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GB/T 35990-2018

Chinese Standard: 'GB/T 35990-2018'
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Detail Information of GB/T 35990-2018; GB/T35990-2018
Description (Translated English): Metal bellows expansion joints for pressure piping
Sector / Industry: National Standard (Recommended)
Classification of Chinese Standard: H48
Classification of International Standard: 77.140.75
Word Count Estimation: 74,799
Date of Issue: 2018-03-15
Date of Implementation: 2018-10-01
Drafting Organization: Nanjing Chenguang Donglu Corrugated Pipe Co., Ltd., Aerospace Chenguang Co., Ltd., China Machine Productivity Promotion Center, National Center for Quality Supervision and Inspection of Instrumentation Components, Jiangsu Institute of Special Equipment Safety Supervision and Inspection, Qinhuangdao Ted Pipe Industry Co., Ltd. , Shanghai Yongxin Bellows Co., Ltd., Qinhuangdao North Pipe Industry Co., Ltd., Ningbo Xingjian Bellows Co., Ltd., Shijiazhuang Juli Technology Co., Ltd., Shenyang Instrument Research Institute Co., Ltd., Luoyang Shuangrui Special Equipment Co., Ltd.
Administrative Organization: National Pipe Fittings Standardization Technical Committee (SAC/TC 237)
Proposing organization: China Machinery Industry Federation
Issuing agency(ies): The General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China and the National Standardization Administration of China


GB/T 35990-2018
Metal bellows expansion joints for pressure piping
ICS 77.140.75
H48
National Standards of People's Republic of China
Metal bellows expansion joint for pressure pipes
Metalbelowsexpansionjointsforpressurepiping
Published on.2018-03-15
2018-10-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
China National Standardization Administration issued
Content
Foreword III
1 range 1
2 Normative references 1
3 Terms and Definitions 2
4 Qualifications and responsibilities 3
4.1 Qualification 3
4.2 Responsibilities 3
5 Category 4
5.1 Expansion Joint Classification 4
5.2 Component classification of expansion joints 7
5.3 Welding joint classification 7
6 Typical Applications 9
7 Material 9
7.1 General Provisions 9
7.2 Bellows 9
7.3 Other pressure components 9
8 design 9
8.1 Design conditions 9
8.2 Welded joint coefficient 12
8.3 Allowable stress 12
8.4 Design of the expansion joint 13
9 manufacturing 18
9.1 Document 18
9.2 Material re-inspection, segmentation and logo transplantation 18
9.3 Welding 18
9.4 Bellows forming 20
9.5 Heat treatment 20
10 Requirements 20
10.1 Appearance 20
10.2 Dimensions and Geometrical Tolerances 21
10.3 Nondestructive testing 21
10.4 Pressure resistance performance 23
10.5 Air tightness (leak test) 24
10.6 Stiffness 24
10.7 Stability 24
10.8 Fatigue life 24
10.9 Blasting test 24
11 Test method 25
11.1 Appearance 25
11.2 Dimensions and Geometrical Tolerances 25
11.3 Nondestructive testing 25
11.4 Pressure resistance performance 25
11.5 Air tightness (leak test) 26
11.6 Stiffness 26
11.7 Stability 27
11.8 Fatigue life 27
11.9 Blasting test 27
12 Inspection rules 28
12.1 Inspection Classification 28
12.2 Factory Inspection 28
12.3 Type Inspection 29
13 Marking, packaging, transport and storage 29
13.1 Sign 29
13.2 Packaging, Transportation 30
13.3 Storage 30
14 Installation 30
Appendix A (informative) Common materials 31
Appendix B (Normative Appendix) Design of the expansion joint 33
B.1 Symbol 33
B.2 Bellows design 42
B.3 Displacement of the expansion joint 48
B.4 Stiffness, force and moment of the expansion joint 51
B.5 Design of the inner liner 56
B.6 outer sheath 58
B.7 Design of bearing members 59
Appendix C (informative) Vibration check 64
C.1 Overview 64
C.2 Natural vibration frequency of expansion joints 64
Reference 67
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard was proposed by the China Machinery Industry Federation.
This standard is under the jurisdiction of the National Pipeline Standardization Technical Committee (SAC/TC237).
