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GB/T 21238-2016: Glass fiber reinforced plastics mortar pipes
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Basic data | Standard ID | GB/T 21238-2016 (GB/T21238-2016) | | Description (Translated English) | Glass fiber reinforced plastics mortar pipes | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | Q23 | | Classification of International Standard | 83.120 | | Word Count Estimation | 46,458 | | Date of Issue | 2016-06-14 | | Date of Implementation | 2017-05-01 | | Older Standard (superseded by this standard) | GB/T 21238-2007 | | Quoted Standard | GB/T 1447; GB/T 1449; GB/T 1458; GB/T 1634.2-2004; GB/T 2567; GB/T 2573-2008; GB/T 2576; GB/T 2577; GB/T 3584; GB/T 5349; GB/T 5351; GB/T 5352; GB/T 8237; GB 13115; GB/T 18369; GB/T 32491; ISO 8483-2003; ISO 8533-2003; ISO 8639-2000; ISO 10928-2009 | | Adopted Standard | ISO 10639-2004, NEQ | | Regulation (derived from) | National Standard Announcement No. 8 of 2016 | | Issuing agency(ies) | General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China, Standardization Administration of the People's Republic of China | | Summary | This standard specifies the terms and definitions, classification and marking, raw materials, requirements, test methods, inspection rules, marking, packaging, transport, storage, factory certificates and technical documents of glass fiber reinforced plastic sand pipes. This standard applies to the nominal diameter of 100mm ~ 4000mm, the pressure level of 0.1MPa ~ 3.2MPa, ring stiffness rating of 1250N/m2 ~ 10000N/m2 underground and ground with drainage, irrigation, farmland irrigation and other glass fiber reinforced plastic Sand pipe (hereinafter referred to as EPRM pipe), the maximum temperature of the medium does not exceed 50 ��. Non-sanding glass fiber reinforced plastic pipe and the nominal diameter, pressure rating, ring stiffness level is not within the scope of this standard FRPM tube, can also refer to the use of this standard. | GB/T 21238-2016: Glass fiber reinforced plastics mortar pipes---This is a DRAFT version for illustration, not a final translation. Full copy of true-PDF in English version (including equations, symbols, images, flow-chart, tables, and figures etc.) will be manually/carefully translated upon your order.
Glass fiber reinforced plastics mortar pipes
ICS 83.120
Q23
National Standards of People's Republic of China
Replace GB/T 21238-2007
Glass fiber reinforced plastic sand pipe
[ISO 10639.2004(E), Plasticspipingsystemsforpressureand
Released.2016-06-14
2017-05-01 implementation
General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
China National Standardization Administration issued
Content
Foreword I
1 Scope 1
2 Normative references 1
3 Terms and Definitions 2
4 Classification and Marking 3
5 raw materials 3
6 Requirements 4
7 Test method 12
8 Inspection rules 14
9 Marking, packaging, transportation, storage, factory certificate and technical documents 16
10 other 17
Appendix A (Normative) Performance requirements for resins 18
Appendix B (Normative Appendix) Initial hoop tensile strength specimen 20
Appendix C (Normative) Long-term bending strain Sb test and determination method 21
Appendix D (informative) Connection technical requirements 25
Appendix E (informative) Pipe fitting technical requirements 28
Foreword
This standard was drafted in accordance with the rules given in GB/T 1.1-2009.
This standard replaces GB/T 21238-2007 "glass fiber reinforced plastic sand pipe".
The main technical changes of this standard compared with GB/T 21238-2007 are as follows.
