CECS 142-2002 in English

1 General Provisions

1.0.1 This Specification was formulated with a view to implementing the national technical and economic policies in structural design of buried cast-iron pipeline of water supply and sewerage engineering and achieving advanced technology, economic feasibility, safety and usability, and quality assurance.
1.0.2 This Specification is applicable to the structural design of buried grey cast-iron pipeline, ductile cast-iron pipeline and as-cast ductile cast-iron pipeline of general water supply and sewerage engineering in public utilities and industrial enterprises. The burying condition of pipelines is flat subgrade or artificial shapped subgrade. This Specification is not applicable to the structural design of such buried cast-iron pipeline with special requirements.
1.0.3 This Specification was compiled according to the principles specified in the current national standard "Structural Design Code for Special Structures of Water Supply and Waste Water Engineering" (GB 50332).
1.0.4 In addition to complying with this Specification, the structural design of buried cast-iron pipeline of water supply and sewerage engineering in earthquake area, collapsible loess area, expansive soil area and other areas with special conditions also shall be in accordance with those specified in the current relevant standards of the nation.
1.0.5 During construction of cast-iron pipeline, the requirements of the current national standard "Code for Construction and Acceptance of Water and Sewerage Pipeline Works" (GB 50268) also shall be complied with.
 
2 Main Symbols

2.0.1 Actions and action effects on pipeline
Eak - the standard value of the resultant force of active earth pressure;
Epk - the standard value of the resultant force of passive earth pressure;
Fep,k - the standard value of lateral active earth pressure;
Ffw,k - the standard value of buoyancy;
Fsv,k - the standard value of vertical earth pressure on pipe top per unit length of pipeline;
Fwd,k - the standard value of designed internal water pressure of pipeline;
Fwk - the standard value of working pressure of pipeline;
Glk - the standard value of structure deadweight of cast-iron pipeline;
Gwk - the standard value of water weight in pipeline;
qvk - the standard value of vertical pressure per unit area on pipe top generated by ground vehicle wheel pressure;
qmk - the standard value of vertical pressure generated by ground heaped load;
ωmax - the maximum vertical deformation of pipeline;
2.0.2 Material performance
Ep - the elasticity modulus of cast-iron pipeline;
Ee - the deformation modulus of pipe-side backfill;
En - the deformation modulus of undisturbed soil on both sides of foundation trench;
Ed - the integrated deformation modulus of pipe-side soil;
fmc - the design value of bending tensile strength of grey cast-iron pipeline;
ftc - the design value of tensile strength of grey cast-iron pipeline;
ftd - the design value of tensile strength of ductile cast-iron pipeline and as-cast ductile cast-iron pipeline.
2.0.3 Geometric parameters
a - the touchdown distribution length of single wheel;
b - the touchdown distribution width of single wheel;
b0 - the calculated width;
D1 - the outside diameter of pipeline;
D0 - the calculated diameter of pipeline;
Hs - the earth cover from pipe top to design ground;
r0 - the calculated radius of pipeline;
r1 - the outside radius of pipeline;
t0 - the calculated wall thickness of pipeline;
t - the design wall thickness of pipeline.
2.0.4 Calculation coefficients
CG1 - the effect coefficient of deadweight of cast-iron pipeline structure;
CG,sv - the effect coefficient of vertical earth pressure;
CG,ep - the effect coefficient of lateral earth pressure;
CGw - the effect coefficient of water weight in pipeline;
CQ,wd - the effect coefficient of designed internal water pressure;
CQv - the effect coefficient of ground vehicle load;
CQm - the effect coefficient of ground heaped load;
DL - the effect coefficient of deformation hysteresis;
kqm, kvm, khm, kwm - the maximum bending moment coefficient of wall section of cast-iron pipeline respectively under the action of structure deadweight, vertical earth pressure, lateral earth pressure and internal water weight of cast-iron pipeline;
kb - the vertical deformation coefficient of flexible pipe under the action of vertical earth pressure;
Ks - the resistance coefficient of anti-slide stability
Kf - the resistance coefficient of anti-floating stability;
γG1 - the partial coefficient of structure deadweight of pipeline;
γG,sv, γG,ep - respectively the partial coefficient of vertical earth pressure and lateral earth pressure;
γGw - the partial coefficient of water weight in pipeline;
γQ - the partial coefficient of designed internal water pressure, ground vehicle load and heaped load;
γs - the unit weight of backfill;
Ψc - the combination coefficient of variable actions;
Ψq - the quasi-permanent value coefficient of variable action;
 
3 Materials

3.1 Material Quality Standards

3.1.1 The quality of grey cast-iron pipes shall respectively comply with the requirements of the current national standards "Cast-iron Pressure Pipe Made by Continuous Casting Process" (GB 3422) and "Soft Mechanical Joint Grey Cast Iron Pipe" (GB 6483).
3.1.2 The quality of ductile cast-iron pipes shall comply with the requirements of the current national standard "Centrifugal Casting Ductile Iron Pipe" (GB 13295).
3.1.3 In addition to that the quality of as-cast ductile cast-iron pipes shall comply with the requirements of the national standard "Centrifugal Casting Ductile Iron Pipe" (GB 13295), the elongation index shall be determined according to the data provided by the manufacturer.

3.2 Calculation Indexes

3.2.1 The design strength values of grey cast-iron pipes shall be adopted according to Table 3.2.1.
Table 3.2.1 Design Strength Values of Grey Cast-iron Pipe (N/mm2)
Strength type Symbol Diameter (mm)
≤300 350~700 ≥800
Bending strength fmc 185 155 135
Tensile strength ftc 78
3.2.2 The design value of tensile strength of ductile cast-iron pipes, ftd, shall be taken as 230N/mm2.
3.2.3 The design value of tensile strength of as-cast ductile cast-iron pipes, ftd, shall be taken as 210N/mm2.
3.2.4 The physical property indexes of cast-iron pipes may be adopted according to Table 3.2.4.
Table 3.2.4 Physical Property Indexes of Cast-iron Pipes
Pipe type Elasticity modulus Ep
(N/mm2) Unit weight γi
(kN/m3)
Grey cast-iron pipe (0.2~0.4)×105 72
Ductile cast-iron pipe and as-cast ductile cast-iron pipe 1.6×105 70.5

1 General Provisions
2 Main Symbols
3 Materials
4 Actions on Cast-iron Pipeline Structure
5 Basic Design Provisions
6 Calculation at Ultimate Limit State
7 Deformation Checking of Ductile Cast-iron Pipeline and As-cast Ductile Cast-iron Pipeline
8 Structure Requirements
Appendix A Bending Moment Coefficient of Round Rigid Pipeline under the Action of Various Loads
Appendix B Maximum Bending Moment Coefficient and Vertical Deformation Coefficient of Round Flexible Pipeline under the Action of Various Loads
Appendix C Integrated Deformation Modulus of Pipe-side Soil
Explanation of Wording in this Specification