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AS 3688:2016


Water supply and gas systems — Metallic fittings and end connectors

​This Standard specifies requirements for metallic body pipe fittings and connectors for use with copper tubes and stainless steel pipes and tubes and adaptor fittings for connection to other pipe materials in water supply and gas systems where the normal working temperature does not exceed 95°C, and where the maximum operating pressure does not exceed 1.4 MPa.
Published: 27/06/2016
Pages: 71
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Table of contents
Cited references
Content history
Table of contents
About this publication
1 Scope and general
1.1 Scope
1.2 Application
1.3 Referenced documents
1.4 Definitions
1.5 Designation of size
1.6 Marking
1.6.1 Space for mark of certifying body
1.6.2 Components
1.6.3 Marking requirements
1.7 Product documentation
2 Materials
2.1 Scope of section
2.2 Materials in contact with drinking water
2.3 Metallic materials
2.3.1 Corrosion-resistant metallic materials
2.3.2 Copper
2.3.3 Copper alloy
2.3.4 Dezincification-resistant (DR) copper alloy
2.3.5 Stainless steel
2.4 Plastic component materials
2.4.1 General
2.4.2 Acetal
2.5 Other component materials
3 Design and dimensions
3.1 Scope of section
3.2 Tube stops
3.3 Slip fittings
3.4 Spigots
3.5 Fixing device
3.6 Waterways
3.6.1 General
3.6.2 Copper and copper alloy
3.6.3 Stainless steel
3.6.4 Stainless steel press fit
3.7 Thickness of metal parts of fittings specified by dimension
3.7.1 General
3.7.2 Minimum thickness of unspecified metal parts
3.8 Pipe threads
3.8.1 General
3.8.2 Sealing pipe threads
3.8.3 Fastening pipe threads
3.8.4 Fastening thread engagement—Assembled joints
3.8.5 Other thread forms
3.9 Fabricated fittings
3.10 Geometry of fittings
3.11 Plating and other surface finishes
3.12 Finish and workmanship
4 Performance requirements
4.1 Scope of section
4.2 Leaktightness under internal pressure test
4.3 Strength of fabricated joint (Torque test)
4.4 Strength of joint assembly (Pressure cycling test)
4.5 Resistance to pull-out of assembled joints
4.6 Strength of nut and assembly (Torque test)
4.7 Leaktightness under internal pressure whilst subjected to bending
4.8 Method for determining compatibility of water fittings with pipe
4.9 Roll-grooved assembly (Joint pressure resistance test)
4.10 Vacuum test for leaktightness of joints with tube under vacuum
4.11 Leaktightness under internal pneumatic pressure
4.12 Resistance of gas press fittings to temperature cycling
4.13 Resistance of press fitting joints and tubes to vibration
4.13.1 Water press fittings
4.13.2 Gas press fittings
4.14 Resistance of gas press fittings to high temperature
5 Capillary fittings—Copper and copper alloy
5.1 Scope of section
5.2 Design and dimensions
5.2.1 General
5.2.2 Internal diameter of socket
5.2.3 Length of socket
5.2.4 Wall thickness
5.2.5 Branches of different nominal size
5.2.6 Waterway diameter
5.3 Performance requirements
6 Compression fittings
6.1 Scope of section
6.2 Design
6.2.1 Copper alloy compression fittings manufactured to dimensions
6.2.2 Compression fittings complying with performance requirements
6.3 Performance requirements
6.3.1 Compression fittings complying with Clause 6.2.1
6.3.2 Compression fittings complying with Clause 6.2.2
7 Threaded-end connectors
7.1 Scope of section
7.2 Dimensions
7.3 Design
7.3.1 Thread stop for fastening thread end connectors
7.3.2 Wrenching flats
