1 General provisions
1.0.1 This specification is formulated with a view to achieving advanced technology, safety and applicability, and economic rationality, and ensuring quality in the design, construction and acceptance of buried plastic pipelines for water supply engineering.
1.0.2 This specification is applicable to the design, construction and acceptance of constructed, extended and renovated buried plastic pipelines for water supply engineering with water temperature less than 40℃.
1.0.3 In addition to this specification, the design, construction and acceptance of buried plastic pipelines for water supply engineering shall also comply with the requirements of the current relevant standards of the nation.
2 Terms and symbols
2.1 Terms
2.1.1 buried plastic pipeline for water supply engineering
a general term for pipelines made of polymer materials or polymer materials combined with metal materials and used to convey water in a buried manner. This specification covers three categories of buried plastic pipelines for water supply engineering: polyethylene (PE) pipeline, polyvinyl chloride (PVC) pipeline, and plastic-steel-plastic composite (PSP) pipeline. Thereinto, the polyethylene (PE) pipelines are classified into PE80 pipes and PE100 pipes; the polyvinyl chloride (PVC) pipelines are classified into unplasticized polyvinyl chloride (PVC-U) pipes and modified polyvinyl chloride (PVC-M) pipes; and the plastic-steel-plastic composite (PSP) pipelines are classified into steel reinforced polyethylene plastic pipes, polyethylene (PE) composite pipes with porous steel strip and steel wire reinforced thermoplastics (PE) composite pipes
2.1.2 operating pressure derating coefficients for various operating temperatures
coefficient of the operating pressure of the pipeline in continuous use at an operating temperature above 20℃ compared with that at 20℃
2.1.3 gasket ring push-on connection
a connection method of inserting the spigot of a pipe into the socket of the adjacent pipe or fitting and also sealing the connecting part with the rubber ring in the socket
2.1.4 solvent cement connection
a connection method of applying the special solvent cement for polyvinyl chloride (PVC) pipelines on the inner surface of the socket and the outer surface of the spigot of polyvinyl chloride (PVC) pipelines to make them bond into one
2.1.5 butt fusion connection
a connection method of heating and melting the end faces of pipelines by using special hot-melt equipment, and then aligning the parts to be connected, and connecting them into a whole under the action of external force
2.1.6 electrofusion jointing
a connection method by which special electrofusion fittings with embedded resistance wire are fusion-welded by controlling the voltage, current and electrification time of the resistance wire embedded in the fittings with special equipment, which is classified into electrofusion socket connection and electrofusion saddle connection
2.1.7 flange connection
a connection method of tightening a plastic pipe segment with root-shaped end with the flange end of the pipe or fitting to be connected with bolts to realize sealing
2.1.8 polyethylene (PE) pipe to steel pipe transition fitting connection
a connection method of connecting the polyethylene (PE) pipe and steel pipe by using the special fittings prefabricated by the factory for this purpose
2.1.9 polyethylene (PE) fitting from butt fusion
fitting made by cutting pipe segments from polyethylene (PE) pipe and welding them with a butt fusion joint using a fillet welder
2.1.10 locating device
device installed above or around a pipeline, which can detect the location of the pipeline at ground level with special equipment
2.1.11 warning tape/plate
tape (plate) indicating the presence of underground pipeline
2.2 Symbols
2.2.1 Loads on the pipeline:
Fwk——the standard value of the operating pressure of pipeline;
Fwd,k——the standard value of the design internal water pressure of pipeline;
Fcr,k——the critical pressure for circumferential instability of the pipe wall section;
Ff——the standard value of uplift force on pipeline;
∑FGk——the sum of the standard values of anti-floating effects formed by various permanent effects;
Fpw,k——the standard value of thrust on the pipeline under the action of the standard design internal water pressure;
Fsv,k——the standard value of vertical earth pressure at pipe top;
Fvk——the standard value of vacuum pressure in pipeline;
MOP——the maximum operating pressure of pipeline;
P——the test pressure;
ΔP——the pressure drop during water pressure test;
PN——the nominal pressure of pipeline;
qvk——the standard value of pressure transmitted from ground to pipe top;
qsv,k——the standard value of vertical earth pressure per unit area of pipe top;
σp——the design value of circumferential tensile stress of pipe wall under the action of design pressure in pipeline;
σm——the design value of maximum circumferential bending stress of the pipe wall under the action of external pressure.
2.2.2 Geometric parameters:
B——the excavation width at the bottom of pipeline trench;
b1——the width of the working face on one side of the pipeline;
b2——the thickness of the support on one side of the pipeline when support is required;
D0——the calculated diameter of pipeline;
Di——the outer diameter of pipe, i=1, 2, 3…;
dn——the nominal diameter of pipe;
di——the inner diameter of pipeline;
en——the nominal wall thickness of pipe;
hd——the thickness of shaped subgrade below the pipe bottom;
L——the length of pipe segment;
ΔL——the longitudinal deformation caused by temperature difference;
S——the design clear distance between two pipes;
SDR——the standard dimension ratio of pipe;
t——the calculated thickness of pipe wall;
V——the total volume of the test pipeline;
ΔV——the volume of water released by pressure drop;
ΔVmax——the maximum volume of water allowed to be released;
ωd,max——the maximum long-term vertical deformation of pipeline under quasi-permanent combination of action effects.