This standard was drafted. Nanjing Chenguang Dongluo Bellows Co., Ltd., Aerospace Chenguang Co., Ltd., China Machine Productivity Promotion Center, China
Home Instrument and Meter Component Quality Supervision and Inspection Center, Jiangsu Special Equipment Safety Supervision and Inspection Institute, Qinhuangdao City Tide Pipe Industry Technology
Company, Shanghai Yongxin Corrugated Pipe Co., Ltd., Qinhuangdao North Pipe Co., Ltd., Ningbo Xingjian Corrugated Pipe Co., Ltd., Shijiazhuang Juli
Technology Co., Ltd., Shenyang Instrument Science Research Institute Co., Ltd., Luoyang Shuangrui Special Equipment Co., Ltd.
The main drafters of this standard. Chen Lisu, Hu Yi, Liu Yong, Wang Zhaojuan, Cheng Yong, Wu Jianfu, Feng Feng, Yu Zhenyi, Zhu Qingnan, Chen Guangbin, Ma Liwei,
Wei Shouliang, Shen Guanqun, Zhu Huihong, Huang Naining, Chen Siping, Zhong Yuping, Zhang Aiqin.
Metal bellows expansion joint for pressure pipes
1 Scope
This standard specifies the terms and definitions, qualifications and responsibilities, classification, typical applications, materials, and design of metal bellows expansion joints for pressure piping.
Metering, manufacturing, requirements, test methods and inspection rules, as well as marking, packaging, transportation and storage.
This standard is applicable to bellows metal bellows expansion joints (hereinafter referred to as expansion joints) integrally formed for pressure pipes.
2 Normative references
The following documents are indispensable for the application of this document. For dated references, only dated versions apply to this article.
Pieces. For undated references, the latest edition (including all amendments) applies to this document.
GB/T 150.3 Pressure Vessels Part 3. Design
GB/T 699 high quality carbon structural steel
GB/T 713 steel plate for boiler and pressure vessel
GB/T 1591 low alloy high strength structural steel
GB/T 1958 Product Geometrical Specification (GPS) Shape and Position Tolerance Inspection Regulations
GB/T 2829-2002 Periodic inspection count sampling procedures and tables (applicable to the inspection of process stability)
GB/T 3077 alloy structural steel
GB/T 3274 carbon structural steel and low alloy structural steel hot rolled steel sheet and strip
GB/T 3280 stainless steel cold rolled steel plate and strip
GB/T 3621 titanium and titanium alloy sheet
GB/T 3880 General industrial aluminum and aluminum alloy sheet
GB/T 9112 Steel Pipe Flange Types and Parameters
GB/T 9113 integral steel pipe flange
GB/T 9114 neck threaded steel pipe flange
GB/T 9115 butt welded steel pipe flange
GB/T 9116 neck welded steel pipe flange
GB/T 9117 neck socket welded steel pipe flange
GB/T 9118 butt weld ring with neck loose steel pipe flange
GB/T 9119 plate type flat welded steel pipe flange
GB/T 9120 Butt welding ring plate loose steel pipe flange
GB/T 9121 flat welded ring plate loose steel pipe flange
GB/T 9122 Flange ring plate loose steel pipe flange
GB/T 9124 steel pipe flange technical conditions
GB/T 12777 metal bellows expansion joint general technical conditions
GB/T 13402 large diameter steel pipe flange
GB/T 20801.2-2006 Specification for pressure piping - Part 2. Materials
GB/T 20801.4-2006 Specification for pressure piping - Part 4. Manufacture and installation
GB/T 20878 Stainless steel and heat resistant steel grades and chemical composition
GB/T 24511 stainless steel plate and steel strip for pressure equipment
GB 50236-2011 Field equipment, industrial pipeline welding engineering construction specifications
GB/T 35979-2018 Metal bellows expansion joint selection, installation, use and maintenance technical specifications
HG/T 20592 Steel Pipe Flange (PN Series)
HG/T 20615 Steel Pipe Flange (Class Series)
HG/T 20623 Large Diameter Steel Pipe Flange (Class Series)
SH/T 3406 petrochemical steel pipe flange
Technical conditions for JB/T 74 steel pipe flange
JB/T 75 Steel Pipe Flange Types and Parameters
JB/T 79 integral steel pipe flange
JB/T 81 plate type flat welded steel pipe flange
JB/T 82 butt welded steel pipe flange
JB/T 83 flat welding ring plate loose steel pipe flange
JB/T 84 Butt welding ring plate loose steel pipe flange
JB/T 85 Flange plate loose steel pipe flange
