1 General Provisions
1.0.1 This specification was formulated with a view to making the engineering design, construction and acceptance of buried polyethylene (PE) water supply pipeline achieve the advanced technology and be safe, hygienic, economic and feasible and convenient for construction.
1.0.2 This specification is applicable to the engineering design, construction and acceptance of buried polyethylene water supply pipeline of which the water temperature is no greater than 40℃ and the working pressure is no greater than 1.0MPa.
1.0.3 In addition to this specification, the engineering design, construction and acceptance of buried polyethylene water supply pipeline still shall comply with those specified in the relevant current compulsory standards of the State.
2 Terms and Symbols
2.1 Terms
2.1.1 Nominal outside diameter
The calibrated outside diameter of pipes and pipe fittings.
2.1.2 Nominal wall thickness
The specified value of the wall thickness of pipe and pipe fittings, which is equivalent to the minimum wall thickness at any point.
2.1.3 Nominal pressure
The maximum working pressure of pipe and pipe fittings at 20℃.
2.1.4 Working pressure
The maximum continuous hydraulic pressure acting on the inner wall of pipe when the pipeline is at the normal working conditions, excluding the surge pressure.
2.1.5 Surge pressure
The transient surge pressure produced due to the abrupt changes in water flow rate during the working process of piping system.
2.1.6 Design pressure
The maximum instantaneous pressure acted on the inner wall of pipe during the working process of piping system, which is the sum of the continuous working pressure and surge pressure of the pipeline.
2.1.7 Minimum required strength
The minimum guarantee value of the circumferential tensile strength of polyethylene pipe when the pipeline bears internal water pressure for 50 years at a water temperature of 20℃, which depends upon the category of polyethylene resin
2.1.8 Compounds
The granular materials manufactured with polyethylene base resin by adding with necessary antioxidant, ultraviolet stabilizer and pigment.
2.1.9 Standard dimension ratio (SDR)
The ratio between the nominal outside diameter (dn) and nominal wall thickness (en) of a pipe.
2.2 Symbols
2.2.1 Actions on pipeline
Fw——the working pressure of pipeline
Fwd——the design pressure of pipeline
Fa——the vacuum pressure in the pipeline
Fc——the earth pressure transferred to the pipe top part in unit length of the pipeline due to the wheel pressure of surface cars
FB——the earth pressure transferred to the pipe top part in unit length of the pipeline due to the deposit on the ground
Fsv.k——the normal value of the vertical earth pressure transferred to the pipe top part in unit length of the pipeline
ΔP——the surge pressure of the pipeline
2.2.2 Geometric parameters
B——the width of the groove at the horizontal center of pipeline or the total width of backfilled soil on both sides
D0——the calculated diameter of the pipeline (=dn-en)
dn——the nominal outside diameter of the pipe
di——the inner wall diameter of the pipe
en——the nominal wall thickness of the pipe
Hs——the height of covering soil from the pipe top to the designed ground
r0——the calculated radius of pipeline
R——the hydraulic radius
Wd,max——the maximum vertical displacement of pipeline
2.2.3 Parameters and coefficients for calculation
Ed——the combined deformation modulus of soil on pipe side
Ee——the deformation modulus of backfilled soil on pipe side
En——the deformation modulus of undisturbed soil on both sides of the groove
Ep——the elastic modulus of the pipe
f——the normal value of circumferential tensile strength of pipe (the minimum required strength MRS)
g——the acceleration of gravity
hf——the friction head loss of pipe flow
△hs——the local head loss
Kf——the resistance factor of the stability against floating of pipeline
Kst——the resistance factor of the circumferential stability of pipeline section
Re——the Reynolds number
υ——the mean flow rate of water flow in pipeline
Δ——the equivalent roughness of pipeline
λ——the hydraulic friction coefficient of pipeline
3 Materials
3.1 General Requirements
3.1.1 The pipes and pipe fittings adopted in the water supply engineering with buried polyethylene pipeline shall respectively comply with those specified in the current national standards "Polyetylene Pipes for Water Supply" (GB/T 13663) and "Polyethylene (PE) Pipings Systems for Water Supply--Part 2: Fittings" (GB/T 13663.2), and their hygienic performances shall meet the requirements of the current national standard "Standard for Safety Evaluation of Equipment and Protective Materials in Drinking Water System" (GB/T 17219).
3.1.2 The acceptance conducted when the users accept pipes, pipe fittings and accessories shall mainly check the following items:
1 Product certificate;
2 Test report;
3 Class (PE80 or PE100) and designation of the used polyethylene raw materials;
4 Appearance;
5 Length;
6 Color;
7 Out-of-roundness;
8 Outside diameter and wall thickness;
9 Production date;
3.1.3 The water supply system of buried polyethylene pipeline shall select the pipes and pipe fittings produced with such polyethylene compounds of which the minimum required strength (MRS) is no less than 8.0MPa.
3.1.4 The pipe fittings connected with the pipes, rubber sealing rings and other accessories should be supplied by the pipe manufacturer in package.
3.2 Pipes
3.2.1 The specifications and dimensions of pipes shall be in accordance with those specified in Table 3.2.1-1 and Table 3.2.1-2.
Contents
1 General Provisions
2 Terms and Symbols
2.1 Terms
2.2 Symbols
3 Materials
3.1 General Requirements
3.2 Pipes
3.3 Pipe Fittings
3.4 Transport and Storage of Pipes and Pipe Fittings
4 Design of Piping System
4.1 General Requirements
4.2 Pipeline Arrangement
4.3 Hydraulic Calculation of Pipeline
4.4 Structural Design of Pipeline
5 Pipeline Connection
5.1 General Requirements
5.2 Hot-melting Connection
5.3 Electro-fusion Connection
5.4 Socket and Spigot Joint Connection
5.5 Flanged connection
5.6 Steel-plastic Transition Joint
5.7 Connection of Branch Pipe, Inlet Pipe and Existing Pipe
6 Pipeline Laying
6.1 General Requirements
6.2 Groove Excavation and Foundation
6.3 Pipeline Laying and Backfilling
7 Hydraulic Test, Flushing and Disinfecting
7.1 General Requirements
7.2 Hydraulic Test
7.3 Flushing and Disinfecting
8 Completion Acceptance of Piping System
9 Pipeline Maintenance
9.1 General Requirements
9.2 Maintenance Method of Pipeline
Appendix A Connection Mode of Polyethylene Water Supply Pipeline
Appendix B Hydraulic Slope Table of Buried Polyethylene Water Supply Pipeline
Appendix C Combined Deformation Modulus of Pipe Lateral Soil
Appendix D Determination of the Standard Value of Vertical Pressure at Pipe Top
Explanation of Wording in this Specification
