5 When seamless steel pipes are used to make pipe fittings, the materials shall comply with the requirements of GB5310, GB6479, GB/T8163 or GB9948; when GB/T9711.1 or GB/T9711.2 steel pipes are used to make pipe fittings, the changes in the mechanical properties of the materials after hot forming shall be considered. 4.1.6 When steel plates are used to make pipe fittings, the materials shall comply with the requirements of GB/T3274, GB3531 and GB6654: When steel plates of the steel grade in GB/T9711.1 or GB/T9711.2 are used, the chemical composition and mechanical properties of the steel plates shall comply with the requirements of the corresponding standards, and the use state should be hot-rolled or normalized. If controlled-rolled steel plates are used, the changes in the mechanical properties of the materials after hot forming shall be considered. 4.1.7 When steel materials other than those listed in Articles 4.1.5 and 4.1.6 of this standard are used, their carbon content, carbon equivalent, sulfur and phosphorus content shall comply with the following provisions.
1 The carbon content shall not be greater than 0.25%, and the carbon equivalent shall not be greater than 0.45%. The carbon equivalent shall be calculated according to formula (4.1.7). Mn + Cr+ Mo+V+ Cu+ Ni
Cea C+
2Smelting analysisThe sulfur content should not be greater than 0.030%, and the phosphorus content should not be greater than 0.035%. (4.1.7)
4.1.8When using steels other than those listed in Articles 4.1.5 and 4.1.6 of this standard, the yield strength ratio of the selected steel should not be greater than the strength ratio of steels of the same strength grade listed in Articles 4.1.5 and 4.1.6 of this standard. 4.1.9When pipe fittings need to consider sulfide corrosion resistance, their materials should also comply with the relevant provisions of "Requirements for Metal Materials for Resistance to Sulfide Stress Cracking of Natural Gas Surface Facilities" SY/T0599. 280
4.2 Impact toughness
SY/T0518—2002
4.2.1 When the service temperature of pipe fittings is higher than -20℃, the steel plates used to make pipe fittings should be subjected to Charpy (V-notch) low-temperature impact toughness test for one steel plate from each batch when the service temperature and steel plate thickness meet the following conditions. The test temperature should be the minimum design temperature of the pipe fittings, or the overflow specified in the design documents, and the sample sampling direction should be horizontal. 1 When the service temperature is lower than 0℃: 2020R with a thickness greater than 25mm, 16MnR, 15MnVR and 15MnNbR with a thickness greater than 38mm, any thickness of standard tensile strength lower limit a,>515MPa～650MPa (such as 1.415 and above steel grade) steel plates. 2 When the use temperature is lower than -10℃: 20, 20R with thickness greater than 12mm, 16MnR15MnVR and 15MnVNbR with thickness greater than 20mm.
The impact work index is determined according to the lower limit of the standard tensile strength of the steel plate in accordance with Table 4.2.2. 4.2.2 When the use temperature of the pipe fitting is lower than or equal to 20℃, the impact test temperature of the steel for pipe fittings shall be based on the minimum design temperature of the pipe fittings, or as specified in the design documents. The impact work index of the steel for pipe fittings at the test temperature shall be determined according to the lower limit of the standard tensile strength of the steel for pipe fittings, and the specific requirements shall not be lower than the requirements of Table 4.2.2. The impact work index of the small specimen shall be reduced in proportion to the thickness of the specimen. The sampling direction of the specimen is horizontal.
Table 4.2.2 Low-temperature Charpy (V-notch) impact test capsule Low impact energy specified value Steel standard tensile strength lower limit a
>450-515
>515～650
Average impact energy of three specimens Ak
10 mm×10 mmX55 mm
Note: The average impact energy of the three specimens at the test temperature shall not be lower than the specified in the table; the impact energy of a single specimen may be less than the average value and shall not be less than 70% of the average value.
5 Design of pipe heads
5.0.1 Pipe heads shall be made of a whole piece of steel plate. 5.0.2 Pipe heads are standard push elliptical heads with a major-minor axis ratio (D:2h,) of 2:1. As shown in Figure 5.0.2. Figure 5.0.2 Standard elliptical head
5.0.3 Height of the straight edge of the pipe head h. Select according to the following provisions based on the nominal thickness of the pipe head: when ≤8mm, take hz=25mm;
When 8 mm<6,≤18 mm, take hz=40 mm; when 9,>18 mm, take h2=50 mm.
SY/T0518—2002
5.0.4 The calculated wall thickness of the pipe head is calculated according to formula (5.0.4). (5.0.4)
5.0.5 For elliptical pipe caps manufactured according to GB/T12459, GB/T13401 or SY/T0510 with a ratio of the major and minor axes of the semi-elliptical part greater than or equal to 2:1, they can be verified according to formula (5.0.5). (5.0.5)
6 Design of reducers
6.0.1 The structural types of reducers are shown in Figures 6.0.1-1, 6.0.1-2, 6.0.1-3 and 6.0.1-4. Figure 6.0.1-1
Concentric reducer with folded edge
Figure 6.0.1-3Eccentric reducer with folded edge
Figure 6.0.1-2Concentric reducer without folded edgeFigure 6.0.1-4Eccentric reducer without folded edge6.0.2 The semi-apex angle or maximum semi-apex angle of the cone shell of the reducer without flange should not be greater than 25°, and the semi-apex angle or maximum semi-apex angle of the cone shell of the reducer with flange should not be greater than 60°.