JB/T 4711 Pressure Vessel Coating and Transport Packaging
NB/T 47008 Carbon steel and alloy steel forgings for pressure equipment
NB/T 47013.2 Non-destructive testing of pressure equipment - Part 2. Radiographic testing
NB/T 47013.3 Non-destructive testing of pressure equipment - Part 3. Ultrasonic testing
NB/T 47013.4 Non-destructive testing of pressure equipment - Part 4. Magnetic particle testing
NB/T 47013.5 Non-destructive testing of pressure equipment - Part 5. Penetration testing
NB/T 47014 Pressure welding equipment welding process evaluation
NB/T 47018 Welding material ordering technical conditions for pressure equipment
TSGZ0004 Basic requirements for quality assurance system for manufacturing, installation, modification and maintenance of special equipment
TSGZ6002 special equipment welding operator assessment rules
YB/T 5354 corrosion resistant alloy cold rolled sheet
3 Terms and definitions
The following terms and definitions as defined in GB/T 35979-2018 apply to this document.
3.1
Bellows belows
A flexible element consisting of one or more corrugations and straight edges.
3.2
Ripple convolution
A basic flexible unit that constitutes a bellows.
3.3
Straight edge endtangent
A straight section of the bellows without corrugations at the end.
3.4
Hoop colar
Used only to strengthen the barrel or ring of the straight section.
3.5
Auxiliary ferrule assistingcolar
Hing the loop of the straight section for easy soldering.
3.6
Reinforcement member reinforcingmember
Suitable for reinforcing U-shaped and omega-shaped bellows, including reinforcing ferrules, reinforcing rings and equalizing rings. The ferrule is used to strengthen the straight section and
A trough or ring of troughs. The reinforcing ring and the equalizing ring are devices for reinforcing the bellows or peaks of the bellows, and the equalizing ring also has a total equivalent of the single wave.
The function of the axial displacement range.
3.7
Pressure thrust pressurethrust
The static axial thrust of the bellows due to pressure.
3.8
Neutral position
The bellows is in a position where the displacement is zero.
3.9
Integral molded bellows integralformingbelows
Bellows without a circumferential weld.
4 Qualifications and responsibilities
4.1 Qualification
For expansion joints within the scope of the Catalogue of Special Equipment, the manufacturing unit and personnel shall have the following qualifications.
a) The manufacturing unit shall establish an applicable quality assurance system in accordance with the provisions of TSGZ0004 and obtain the “Special Equipment Manufacturing License”;
b) The welding personnel shall hold the special equipment operator certificate of the corresponding project in accordance with the provisions of TSGZ6002;
c) Non-destructive testing personnel shall obtain corresponding non-destructive testing personnel in accordance with the relevant provisions of the national special equipment non-destructive testing personnel assessment.
qualifications.
4.2 Duties
4.2.1 Responsibilities of the user or system designer
The user or system designer shall submit the design conditions in writing to the expansion joint design unit and be responsible for their completeness and accuracy.
4.2.2 Expansion unit design unit (department) duties
4.2.2.1 The design unit (department) shall be responsible for the completeness and correctness of the design documents.
4.2.2.2 The design documentation for the expansion joint shall include at least the design calculations and design drawings and, if necessary, installation instructions.
4.2.2.3 The design shall take into account all failure modes that may occur during the use of the expansion joint, and take corresponding measures to prevent failure, if necessary, to
The user issues a risk assessment report.
4.2.2.4 The design unit (department) shall save all design documents during the design life of the expansion joint.
4.2.3 Manufacturing unit responsibilities
4.2.3.1 The manufacturing unit shall strictly implement relevant regulations, safety technical specifications and corresponding standards, and manufacture, inspect and accept according to the design drawings.
Expansion joint.