--- Added "3.2MPa" to the pressure rating (see 4.1.4);
--- Increased the stiffness level by "7500N/m2" (see 4.1.5);
--- Revised the resin performance requirements, increased the bending strength of the inner liner resin and the structural layer resin in the fixed length winding process and the continuous winding process
Degree and accelerated aging bending strength retention requirements (see 5.2.4 and Appendix A,.2007 edition of 5.2.4);
--- Added "18m" to the effective length and modified the length deviation requirement (see 6.2.2, 6.2.2 of the.2007 edition);
--- Revised the wall thickness requirements (see 6.2.3,.2007 version 6.2.3,);
--- Revised the requirements for the component content of the straight pipe section wall (see 6.5, 6.5 of the.2007 edition);
--- Increased the initial hoop tensile strength requirement of 3.2MPa pressure rating (see 6.6.2);
--- Increased initial axial tensile strength and tensile fracture strain requirements for a pressure rating of 3.2 MPa (see 6.6.3);
--- Cancellation of short-term failure water pressure requirements (see 6.6.5 of the.2007 edition);
--- Increased the initial flexibility requirement of 7500 N/m2 stiffness rating (see 6.6.5);
--- Modified the formula for determining the minimum initial hoop bending strength (see 6.6.6, 6.6.7 of the.2007 edition);
--- Cancel the hygienic performance requirements (see Chapter 7 of the.2007 edition);
--- Modified the test method for the component content of the straight pipe section wall (see 7.5, 8.5 of the.2007 edition);
--- Revised the test method for the pressure design basis PDB (see 7.7.1, 8.7.1 of the.2007 edition);
--- Revised the number of samples required for water pressure leak test at the factory inspection (see 8.2.2.3 and 8.2.2.4,.2007 edition 9.2.2.3);
--- Added "factory certificate and technical documents" (see 9.5);
--- Cancel the long-term hydrostatic performance test and determination method (see Appendix B of the.2007 edition);
--- The continuous pressure in the internal pressure and cyclic pressure of the butt joint is changed from "1.5 × PN" to "2.0 × PN" (see D.3.1.1,
2007 edition of D.3.1.1);
---Pre-pressure in the circulating pressure of the flange joint and the continuous pressure in the internal pressure under bending are changed from "1.5 × PN" to "2.0 × PN"
(See D.3.2.1,.2007 edition of D.3.2.1).
This standard uses the redrafting method to refer to ISO 10639.2004 "pressure and non-pressure water supply plastic pipe system glass fiber reinforced thermosetting
The plastic (unsaturated polyester resin) tube is compiled and has a degree of consistency with ISO 10639.2004.
This standard was proposed by the China Building Materials Federation.
This standard is under the jurisdiction of the National Fiber Reinforced Plastics Standardization Technical Committee (SAC/TC39).
This standard is drafted by. Tongji University, Beijing FRP Research and Design Institute Co., Ltd.
Participated in the drafting of this standard. Wuhan University of Technology, Harbin FRP Research Institute, Shanghai Yaohua FRP Co., Ltd., Zhongfu Lianzhong
Materials Group Co., Ltd., Yuhua Zhongyi FRP Co., Ltd., Zhejiang Dongfang Haobo Pipe Co., Ltd., Yongchang Seki Composite Materials Co., Ltd.
Company, Quanzhou Lutong Pipe Industry Technology Co., Ltd., Shenzhen Kangqiang Building New Technology Engineering Co., Ltd.
The main drafters of this standard. Zhou Shigang, Xue Yuande, Hu Zhongyong, Li Zhuoqiu, Liu Zaiyang, Shen Bixia.
The previous versions of the standards replaced by this standard are.
---GB/T 21238-2007.
Glass fiber reinforced plastic sand pipe
1 Scope
This standard specifies the terms and definitions, classification and marking, raw materials, requirements, test methods, inspections of glass fiber reinforced plastic sand pipes.
Rules, signs, packaging, transportation, storage, factory certificates and technical documents.
This standard applies to the nominal diameter of 100mm~4000mm, the pressure grade is 0.1MPa~3.2MPa, and the ring stiffness grade is
1250N/m2~10000N/m2 Glass fiber reinforced plastic sand for pipeline engineering such as water supply and drainage, water conservancy and farmland irrigation for underground and ground
Tube (hereinafter referred to as FRPM tube), the maximum temperature of the medium does not exceed 50 °C.
Non-sanded glass fiber reinforced plastic pipes and nominal diameter, pressure rating and ring stiffness are not within the scope of this standard.
FRPM tubes can also be used with reference to this standard.
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.