6.0.3 The straight side length L of the large end of the reducer with flange should not be less than 2Vo.5Ds,, and the straight side length L2 of the small end should not be less than /ds.. 6.0.4 The corner radius R of the transition section of the large end of the reducer with flange should not be less than 10% of the outer diameter D of the large end of the reducer, and should not be less than 3 times the nominal thickness of the reducer. The corner radius R2 of the transition section of the small end should not be less than 5% of the outer diameter d of the small end of the reducer, and should not be less than 3 times the nominal thickness of the reducer.
6.0.5 Reducers should be seamless or have only one longitudinal weld. For eccentric reducers, the weld should be placed at a non-inclined position. 6.0.6 The wall thickness of the reducer is calculated according to formula (6.0.6). pD
2ocosα
Where: α-
The half-vertex angle or maximum half-vertex angle of the reducer (as shown in Figure 6.0.1-1 to Figure 6.0.1-4) (). (6.0.6)
6.0.7 For reducers manufactured according to GB/T12459, GB/T13401 or SY/T0510, the calculation can be carried out according to formula (6.0.7). ≥
7 Design of elbows or bends
7.0.1 When the bending radius R is 1 to 3 times the outer diameter of the pipe, it is generally called an elbow. When the bending radius R is greater than 3 times the outer diameter of the pipe, it is generally called a bend. bzxZ.net
7.0.2 Elbows and bends should be seamless or have only one longitudinal weld. The position of the weld should be as shown in Figure 7.0.2. Figure 7.0.2
Elbow or bend
7.0.3 The calculated wall thickness of the elbow or bend is calculated according to formula (7.0.3). pD
2L054R-2D
Where: R is the bending radius of the elbow or bend (mm). (7.0.3)
7.0.4 For elbows or bends manufactured according to GB/T12459, GB/T13401, SY/T0510 or SY/T5257, they can be verified according to formula (7.0.4).
8 Design of Tees
8.1 General Provisions
8.1.1 For the reinforcement of the opening of tees, this standard recommends the following two reinforcement calculation methods: 1. Equal area reinforcement method, 2. Pressure reduction coefficient method. These two methods are applicable to both drawn tees and extruded tees, as well as integrally reinforced welded tees with thickened main and branch pipe walls. 8.1.2 Drawn tees, extruded tees, and integrally reinforced welded tees should be made of seamless steel pipes, straight seam steel pipes or steel plates. When straight seam steel 283
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pipes or steel plates are used for manufacturing, the longitudinal welds of the main pipes should be placed as shown in Figure 8.1.2-1; the longitudinal welds of the branch pipes should be placed as shown in Figure 8.1.2-2.
Figure 8.1.2-1
Position of longitudinal weld of main pipe of tee
Figure 8.1.2-2
Position of longitudinal weld of branch pipe of tee
8.1.3 The intersecting weld of main pipe and branch pipe of integral reinforcement welded tee must adopt full penetration structure. 8.2 Equal area reinforcement method
8.2.1 The reinforcement calculation diagram of main pipe and branch pipe of drawn tee and extruded tee is shown in Figure 8.2.1-1, and the reinforcement calculation diagram of main pipe and branch pipe of integral reinforcement welded tee is shown in Figure 8.2.1-2, where C is the corrosion allowance. 8.2.2 The reinforcement area required for the opening is calculated according to formula (8.2.2-1) and formula (8.2.2-2). Drawn or extruded tee:
Ax = dd,
Integrally reinforced welded tee:
Ar d.8, + 28,8(1 - f.)
8.2.3 Calculated wall thickness 3 of tee main pipe is calculated according to formula 8.2.3). S
Note: This figure shows the general reinforcement form, and other structural forms can also be adopted. Figure 8.2.1-1 Schematic diagram of reinforcement calculation of drawn or extruded tee284
(8.2.2-1)
(8. 2. 2 -2)
Note: This figure shows the general reinforcement form, and other forms can also be adopted. Figure 8.2.1-2
Schematic diagram of reinforcement calculation of integral welded tee
Calculated wall thickness % of tee branch pipe is calculated according to formula (8.2.4). 8.2.4
8.2.5 The effective reinforcement width W is calculated according to formula (8.2.5), and the smaller value is taken. W-
8.2.6 The effective reinforcement height H is calculated according to formula (8.2.6-1) or formula (8.2.6-2). Drawn or extruded tee:
H= do.
Integrally reinforced welded tee:
8.2.7 Within the effective reinforcement range, the cross-sectional area that can be reinforced is calculated according to formula (8.2.7-1). Ae = A + A2 +As
SY/T 0518—2002
(8.2.6-1)
(8.2.6-2)
(8. 2. 7-1)
Wherein, A,—--In the effective reinforcement area, the effective thickness of the tee pipe minus the reinforcement area outside the calculated thickness, calculated according to formula (8.2.7-2) or formula (8.2.7-3).