4.2.3.2 The manufacturing unit shall be manufactured according to the design drawings, and the design documents shall be changed by the original design unit (department), and the manufacturing unit shall
Modifications of the original design and substitution of materials for pressure-bearing components (see A, B in 5.2.1) shall be obtained in advance by the original design unit (department).
Approved.
4.2.3.3 When each batch of expansion joints is shipped from the factory, the manufacturer shall provide the following technical documents and materials to the user at least.
a) as-built drawings;
b) If material substitution, non-destructive testing method change, processing size change, etc. occur during manufacturing, the manufacturing unit shall follow the design unit book.
The requirements for the approval document are clearly marked on the as-built drawings, with the signature of the person modified and the date of modification;
c) The factory documents specified in this standard, including the certificate of conformity, the certificate of product quality and the instructions for installation and use.
5 classification
5.1 Expansion section classification
5.1.1 Classification according to whether it can withstand pressure thrust
According to whether the expansion joint itself can withstand the pressure thrust, the expansion joint is divided into two types. unconstrained type and constrained type. For common structural types, see
Table 1.
a) Unconstrained type. an expansion joint that cannot withstand pressure thrust itself, called an unconstrained expansion joint.
b) Constrained type. an expansion joint that can withstand pressure thrust, called a constrained expansion joint.
5.1.2 Classification according to absorption displacement type
According to the type of absorption displacement of the expansion joint, the expansion joint is divided into four types. axial type, angular type, transverse type and universal type. Common structural types
See Table 1.
a) Axial type. mainly used to absorb axial displacement. Can be designed to be unconstrained or constrained.
b) Angular type. Constrained expansion joint. Used to absorb angular displacement. When setting the hinge, it is used to absorb the single plane angular displacement;
When the universal ring is placed, it is used to absorb multi-plane angular displacement.
c) Lateral type. Constrained expansion joint. Used to absorb lateral displacement. When two tie rods are provided in the expansion joint, it can be used to absorb perpendicular to
The two tie rods form a planar angular displacement; the expansion joints with double or double universal joints can also be used to absorb angular displacement.
d) Universal type. used to absorb displacement in multiple directions. Can be designed to be unconstrained or constrained.
Table 1 Common expansion joint structure type
Can it be itself?
Under pressure
Thrust type
Absorption position
Shift type
Type diagram
Displacement
Axial
Transverse angle
single
flat
Multiple
flat
single
flat
Multiple
flat
Unconstrained
Unconstrained
Axial type
Single shaft
Direction type
● ○ ○ ○ ○
External pressure shaft
Direction type
● ○ ○ ○ ○
Table 1 (continued)
Can it be itself?
Under pressure
Thrust type
Absorption position
Shift type
Type diagram
Displacement
Axial
Transverse angle
single
flat
Multiple
flat
single
flat
Multiple
flat
Constrained
Constrained
Constrained
Axial type
Straight pipe pressure
Balanced
● × × × ×
Bypass
Tube pressure
Balanced
● × × × ×
Bending pressure
Balanced
● ○ ○
only
2 roots
Pull rod
Constrained
Constrained
Angular
Single
Hinge type
× × × ● ×
Single universal
Hinge type
× × × ● ●
Constrained lateral type
Duplex
Tie rod type
× ● ●
only
2 roots
Pull rod
Table 1 (continued)
Can it be itself?
Under pressure
Thrust type
Absorption position
Shift type
Type diagram
Displacement
Axial
Transverse angle
single
flat
Multiple
flat
single
flat
Multiple
flat
Constrained
Constrained
Constrained
Lateral type
Compound universal
Hinge type
× ● ● ● ×
Duplex
Hinge type
× ● × ● ×
Duplex
Angle type
× ● ● ● ●
Unconstrained
Constrained
Constrained
Constrained
Universal type
Duplex
Free type
● ● ● ● ●
Bending tube pressure
Liping
Balance type
● ● ●
only
2 roots
Pull rod
Straight pipe pressure
Force balance
Tie rod type
● ● ●
only
2 roots
Pull rod
Straight pipe pressure
Force balance
Universal joint
Chain type
● ● ● ● ●
Note. ●---applicable; ◎---conditions apply; ○---limited range applies; ×--- not applicable.
