CJ/T 445-2014 Pipes and joints made of oriented unplasticized poly (vinyl chloride) (PVC-O) for the conveyance of water under pressure
1 Scope
This standard specifies the general aspects of pipes and joints made of PVC-O, for piping systems intended to be used underground or above-ground where not exposed to direct sunlight, for water mains and services, pressurized sewer systems and irrigation systems.
The piping system according to this standard is intended for the conveyance of cold water under pressure, for drinking water and for general purposes up to and including 45 ℃, and especially in those applications where special performance requirements are needed, such as impact loads and pressure fluctuations, up to pressure ratings of 2.5MPa.
The pipe fittings made of other materials involved in this standard shall conform to the current national standards in addition to the provisions of this standard.
2 Normative references
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 321-2005 Preferred numbers - Series of preferred numbers (ISO 3 : 1997, IDT)
GB/T 1633 Plastics - Thermoplastic materials - Determination of Vicat softening temperature (VST)
GB/T 3401 Determination of the viscosity of Poly(vinyl chloride) resins in dilute solution using capillary viscometers (GB/T 3401-2007, ISO 1648-2 : 1998, MOD)
GB/T 4217 Thermoplastics pipes for the conveyance of fluids - Nominal outside diameters and nominal pressures (GB/T 4217-2008, ISO 161-1 : 1996, IDT)
GB/T 6111 Thermoplastics pipes for the conveyance of fluids - Resistance to internal pressure - Test method (GB/T 6111-2003, ISO 1167 : 1996, IDT)
GB/T 8804.2-2003 Thermoplastic pipes-Determination of tensile properties - Part 2 : Pipes made of unplasticized poly (vinyl chloride)(PVC-U),chlorinated poly (vinyl chloride)(PVC-C) and high-impact poly (vinyl chloride)(PVC-HI) (ISO 6259-2 : 1997, IDT)
GB/T 8806 Plastics piping systems - Plastics components - Determination of dimensions (GB/T 8806-2008, ISO 3126 : 2005, IDT)
GB/T 9647 Thermoplastics pipes - Determination of ring stiffness (GB/T 9647-2003, ISO 9969 : 1994, IDT)
GB/T 10002.2-2003 Fittings made of unplasticized poly(vinyl chloride)(PVC-U) for water supply (ISO 4422-3 : 1996, MOD; ISO 4422-5 : 1996, IDT)
GB/T 10798 Table of universal wall thickness of thermoplastics pipe (GB/T 10798-2001, ISO 4065 : 1996, IDT)
GB/T 13295 Ductile iron pipes, fittings and accessories for water or gas applications (GB/T 13295-2008, ISO 2531 : 1998, MOD)
GB/T 14152 Thermoplastics pipes - Determination of resistance to external blows - Round-the-clock method (GB/T 14152 - 2001, eqv ISO 3127 : 1994)
GB/T 17219 Standard for safety evaluation of equipment and protective materials in drinking water system
GB/T 18252-2008 Plastics piping and ducting systems - Determination of the long - term hydrostatic strength of thermoplastics materials in pipe form by extrapolation (ISO 9080 : 2003, IDT)
GB/T 18475 Thermoplastics materials for pipes and fittings for pressure applications - Classification and designation - Overall service (design) coefficient (GB/T 18475-2001, eqv ISO 12162 : 1995)
GB/T 19471.1 Plastics piping systems - Elastomeric-sealing-ring-type socket joints for use with unplasticized poly (vinyl chloride)(PVC-U) pipes - Test method for leaktighness under internal pressure and angular deflection (GB/T 19471.1-2004, ISO 13845 : 2000, IDT)
GB/T 19471.2 Plastics piping systems - Elastomeric-sealing-ring-type socket joints of unplasticized poly (vinyl chloride) (PVC-U) for use with PVC-U pipes - Test method for leaktightness under negative pressure (GB/T 19471.2-2004, ISO 13844 : 2000, IDT)
GB/T 21300 Plastics pipes and fittings - Determination of opacity (GB/T 21300-2007, ISO 7686 : 2005, IDT)
GB/T 21873 Rubber seals - Joint rings for water supply drainage and sewerage pipelines - Specification for materials (GB/T 21873-2008, ISO 4633 : 2002, MOD)
ISO 11922-1 Thermoplastics pipes for the conveyance of fluids-Dimensions and tolerance - Part 1 : metric series
ISO 13783 Plastics piping systems - Unplasticized poly (vinyl chloride)(PVC-U) end-load-bearing double-socket joints - Test method for leaktightness and strength while subjected to bending and internal pressure
ISO 13846 Plastics piping systems - End-load-bearing and non-end-load-bearing assemblies and joints for thermoplastics pressure piping - Test method for long-term leaktightness under internal water pressure
3 Terms and definitions
For the purpose of this document, the following terms and definitions apply.