Drawn or extruded tee:
A, =(2W-d)(der -8)
Integrally reinforced welded tee:
Ar = (2W -- d)(d-8) - 28(d—a)(1 - f)A
(8. 2. 7-2)
(8. 2. 7-3)
In the effective reinforcement area, the effective thickness of the tee branch minus the reinforcement area outside the calculated thickness shall be calculated according to formula (8.2.7-4) or formula (8.2.7-5).
Drawn or extruded tee:
A, 2H(-%)
Integrally reinforced welded tee:
A, 2H(8h-).f,
In the effective reinforcement area, other available reinforcement area shall be calculated according to formula (8.2.7-6) or formula (8.2.7-7). (8.2.7-4)
(8.2.7-5)
SY/T0518--2002
Drawn or extruded tee:
Where: R—
A, = 2(.-.)R
The radius of curvature of the arc at the flange of the shoulder of the drawn or extruded tee (mm). The radius of curvature is subject to the following restrictions: ① Minimum radius: R should be greater than 0.05d;
② Maximum radius: R should be less than 0.1d+13mm; ③ Machining methods shall not be used to meet the above requirements. Overall reinforcement welded tee:
Where: K-height of the shoulder fillet weld of the overall reinforcement welded tee (mm). 8.2.8 The calculation of equal area reinforcement shall satisfy formula (8.2.8). AE ≥ AR
8.3 Pressure reduction coefficient method
8.3.1 The allowable working pressure calculated by the pressure reduction coefficient method shall satisfy formula (8.3.1). 2[o]derd
Ep]= -
8.3.2 The pressure reduction coefficient is calculated according to formula (8.3.2-1). 1
Where: a-
coefficient, calculated according to formula (8.3.2-2).
Where: a =
b coefficient, calculated according to formula (8.3.2-3).
aV1+b2
r + eb
b = 4.05 -
(8.2.7-6)
(8.2.7-7)
(8.3.1)
(8.3.2-1)
(8.3.2-2)
(8.3.2-3)
For tees whose wall thickness is calculated by the pressure weakening coefficient method, the main pipe length is generally taken as 3.5D, but should not be less than 2d; the height from the branch pipe to the outer wall of the lower part of the main pipe is generally taken as 1.7D.5 Reducers should be seamless or have only one longitudinal weld. For eccentric reducers, the weld should be placed at a non-inclined position. 6.0.6 The wall thickness of the reducer is calculated according to formula (6.0.6). pD
2ocosα
Where: α-
The half-vertex angle or maximum half-vertex angle of the reducer (as shown in Figure 6.0.1-1 to Figure 6.0.1-4) (). (6.0.6)
6.0.7 For reducers manufactured in accordance with GB/T12459, GB/T13401 or SY/T0510, the calculation can be carried out according to formula (6.0.7). ≥
7 Design of elbows or bends
7.0.1 When the bending radius R is 1 to 3 times the outer diameter of the pipe, it is generally called an elbow. When the bending radius R is greater than 3 times the outer diameter of the pipe, it is generally called a bend.
7.0.2 Elbows and bends should be seamless or have only one longitudinal weld. The weld position should be as shown in Figure 7.0.2. Figure 7.0.2
Elbow or bend
7.0.3 The calculated wall thickness of the elbow or bend shall be calculated according to formula (7.0.3). pD
2L054R-2D
Where: R is the bending radius of the elbow or bend (mm). (7.0.3)
7.0.4 For elbows or bends manufactured according to GB/T12459, GB/T13401, SY/T0510 or SY/T5257, they can be verified according to formula (7.0.4).
8 Design of Tees
8.1 General Provisions
8.1.1 For the reinforcement of the opening of tees, this standard recommends the following two reinforcement calculation methods: 1. Equal area reinforcement method, 2. Pressure reduction coefficient method. These two methods are applicable to both drawn tees and extruded tees, as well as integrally reinforced welded tees with thickened main and branch pipe walls. 8.1.2 Drawn tees, extruded tees, and integrally reinforced welded tees should be made of seamless steel pipes, straight seam steel pipes or steel plates. When straight seam steel 283
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pipes or steel plates are used for manufacturing, the longitudinal welds of the main pipes should be placed as shown in Figure 8.1.2-1; the longitudinal welds of the branch pipes should be placed as shown in Figure 8.1.2-2.
Figure 8.1.2-1
Position of longitudinal weld of main pipe of tee
Figure 8.1.2-2
Position of longitudinal weld of branch pipe of tee
8.1.3 The intersecting weld of main pipe and branch pipe of integral reinforcement welded tee must adopt full penetration structure. 8.2 Equal area reinforcement method
8.2.1 The reinforcement calculation diagram of main pipe and branch pipe of drawn tee and extruded tee is shown in Figure 8.2.1-1, and the reinforcement calculation diagram of main pipe and branch pipe of integral reinforcement welded tee is shown in Figure 8.2.1-2, where C is the corrosion allowance. 8.2.2 The reinforcement area required for the opening is calculated according to formula (8.2.2-1) and formula (8.2.2-2). Drawn or extruded tee:
Ax = dd,
Integrally reinforced welded tee:
Ar d.8, + 28,8(1 - f.)