Test method for tensile properties of GB/T 1447 fiber reinforced plastics
GB/T 1449 fiber reinforced plastic bending performance test method
GB/T 1458 filament wound reinforced plastic ring specimen tensile test method
Plastics -- Determination of deformation temperature of plastics - Part 2. Plastics, hard rubber and long fibre reinforced composites
material
GB/T 2567 resin casting body performance test method
GB/T 2573-2008 Test method for aging properties of glass fiber reinforced plastics
GB/T 2576 fiber reinforced plastic resin insoluble content test method
GB/T 2577 glass fiber reinforced plastic resin content test method
GB/T 3854 reinforced plastic Bachel hardness test method
Test method for axial tensile properties of GB/T 5349 fiber reinforced thermosetting plastic tubes
GB/T 5351 fiber reinforced thermosetting plastic pipe short-time water pressure failure pressure test method
GB/T 5352 fiber reinforced thermosetting plastic tube parallel plate external load performance test method
GB/T 8237 liquid unsaturated polyester resin for fiber reinforced plastics
GB 13115 Hygienic standard for unsaturated polyester resin and its FRP products for food containers and packaging materials
GB/T 18369 glass fiber roving
GB/T 32491 Glass fiber reinforced thermosetting resin tube and pipe fittings for long-term hydrostatic test
ISO 8483.2003 Glass fibre reinforced thermosetting plastic pipes and fittings - Test method for the design of flanged joints [Glass-
Reinforcedmosettingpastics(GRP)pipesandfittings-Testmethodstoprovethedesignofbolted
Flangejoints]
ISO 8533.2003 Test methods for glass-reinforced thermosetting plastic tubes and fittings
[Glass-reinforcedthermosettingplastics(GRP)pipesandfittings-Testmethodstoprovethedesignof
Cementedorwrappedjoints]
ISO 8639.2000 Glass fiber reinforced thermosetting plastic pipes and fittings - Flexible joints - Test method - s.
Thermosettingplastics(GRP)pipesandfittings-Testmethodsforleaktightnessofflexiblejoints]
ISO 10928.2009 Plastic tube system glass fiber reinforced thermosetting plastic tube and fittings regression analysis method and its application
[Plasticspipingsystems-Glass-reinforcedthermosettingplastics(GRP)pipesandfittings-Methods
Forregressionanalysisandtheiruse]
3 Terms and definitions
The following terms and definitions apply to this document.
3.1
Glass fiber and its products are used as reinforcing materials, unsaturated polyester resin as matrix material, inorganic non-gold such as quartz sand and calcium carbonate.
The material is a filler, and the pipe is made by a fixed length winding process, a centrifugal casting process, and a continuous winding process. Commonly known as glass fiber reinforced plastic sand pipe.
3.2
Ring stiffness ringstiffness
The load of the tube length per unit length under the action of external pressure under a certain radial deformation. It characterizes that the pipe ring is under the external load
Resistance to deformation. Calculated as follows. S = EI/D3, where S is the ring stiffness, usually in N/m2 as the unit; EI is the length of the pipe along the axial unit
The inner wall has a circumferential bending stiffness and D is the pipe diameter.
3.3
Fixed length winding process filamentwindingprocess
On a pipe mold of a certain length, the pipe is manufactured from the inside to the outside by the spiral winding and/or hoop winding process within the length of the pipe mold.
a production method.
3.4
Centrifugal casting process centrifugalcastingprocess
Using a feeder to cast glass fiber, resin, quartz sand, etc. into a rotating mold according to certain requirements, and forming a tube after curing
production method.
3.5
Continuous winding process continuousadvancingmandrelmethod
On the continuous output mold, the resin, continuous fiber, chopped fiber and quartz sand are continuously laid by the hoop winding method according to certain requirements.
A production method in which a layer is cured and cut into a length of tubing.
3.6
Pressure design basis pressuredesignbasis; PDB
Apply different hydrostatic internal pressures to a set of FRPM tube samples of the same specification, measure the failure time of each sample, and then return
The curve is extrapolated to the hydrostatic internal pressure value that the tube can withstand after 50 years (4.38×105h).
3.7
Hydrostatic design benchmark hydrostaticdesignbasis; HDB
Apply different hydrostatic internal pressures to a set of FRPM tube samples of the same specification, measure the failure time of each sample, and then return
The curve is extrapolated to the hoop tensile stress value that the tube can withstand after 50 years (4.38 x 105h).
3.8
Long-term bending strain long-termring-bendingstrain
Sb
Use a set of FRPM pipe specimens of the same specification, apply a constant external force by parallel plates to destroy the specimen or apply external force to protect it.
Holding a certain diameter change value to make the sample break, measure the damage time of each sample, and convert the corresponding bending strain, and then
The regression curve was extrapolated to the bending strain value of the tube after 50 years (4.38 × 105 h).
4 Classification and marking
4.1 Classification
4.1.1 FRPM tubes are classified according to process, nominal diameter, pressure rating and ring stiffness rating.
4.1.2 Process method. I---fixed length winding process; II---centrifugal casting process; III---continuous winding process.
