A Guide to
Sewer Selection
and Installation
ISSUE: 01A Guide to
Sewer Selection
and Installation
1.0
INTRODUCTION
1
1.1
Purpose of This Guide
1
1.2
Who Should Use This Guide
1
1.3
How to Use This Guide
1
2.0
SEWER PIPELINE - REGISTRATION AND APPROVAL
2
2.1
General
2
2.2
Pipes Submission and Evaluation
2
2.2.1 General
2
2.2.2 Submission Procedures
3
2.2.3
Evaluation Process
3
3.0
SEWER PIPELINE - SELECTION GUIDE
5
3.1
General
5
3.2
Selection Criteria
5
3.2.1
Material
6
3.2.2
Joint
6
3.2.3
Structural Design
7
3.2.4
Quality Assurance
7
3.3
Selection Process
7
3.3.1 Exclusions of Use Explanations
12
4.0
SEWER PIPELINE – MATERIAL SELECTION
15
4.1
Gravity Sewerage System
15
4.1.1
General
15
4.1.2
Definition
15
4.1.3
Precautions and Principal Applications of Sewerage Gravity
4.2.1 Manufacture
18
4.2.2 Protective Coatings/Linings
20
4.2.3 Sizes/Classes
20
4.2.4 Joints
21
4.2.5 Fittings
22
4.2.6 Pipeline Hydraulic Design
24
4.2.7 Application of Pipes
25
4.3
Reinforced Concrete (RC) Pipe
26
4.3.1
Manufacture
27
4.3.2
Protective Coatings/Linings
28
4.3.3
Sizes/Classes
28
4.3.4
Joints
29
4.3.5
Fittings
31
4.3.6
Pipeline Hydraulic Design
32
4.3.7
Application of Pipes
33
4.4
Ductile Iron (DI) Pipe
34
4.4.1
Manufacture
35
4.4.2
Protective Coatings/Linings
37
4.4.3
Sizes/Classes
37
4.4.4
Joints
38
4.4.5
Fittings
40
4.4.6
Pipeline Hydraulic Design
41
4.4.7
Application of Pipes
42
4.5
Glass-fibre Reinforced Plastic (GRP) Pipe
43
4.5.1 Manufacture
44
4.5.2 Protective Coatings/Linings
45
4.5.3 Sizes/Classes
45
4.5.4 Joints
46
4.5.5 Fittings
47
4.5.6 Pipeline Hydraulic Design
48
4.6.1 Manufacture
51
4.6.2
Protective Coatings/Linings
55
4.6.3
Sizes/Classes
55
4.6.4 Joints
55
4.6.5
Fittings
58
4.6.6
Pipeline Hydraulic Design
58
4.6.7
Application of Pipes
59
5.0
FORCE MAIN
63
5.1
General
63
5.1.1 Definition
63
5.1.2 Pipe Materials and Application Conditions
63
5.2
Ductile Iron (DI) Pipe
64
5.2.1
Manufacture
65
5.2.2
Protective Coatings/Linings
65
5.2.3
Sizes/Classes
65
5.2.4
Joints
65
5.2.5
Fittings
67
5.2.6
Pipeline Hydraulic Design
68
5.2.7 Application of Pipe
68
5.3
Steel Pipes
69
5.3.1
Manufacture
71
5.3.1.1
Mild Steel
71
5.3.1.2
Stainless Steel
72
5.3.2
Protective Coatings/Linings
72
5.3.2.1
Mild Steel
73
5.3.2.2
Stainless Steel
73
5.3.3
Sizes/Classes
72
5.3.4
Joints
74
5.3.5
Fittings
75
5.3.6
Pipeline Hydraulic Design
76
5.4.1 Manufacture
78
5.4.2 Protective Coatings/Linings
78
5.4.3 Sizes/Classes
78
5.4.4 Joints
78
5.4.5 Fittings
80
5.4.6 Pipeline Hydraulic Design
80
5.4.7 Application of Pipes
81
5.5
Acrylonitrile Butadiene Styrene (ABS) Pipe
82
5.5.1
Manufacture
83
5.5.2
Protective Coatings/Linings
84
5.5.3
Sizes/Classes
84
5.5.4
Joints
85
5.5.5
Fittings
86
5.5.6
Pipeline Hydraulic Design
87
5.5.7
Application of Pipes
87
5.6
Solid Wall HDPE Pipe
88
5.6.1
Manufacture
89
5.6.2
Protective Coatings/Linings
90
5.6.3
Sizes/Classes
90
5.6.4
Joints
90
5.6.5
Fittings
92
5.6.6
Pipeline Hydraulic Design
92
5.6.7 Application of Pipes
93
6.0
VACUUM SEWERAGE SYSTEMS
94
6.1
General
94
6.2
Acrylonitrile Butadiene Styrene (ABS) Pipe
95
6.2.1 Manufacture
96
6.2.2 Protective Coatings/Linings
96
6.2.3
Sizes/Classes
96
6.2.4
Joints
97
6.2.5
Fittings
97
6.3.1
Manufacture
99
6.3.2
Protective Coatings/Linings
99
6.3.3
Sizes/Classes
99
6.3.4
Joints
99
6.3.5
Fittings
99
6.3.6
Pipeline Hydraulic Design
99
7.0
PIPE JACKING
100
7.1
General
100
7.2
Vitrified Clay (VC) Pipe
101
7.2.1
Manufacture
102
7.2.2
Protective Coatings/Linings
102
7.2.3
Sizes/Classes
102
7.2.4
Joints
103
7.2.5
Pipeline Hydraulic Design
103
7.3
Reinforced Concrete (RC) Pipe
104
7.3.1
Manufacture
105
7.3.2
Protective Coatings/Linings
105
7.3.3
Sizes/Classes
105
7.3.4
Joints
106
7.3.5
Pipeline Hydraulic Design
106
8.0
SEWER PIPELINE - DESIGN GUIDE
107
8.1
General
107
8.2
Rigid Pipe
107
8.2.1 Vitrified Clay (VC) Pipe
107
8.2.1.1
Pipeline Structural Design
107
8.2.1.2
Pipeline Embedment
108
8.2.2 Reinforced Concrete (RC) Pipe
110
8.2.2.1
Pipeline Structural Design
110
8.3.1
Flexible Pipeline Structural Design
113
8.3.2
Flexible Pipeline Embedment
114
8.3.3
DI Pipe
116
8.3.4 GFRP Pipe
117
8.3.5 Profile Wall HDPE Pipe
118
8.3.6 ABS Pipe
118
8.3.7 Steel Pipe
119
8.3.7.1
Pipeline Structural Design
119
8.3.7.2
Pipeline Embedment
119
8.3.8 Solids Wall HDPE Pipe
120
8.3.8.1
Pipeline Structural Design
120
8.3.8.2
Pipeline Embedment
120
9.0
SEWER PIPELINE – TESTING GUIDE, SITE HANDLING AND
INSTALLATION 123
9.1
General
123
9.2
Field Testing
123
9.2.1
General Pipeline Testing Guide
124
9.2.2
Test for Straightness, Obstruction and Grade
124
9.2.3
Low Pressure Air Test
124
9.2.4 Hydrostatic Test
124
9.2.5 High Pressure Water Test
125
9.2.6 High Pressure Leakage Test
125
9.2.7 Vacuum Test
126
9.2.8 Infiltration Test
126
9.2.9 CCTV Inspection
126
9.3
Factory Testing
127
9.4
Site Handling and Installation Guide
128
9.4.1
Dos and Don’ts
128
9.5
Handling and Installation Practice
133
9.5.1
Storage
133
9.5.2
Excavation
133
9.5.3
Pipe Cutting
134
9.5.4
Pipe Jointing
134
APPENDIX B :
Product Details: Sewer Pipes and Fittings Form
APPENDIX C :
Evaluation Criteria Form
Table 3.1 Type of Pipelines for Various Sewerage Systems
Table 3.2 Application of Various Types of Pipes in Sewerage Systems Table 3.3 Limit on Use for Various Types of Pipes for Sewerage Systems Table 3.4 Exclusion of Use
Table 4.1 Gravity Sewer Pipeline Materials and Application
Table 4.2 Precautions and Principal Applications of Gravity Sewer Pipeline System Table 4.3 Summary of VC Pipes Design and Specifications for Gravity Sewerage System Table 4.4 Preferred Nominal Lengths of VC Pipes
Table 4.5 Crushing Strength (FN) in kN/m for Various Sizes of VC Pipes Table 4.6 Allowable Angular Deflection of VC Pipes
Table 4.7 Colebrook-White Roughness Coefficient, kBBBsBBB for VC Pipes
Table 4.8 Various Pipeline Hydraulic Design Equations of VC Pipes for Gravity Sewerage System Table 4.9 Advantages and Disadvantages of VC Pipes
Table 4.10 Summary of RC Pipes Design and Specifications for Gravity Sewerage System Table 4.11 Crushing Test Loads of RC Pipes for Gravity Sewerage System