8.2.3 Calculated wall thickness 3 of tee main pipe is calculated according to formula 8.2.3). S
Note: This figure shows the general reinforcement form, and other structural forms can also be adopted. Figure 8.2.1-1 Schematic diagram of reinforcement calculation of drawn or extruded tee284
(8.2.2-1)
(8. 2. 2 -2)
Note: This figure shows the general reinforcement form, and other forms can also be adopted. Figure 8.2.1-2
Schematic diagram of reinforcement calculation of integral welded tee
Calculated wall thickness % of tee branch pipe is calculated according to formula (8.2.4). 8.2.4
8.2.5 The effective reinforcement width W is calculated according to formula (8.2.5), and the smaller value is taken. W-
8.2.6 The effective reinforcement height H is calculated according to formula (8.2.6-1) or formula (8.2.6-2). Drawn or extruded tee:
H= do.
Integrally reinforced welded tee:
8.2.7 Within the effective reinforcement range, the cross-sectional area that can be reinforced is calculated according to formula (8.2.7-1). Ae = A + A2 +As
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(8.2.6-1)
(8.2.6-2)
(8. 2. 7-1)
Wherein, A,—--In the effective reinforcement area, the effective thickness of the tee pipe minus the reinforcement area outside the calculated thickness, calculated according to formula (8.2.7-2) or formula (8.2.7-3).
Drawn or extruded tee:
A, =(2W-d)(der -8)
Integrally reinforced welded tee:
Ar = (2W -- d)(d-8) - 28(d—a)(1 - f)A
(8. 2. 7-2)
(8. 2. 7-3)
In the effective reinforcement area, the effective thickness of the tee branch minus the reinforcement area outside the calculated thickness shall be calculated according to formula (8.2.7-4) or formula (8.2.7-5).
Drawn or extruded tee:
A, 2H(-%)
Integrally reinforced welded tee:
A, 2H(8h-).f,
In the effective reinforcement area, other available reinforcement area shall be calculated according to formula (8.2.7-6) or formula (8.2.7-7). (8.2.7-4)
(8.2.7-5)
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Drawn or extruded tee:
Where: R—
A, = 2(.-.)R
The radius of curvature of the arc at the flange of the shoulder of the drawn or extruded tee (mm). The radius of curvature is subject to the following restrictions: ① Minimum radius: R should be greater than 0.05d;
② Maximum radius: R should be less than 0.1d+13mm; ③ Machining methods shall not be used to meet the above requirements. Overall reinforcement welded tee:
Where: K-height of the shoulder fillet weld of the overall reinforcement welded tee (mm). 8.2.8 The calculation of equal area reinforcement shall satisfy formula (8.2.8). AE ≥ AR
8.3 Pressure reduction coefficient method
8.3.1 The allowable working pressure calculated by the pressure reduction coefficient method shall satisfy formula (8.3.1). 2[o]derd
Ep]= -
8.3.2 The pressure reduction coefficient is calculated according to formula (8.3.2-1). 1
Where: a-
coefficient, calculated according to formula (8.3.2-2).
Where: a =
b coefficient, calculated according to formula (8.3.2-3).
aV1+b2
r + eb
b = 4.05 -
(8.2.7-6)
(8.2.7-7)
(8.3.1)
(8.3.2-1)
(8.3.2-2)
(8.3.2-3)
For tees whose wall thickness is calculated by the pressure weakening coefficient method, the main pipe length is generally taken as 3.5D, but should not be less than 2d; the height from the branch pipe to the outer wall of the lower part of the main pipe is generally taken as 1.7D.5 Reducers should be seamless or have only one longitudinal weld. For eccentric reducers, the weld should be placed at a non-inclined position. 6.0.6 The wall thickness of the reducer is calculated according to formula (6.0.6). pD
2ocosα
Where: α-
The half-vertex angle or maximum half-vertex angle of the reducer (as shown in Figure 6.0.1-1 to Figure 6.0.1-4) (). (6.0.6)
6.0.7 For reducers manufactured in accordance with GB/T12459, GB/T13401 or SY/T0510, the calculation can be carried out according to formula (6.0.7). ≥
7 Design of elbows or bends
7.0.1 When the bending radius R is 1 to 3 times the outer diameter of the pipe, it is generally called an elbow. When the bending radius R is greater than 3 times the outer diameter of the pipe, it is generally called a bend.
7.0.2 Elbows and bends should be seamless or have only one longitudinal weld. The weld position should be as shown in Figure 7.0.2. Figure 7.0.2
Elbow or bend
7.0.3 The calculated wall thickness of the elbow or bend shall be calculated according to formula (7.0.3). pD
2L054R-2D
Where: R is the bending radius of the elbow or bend (mm). (7.0.3)
7.0.4 For elbows or bends manufactured according to GB/T12459, GB/T13401, SY/T0510 or SY/T5257, they can be verified according to formula (7.0.4).