5.2 Component classification of expansion joints
5.2.1 Pressure components
5.2.1.1 Main pressure components (A)
The components that make up the pressure boundary (including the ferrule and the reinforcement) will cause a sudden burst of pressure, as shown in Figure 1.
5.2.1.2 Non-main pressure components (B)
The components that are subjected to pressure thrust are shown in Figure 1.
5.2.2 Non-pressure components
5.2.2.1 Parts connected to main pressure components and non-main pressure components (C)
Components soldered directly to A or B, see Figure 1.
5.2.2.2 Other components (D)
For components other than A, B or C components, see Figure 1.
a) Single axial type b
External pressure axial type
c) single hinge type d
Double lever type
Description.
A---main pressure components;
B---non-main pressure components;
C---parts connected to the main pressure-bearing components and non-main pressure components;
D---other components;
1 --- pre-stretching or transporting the tie rods;
a If it is a ferrule or a ferrule, it is a Class A component.
Figure 1 Schematic diagram of common expansion joint components
5.3 Welding joint classification
Typical expansion joint welded joints are divided into four categories. W1~W7, as shown in Figure 2.
---W1 Pressure pipe, ferrule and reinforcement longitudinal butt joint;
---W2 bellows longitudinal butt joint;
---W3 Pressure-bearing pipe type circumferential butt joint, pressure ring type splicing butt joint;
---W4 Welded joint of bellows and connecting piece (plug welded butt joint, lap joint, end welded butt joint);
---W5 Weld joints between pressure-bearing components (A and A, A and B) except W3 and W4;
---W6 is connected to the welded joint between the non-main pressure components (B and B);
---W7 Welded joints for non-pressure components (C and D).
Figure 2 Welding joint classification
6 Typical applications
Typical applications for expansion joints are given in Chapter 4 of GB/T 35979-2018.
7 materials
7.1 General provisions
7.1.1 The material selection should take into account the mechanical properties, chemical properties, physical properties and process properties of the material, and the functions and working conditions to be achieved.
Compatible with the expected manufacturing technology.
7.1.2 Components connected to pressure-bearing components shall not affect the use of pressure-bearing components connected to them, in particular
The components of the welded joint should also take into account the weldability of the material.
7.1.3 The quality, specifications and markings of the materials used for the pressure-bearing components of the expansion joints shall comply with the requirements of the corresponding material standards.
a) When the expansion joint manufacturing unit obtains the material for the expansion joint pressure component from the material manufacturing unit, the material manufacturing unit shall guarantee the quality, and
Meet the following requirements.
1) Provide the material quality certificate (original) according to the corresponding standards, the content of the material quality certificate shall be complete and clear, and
Covered with the quality inspection certificate of the material manufacturing unit;
2) Make clear signs on the obvious parts of the material in accordance with the relevant standards.
b) When the expansion joint manufacturing unit obtains the material for the expansion joint pressure component from the non-material manufacturing unit, it shall obtain the material manufacturing unit
The original certificate of the quality certificate or the copy of the official seal and the manager's seal of the supplier of the capping material; the expansion unit manufacturing unit
Responsible for the authenticity and consistency of the materials obtained for expansion joints and the quality certificate of materials.
7.1.4 The expansion joint manufacturing unit shall accept the materials according to the material quality certificate.
7.2 Bellows
7.2.1 The materials selected shall be sufficiently resistant to corrosion by all corrosive media that may be encountered during the life of the system. Usually ripple
The tube is made of a material that is more resistant to corrosion than other components in the system.
7.2.2 The materials selected shall meet the requirements of the bellows forming and welding process.
7.2.3 When the bellows is a multi-layer structure, each layer of material is allowed to be different, but the material should not exceed two.
7.2.4 See Appendix A for commonly used bellows materials.
7.3 Other pressure components
7.3.1 The material selected for contact with the medium shall be the same as or the lower than the material of the pipe in the pipe in which the expansion joint is installed.
Material, when welding with the pipe should have good welding performance, commonly used materials see GB/T 20801.2-2006.
7.3.2 Materials for non-main pressure components shall be considered for safety and reliability under loads such as pressure and thrust.