Table 4.12 Allowable Angular Deflection of RC Pipes
Table 4.13 Colebrook-White Roughness Coefficient, kBBBsBBB for RC Pipes
Table 4.14 Various Pipeline Hydraulic Design Equations of RC Pipes for Gravity Sewerage System Table 4.15 Advantages and Disadvantages of RC Pipe
Table 4.16 Summary of Ductile Iron Pipes Design and Specifications for Gravity Sewerage System Table 4.17 HAC Lining Thickness of Various Sizes of DI Pipes
Table 4.18 Standard Pipe Lengths of Various Sizes of DI Pipes Table 4.19 Allowable Angular Deflection of Jointing for DI Pipes
Table 4.20 Various Pipeline Hydraulic Design Equations of DI Pipes for Gravity Sewerage System Table 4.21 Advantages and Disadvantages of Ductile Iron Pipes
Table 4.22 Summary of GFRP Pipes Design and Specifications for Gravity Sewerage System Table 4.23 Nominal Sizes of GFRP Pipes
Table 4.24 Angular Deflection Limits Relative to the Nominal Size of the GFRP Pipework Table 4.25 Methods of Hydraulic Design of GFRP Pipe
Table 4.26 Advantages and Disadvantages of GFRP Pipe
Table 4.27 Summary of Profile Wall HDPE Pipes Design and Specifications for Gravity Sewerage System
Table 4.28 Classifications of Profile Wall HDPE Pipe
Table 4.29 Colebrook-White Roughness Coefficients (kBBBsBBB) for Profile Wall HDPE Pipe Table 4.30 Advantages and Disadvantages of Profile Wall HDPE Pipe
Table 4.31 Technical Comparison of Various Types of Pipe for Gravity Sewerage System Table 4.32 Summary of Comparison for Various Types of Pipe for Gravity Sewerage System Table 5.1 Pressure Sewer Pipe Materials and Application
Table 5.2 Summary of DI Pipes Design and Specifications for Force Main Table 5.3 Colebrook-White Roughness Coefficient, kBBBsBBB for DI Pipes Table 5.4 Advantages and Disadvantages of DI Pipes for Force Main
Table 5.5 Summary of Mild Steel Pipes Design and Specifications for Force Main Table 5.6 Summary of Stainless Steel Pipes Design and Specifications for Force Main Table 5.7 Colebrook-White Roughness Coefficient (kBBBsBBB) for Steel Pipes
Table 5.8 Advantages and Disadvantages of Steel Pipes
Table 5.9 Summary of GRP Pipe Design and Specifications for Force Main
Table 5.10 Angular Deflection Limits Relative to the Nominal Size of GRP Pipelines Table 5.11 Colebrook-White Roughness Coefficient, kBBBsBBB for GRP Pipes
Table 5.12 Advantages and Disadvantages of GRP Pipes for Force Main Table 5.13 Summary of ABS Pipes Design and Specifications for Force Main Table 5.14 Dimensions of ABS for Force Main
Table 5.15 Classifications of ABS Pipes for Force Main
Table 5.16 Colebrook-White Roughness Coefficients (kBBBsBBB) of ABS Pipes Table 5.17 Advantages and Disadvantages of ABS Pipes
Table 6.1 Summary of ABS Pipes Design and Specifications for Vacuum Sewerage System Table 6.2 Dimensions Of Abs For Vacuum Sewerage System
Table 6.3 Classifications of ABS Pipes for Vacuum Sewerage System
Table 6.4 Summary of Solid Wall HDPE Pipe Design and Specifications for Vacuum Sewerage System
Table 7.1 Summary of VC Pipes Design and Specifications for Pipe Jacking Table 7.2 Tolerance on Internal and External Diameter of VC Pipes for Pipe Jacking Table 7.3 Allowable Angular Deflection of VC Pipes for Pipe Jacking
Table 7.4 Summary of RC Pipes Design and Specifications for Pipe Jacking Table 7.5 Crushing Loads of RC Pipes for Jacking Pipe
Table 7.6 Minimum Angular Deflection and Straight Draw Joints of RC Pipes for Pipe Jacking
Table 8.1 Compositions of Fill Material for RC Pipeline Embedment
Table 8.2 Bedding Factors for Working Dead Loads for Various Types of Support Table 8.3 Typical Flexible Pipe Materials
Table 8.4 Maximum Particle Size of Embedment Material for Flexible Pipeline Table 8.5 Minimum Relative Compaction of Embedment Material for Flexible Pipeline Table 8.6 Notations Applicable in the Guidelines
Table 8.7 Minimum Cover (H) for Flexible Pipeline Table 8.8 Minimum Embedment Zone Dimensions Table 9.1 Summary of Field Testing for Sewer Pipelines
Figure 2.1 Flow Chart of Product Registration and Approval Procedures Figure 3.1 Steps of Preliminary Selection of Sewer Pipeline
Figure 4.1 Types of VC Pipes
Figure 4.2 Typical Manufacturing Process for VC Pipes
Figure 4.3 Spigot Socket with Rubber ‘O’ Ring Joint for VC Pipes Figure 4.4 Skid Type Sealing Joints for VC Pipes
Figure 4.5 Typical Range of Fittings for VC Pipes Figure 4.6 Types of RC Pipes
Figure 4.7 Typical Flexible Joint of Spigot Socket RC Pipes Figure 4.8 Typical Flexible Joint of Rebated/Ogee RC Pipes Figure 4.9 Typical Double Spigot Joint with Collar of RC Pipes Figure 4.10 Typical Range of Fittings for RC Pipes
Figure 4.11 Types of DI Pipes
Figure 4.12 Typical Manufacturing Process of Centrifugal Casting for DI Pipes Figure 4.13 Typical Push in Joints for DI Pipes
Figure 4.14 Typical Self-anchoring Push-in Joint for DI Pipes Figure 4.15 Typical Ranges of Flange for DI Pipes
Figure 4.16 Various Range of Fittings for DI Pipes Figure 4.17 Typical Filament Wound GRP Pipes Figure 4.18 Typical Centrifugally Cast GRP Pipes Figure 4.19 Definition of Stiffness for GRP Pipes
Figure 4.20 Typical Integral Socket and Spigot Joint of GRP Pipes Figure 4.21 Typical Loose Collar Joint of GRP Pipes
Figure 4.22 Typical Rigid Joints of GRP Pipe Figure 4.23 Various Ranges of Fittings for GRP Pipe
Figure 4.24 Types of Profile Wall HDPE Pipe for Gravity System
Figure 4.25 Various Forms of Profile Wall HDPE Pipe
Figure 4.26 Typical Manufacturing Process of Rotational Moulding Helical Profile Wall HDPE Pipes (Option 1)
Figure 4.27 Typical Manufacturing Process of Rotational Moulding Helical Profile Wall HDPE Pipes (Option 2)
Figure 4.28 Helical Pattern of Profile Wall HDPE Pipe
Figure 4.29 Typical Manufacturing Process of Annular Profile Wall HDPE Pipe Figure 4.30 Annular Pattern of Profile Wall HDPE Pipe
Figure 4.31 Spigot Socket with Rubber Ring Seals Joint for Profile Wall HDPE Pipes Figure 4.32 Typical Socket Fusion Welding for Profile Wall HDPE Pipes