8 Design of Tees
8.1 General Provisions
8.1.1 For the reinforcement of the opening of tees, this standard recommends the following two reinforcement calculation methods: 1. Equal area reinforcement method, 2. Pressure reduction coefficient method. These two methods are applicable to both drawn tees and extruded tees, as well as integrally reinforced welded tees with thickened main and branch pipe walls. 8.1.2 Drawn tees, extruded tees, and integrally reinforced welded tees should be made of seamless steel pipes, straight seam steel pipes or steel plates. When straight seam steel 283
SY/T0518-2002
pipes or steel plates are used for manufacturing, the longitudinal welds of the main pipes should be placed as shown in Figure 8.1.2-1; the longitudinal welds of the branch pipes should be placed as shown in Figure 8.1.2-2.
Figure 8.1.2-1
Position of longitudinal weld of main pipe of tee
Figure 8.1.2-2
Position of longitudinal weld of branch pipe of tee
8.1.3 The intersecting weld of main pipe and branch pipe of integral reinforcement welded tee must adopt full penetration structure. 8.2 Equal area reinforcement method
8.2.1 The reinforcement calculation diagram of main pipe and branch pipe of drawn tee and extruded tee is shown in Figure 8.2.1-1, and the reinforcement calculation diagram of main pipe and branch pipe of integral reinforcement welded tee is shown in Figure 8.2.1-2, where C is the corrosion allowance. 8.2.2 The reinforcement area required for the opening is calculated according to formula (8.2.2-1) and formula (8.2.2-2). Drawn or extruded tee:
Ax = dd,
Integrally reinforced welded tee:
Ar d.8, + 28,8(1 - f.)
8.2.3 Calculated wall thickness 3 of tee main pipe is calculated according to formula 8.2.3). S
Note: This figure shows the general reinforcement form, and other structural forms can also be adopted. Figure 8.2.1-1 Schematic diagram of reinforcement calculation of drawn or extruded tee284
(8.2.2-1)
(8. 2. 2 -2)
Note: This figure shows the general reinforcement form, and other forms can also be adopted. Figure 8.2.1-2
Schematic diagram of reinforcement calculation of integral welded tee
Calculated wall thickness % of tee branch pipe is calculated according to formula (8.2.4). 8.2.4
8.2.5 The effective reinforcement width W is calculated according to formula (8.2.5), and the smaller value is taken. W-
8.2.6 The effective reinforcement height H is calculated according to formula (8.2.6-1) or formula (8.2.6-2). Drawn or extruded tee:
H= do.
Integrally reinforced welded tee:
8.2.7 Within the effective reinforcement range, the cross-sectional area that can be reinforced is calculated according to formula (8.2.7-1). Ae = A + A2 +As
SY/T 0518—2002
(8.2.6-1)
(8.2.6-2)
(8. 2. 7-1)
Wherein, A,—--In the effective reinforcement area, the effective thickness of the tee pipe minus the reinforcement area outside the calculated thickness, calculated according to formula (8.2.7-2) or formula (8.2.7-3).
Drawn or extruded tee:
A, =(2W-d)(der -8)
Integrally reinforced welded tee:
Ar = (2W -- d)(d-8) - 28(d—a)(1 - f)A
(8. 2. 7-2)
(8. 2. 7-3)
In the effective reinforcement area, the effective thickness of the tee branch minus the reinforcement area outside the calculated thickness shall be calculated according to formula (8.2.7-4) or formula (8.2.7-5).
Drawn or extruded tee:
A, 2H(-%)
Integrally reinforced welded tee:
A, 2H(8h-).f,
In the effective reinforcement area, other available reinforcement area shall be calculated according to formula (8.2.7-6) or formula (8.2.7-7). (8.2.7-4)
(8.2.7-5)
SY/T0518--2002
Drawn or extruded tee:
Where: R—
A, = 2(.-.)R
The radius of curvature of the arc at the flange of the shoulder of the drawn or extruded tee (mm). The radius of curvature is subject to the following restrictions: ① Minimum radius: R should be greater than 0.05d;
② Maximum radius: R should be less than 0.1d+13mm; ③ Machining methods shall not be used to meet the above requirements. Overall reinforcement welded tee:
Where: K-height of the shoulder fillet weld of the overall reinforcement welded tee (mm). 8.2.8 The calculation of equal area reinforcement shall satisfy formula (8.2.8). AE ≥ AR
8.3 Pressure reduction coefficient method
8.3.1 The allowable working pressure calculated by the pressure reduction coefficient method shall satisfy formula (8.3.1). 2[o]derd
Ep]= -
8.3.2 The pressure reduction coefficient is calculated according to formula (8.3.2-1). 1
Where: a-
coefficient, calculated according to formula (8.3.2-2).