Appendix A.
8 design
8.1 Design conditions
8.1.1 Precautions
The user or system designer shall provide design conditions at least in accordance with Table 2, and shall be aware of the following.
a) The type of pipeline support, the location, and the extent to which the displacement is to be absorbed shall be considered in accordance with the provisions of Chapter 4 of GB/T 35979-2018.
To determine the type, displacement and stiffness of the most suitable expansion joint to meet the force requirements of the piping and equipment. should
Avoid twisting the bellows. When the twisting is unavoidable, the specific requirements of the torque should be made.
b) The material of the bellows should be compatible with the medium, the external environment and the working temperature, and consider the possible corrosion (special attention to stress)
corrosion). The materials selected should also be able to accommodate the chemicals used in water treatment or cleaning of the pipeline. When there is a heat insulation layer, absolutely
Corrosive substances that permeate through the hot layer may also cause corrosion.
c) If the flow rate of the medium causes resonance of the bellows or erosion of the corrugations, the liner shall be provided in accordance with B.5.
d) The maximum working pressure, design pressure and test pressure should be given and determined according to the actual situation, and should not be arbitrarily increased. According to excessive pressure
Force design will excessively increase the thickness of the bellows, but will reduce the fatigue life of the bellows and increase the expansion joints for the piping system.
Use force.
e) The maximum working temperature and the minimum operating temperature should be specified according to the actual situation. Temperature may change greatly during pipeline construction
Where it is necessary, pre-displacement may be required when installing the expansion joint.
f) The displacement value should be specified according to the actual situation. Using too high safety factor will increase the flexibility of the expansion joint and reduce the expansion joint in the pressure state.
Stability under. The displacement to be absorbed by the expansion joint includes the amount of expansion and contraction of the pipe, the equipment connected to the expansion joint, the fixing bracket, etc.
Displacement of the device, as well as possible deviations during installation (should avoid installation deviations of the expansion joints beyond the design allowable values).
If the displacement is cyclic, the expected fatigue life should also be specified.
g) For media that will accumulate or solidify, measures should be taken to prevent it from stagnation and damaging the expansion joints or pipelines within the corrugations.
h) The liner should generally be placed in the direction of the flow of the medium. To avoid the flow medium being blocked in the back of the liner, it should be stated
It is necessary to open a drain hole or a purge nozzle on the liner. When backflow may occur, a thickened liner shall be specified.
Prevent the inner liner from buckling.
i) If the bellows is subjected to external mechanical vibrations (for example, vibrations generated by reciprocating or pulsating machinery), the vibration of the vibration should be stated.
Amplitude and frequency. Design expansion joints to avoid bellows resonance to eliminate the possibility of sudden fatigue damage. Possible at the scene
Modifications must also be made to the expansion joint or other components of the system.
Table 2 Design conditions
Serial design condition
1 expansion joint type
2 nominal size DN, related diameter and installation size
3 connection
material
size
standard
4 Pressure (internal pressure/external pressure)/MPa
Design pressure (nominal pressure)
Maximum working pressure
test pressure
5 temperature/° C
Maximum working temperature
Minimum operating temperature
Maximum ambient temperature
Minimum ambient temperature
Table 2 (continued)
Serial design condition
6 media
name
Flow rate
Flow direction
Displacement amount and
Fatigue life
installation
Axial (stretching/compression)/mm
Landscape/mm
Angular direction/(°)
Cycles
jobs
Working condition 1
Axial (stretching/compression)/mm
Landscape/mm
Angular direction/(°)
Cycles
Working condition 2
Axial (stretching/compression)/mm
Landscape/mm
Angular direction/(°)
Cycles
Working condition i
Axial (stretching/compression)/mm
Landscape/mm
Angular direction (°)
Cycles
8 materials
Bellows material (adapted to medium, external environment and working conditions)
Other materials (such as liners)
9 way of insulation layer insulation
10 additional load
Internal load of the expansion joint.
--- Expansion joint lining weight;
---The weight of the flowing medium in the expansion joint;
--- Dynamic load due to the flow of the medium.
External loads generated by adjacent pipes or equipment.