Figure 4.33 Butt Weld Joint of Profile Wall HDPE Pipe
Figure 4.34 Butt Welded Joint of Spigot Socket Profile Wall HDPE Pipe Figure 4.35 Flange Ends Joint of Profile Wall HDPE Pipe
Figure 4.36 Screwed Fittings for Jointing of Profile Wall HDPE Pipe Figure 4.37 Plastic Fittings for Jointing of Profile Wall HDPE Pipe
Figure 4.38 Various Ranges of Fittings for Profile Wall HDPE Pipe for Gravity System Figure 5.1 Typical Bolted Mechanical Joint of DI Pipes for Force Main
Figure 5.2 Typical Flange Adapters of DI Pipe for Force Main
Figure 5.3 Typical Self-anchoring Flange Adapters of DI Pipe for Force Main
Figure 5.4 Typical Self -anchoring Bolted Mechanical Joints of DI Pipe for Force Main Figure 5.5 Typical Slip-on Coupling for DI Pipes
Figure 5.6 Typical Self-anchoring Tie-bar Joints for DI Pipes Figure 5.7 Additional Ranges of DI Fittings for Force Main
Figure 5.8 Typical Manufacturing Process of Mild Steel Pipes for Force Main Figure 5.9 Typical Manufacturing Process for Stainless Steel Pipes for Force Main
Figure 5.10 Butt-welded Joint Preparation of Steel Pipes Figure 5.11 Sleeve Welded Joints of Steel Pipes Figure 5.12 Slip-on Type Coupling of Steel Pipes
Figure 5.13 Threaded and Coupled Joints Recessed for Bitumen Lining Figure 5.14 Various Ranges of Fittings for Steel Pipes
Figure 5.15 Typical slip-on coupling Figure 5.16 Typical stepped slip-on coupling
Figure 5.19 Typical flange joints
Figure 5.20 Various Ranges of DI Fittings for GFRP Pipes Figure 5.21 Typical Manufacturing Process Flow of ABS Pipes
Figure 5.22 Types of ABS Pipes
Figure 5.23 Typical Spigot-socket with Solvent Cement Joint of ABS Pipes Figure 5.24 Typical Spigot-socket with Elastomeric Seal Joint of ABS Pipes Figure 5.25 Typical Stub Flange Joint for ABS Pipes
Figure 5.26 Various Ranges of Fittings for ABS Pipes
Figure 5.27 Typical Manufacturing Process of Solid Wall PE Pipe Figure 5.28 Typical Butt Fusion Welding for Solid Wall HDPE Pipes
Figure 5.29 Butt Fusion Welding of Spigot socket Joints for Solid Wall HDPE Pipes Figure 5.30 Typical Flange Joints of Solid Wall HDPE Pipes
Figure 5.31 Fabricated Fittings for Butt Fusion of Solid Wall HDPE Pipes
Figure 5.32 Stub End and MS Flange Fittings for Solid Wall HDPE Pipes Figure 5.33 Plastics Compression Fittings for Solid Wall HDPE Pipes Figure 6.1 Typical Spigot-socket with Solvent Cement Joint of ABS Pipes Figure 6.2 Typical Stub Flange Joint for ABS Pipes
Figure 7.1 Type of VC Pipe for Pipe Jacking Figure 7.2 Types of RC Pipes for Pipe Jacking
Figure 7.3 Typical Flexible Joint of Rebated/Ogee RC Pipes Figure 7.4 Typical Double Spigot Joint with Collar of RC Pipes Figure 8.1 Construction Method of Class ‘A’ Bedding
Figure 8.2 Construction Method of Class ‘B’ Bedding Figure 8.3 Construction Method of Concrete Encasement
Figure 8.4 Construction Method of Type H1 and Type H2 Support Figure 8.5 Construction Method of Type H3 Support
Figure 8.6 Construction Method of Type HS Support
Figure 8.7 Terminology and Typical Construction of Pipe Support for Flexible Pipeline Figure 9.1 Typical Field Pressure Test Equipment Layout
1.0 INTRODUCTION
1.1
Purpose of This Guide
This Guide provides guidelines to material selection of sewers for appropriate application as well as some recommendation for proper pipe handling, installation and testing practices. It draws on a wide base of knowledge and experience from operators and manufacturers.
The Guide also contains reference information on pipe registration requirements and the approval status of the pipe manufacturers/suppliers. Product information such as pipe material, sizes and limitation on use of sewer pipes available in Malaysia and information on pipe handling, installation and testing are included in the Guide.
The Guide does not cover the installation of internal plumbing systems to buildings as these procedures are managed by Local Authorities.
1.2
Who Should Use This Guide
This Guide is primarily for owners, developers, consulting engineers, manufacturers, suppliers and Public Authorities whose developments or products involved sewer pipes.
1.3
How to Use This Guide
The information in this Guide is listed in five main categories described in the following sections:
• Sewer Pipeline - Registration & Approval Section 2.0
• Sewer Pipeline - Selection Guide Section 3.0
• Sewer Pipeline - Material Selection
- Gravity Sewerage System Section 4.0
- Force Main Section 5.0
- Vacuum Sewerage System Section 6.0
- Pipe Jacking Section 7.0
• Sewer Pipeline - Design Guide Section 8.0
2.0 SEWER PIPELINE - REGISTRATION AND
APPROVAL
2.1 General
All manufacturers/suppliers must obtain approval from the Director General of Sewerage Services (DGSS) for the ranges of pipes, which they intend to supply to the sewerage industries in Malaysia.
2.2
Pipes Submission and Evaluation
2.2.1 General
Flow chart of the sewer pipe submission and evaluation process is shown in Figure 2.1.
2.2.2 Submission
Procedures
The following are procedures for the preparation and submission of document to DGSS: 1. Obtain submission forms of
a. Checklist B (see Appendix A); and
b. Product Details – Sewer Pipes and Fittings Form (see Appendix B) from DGSS offices or from the DGSS website at www.jpp.gov.my.
Photocopies of the submission forms attached in this Guide are acceptable, however a confirmation shall be made with the relevant authority if there is any latest revision being issued.
2. Prepare a complete set of document as per Checklist B including company profile and technical details of the products. All the submission documents shall be bound neatly.
3. Submit two (2) copies of the submission documents together with the Checklist B and the Product Details – Sewer Pipes and Fittings Form to DGSS for evaluation.
4. The manufacturer/supplier will be notified on the status of evaluation within 1 month of the date of submission received whether:
• Additional information/clarification may be requested; The product has been approved with or without conditions; •
• The product has been rejected.