Where: a =
b coefficient, calculated according to formula (8.3.2-3).
aV1+b2
r + eb
b = 4.05 -
(8.2.7-6)
(8.2.7-7)
(8.3.1)
(8.3.2-1)
(8.3.2-2)
(8.3.2-3)
For tees whose wall thickness is calculated by the pressure weakening coefficient method, the main pipe length is generally taken as 3.5D, but should not be less than 2d; the height from the branch pipe to the outer wall of the lower part of the main pipe is generally taken as 1.7D.1 General Provisions
8.1.1 For the reinforcement of the opening of the tee, this standard recommends the following two reinforcement calculation methods: 1. Equal area reinforcement method, 2. Pressure reduction coefficient method. These two methods are applicable to both drawn tees and extruded tees, as well as integrally reinforced welded tees with thickened main and branch pipe walls. 8.1.2 Drawn tees, extruded tees, and integrally reinforced welded tees should be made of seamless steel pipes, straight seam steel pipes or steel plates. When straight seam steel 283
SY/T0518-2002
pipes or steel plates are used for manufacturing, the longitudinal welds of the main pipes should be placed as shown in Figure 8.1.2-1; the longitudinal welds of the branch pipes should be placed as shown in Figure 8.1.2-2.
Figure 8.1.2-1
Position of longitudinal weld of main pipe of tee
Figure 8.1.2-2
Position of longitudinal weld of branch pipe of tee
8.1.3 The intersecting weld of main pipe and branch pipe of integral reinforcement welded tee must adopt full penetration structure. 8.2 Equal area reinforcement method
8.2.1 The reinforcement calculation diagram of main pipe and branch pipe of drawn tee and extruded tee is shown in Figure 8.2.1-1, and the reinforcement calculation diagram of main pipe and branch pipe of integral reinforcement welded tee is shown in Figure 8.2.1-2, where C is the corrosion allowance. 8.2.2 The reinforcement area required for the opening is calculated according to formula (8.2.2-1) and formula (8.2.2-2). Drawn or extruded tee:
Ax = dd,
Integrally reinforced welded tee:
Ar d.8, + 28,8(1 - f.)
8.2.3 Calculated wall thickness 3 of tee main pipe is calculated according to formula 8.2.3). S
Note: This figure shows the general reinforcement form, and other structural forms can also be adopted. Figure 8.2.1-1 Schematic diagram of reinforcement calculation of drawn or extruded tee284
(8.2.2-1)
(8. 2. 2 -2)
Note: This figure shows the general reinforcement form, and other forms can also be adopted. Figure 8.2.1-2
Schematic diagram of reinforcement calculation of integral welded tee
Calculated wall thickness % of tee branch pipe is calculated according to formula (8.2.4). 8.2.4
8.2.5 The effective reinforcement width W is calculated according to formula (8.2.5), and the smaller value is taken. W-
8.2.6 The effective reinforcement height H is calculated according to formula (8.2.6-1) or formula (8.2.6-2). Drawn or extruded tee:
H= do.
Integrally reinforced welded tee:
8.2.7 Within the effective reinforcement range, the cross-sectional area that can be reinforced is calculated according to formula (8.2.7-1). Ae = A + A2 +As
SY/T 0518—2002
(8.2.6-1)
(8.2.6-2)
(8. 2. 7-1)
Wherein, A,—--In the effective reinforcement area, the effective thickness of the tee pipe minus the reinforcement area outside the calculated thickness, calculated according to formula (8.2.7-2) or formula (8.2.7-3).
Drawn or extruded tee:
A, =(2W-d)(der -8)
Integrally reinforced welded tee:
Ar = (2W -- d)(d-8) - 28(d—a)(1 - f)A
(8. 2. 7-2)
(8. 2. 7-3)
In the effective reinforcement area, the effective thickness of the tee branch minus the reinforcement area outside the calculated thickness shall be calculated according to formula (8.2.7-4) or formula (8.2.7-5).
Drawn or extruded tee:
A, 2H(-%)
Integrally reinforced welded tee:
A, 2H(8h-).f,
In the effective reinforcement area, other available reinforcement area shall be calculated according to formula (8.2.7-6) or formula (8.2.7-7). (8.2.7-4)
(8.2.7-5)
SY/T0518--2002
Drawn or extruded tee:
Where: R—
A, = 2(.-.)R
The radius of curvature of the arc at the flange of the shoulder of the drawn or extruded tee (mm). The radius of curvature is subject to the following restrictions: ① Minimum radius: R should be greater than 0.05d;
② Maximum radius: R should be less than 0.1d+13mm; ③ Machining methods shall not be used to meet the above requirements. Overall reinforcement welded tee:
Where: K-height of the shoulder fillet weld of the overall reinforcement welded tee (mm). 8.2.8 The calculation of equal area reinforcement shall satisfy formula (8.2.8). AE ≥ AR
8.3 Pressure reduction coefficient method
8.3.1 The allowable working pressure calculated by the pressure reduction coefficient method shall satisfy formula (8.3.1). 2[o]derd
Ep]= -
8.3.2 The pressure reduction coefficient is calculated according to formula (8.3.2-1). 1
Where: a-
coefficient, calculated according to formula (8.3.2-2).