4.1.3 The nominal diameter DN is shown in Tables 1 and 2.
4.1.4 Pressure rating PN. 0.1MPa, 0.25MPa, 0.4MPa, 0.6MPa, 0.8MPa, 1.0MPa, 1.2MPa, 1.4MPa,
1.6 MPa, 2.0 MPa, 2.5 MPa, 3.2 MPa.
4.1.5 Ring stiffness grade SN. 1250N/m2, 2500N/m2, 5000N/m2, 7500N/m2, 10000N/m2.
4.2 Marking
The marking method of the FRPM tube is as follows.
FRPM
product code
Production Process
Nominal diameter
Pressure Level
Ring stiffness rating
Example. The nominal diameter is 1200mm, the pressure rating is 0.6MPa, and the ring stiffness rating is 5000N/m2, which is produced according to this standard.
The FRPM tubes produced are marked as.
5 raw materials
5.1 reinforcement materials
FRPM tubes should be made from alkali-free glass fibers and their products. The alkali-free and untwisted glass fiber yarn used should conform to GB/T 18369
Provisions. E-glass fiber products shall comply with the relevant national or industry standards.
Note. Where specific media needs to be transported, other reinforcing materials with performance requirements may be used after agreement between the supplier and the purchaser.
5.2 Resin
5.2.1 The unsaturated polyester resin used should meet the requirements of GB/T 8237. Other resins should comply with the corresponding national or industry standards
Provisions.
5.2.2 The inner liner resin shall be made of isophthalic unsaturated polyester resin, bisphenol A unsaturated polyester resin or vinyl ester resin.
5.2.3 The sanitary index of the inner liner resin of FRPM pipe for water supply engineering shall meet the requirements of GB 13115.
5.2.4 See Appendix A for the performance requirements of resin castings.
5.3 Filler
The maximum particle size of the filler does not permit a smaller value between greater than 2.5 mm and one-fifth of the wall thickness. Among them, quartz sand contains SiO2
The amount should be greater than 95%, the water content should be no more than 0.2%; the CaCO3 content of calcium carbonate should be greater than 98%, and the water content should be no more than 0.2%.
6 requirements
6.1 Appearance quality
The inner surface of the FRPM tube should be smooth and flat, without cracks, delamination, pinholes, impurities, gel-in areas, bubbles and fibers that have an impact on performance.
Dimensional infiltration and other phenomena; the end of the tube should be flush; the edges should be free of burrs; the outer surface has no obvious defects.
6.2 size
6.2.1 Diameter
The outer diameter series shall comply with the requirements of Table 1, and the inner diameter series shall comply with the requirements of Table 2. In order to facilitate the connection with other material pipes, supply and demand
The two sides negotiated to determine the size of other material pipes and meet the corresponding requirements.
6.2.2 Length
6.2.2.1 The effective length of the FRPM pipe is 3m, 4m, 5m, 6m, 9m, 10m, 12m, 18m. If you need a special length of tube,
It is agreed upon by the supplier and the buyer at the time of delivery.
6.2.2.2 Length deviation of FRPM tube. ±0.5% of effective length and not exceeding ±60mm.
6.2.3 Wall thickness
The average wall thickness of any section shall not be less than the design thickness, and the minimum wall thickness shall not be less than 90% of the design thickness. When the pipe wall is set
When the thickness is not more than 20mm, the average wall thickness shall not exceed 1.15t; when the design thickness of the pipe wall is greater than 20mm, the average thickness of the pipe wall
Should not be greater than (t 3) mm.
Note. t is the design thickness of the pipe wall, determined by the pipe manufacturer through design, and given in the technical documents.
Table 1 Dimensions and deviations of the outer diameter series FRPM tube are in millimeters
Nominal diameter DN outer diameter deviation
1.0,-1.0
1.0,-1.0
1.0,-1.0
1.0,-1.2
1.0,-1.4
1.0,-1.6
1.0,-1.8
1.0,-2.0
1.0,-2.2
1.0,-2.4
1.0,-2.6
2.0,-2.6
2.0,-2.6
2.0,-2.8
2.0,-2.8
Table 1 (continued) Unit is mm
Nominal diameter DN outer diameter deviation
2.0,-3.0
2.0,-3.0
2.0,-3.2
2.0, -3.4
2.0, -3.6
2.0,-3.8
2.0,-4.0
2.0,-4.2
2.0, -4.4
2.0,-4.6
2.0,-4.8
2.0,-5.0
Other outer diameter series sizes can be used according to actual conditions, but the outer diameter deviation should meet the corresponding requirements.