5. The manufacturer/supplier shall give the feedback on additional information/clarification requested within two (2) months; if not the DGSS will close the submission file and any respond after that will be considered as a new submission.
6. The manufacturer/supplier, whose product has been rejected, may appeal to the DGSS by providing valid reasons.
2.2.3 Evaluation
Process
The following are steps of evaluation adopted by the technical evaluation committee:
1. Check if the submission of the document contains all the necessary information for evaluation. If not, the manufacturer will be requested to submit the outstanding information.
2. Evaluate the submission of the document based on a set of evaluation criteria as attached in Appendix C, the DGSS Guidelines and other relevant standards.
3. Notify the manufacturers/suppliers within 3 months of the date of submission received whether:
Further information/clarification is required; •
•
• The product has been approved, with or without conditions; The product has been rejected.
Figure 2.1: Flow Chart of Product Registration and Approval Procedures
Notify the manufacturer/supplier
that the submission's rejected
Submission Satisfactory
Notify the manufacturer/supplier on
the approval granted Yes
No DGSS Design
Guidelines & Policy DGSS Technical Committee
evaluating the submission Yes Submission Complete? Notify
manufacturer/supplier No
Obtain Checklist B and Product ails-Sewer Pipes and Fittin
Form from DGSS
Det gs
(Sample in Appendix A & B)
Prepare & submit two (2) complete sets of documents to DGSS DGSS initial check Manufacturer/supplier to complete the submission Start Evaluation Criteria (See Appendix C) Related Reference Material
3.0
SEWER PIPELINE - SELECTION GUIDE
3.1 General
Within the past few decades there has been a growing choice of sewerage system. There is an increased range of materials available for sewerage applications and there may be significant economic advantages to a more informed approach to materials selection.
New sewerage systems are being introduced as a result of the utilisation of various plastic materials while traditional systems are being improved to overcome deficiencies.
A greater choice of sewerage systems means more sewer materials can be applicable. The selection of suitable pipe material for the sewerage system and particular application requires knowledge outside the normal training of the designer with some complex issues requiring specialist materials and structural knowledge.
Handling, installation and testing methods could also vary for different pipe materials.
An increasingly competitive market place has made it more difficult to formulate objective technical decisions on materials. Information from suppliers is fragmented and focuses on the advantages rather than the disadvantages of a particular material.
The section provides a summary of necessary information to lead to the accurate selection of sewer pipeline system.
3.2 Selection
Criteria
The fundamental requirements of a piping selection for sewage conveyance system are:
• Availability of complete range of components to suit the system’s design, function and repair, e.g. where service connections are required, appropriate fittings must be available
• Achieving the specified design life within the specified level of maintenance.
Specified design life may be for the length of time that a service is to be provided to an area of
customers or shorter time if there is plan to renovate, upgrade or replace the piping system in future. The design life generally sought by authorities for most instances is at least 100 years with special circumstances permitting a shorter life.
Specified level of maintenance that would be desirable by most authorities at a minimum as
to require infrequent cleaning of silts and slimes.
The design life, maintenance level and ranges of product form the basis for establishing criteria for selecting sewer material. The main criteria identified for the purposes of selecting sewer material are as follows: Material; • • • • Joint;
Structural design; and Quality assurance.
3.2.1 Material
Materials to be used in sewer pipe, fittings, elastomeric seals, pipe coatings and other accessories must have the following properties:
Good corrosion resistance at the internal wall to hydrogen sulphide and sulphuric acid produced in septic sewage, and any industrial discharges attacks;
• • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • •
External wall to remain chemically stable when exposed to aggressive soils and groundwater; Resist microbiological attack from the internal and external environment;
Good resistance to abrasion caused by sewage flow and any maintenance cleaning; Remain sufficiently impermeable;
Suitable for the site condition;
Factors to be taken into account in selecting materials should include:
The nature of the effluent and the possibility of chemical attack or mechanical damage; The nature of the ground conditions and the possibility of subsidence or chemical attack; The quality of workmanship which may be expected and the degree of supervision to be provided;
Third party interference to the pipe surrounding.
3.2.2
Joint
The pipe and fittings jointing systems and access chamber connections need to have the following characteristics:
Able to be consistently constructed in the specified manner under field conditions; Resist groundwater infiltration;
Resist sewage exfiltration; Resist root intrusion;
Resist pullout for an elastomeric sealing joint;
Have sufficient tensile, shear and bending strength for welded joints; Not cause excessive snagging and fouling;
Not significantly affect the hydraulic flow roughness, through mismatching of surfaces and joint gap;
Not impede routine maintenance operations; Resistance to damage due expansion; and Able to joint two pipes of different materials.
For elastomeric sealing joints, such performance is required for one and a combination of configurations that are possible with the joints such as:
Axial displacement (minimum insertion of spigot);
Axial deflection (relative deflection of one pipe length to adjoining pipe length);
Ring misalignment (shear); Ring ovalisation (for flexible pipe);
The elastomer properties affecting long term sealing performance are: Hardness;
Rate of compression; Stress relaxation; Water absorption; Resistance to ageing; Resistance to chemicals; and
3.2.3 Structural
Design
The selected sewer at most installation conditions should not result in excessive complication in the installation process, e.g. internal bracing of flexible pipe, but capable to offer the following structural properties:
Resist ring cracking or crushing, where rigid pipe is used; •
• • • •
Resist excessive ring deflection, circumferential strain and ring buckling where flexible pipe is used;
Resist shearing and longitudinal bending where sufficient or uniform underlying support cannot be provided to the pipeline or excessive ground movement is expected;
For rising mains, resist cyclic pressure loading; and The shape of the pipe should not deform easily.
3.2.4 Quality
Assurance
Assurance is required that the material, pipe and fittings are manufactured and supplied so that they will consistently meet nominated standards/specifications. Such assurance is achieved by requiring the manufacturer to have a quality management system certified to comply with the International standard ISO 9001 or 9002 and an approved inspection and test plan to ensure conformance with the nominated material, pipe and fittings standards/specifications.
3.3 Selection
Process
Compliance to the selection criteria may vary among the pipeline systems under various installation conditions. The following steps shown in Figure 3.1 below can be adopted for preliminary selection of suitable pipeline systems using this guideline:
Figure 3.1: Steps of Preliminary Selection of Sewer Pipeline
Identify the type of pipeline from Table 3.1
Getting the product information of the selected pipeline from Section 4.0, 5.0 and 6.0 Identify the approved
manufacturers/suppliers from Appendix D, Table D1
Identify the exclusion of use in certain pipeline system under specific condition from Table 3.4 Check the suitability of the selected
pipeline to the design condition from Table 3.2 and 3.3
Table 3.1: Type of Pipelines for Various Sewerage Systems
System Type of Pipelines Available Size (Diameter)
VC Pipe 100 mm to 600 mm (locally made) 400 mm to 600 mm (imported)
RC Pipe 150 mm to 3600 mm
GRP Pipe 50 mm to 3000 mm
DI Pipe 80 mm to 1200 mm
Gravity Sewer
Profile Wall HDPE Pipe 100 mm to 3000 mm
DI Pipe 80 mm to 1200 mm
Steel Pipe 100 mm to 2200 mm
GFRP Pipe 50 mm to 3000 mm
ABS Pipe 10 mm to 630 mm
Force Main
Solid Wall HDPE Pipe 20 mm to 900 mm Solid Wall HDPE Pipe 20 mm to 900 mm
Vacuum Sewer
ABS Pipe 10 mm to 630 mm
Table 3.2: Application of Various Types of Pipes in Sewerage Systems
Type of Pipe Application
VC • All sizes are applicable.
• Short pipe lengths can be specially used in mine subsidence areas. • Applicable as trenchless technology of pipe.