Where: a =
b coefficient, calculated according to formula (8.3.2-3).
aV1+b2
r + eb
b = 4.05 -
(8.2.7-6)
(8.2.7-7)
(8.3.1)
(8.3.2-1)
(8.3.2-2)
(8.3.2-3)
For tees whose wall thickness is calculated by the pressure weakening coefficient method, the main pipe length is generally taken as 3.5D, but should not be less than 2d; the height from the branch pipe to the outer wall of the lower part of the main pipe is generally taken as 1.7D.1 General Provisions
8.1.1 For the reinforcement of the opening of the tee, this standard recommends the following two reinforcement calculation methods: 1. Equal area reinforcement method, 2. Pressure reduction coefficient method. These two methods are applicable to both drawn tees and extruded tees, as well as integrally reinforced welded tees with thickened main and branch pipe walls. 8.1.2 Drawn tees, extruded tees, and integrally reinforced welded tees should be made of seamless steel pipes, straight seam steel pipes or steel plates. When straight seam steel 283
SY/T0518-2002
pipes or steel plates are used for manufacturing, the longitudinal welds of the main pipes should be placed as shown in Figure 8.1.2-1; the longitudinal welds of the branch pipes should be placed as shown in Figure 8.1.2-2.
Figure 8.1.2-1
Position of longitudinal weld of main pipe of tee
Figure 8.1.2-2
Position of longitudinal weld of branch pipe of tee
8.1.3 The intersecting weld of main pipe and branch pipe of integral reinforcement welded tee must adopt full penetration structure. 8.2 Equal area reinforcement method
8.2.1 The reinforcement calculation diagram of main pipe and branch pipe of drawn tee and extruded tee is shown in Figure 8.2.1-1, and the reinforcement calculation diagram of main pipe and branch pipe of integral reinforcement welded tee is shown in Figure 8.2.1-2, where C is the corrosion allowance. 8.2.2 The reinforcement area required for the opening is calculated according to formula (8.2.2-1) and formula (8.2.2-2). Drawn or extruded tee:
Ax = dd,
Integrally reinforced welded tee:
Ar d.8, + 28,8(1 - f.)
8.2.3 Calculated wall thickness 3 of tee main pipe is calculated according to formula 8.2.3). S
Note: This figure shows the general reinforcement form, and other structural forms can also be adopted. Figure 8.2.1-1 Schematic diagram of reinforcement calculation of drawn or extruded tee284
(8.2.2-1)
(8. 2. 2 -2)
Note: This figure shows the general reinforcement form, and other forms can also be adopted. Figure 8.2.1-2
Schematic diagram of reinforcement calculation of integral welded tee
Calculated wall thickness % of tee branch pipe is calculated according to formula (8.2.4). 8.2.4
8.2.5 The effective reinforcement width W is calculated according to formula (8.2.5), and the smaller value is taken. W-
8.2.6 The effective reinforcement height H is calculated according to formula (8.2.6-1) or formula (8.2.6-2). Drawn or extruded tee:
H= do.
Integrally reinforced welded tee:
8.2.7 Within the effective reinforcement range, the cross-sectional area that can be reinforced is calculated according to formula (8.2.7-1). Ae = A + A2 +As
SY/T 0518—2002
(8.2.6-1)
(8.2.6-2)
(8. 2. 7-1)
Wherein, A,—--In the effective reinforcement area, the effective thickness of the tee pipe minus the reinforcement area outside the calculated thickness, calculated according to formula (8.2.7-2) or formula (8.2.7-3).
Drawn or extruded tee:
A, =(2W-d)(der -8)
Integrally reinforced welded tee:
Ar = (2W -- d)(d-8) - 28(d—a)(1 - f)A
(8. 2. 7-2)
(8. 2. 7-3)
In the effective reinforcement area, the effective thickness of the tee branch minus the reinforcement area outside the calculated thickness shall be calculated according to formula (8.2.7-4) or formula (8.2.7-5).
Drawn or extruded tee:
A, 2H(-%)
Integrally reinforced welded tee:
A, 2H(8h-).f,
In the effective reinforcement area, other available reinforcement area shall be calculated according to formula (8.2.7-6) or formula (8.2.7-7). (8.2.7-4)
(8.2.7-5)
SY/T0518--2002
Drawn or extruded tee:
Where: R—
A, = 2(.-.)R
The radius of curvature of the arc at the flange of the shoulder of the drawn or extruded tee (mm). The radius of curvature is subject to the following restrictions: ① Minimum radius: R should be greater than 0.05d;
② Maximum radius: R should be less than 0.1d+13mm; ③ Machining methods shall not be used to meet the above requirements. Overall reinforcement welded tee:
Where: K-height of the shoulder fillet weld of the overall reinforcement welded tee (mm). 8.2.8 The calculation of equal area reinforcement shall satisfy formula (8.2.8). AE ≥ AR
8.3 Pressure reduction coefficient method
8.3.1 The allowable working pressure calculated by the pressure reduction coefficient method shall satisfy formula (8.3.1). 2[o]derd
Ep]= -
8.3.2 The pressure reduction coefficient is calculated according to formula (8.3.2-1). 1
Where: a-
coefficient, calculated according to formula (8.3.2-2).