Table 2 Dimensions and deviations of the inner diameter series FRPM tube are in millimeters
Nominal diameter DN
Inner diameter range of both ends
Minimum Maximum
deviation
±1.5
±1.5
±1.5
±1.5
±1.5
±1.8
±2.1
±2.4
±2.7
±3.0
±3.6
±4.2
±4.2
±4.2
±4.2
±5.0
Table 2 (continued) Unit is mm
Nominal diameter DN
Inner diameter range of both ends
Minimum Maximum
deviation
±5.0
±5.0
±5.0
±5.0
±5.0
±6.0
±6.0
±6.0
±6.0
±6.0
±6.0
±6.0
±7.0
±7.0
For taper tube designs, the design values shall be within the inner diameters of the ends specified in this table. The actual value of the inner diameter of the two ends of the pipe may be different.
The provisions of the full table.
6.2.4 Inner liner thickness
It should be no less than 1.2mm.
6.2.5 Tube end face verticality
It should meet the requirements of Table 3.
Table 3 Tube end face verticality requirements in millimeters
Nominal diameter DN tube end face vertical deviation
DN< 600 4
600≤DN< 1000 6
DN≥1000 8
6.3 Barcol hardness
The Bakr hardness of the outer surface of the FRPM tube should be not less than 40.
6.4 Resin insoluble content
The insoluble content of the resin in the pipe wall should be not less than 90%.
6.5 Direct pipe section wall component mass percentage
The content of glass fiber, resin and filler in the pipe wall of the straight pipe section is determined by the pipe design and shall be clearly stated in the technical documents. Components
The mass percentage tolerance is ±3.
6.6 Initial mechanical properties
6.6.1 Initial ring stiffness S0
The initial ring stiffness S0 should not be less than the corresponding ring stiffness class value SN.
6.6.2 Initial hoop tensile strength Fth
The initial hoop tensile strength Fth of the pipe wall shall be determined according to the engineering design, but the minimum value is determined according to formula (1).
Fth=C1·PN·DN/2 (1)
In the formula.
Fth---initial hoop tensile strength in units of kilonewtons per meter (kN/m);
C1---Initial hoop tensile strength safety factor, see Table 4; when no pressure design basis PDB test results, take C1=6.3;
The minimum value of the initial hoop tensile strength at C1=6.3 is shown in Table 5;
PN---pressure rating in MPa (MPa);
DN---Nominal diameter in millimeters (mm).
Table 4 Initial hoop tensile strength safety factor C1
Pressure rating PN
MPa
1.5 1.75 2.0 2.5 3.0
0.1
0.25
0.4
0.6
0.8
1.0
1.2
1.4
1.6
2.0
2.5
3.2
4.2
4.2
4.1
5.3
5.3
5.1
5.0
4.9
4.8
4.7
4.6
4.5
4.3
6.3
6.3
6.2
6.0
5.9
5.7
5.6
5.5
5.4
5.1
4.8
4.5
α=P0/PDB; where. P0 is the short-time failure water pressure; PDB is the pressure design basis.
When the coefficient of dispersion of the initial hoop tensile strength of the tube is CV >9.0%, C1 should be taken as the table median multiplied by 0.8236/(1-1.96 CV).
Table 5 The minimum value of the initial hoop tensile strength without PDB is Fth. The unit is kilograms per meter.
Nominal diameter DN
Mm
Pressure Level
MPa
0.1 0.25 0.4 0.6 0.8 1.0 1.2 1.4 1.6 2.0 2.5 3.2
6.6.3 Initial axial tensile strength and tensile strain at break
The initial axial tensile strength and tensile strain at break are determined according to whether the pipe produces axial force.
a) Initial axial tensile strength of the pipe wall when the pipe is not subjected to axial forces directly generated by the pipe internal pressure or is not subjected to special axial forces
FtL shall not be less than the value specified in Table 6; the axial tensile fracture strain of the pipe wall shall be not less than 0.25%.
Table 6 Initial axial tensile strength minimum FtL Unit is kilograms per meter
Nominal diameter DN
Mm
Pressure Level
MPa
≤0.4 0.6 0.8 1.0 1.2 1.4 1.6 2.0 2.5 3.2
b) When the pipeline is subjected to the axial force generated by the internal pressure of the pipe, the initial axial tensile strength FtL of the pipe wall shall satisfy the requirements of formula (2). tube
The axial tensile strain at wall is not less than 0.25%.
FtL ≥C1·PN·DN/4 (2)
In the formula.
FtL---the initial axial tensile strength of the pipe, in units of kilonewtons per meter (kN/m);
C1 --- the same formula (1), when no pressure design basis PDB test results, take C1 = 6.3;
PN, DN are the same formula (1).