• Longer pipe length is not recommended because the pipe is likely to suffer beam failure due to the loss of flexibility since less flexible joints will be required for longer pipe.
RC • Where VC pipes is not available. Under local context, only RC pipes with
DN375 mm and above is allowed.
• Applicable as trenchless technology of pipe.
• As an alternative to large diameter flexible pipes where:
a. Native ground modulus inadequate to provide structural support. b. Inadequate geotechnical data available.
c. Inadequate control over embedment placement and compaction. d. Likely third party interference to the pipe surrounding.
GRP • Only for nominated projects or as permitted by the relevant authority.
• Under local context, only size DN 600mm or above are allowed.
• Allowed for above ground use where pipeline is protected from vandalism. • Applicable as trenchless technology of pipe.
• Use under railways only with encasing pipe. • Ends of cut pipe shall be sealed with resin.
• Pipes and couplings used above ground to have power and water approved UV protection.
• Only on sewers that would not require provision of junction for future pipeline extension.
DI • Suitable for above ground use, i.e where bridging support is provided such
as water course, culvert, drain and exposed bridge crossings.
• Only for area where superimposed loading are excessive for other types of pipe.
Table 3.2: Application of Various Types of Pipes in Sewerage Systems (continued)
Type of Pipe Application DI
(continued)
• Pipe lining of high alumina cement or sulphate resisting cement or PPFA cement such as Mascrete is required to minimise corrosion possibility by septic sewage. All linings shall be hydraulically proven of conveying the sewage inside the pipe.
• Where there is potential for excessive differential settlement such as in fill ground (specify DI pipes with locking flexible joints to prevent joint pull out). • Where minimum pipe covers are not possible.
• Where superimposed loadings are excessive for other pipe types.
• Only use in corrosive soil conditions, tidal zones, anaerobic ground conditions and aggressive groundwater when it has an external polyethylene sleeving.
• When used in unstable ground, locking gasket must be provided.
• Use restraining elastomeric seals where buried service congestion prevents the use of thrust blocks or is subject to extreme ground movement.
• Fittings for the pipe shall be made of mild steel.
• Only use under or near DC traction systems with appropriate stray current insulation.
• Suitable for use as conduit pipe for high loading applications.
Steel • Only allow for pressure sewer larger than DN 600mm and with relevant
authority approval.
• Not to be used near electricity transmission lines.
• Suitable for above-ground use and inverted siphon application. • Welding of joints to be performed by qualified welders
• Welded joints to have reinstatement of protection systems on site
• Polyethylene coating should not be used where there is extended exposure to direct sunlight.
ABS • Only for specified depths of cover
• Applicable for above ground use (within conduits) where DI or steel are not suitable.
• Applicable in aggressive groundwater and tidal zone. • Applicable as inverted siphon under watercourse crossings.
Profile Wall PE
• Where VC or RC are not suitable
• Only on sewers that would not require provision of junction for future pipeline extension.
Solid Wall PE
• Applicable in aggressive groundwater and tidal zone. • Suitable in soils with differential movement.
• Applicable as trenchless technology of pipe. • Applicable as syphon under watercourse crossings.
• Not suitable for crossing under railways or major roadways unless within an encasing pipe.
Table 3.3: Limit on Use for Various Types of Pipes for Sewerage Systems
Type of Pipe Limit on Use
VC • Not in unstable ground, i.e refilled ground, tidal zone.
• Not suitable for above ground installation.
• Not in the vicinity of trees with aggressive root systems. • Not use for crossing under water courses.
RC • Not suitable for high H2S levels unless good lining such as HDPE lining is
provided.
• Not in aggressive soils/groundwater or tidal zone unless sulphate resistant cement is used.
GRP • Not in area where future works may affect the pipe side support.
• Not in ground contaminated or possibly contaminated by certain chemicals in concentrations deleterious to GRP resin.
• Do not use pipes/couplings with chips, cracks, crazing, layer delamination or exposed fibres.
• Ends of cut pipe shall be sealed with resin.
• Do not use pipe and couplings, stored unprotected from sunlight for more than 9 months.
• Do not use in ground conditions having low stiffness, e.g. tidal zone. • Not in location subjected to vehicular load and has insufficient cover. • Not in areas subjected to third party interference, e.g. excavations within
2m of pipeline by other parties.
• Not in ground subject to differential settlement or extreme movement • Not in ground offering low side support strength to the pipe.
• Do not use when control of construction practices is not adequate to ensure quality of embedment for flexible pipes.
• Not suitable for uncertainties in geotechnical analysis to determine if flexible pipe structurally suitable.
DI • Not to be used near electricity transmission lines.
• Corrosion may occur when installed above ground because of the tendency of temperature rise at the pipe and sewage, which thus promotes septicity and corrosive conditions.
• Externally coated bitumen pipes not suitable for use in extreme marine environment
Profile Wall PE and Solid Wall PE
• Not in location subjected to vehicular load and has insufficient cover.
• Not in areas subjected to third party interference, e.g. excavations within 2m of pipeline by other parties.
• Not in ground offering low side support strength to the pipe
• Not in ground which allows migration of pipe embedment material into it • Not in ground contaminated with chemicals deleterious to HDPE
• Not suitable for above ground installation
• Not suitable as reticulations systems except for special applications.
ABS • Not suitable for crossing under railways or major roadways unless within
an encasing pipe.
• Not in areas subjected to third party interference, e.g. excavations within 2m of pipeline by other parties.
• Not in ground offering a low side support strength to the pipe
• Not in ground which allows migration of pipe embedment material into it.
Table 3.4: Exclusion of Use
Exclusion of Use Condition
Pipeline System Reason
• VC Subject to low impact damage. • GRP Subject to impact damage. Above ground installation
• HDPE Excessive change in length with change in temperature.
Conditions conducive to septic sewage (e.g. low flows, shallow grades, sewers receiving old sewage or turbulence is expected etc.)
• RC • DI • Steel
Potential for cement mortar corrosion subsequent metallic corrosion.
Environment corrosive to metals • DI
• Steel Potential for metallic corrosion.
• VC
• GRP Subject to low impact damage
Minimum coverage not provided.
• HDPE Side support might be interfered with due to the impact.
• VC (unencased)
• GRP (unencased) Subject to low impact damage (shallow cover).
Crossing under railway
• HDPE (unencased) Difficult to guarantee that side support will not be interfered with. • VC
• GRP Vulnerable to beam and shear failure due to low beam and shear strength.
Extreme Ground Movement
• RC, Steel, DI with
elastomeric joint Susceptible to elastomeric joints pullout.
Very low pipe gradient • RC Vulnerable to have septic sewage which generate high hydrogen sulphide and cause corrosion at the cement mortar.
Ground contaminated with chemicals deleterious to plastic
• HDPE
• ABS The plastic will degrade if the chemical present is deleterious to the plastic. Crossing under water courses • Any pipes with
elastomeric joint
The ground is susceptible to settlement, which may lead to potential pullout of the joint and caused infiltration.
3.3.1
Exclusions of Use Explanations
1. Above ground installation
Pipelines above ground are in many instances exposed to vandalism, so the pipeline material and any corrosion protection coatings must have high resistance to impact and abrasion damage. Direct exposure to sunlight is another concern as this may cause degradation to some plastic materials. 2. Conditions conducive to septic sewage
Under these conditions, the sewage may become septic and produce hydrogen sulphide which may convert to sulphuric acid when released to the atmosphere. Sulphuric acid will corrode concrete pipes and cement mortar used to line ductile iron and steel pipelines and cause subsequent corrosion at the reinforcement bars or other metal parts.