7.3.3 Thickness of threaded-end connectors with fastening threads
7.3.4 Sealing thread end connectors
7.4 Performance requirements
8 Union end connectors and couplings
8.1 Scope of section
8.2 Design
8.2.1 Minimum wall thickness
8.2.2 Screw threads
8.2.3 Provision for tightening
8.2.4 Performance requirements
9 Roll-grooved jointing end connectors and coupling body
9.1 Scope of section
9.2 Materials
9.3 Design
9.3.1 Fittings General design and dimensions Roll-grooved connection ends Adaptor connection ends Fabricated end connectors
9.3.2 Coupling adjustment
9.4 Performance requirements and test methods
9.5 Installation instructions
10 Mechanical jointing push-on and press-fit end connectors
10.1 Scope of section
10.2 Design
10.2.1 General
10.2.2 Joint assembly—Push-on-end connectors
10.2.3 Joint assembly—Press-fit end connectors
10.3 Performance
10.4 Installation instructions
10.5 Marking for gas press-fit fittings
11 Other copper alloy fittings
11.1 Scope of section
11.2 Threaded sockets
11.2.1 General
11.2.2 The design of sockets with sealing pipe threads
11.2.3 The design of sockets with fastening pipe threads
11.3 Reducing bushes with overlapping internal and external threads
11.3.1 General
11.3.2 Reducing bushes with sealing pipe threads
11.3.3 Reducing bushes with fastening pipe threads
11.4 Continuously threaded fittings
11.5 Performance requirements
Appendix A
A1 Scope
A2 Relevance
A3 Product certification
A4 Definitions
A5 Testing
A5.1 Type testing
A5.2 Batch release testing
A5.3 Retesting
A6 Type tests
A7 Batch tests
Appendix B
Appendix C
C1 Fitting sizes
C2 End connections
C3 Examples
Appendix D
D1 Scope
D2 Principle
D3 Apparatus
D4 Test conditions
D5 Procedure
D5.1 Hydrostatic test (All fittings)
D5.2 Pneumatic test (In conjunction with hydrostatic test for cast fittings only)
D6 Test report
Appendix E
E1 Scope
E2 Principle
E3 Apparatus
E4 Procedure
E5 Test report
Appendix F
F1 Scope
F2 Principle
F3 Apparatus
F4 Procedure
F5 Test report
Appendix G
G1 Scope
G2 Principle
G3 Apparatus
G4 Test environment
G4.1 Metal joints
G4.2 Composite joints
G5 Procedure
G6 Test report
Appendix H
H1 Scope
H2 Principle
H3 Apparatus
H4 Procedure
H5 Test report
Appendix I
I1 Scope
I2 Apparatus
I3 Preparation of joint assemblies
I4 Procedure
I5 Test report
Appendix J
J1 Scope
J2 Principle
J3 Apparatus
J4 Preparation of test specimens
J5 Conditioning of test specimens
J6 Procedure
J7 Test report
Appendix K
K1 Scope
K2 Principle
K3 Apparatus
K4 Test conditions
K5 Procedure
K6 Test report
Appendix L
L1 Scope
L2 General
L3 Typical examples of simulated samples
L4 Special issues
L5 Component documentation
L6 Acceptance
Appendix M
M1 Scope
M2 Principal
M3 Apparatus
M4 Test conditions
M5 Procedure
M6 Test report
Appendix N
N1 Scope
N2 Principal
N3 Apparatus
N4 Procedure
N5 Test report
Appendix O
O1 Scope
O2 Principal
O3 Apparatus
O4 Procedure
O5 Test report
Appendix P
P1 Scope
P2 Principal
P3 Apparatus
P4 Test sample set-up
P5 Procedure for water fittings
P6 Procedure for gas fittings
P7 Test report
Appendix Q
Q1 Scope
Q2 Principal
Q3 Apparatus
Q4 Procedure
Q5 Test report
Cited references in this standard
Copper tubes for plumbing, gasfitting and drainage applications
Method for testing pressure cycling resistance of pipes and fittings
Copper and copper alloys — Ingots and castings
Copper and copper alloys — Seamless tubes for engineering purposes
Elastomeric seals for waterworks purposes
Content history
[Available Superseded]
[Available Superseded]
DR AS 3688:2015