Note. The tubes that are subjected to the axial force generated by the internal pressure of the pipe mainly include. a pipe whose one end is connected with a valve, a blind plug, etc., and which is not provided with a reliable buttress.
6.6.4 Water pressure leakage
Apply the water pressure of 1.5 times the pressure of the whole pipe or the whole pipe with the joint to maintain the pressure of 2.0 min, the pipe body and the joint
The position should not leak.
6.6.5 Initial flexibility
The initial deflection level A and deflection level B of each sample shall meet the requirements of Table 7.
Table 7 Radial Deformation Rate and Requirements for Initial Flexibility
Flexural level
Ring stiffness rating
N/m2
1250 2500 5000 7500 10000
Claim
A 18 15 12 10.5 9 No cracks on the inner wall of the tube
B 30 25 20 17.5 15 Tube wall structure without delamination, fiber breakage and buckling
Note. The radial deformation rate for the initial flexibility of other ring stiffness tubes is performed as follows.
a) For tubes with a ring stiffness class between the standard levels, the radial deformation rates corresponding to the deflection levels A and B are linearly interpolated
determine;
b) For tubes with ring stiffness class ≤1250N/m2 or ≥10000N/m2, the deflection levels A and B are calculated as follows.
The radial deformation rate corresponding to the deflection level A = 18 × (1250/S0) 1/3
The radial deformation rate corresponding to the deflection level B = 30 × (1250/S0) 1/3.
6.6.6 Initial hoop bending strength
The initial hoop bending strength Ftm of the pipe wall shall be determined according to the engineering design, but the minimum value is determined according to formula (3).
Ftm=4.28
kEptΔ
(D Δ/2) 2
(3)
In the formula.
Ftm---the initial bending strength of the pipe wall, in megapascals (MPa);
k --- hoop bending strength special coefficient, for the tube produced by the fixed length winding process and the centrifugal casting process, k is taken as 1.0; for continuous
The tube produced by the winding process, k takes 1.2;
t --- the actual thickness of the pipe wall, in millimeters (mm);
Δ --- initial flexurality test of the pipe reaches the radial compression deformation amount at the deflection level B, in millimeters (mm);
D --- calculated diameter of the tube, in millimeters (mm), D = Dn t;
Dn --- the inner diameter of the tube in millimeters (mm);
Ep --- wall bending elastic modulus, in megapascals (MPa); determined by equation (4).
Ep=12×10-6S0D3/t3 (4)
In the formula.
S0---initial ring stiffness in units of cattle per square meter (N/m2);
D, t is the same formula (3).
Note 1. For the FRPM pipe produced by the centrifugal casting process, when calculating Ep, the corresponding deformation of the S0 when using the deflection test reaches the deflection level A.
The value of the ring stiffness is calculated from the load value.
Note 2. When the long-term bending strain Sb is obtained through the test, the product with the same pressure level and stiffness grade may not be subjected to the initial hoop bending strength.
Inspection.
6.7 Long-term performance
6.7.1 Pressure Design Benchmark PDB
The pressure design basis PDB should meet the requirements of equation (5).
PDB≥C3·PN (5)
In the formula.
PDB---pressure design basis in MPa (MPa);
PN --- pressure rating in MPa (MPa);
C3 --- Long-term hoop tensile strength safety factor, see Table 8.
Table 8 Long-term circumferential tensile strength safety factor C3
Pressure rating PN
MPa
Coefficient C3
≤0.25 2.1
0.4 2.05
0.6 2.0
0.8 1.95
1.0 1.9
1.2 1.87
1.4 1.84
1.6 1.8
2.0 1.7
2.5 1.6
3.2 1.6
6.7.2 Long-term bending strain Sb
The long-term bending strain Sb value should meet the requirements of equation (6).
Sb≥4.28
Δs·t
(D Δs/2) 2
(6)
In the formula.
Sb---long-term bending strain;
Δs --- initial flexurality test of the pipe reaches 60% of the radial compressive deformation Δ at the deflection level B, in millimeters (mm);
D, t is the same formula (3).
Note. When there is no long-term bending strain Sb value, it is recommended to calculate according to formula (6) in the design of pipeline engineering structure, where Δ/2 is taken for the water supply pipeline Δs;
For the sewage pipe Δs is taken as Δ/3; Δ is the amount of radial compression deformation when the initial deflection test of the pipe reaches the deflection level B.
7 Test methods
7.1 Appearance quality
Visually inspect the inner, outer and b...
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