3. Environment corrosive to metals
Environments corrosive to metals include marine environments and may also include some types of atmospheric industrial discharges. A marine environment is an environment in proximity to sea spray or wash.
4. Cover less than minimum
Installation with less than minimum cover may be considered where a downstream sewer level needs to be tied into, where it is not possible to go under existing pipelines, where crossing a watercourse or where installing with minimum cover will result in considerable increase in construction depth elsewhere. Prior approval must be obtained from the relevant authority.
5. Crossing under railway
The following factors limit the suitable pipeline systems and method of support of the pipeline under railways in general:
• Catastrophic consequence from train derailment - pipelines and support conditions having a low risk of deformation or collapse are required
• Railways are generally active - pipelines suitable for installation by boring or tunnelling/jacking are required
• Trains generally pass frequently - cased boring or pipe jacked in closely behind the bore or tunnel excavation is required to prevent ground collapse (not required for excavations 100 mm diameter or less where the size of any collapse generally would not be expected to cause significant overburden subsidence)
The following factors limit the pipeline systems and method of support in special circumstances: • Trains apply high impact loading - pipelines with good impact resistance is required
• Disturbance during maintenance of rails and ballast - for shallow cover, pipelines that require negligible side support required.
• Catastrophic consequence from train derailment - blow out of a sewage rising main from joint, corrosion or material fatigue failure leading to erosion of rail support
For pressure pipelines, such as sewerage rising mains, it is required to encase the carrier pipeline with either another pipeline or reinforced concrete. For non-pressure pipelines, such as gravity sewers, encasement will lower the risk of failure and is thus recommended.
High stiffness pipelines with high corrosion resistance (using appropriate coatings and linings and other means as required) offer the most foolproof solution.
Plastic pipelines should be encased either with concrete or cementitious grout (whilst ensuring the pipeline does not substantially deform during the grouting process) or with a very stiff pipeline of reinforced concrete, ductile iron or steel.
Low ductility pipelines, such as GRP and VC at shallow cover should be similarly encased.
6. Extreme ground movement
All pipelines will be subject to some downward (and unusually upward) movement due to underlying material movement. The degree of movement will vary with the magnitude of loading and the movement modulus of the underlying material.
Along a pipeline the degree of movement will be different due to variations in dead loads (depth of covered soil density) and live loads and variation in the movement modulus due to variations in bedding thickness/compaction and foundation composition. Upward movement may occur due to swelling clay types (depending on the season) or by tree root growth.
The ability of a pipeline to accommodate differential movement of the support depends on the maximum angular deflection at the joints, pipe length bendability and pipe length beam strength and shear strength. All pipeline systems have either joint angular deflection capability and for pipe length bendability and/or sufficient beam strength/shear strength to accommodate some degree of differential movement. Each pipeline system will have different limits and this needs to be determined for the particular loading and underlying modulus movement conditions on the pipeline.
Where there is large differential movement over short distances, the beam strength and shear strength of individual pipe lengths and the ability to resist joint failure will determine the pipeline system to use. VC and GRP pipes are the most vulnerable to beam and shear failure within a length. RC, steel and DI pipes will withstand greater beam and shear load but will be susceptible to elastomeric joint pullout (ductile iron pipelines are available with a lock-in elastomeric joint to counter pull out). uPVC will flex to a degree but its low beam strength will eventually cause failure.
Solid wall polyethylene pipe is much more flexible than the other plastic sewerage pipeline systems so will accommodate much greater differential movement over short distances. In additional solid wall PE pipeline systems having welded joints will not be subject to joint pullout like elastomeric sealing joints.
It may be difficult to determine the possible level of movement of a ground. Therefore it is advisable, where ground known to have potential for large movement such as fill sites, soft sands, and silts, saturated sands and silts and clays renowned for substantial swelling; to select a welded PE pipelines if structural design is favourable. Otherwise where design shows that the soft soils do not provide sufficient side support to PE, below certain depths of cover, a steel pipeline with welded joints should be used or pipes supported on piles.
7. Pipeline grading affected critically
Loss of gradient may be so severe that it may lead to surcharge and spillage of sewage upstream. Also with the loss of gradient, sewage may stagnate and become septic. Septic sewage which can produce hydrogen sulphide and subsequently sulphuric acid is not a concern with plastic pipelines recommended in such conditions but consideration needs to be given to downstream assets such as large diameter concrete pipelines.
8. Ground contaminated with chemicals deleterious to plastics
The chemicals which can be deleterious to plastics in general are principally organic solvents and for some plastics, strong acids and alkalis. The likelihood of damage depends on the contact time, chemical concentration, and temperature and for some plastics the strain in the plastics. However it is difficult to analyse the ground conditions to determine the degree of hazard at sites that may be a concern.
Plastics like HDPE and ABS are therefore excluded outright from use near petrol stations, oil storage sites, land fill sites with known or suspected chemical dumping and chemical manufacturing sites. For other sites suspected of being contaminated or may be contaminated in the future with specific chemicals deleterious to plastics, the designer must obtain further advise and chemical resistance charts from pipe suppliers and undertake some site sampling to roughly gauge the likely hazard.
9. Crossing under water courses
Infiltration into a sewer under a watercourse is a major concern. Rehabilitation of such sewer is also relatively difficult and costly. Therefore pipeline system which offers the least chance of infiltration and failure needs to be selected. Welded joints pipeline system is also preferred because as the elastomeric joints are likely to fail of under such condition the ground conditions are generally more prone to differential settlement (permitting joint pullout), and greater external water pressure (particularly in extreme wet weather conditions). Pipeline systems with welded joints therefore offer the safest solution. (Note: Where pipeline are installed under watercourses using directional drilling techniques, a welded pipeline must be used anyway).
4.0 SEWER PIPELINE – MATERIAL SELECTION
4.1 GRAVITY SEWERAGE SYSTEM
4.1.1 General
This section provides the product data and information on manufacturers of the approved products for gravity pipeline system. The data is a summary of the information provided by the manufacturers during submission for approval and may not represent the latest products available
.
Minimum design requirements of gravity sewerage system in Malaysia as stated in MSIG Volume 3 are summarised as follows:
• Domestic connection sewer - DN 150 minimum
• Public sewer - DN 200 and above
Table 4.1 showed the pipe materials and application conditions as approved by DGSS:
Table 4.1: Gravity Sewer Pipeline Materials and Application
Pipe Material Application
VC DN100 and above
RC DN375 and above
GRP DN600 and above with prior approval from DGSS
DI High load application
Profile Wall PE For special circumstances with prior approval from DGSS
4.1.2 Definition
A pipeline system is considered as gravity system when: a. It can operate at atmospheric pressure;
b. There is no differential pressure; or
c. There is no any additional internal pressure inside the system; and
d. There is no additional force inside the system to assist the flow of the sewage. The gravity pipelines shall be able to withstand a buoyancy effect.
4.1.3 Precautions and Principal Applications of Sewerage Gravity Pipeline
System
The precautions and basic principal applications of the pipe for sewerage gravity systems are shown in Table 4.2 below:
Table 4.2: Precautions and Principal Applications of Gravity Sewer Pipeline System
GENERAL PRECAUTION
• All pipelines may be damaged, rendered structurally unsound or have inadequate joint performance due to incorrect installation practices. • All pipes and fittings may be damaged prior to installation by
inappropriate transportation, storage and handling practices.
• All pipelines shall be constructed by trained and certified pipelayers with a system of documentation for quality control of installation in place.