3.1
nominal outside diameter
dn
specified value of the outside diameter of the socket of pipes and fittings, in millimeters
3.2
nominal wall thickness
en
specified wall thickness of pipes, in millimetres, identical to the minimum wall thickness ey, min
3.3
nominal pressure
PN
reference value related to the pressure resistance of piping system components usually, for which the priority number of R10 series is often taken for the convenience of use.
3.4
hydrostatic pressure
p
force exerted by the medium in pipes on the unit area, in MPa
3.5
working pressure
maximum pressure which a piping system can sustain in continuous use, in MPa
3.6
hydrostatic stress
σ
stress in the circumferential direction, expressed in megapascals (MPa), induced in the wall of a pipe when it is subjected to internal pressure
It is calculated using equation (1):
(1)
where
p——internal pressure, in MPa;
dem ——mean outside diameter of the pipe, in mm;
ey, min ——minimum wall thickness of pipe measured, in mm.
3.7
long-term hydrostatic strength for 50 years at 20℃
σLTHS
average or predicted strength of pipes at a temperature of 20℃ and for a time of 50 years, in MPa
3.8
lower confidence limit of the predicted
σLPL
lower limit of the predicted hydrostatic strength corresponding to temperature T and time t is σLPL=σ(T, t, 0.975) when the confidence is 97.5%, having the same dimension as stress
3.9
minimum required strength
MRS
stress value obtained by rounding the lower confidence limit σLCL at a temperature of 20℃ and for a time of 50 years down to the nearest priority number according to R10 or R20 series, in MPa. When σLCL is less than 10MPa, it shall be rounded according to R10 series, and when σLCL is greater than or equal to 10MPa, it shall be rounded according to R20 series
3.10
overall service (design) coefficient
C
a value greater than one, which takes into consideration service conditions as well as properties of other components of a pipe, which is the safety margin of piping system considered beyond the factors included in the lower confidence limit
3.11
pipe series
S
dimensionless numbers related to nominal outer diameter and nominal wall thickness, which may be used to guide the selection of pipe specifications. The value S can be calculated by any of the following formulas (2), (3) or (4) and rounded according to certain rules.
S=(dn-en)/2en (2)
S=(SDR-1)/2 (3)
S=σ/p (4)
where
dn ——nominal outside diameter of pipe, in mm;
en ——nominal wall thickness, in mm;
SDR——standard dimension ratio;
p——internal pressure, in MPa;
σ——hydrostatic stress, in MPa。
3.12
standard dimension ratio
SDR
ratio between the nominal outer diameter dn and the nominal wall thickness en of pipe, which is calculated by either formulas (5) or (6) and rounded according to certain rules:
SDR=dn/en (5)
SDR=2S+1 (6)
where
dn——nominal outside diameter of pipe, in mm;
en ——nominal wall thickness, in mm;
S——pipe series.
4 Symbols and abbreviated terms
4.1 Symbols
The following symbols apply to this document.
C: overall service(design) coefficient
Foreword I
1 Scope
2 Normative references
3 Terms and definitions
4 Symbols and abbreviated terms
5 Material
6 Effect of materials on water quality
7 Material classification
8 Classification and selection of pipes
9 General requirements for pipes
10 Geometrical characteristics for pipes
11 Mechanical characteristics of pipes
12 Physical characteristics - Tensile strength
13 System suitability test
14 Elastomeric sealing rings
15 Marking
Annex A (Normative) Establishment of the minimum required strength (MRS)
Annex B (Informative) Minimum depth of engagement of sockets
Annex C (Normative) Temperature derating factor
Annex D (Informative) Rigid polyvinyl chloride (PVC-U) and chlorinated polyvinyl chloride (PVC-C) pressure pipes with elastic sealing ring single socket fittings - minimum socket depth
Annex E (Informative) Ring stiffness of pipes
Annex F (Informative) Explanation of calculated pressures for long-term leak-tightness testing