--- Unsupported weight of adjacent pipes/equipment (such as pipes and linings, etc.);
---Pipe prestressing;
---thermal load;
---Environmental load (ie snow load, wind load, etc.);
---Vibration of adjacent equipment (ie pumps, compressors, machines, etc.);
--- Impact load (ie earthquake, explosion load, etc.);
--- Dynamic load due to the flow of the medium.
Table 2 (continued)
Serial design condition
11 stiffness requirements
Axial/(N/mm)
Horizontal/(N/mm)
Angular direction/(N·mm/°)
12 Torque torque/(N·mm)
13 Other additional information (such as non-destructive testing, physical dimensions, mounting orientation, temporary loads generated by pressure tests, etc.)
8.1.2 Design pressure
8.1.2.1 The design pressure should not be lower than the maximum working pressure specified in the design conditions, and should be the highest working pressure; it should be selected according to the nominal pressure.
When the design pressure is taken near the nominal pressure.
8.1.2.2 When the expansion joint is subjected to internal pressure and external pressure or under vacuum conditions, the design pressure shall be considered under normal working conditions.
The maximum internal and external pressure difference that can occur.
8.1.3 Design temperature
8.1.3.1 The maximum design temperature shall not be lower than the maximum working temperature specified in the design conditions, and the maximum design temperature shall not be higher than the design condition.
The minimum operating temperature is set.
8.1.3.2 For the determination of the design temperature of the bearing members, see the requirements of B.7.3.
8.1.3.3 When determining the minimum design temperature, full consideration should be given to the effect of low temperature conditions on the temperature of the expansion joint metal during operation.
ring. Atmospheric low temperature conditions refer to the average monthly minimum temperature (the sum of the lowest temperature values of each day of the month divided by the number of days in the month).
Low value.
8.2 Welded joint coefficient
The welded joint coefficient Φ is shown in Table 3.
Table 3 Welding joint coefficient Φ
Weld seam type non-destructive testing method and detection range welding joint coefficient Φ
W1, W3
Do not do non-destructive testing 0.7
Local RT or UT 0.85
100% RT or UT 1
W2 100% PT or RT 1
W4 100%PT 1
W5, W6
Do not do non-destructive testing 0.85
Non-destructive testing 1
W7 - 1
8.3 Allowable stress
8.3.1 The allowable stress shall be in accordance with the relevant material standards.
8.3.2 When the bellows design temperature is lower than 20 °C, the allowable stress of the material shall be 20 °C.
8.3.3 For multi-layer bellows composed of different materials, the allowable stress at the design temperature is determined by equation (1).
σ[ ]t=
σ[ ]t1δ1 σ[ ]t2δ2 σ[ ]tiδi
Δ1 δ2 δi
(1)
In the formula.
σ[ ]ti --- the allowable stress of the i-th layer material at the design temperature, in megapascals (MPa);
Δi --- The nominal thickness of the i-th layer in the composite material, in millimeters (mm).
8.4 Design of the expansion joint
8.4.1 Overview
The design of the expansion joint mainly includes the corrugated pipe, the corrugated pipe connection weld structure, the flange, the joint, the inner liner, the outer sheath and the non-main pressure element.
The design of the piece. The specific design method of the bellows, the inner liner, the outer sheath and the non-main pressure components is shown in Appendix B. Vibrating occasion
For the expansion joint, the corresponding vibration check should also be carried out. For details, see Appendix C.
8.4.2 Bellows
8.4.2.1 Overview
The bellows should have the ability to withstand the required pressure resistance and absorb displacement. The design involves many variables, such as the form of bellows,
Material, diameter, wall thickness, number of layers, wave height, wave pitch, wave number, manufacturing process, etc., all affect the performance of the bellows. The design of the bellows should at least be tested
Consider the following.
a) Calculate the maximum pressure stress generated in the bellows by the pressure (internal and external pressure) and limit the maximum stress value to the allowable value, thus
Solve the problem of pressure failure;
b) Calculate the limit design pressure based on instability to solve the column instability (internal pressure only) and plane instability failure caused by pressure
problem;
c) Calculate the circumferential stability of the external pressure to solve the circumferential direction caused by external pressure.
Related standard:   GB/T 37357-2019  GB/T 37577-2019
   
 
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