Table 4.2: Principal Application of Gravity Sewer Pipeline System (continued) GENERAL PRECAUTION • • • •
All pipelines can be adversely affected in both the short and long term by third party damage to the pipe or corrosion protection system. All pipelines shall be installed with proper methods of pipeline embedment and haunches.
All pipes require verification of the internal diameter for hydraulic design – the nominal size does not necessarily represent accurately the internal diameter.
Larger diameter flexible pipelines require knowledge of the soil properties along the route of the pipeline and at the intended depth of the pipeline for accurate structural design.
GENERAL LIMITATIONS
• • •
All pipelines require detailed site investigation and special designs for installations in contaminated land and sites where the ground is subject to significant movement or subsidence.
All pipes and fittings may be damaged by inappropriate cleaning practices and maintenance equipment.
All pipeline systems have components that can be damaged by illegal discharges of trade waste.
GENERAL ADVANTAGES • • • • • • •
Plastic pipes are resistant to H2S gas attack, impervious to
groundwater and resistant to corrosion by almost all chemicals found in sewage except some specific organic compounds.
Thermoplastic pipes allow handling of much longer lengths and larger sizes than VC and GRP pipes, and are easier to cut.
Rubber ring jointed pipes are easily jointed and tolerate some joint deflection.
All pipes can be used as slip liners inside microtunnelled/jacked encasing pipe.
GRP, RC, VC and DI pipes can be supplied in designs for pipe jacking in microtunnelling installations.
Rigid pipes have one or more pipe classes that have sufficient ring strength to not rely on side support for achieving structural adequacy. Metallic pipe are easy to trace and, when fully welded, are impermeable to organic contaminants and gases.
GENERAL DISADVANTAGES • • • • • • •
Flexible pipes may be susceptible to deflection after placement and compaction of embedment and fill.
Plastic pipes may be susceptible to permeation and degradation by certain organic contaminants in soils.
Plastic pipes and plastic coating or sleeving on metal pipes may be susceptible to degradation by certain organic contaminants in soils. Plastic pipelines are sensitive to point loading.
Rubber rings may be susceptible to degradation by certain organic contaminants in soils and exposure to the sunlight and UV.
Flexible pipes rely on support for embedment and adjacent native soil to achieve structural adequacy in buried installations (except for some shallow installations without live loadings)
Non-black plastic pipes and fittings and plastic pipe coatings suffer UV degradation on prolonged exposure to direct sunlight (generally 12 to 24 months depending on the local condition)
4.2
Vitrified Clay (VC) Pipe
The design data and specifications of VC pipes for gravity sewerage system are summarised in Table 4.3 below:
Table 4.3: Summary of VC Pipes Design and Specifications for Gravity Sewerage System
Summary
Material Vitrified clay
Nominal Size (DN), mm DN100 to DN1200 mm
Nominal Length, m 1.5, 1.75, 2.0, 2.5, 3.0 m
Classes
• Crushing Strength (FN) • • Conform to MS 1061:1999 and BS EN 295: 1991 Refer to Table 4.5
Jointing Methods •
• Spigot and socket with rubber ‘O’ ring Spigot and socket with skid type (prefabricated) seals
Protective Coating
•
• External Internal
With or without glazing (depends on the product) With or without glazing (depends on the product)
Standards Manufacture Design Installation MS 1061:1999 BS EN 295-1:1991 BS EN 295-2:1996 BS 65:1991 BS EN 752:1997 BS EN 752:1997 ASTM C12-91 Malaysian Sewerage Industry Guidelines (MSIG) •
• Intercepting sewer Public gravity sewer • •
150 mm minimum diameter 200 mm minimum diameter
Approved
Manufacturers/Suppliers Refer to Table D1 and DGSS latest approval list
4.2.1 Manufacture
Material compositions of VC pipes as in accordance with MS 1061:1999 comprise blends of
suitable clays source from different locations and/or strata in a form of grog and fired to vitrification. The clays may contain shale, sand, prefired material of such a quality and homogeneity. Calcine clays shall be included to minimize pipe wall permeability. Recycle materials are not allowed in producing the VC pipes.
The VC pipes can be manufactured into two different types of pipe as shown in Figure 4.1 below:
Figure 4.1: Types of VC Pipes
Spigot-socket pipe
Typical manufacturing process of VC pipes is shown in Figure 4.2 below:
Figure 4.2: Typical Manufacturing Process for VC Pipes
Store Final Inspection Cooling 650ºC to 450ºC Firing 1050ºC to 1250ºC Glazing (optional)
Trim and dry Cut and joints
Extrusion Mixing
/Blend Selection of raw material
Pipes, bends and fittings are coated with a solution of salts to form ceramic glaze to reduce permeability
Pipes, bends and fittings are trimmed and dried with hot air
Pipes are cut and jointed to form junctions and fittings
Blend clay is extruded to form the pipes or bends
The selected fine particles of dry clay is blended with water
Dry clay is crushed, grounded and screened to achieve desired fine particles
4.2.2 Protective
Coatings/Linings
External and internal glazing is a mean of improving impermeability of VC pipes. The process
involves coating the dried pipes prior to firing stage with a solution of salts to form ceramic glaze on pipe wall. Glazing is not compulsory so long the products perform to requirements. When glazed they need not be glazed on the jointing surfaces of the spigot and socket.
4.2.3 Sizes/Classes
Nominal size (DN) is a numerical designation of the minimum internal diameter of VC pipes. It is
a convenient round number approximately equal or equal to a manufacturing dimension and the bore of the pipe shall not deviate from the nominal size beyond the set limits in MS 1061: 1999.
Nominal length of VC pipes for DN 200 and greater either shall be as in Table 4.4 or they shall be
whole multiples of 250mm. There are no preferred nominal lengths for DN 100 and DN 150 pipes. The pipes length other than the offered standard length can be obtained by cutting the pipes with pipe cutting chain.
Table 4.4: Preferred Nominal Lengths of VC Pipes
Nominal Size (DN), mm Length, m
200 1.5, 2.0
225 1.5, 1.75, 2.0
250 1.5, 2.0
300 1.5, 2.0, 2.5
≥ 350 1.5, 2.0, 2.5, 3.0
(Ref: MS 1061: Part 1: 1999, page 4)
Classes of VC pipes is defined by the ring crushing strength (FN), which can be directly used in
structural design calculations. The crushing strengths (kN/m) for various sizes of VC pipes as recommended in MS 1061: 1999 are shown in Table 4.5 below:
Table 4.5: Crushing Strength (FN) in kN/m for Various Sizes of VC Pipes
Class Number Nominal Sizes (DN) L# 95 120 160 200 ≤ 150* N.A N.A 22 28 34 200 N.A N.A 24 32 40 225 N.A N.A 28 36 45 250 N.A N.A 30 40 50 300 N.A N.A 36 48 60 350 N.A N.A 42 56 70 400 N.A 38 48 64 N.A 450 N.A 43 54 72 N.A 500 N.A 48 60 80 N.A 600 48 57 72 N.A N.A 700 60 67 84 N.A N.A
800 60 76 N.A N.A N.A
1000 60 95 N.A N.A N.A
1200 60 N.A N.A N.A N.A
#
Lower strength pipe
* Class numbers do not apply for DN ≤ 150 pipe. Higher crushing strengths may be declared, provided that the increase is in steps of 6 kN/m.
Crushing strength (FN) of the VC pipes shall be batch tested using either three-edge bearing test
or segmented bearer test as described in MS 1061: 1999. Rigid bearer test may only be used for pipes of nominal length lower than 1.10m. The crushing strength of VC pipes may vary slightly but not significantly between batches.
Only pipes of the same class and jointing system are compatible.