Where: a =
b coefficient, calculated according to formula (8.3.2-3).
aV1+b2
r + eb
b = 4.05 -
(8.2.7-6)
(8.2.7-7)
(8.3.1)
(8.3.2-1)
(8.3.2-2)
(8.3.2-3)
For tees whose wall thickness is calculated by the pressure weakening coefficient method, the main pipe length is generally taken as 3.5D, but should not be less than 2d; the height from the branch pipe to the outer wall of the lower part of the main pipe is generally taken as 1.7D.---In the effective reinforcement area, the effective thickness of the tee pipe minus the reinforcement area outside the calculated thickness shall be calculated according to formula (8.2.7-2) or formula (8.2.7-3).
Drawn or extruded tee:
A, =(2W-d)(der -8)
Integrally reinforced welded tee:
Ar = (2W -- d)(d-8) - 28(d—a)(1 - f)A
(8. 2. 7-2)
(8. 2. 7-3)
In the effective reinforcement area, the effective thickness of the tee branch pipe minus the reinforcement area outside the calculated thickness shall be calculated according to formula (8.2.7-4) or formula (8.2.7-5).
Drawn or extruded tee:
A, 2H(-%)
Integrally reinforced welded tee:
A, 2H(8h-).f,
In the effective reinforcement area, other available reinforcement area shall be calculated according to formula (8.2.7-6) or formula (8.2.7-7). (8.2.7-4)
(8.2.7-5)
SY/T0518--2002
Drawn or extruded tee:
Where: R—
A, = 2(.-.)R
The radius of curvature of the arc at the flange of the shoulder of the drawn or extruded tee (mm). The radius of curvature is subject to the following restrictions: ① Minimum radius: R should be greater than 0.05d;
② Maximum radius: R should be less than 0.1d+13mm; ③ Machining methods shall not be used to meet the above requirements. Overall reinforcement welded tee:
Where: K-height of the shoulder fillet weld of the overall reinforcement welded tee (mm). 8.2.8 The calculation of equal area reinforcement shall satisfy formula (8.2.8). AE ≥ AR
8.3 Pressure reduction coefficient method
8.3.1 The allowable working pressure calculated by the pressure reduction coefficient method shall satisfy formula (8.3.1). 2[o]derd
Ep]= -
8.3.2 The pressure reduction coefficient is calculated according to formula (8.3.2-1). 1
Where: a-
coefficient, calculated according to formula (8.3.2-2).
Where: a =
b coefficient, calculated according to formula (8.3.2-3).
aV1+b2
r + eb
b = 4.05 -
(8.2.7-6)
(8.2.7-7)
(8.3.1)
(8.3.2-1)
(8.3.2-2)
(8.3.2-3)
For tees whose wall thickness is calculated by the pressure weakening coefficient method, the main pipe length is generally taken as 3.5D, but should not be less than 2d; the height from the branch pipe to the outer wall of the lower part of the main pipe is generally taken as 1.7D.---In the effective reinforcement area, the effective thickness of the tee pipe minus the reinforcement area outside the calculated thickness shall be calculated according to formula (8.2.7-2) or formula (8.2.7-3).
Drawn or extruded tee:
A, =(2W-d)(der -8)
Integrally reinforced welded tee:
Ar = (2W -- d)(d-8) - 28(d—a)(1 - f)A
(8. 2. 7-2)
(8. 2. 7-3)
In the effective reinforcement area, the effective thickness of the tee branch pipe minus the reinforcement area outside the calculated thickness shall be calculated according to formula (8.2.7-4) or formula (8.2.7-5).
Drawn or extruded tee:
A, 2H(-%)
Integrally reinforced welded tee:
A, 2H(8h-).f,
In the effective reinforcement area, other available reinforcement area shall be calculated according to formula (8.2.7-6) or formula (8.2.7-7). (8.2.7-4)
(8.2.7-5)
SY/T0518--2002
Drawn or extruded tee:
Where: R—
A, = 2(.-.)R
The radius of curvature of the arc at the flange of the shoulder of the drawn or extruded tee (mm). The radius of curvature is subject to the following restrictions: ① Minimum radius: R should be greater than 0.05d;
② Maximum radius: R should be less than 0.1d+13mm; ③ Machining methods shall not be used to meet the above requirements. Overall reinforcement welded tee:
Where: K-height of the shoulder fillet weld of the overall reinforcement welded tee (mm). 8.2.8 The calculation of equal area reinforcement shall satisfy formula (8.2.8). AE ≥ AR
8.3 Pressure reduction coefficient method
8.3.1 The allowable working pressure calculated by the pressure reduction coefficient method shall satisfy formula (8.3.1). 2[o]derd
Ep]= -
8.3.2 The pressure reduction coefficient is calculated according to formula (8.3.2-1). 1
Where: a-
coefficient, calculated according to formula (8.3.2-2).
Where: a =
b coefficient, calculated according to formula (8.3.2-3).
aV1+b2
r + eb
b = 4.05 -
(8.2.7-6)
(8.2.7-7)
(8.3.1)
(8.3.2-1)
(8.3.2-2)
(8.3.2-3)
For tees whose wall thickness is calculated by the pressure weakening coefficient method, the main pipe length is generally taken as 3.5D, but should not be less than 2d; the height from the branch pipe to the outer wall of the lower part of the main pipe is generally taken as 1.7D.
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