2.2.3 Calculation parameters and coefficients:
Cp——the linear expansion coefficient of pipe;
Df——the shape coefficient of pipeline;
DL——the deformation hysteresis coefficient;
Ed——the deformation modulus for pipe lateral earth;
Ee——the deformation modulus for pipe lateral earth at the required compaction density;
En——the deformation modulus for undisturbed soil on both sides of trench;
Ep——the elastic modulus of pipe;
Epk——the standard value of the resultant force of passive earth pressure acting on the anti-thrust side of buttress;
Eαk——the standard value of the resultant force of active earth pressure acting on the thrust side of buttress;
Ew——the bulk modulus of water;
Ffk——the standard value of friction resistance on the sliding plane at buttress bottom;
fm——the design value of bending strength of pipes;
fp——the design value of tensile strength of pipes;
fa——the characteristic value of foundation bearing capacity after depth correction;
ft——the operating pressure derating coefficients for various operating temperatures of pipeline;
g——the gravitational acceleration;
hy——the frictional head loss of pipeline;
hj——the local head loss of pipeline;
hz——the total head loss of pipeline;
Ip——the moment of inertia per unit length of longitudinal section of pipe wall;
Kd——the vertical deformation coefficient of the pipeline under the action of vertical pressure;
Kf——the resistance coefficient for anti-floating stability;
Ks——the resistance coefficient for anti-sliding stability;
Kst——the resistance coefficient for circumferential stability of the pipe wall section;
n——the value of wave number due to pipe wall instability;
PT——the thrust generated by the buried plastic pipeline for water supply engineering onto the buttress;
PT1——the horizontal component of the thrust PT;
PT2——the vertical component of the thrust PT;
ρ——the average pressure of buttress acting on foundation;
ρmin——the minimum pressure of the buttress acting on foundation;
ρmax——the maximum pressure of the buttress acting on foundation;
q——the allowable seepage quantity;
Re——the Reynolds number;
rc——the pressure influence coefficient of pipeline;
SN——the rigidity grade of pipeline;
T——the water temperature;
Δt——the maximum temperature difference between construction/installation and operation at the pipe wall;
v——the average flow velocity in the pipeline;
νp——the Poisson's ratio for pipe;
νs——the Poisson's ratio for pipe lateral earth;
Δ——the equivalent roughness of pipeline;
λ——the hydraulic friction coefficient of pipeline;
ζ——the local resistance coefficient of pipeline;
ζ0——the comprehensive correction coefficient;
αf——the ratio of the design value of tensile strength to the design value of bending strength of pipe;
γ——the kinematic viscosity of water;
γ0——the importance coefficient of pipeline;
γG——the partial coefficient of permanent load;
γQ——the partial coefficient of variable load;
ψq——the quasi-permanent value coefficient of pressure transmitted from ground to pipe top;
ψc——the load combination coefficient for pipeline strength calculation;
η——the adjustment coefficient for pipeline pressure calculation;
ηE——the long-term performance adjustment coefficient for elastic modulus of pipe.
3 Materials
3.1 General requirements
3.1.1 The hygienic performance of pipes, fittings, appurtenances and auxiliaries, and related materials used in the buried plastic pipeline system for water supply engineering shall meet the relevant requirements of the current national standard GB/T 17219 Standard for safety evaluation of equipment and protective materials in drinking water system.
3.1.2 The fittings, rubber sealing rings, solvent cements, and other appurtenances and auxiliaries connected with pipes in the pipeline system shall be supplied together.
3.2 Quality requirements
3.2.1 The pipes in the pipeline system shall meet the following requirements:
1 The polyethylene (PE) pipes shall meet the relevant requirements of the current national standard GB/T 13663 Polyethylene pipes for water supply, and their resistance to rapid crack propagation and resistance to slow crack growth shall meet the requirements of Table 3.2.1.
1 General provisions
2 Terms and symbols
2.1 Terms
2.2 Symbols
3 Materials
3.1 General requirements
3.2 Quality requirements
3.3 Design calculation parameters
3.4 Transportation and storage
4 Pipeline system design
4.1 General requirements
4.2 Pipeline layout and laying
4.3 Pipeline hydraulic calculation
4.4 Pipeline structural design
4.5 Pipeline appurtenances and buttresses
5 Pipeline engineering construction
5.1 General requirements
5.2 Trench excavation and soil treatment
5.3 Pipeline connection
5.4 Pipeline laying
5.5 Trench backfill
5.6 Pipeline appurtenances and auxiliaries installation
5.7 Connection of branch pipe/service pipe to existing pipeline
6 Water pressure test, flushing and disinfection
6.1 General requirements
6.2 Water pressure test
6.3 Flushing and disinfection
7 Construction completion and final acceptance
Annex A Deformation modulus for the pipe lateral earth
Explanation of wording in this specification
List of quoted standards