4.2.4 Joints
Joints method of VC pipes is basically of the type of flexible joints. The types of jointing available from the approved manufacturers are generally of the following types:
1. Rubber ‘O’ ring joint - Spigot-socket with rubber ‘O’ ring type is available from all
approved manufacturers and is the recommended type to be used in most applications. Figure 4.3 shows an example of spigot socket with rubber ‘O’ ring joint.
Figure 4.3: Spigot Socket with Rubber ‘O’ Ring Joint for VC Pipes
2. Skid type sealing joint - This is another type of push-in flexible mechanical joint which is
already prefabricated into the spigot/socket. There are two main types of skid type sealing joint:
a. L-Joint by Sunway Keramo Sdn. Bhd. and GBH Clay Pipes Sdn. Bhd. and b. K-Joint by Sunway Keramo Sdn. Bhd. and JPC-Intan Sdn. Bhd.
The samples of skid type sealing joint are shown in Figure 4.4 below:
Figure 4.4: Skid Type Sealing Joints for VC Pipes
L-Joint K-joint
Sealing material used for the joints is varies depending on the type of joints used and shall be in
accordance with BS EN 681-1: 1996. It shall be made of elastomeric compounds comprising suitable polymers that need to ensure long term sealing of the joint.
There are two common types and materials used as a joint seals for VC pipes that are approved by DGSS in Malaysia, which are:
1. Rubber ring seals – The rubber ring seals shall be made of EPDM or styrene butadiene rubber (SBR). When placed at the correct position over the end of the spigot, it will roll 360° (one full turn) into place when the joint is pushed in. It is critical that the ring is not twisted and the joint shall be cleaned before jointing to avoid loose joint.
The limitation of the rubber ‘O’ ring is that it cannot fill the gap between the spigot and socket completely because of its circular profile. It allows higher point compression and deteriorates with time. Therefore proper control of the spigot-socket diameters is crucial to prevent very high rubber compression (cause difficulty in jointing or additional cracking force on the socket) and very low compression (not effective jointing).
2. Rubber or polyurethane seals - These sealing elements is used in skid type sealing. The
prefabricated lip ring (L-Joint) has a rubber lip ring fixed in the pipe socket with an epoxy sealant bonded to the pipe socket. No joint in the spigot is required. Light lubrication of the seal is needed before the spigot skids in.
The conical joint (K-Joint) consists of a hard polyurethane compound cast inside the socket and a soft polyurethane element on the spigot end, providing a tight and flexible connection. Lubrication on the seals is required before jointing. Control of spigot and socket diameters during manufacture is less critical as the polyurethane seal can be cast to tighter tolerances.
Angular deflections of the joints in the field achieving two thirds of that specified in MS 1061:
1999 are acceptable. Table 4.6 lists the acceptable angular deflections for various sizes of VC pipes.
Table 4.6: Allowable Angular Deflection of VC Pipes
Nominal Size (DN) Angular Deflection
DN 100 to DN 200 4.6° or 80mm per metre length DN 225 to DN 500 1.7° or 30mm per metre length DN 600 to DN 800 1.1° or 20mm per metre length > DN 800 0.6° or 10mm per metre length
(Ref: MS 1061: Part 1: 1999, page 10)
4.2.5 Fittings
Fittings for VC pipes to BS EN 295-1: 1991 has a minimum internal diameter closely
approximating the nominal size. The deviation of the minimum internal diameter from the nominal size increases as pipe diameter increases.
Fittings are prone to unusual loading, which can cause differential loads and settlement. Therefore it is necessary to encase the fittings in concrete to prevent bending and shear failures which VC fittings are vulnerable to. Figure 4.5 shows the typical range of fittings available for VC pipes.
Figure 4.5: Typical Range of Fittings for VC Pipes
Figure 4.5: Typical Range of Fittings for VC Pipes (continued)
Spigot-spigot taper Stopper
Spigot-socket bend Spigot-spigot bend
Single T joint Single Y joint
Double T joint Double Y joint
Backdrop Tumbling bay
Riley slope junction Slope junction
Spigot oblique saddle* Spigot square saddle*
Figure 4.5: Typical Range of Fittings for VC Pipes (continued)
Coupling with elastomeric seal
4.2.6 Pipeline Hydraulic Design
Typical roughness coefficient, ks values of Colebrook-White equation as recommended in MSIG
Volume 3 given in Table 4.7 shall be referred to when determining discharge capacity of the VC pipes for gravity sewer application.
Table 4.7: Colebrook-White Roughness Coefficient, ks for VC Pipes
Pipe Condition Roughness, ks (mm)
New Old
0.06 1.5
Whilst, the selection of the VC pipes diameter and gradient for gravity sewer application to cope with the peak flow, can be also based on the one of the following equations as shown in Table 4.8 below.
Table 4.8: Various Pipeline Hydraulic Design Equations of VC Pipes for Gravity Sewerage System
Design Equations Name of Coefficient Pipeline Condition Typical Value of Coefficient
Good 0.010 Manning Equation Manning Coefficient, n
Bad 0.017 Hazen-Williams
Equation
Hazen-Williams
Coefficient, C N/A* 110
*N/A – not applicable
Frictional head losses at the joints between VC pipes could be higher than other types of pipe due to its relatively short length but it could be minimised by proper jointing. Head losses due to pounding along the barrel should be minima provided that the VC pipes barrel is manufactured within straightness tolerances given in the manufacturing specification.
4.2.7 Application of Pipes
The application of VC pipes for the gravity system may subject to certain conditions and limitations as described in Section 3, Table 3.2 and Table 3.3. The advantages and disadvantages of the VC pipes for this application are listed in Table 4.9 below.
Table 4.9: Advantages and Disadvantages of VC Pipes
Advantages Disadvantages
• Installation requirements are less stringent than flexible pipes. Less imported granular material needed.
• Resistant to H2S attack, unlike RC.
• More resistant to abrasion than RC.
• Most resistant material to chemical corrosion found in sewage.
• Not degraded by UV radiation, unlike plastics without carbon black.
• No significant variation in dimensions or shape with temperature variation, unlike plastics.
• Proven long term performance, unlike plastics.
• Jointing procedure relatively simple. A rolling rubber ring requires no lubricant, unlike skid joints.
• Some rotational movement of the joint is possible, unlike the uPVC solvent cement joint.
• Disturbance of pipe side support does not substantially impair structural performance unlike flexible pipe.
• VC pipe is not buoyant like plastic pipe, therefore is not likely to move off line and grade due to water in the trench.
• VC pipe will not bend along its length, unlike plastic pipe, which can bend along its length from loading or from temperature variations during storage. Such bending lends to pounding of flows. • VC pipes do not need special procedures
to retain a round profile unlike low stiffness large diameter plastic pipe.
• High ring strength.
• Heavier than plastic pipes. Mechanical lifting equipment is required in sizes DN 225 and above.
• Shorter pipe lengths than plastic pipes, thus more joints.
• Rougher bore than plastics, requiring steeper grades or larger diameter pipes. Slime adheres to VC more readily than plastics and is less easily washed off. • Care is required in handling as pipes are
susceptible to lower the impact damage. • Pipes may fracture under differential
settlement within a pipe length.
• Where poor bedding results in support only at the socket, pipes may fracture, depending on the load magnitude.
• Low shear strength.
• Beam strength may be insufficient if pipe barrel is not offered continuous support (load dependent).
• High protrusion of socket requires more careful preparation of bedding to prevent a pipe length just being supported at the socket.
• No longitudinal pipe barrel flexibility to accommodate any loss of pipe bedding continuity.
• Even minor cracks can lead to penetration and chokes by aggressive root systems. • Fittings in riser structures more prone to