1 Scope
This standard specifies product structures, requirements, test methods, inspection rules as well as identification, transport and storage of prefabricated directly buried insulating pipe (hereinafter referred to as insulating pipe) composed of high density polyethylene external protecting pipe (hereinafter referred to as external protecting pipe), rigid polyurethane foam insulating layer (hereinafter referred to as insulating layer) and working steel pipes or steel fittings as well as its insulating fittings and insulating joints.
This standard is applicable to the fabrication and inspection of prefabricated directly buried insulating pipes, insulating fittings and insulating joints with the conveyance medium temperature (long-term operating temperature) not higher than 120℃ and occasional peak temperature not higher than 140℃.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 8163 Seamless Steel Tubes for Liquid Service
GB/T 8923.1 Rust Grades and Preparation Grades of Uncoated Steel Substrates
GB/T 9711 Petroleum and Natural Gas Industries - Steel Pipe for Pipeline Transportation Systems
GB/T 12459 Steel Butt-welding Seamless Pipe Fittings
GB/T 13401 Steel Plate Butt-welding Pipe Fittings
GB/T 18475-2001 Thermoplastics Materials for Pipes and Fittings for Pressure Applications - Classification and Designation - Overall Service (Design) Coefficient
GB/T 29046-2012 Test Methods of Technical Specification for Pre-insulated Directly Buried District Heating Pipes
GB 50236-2011 Code for Construction of Field Equipment, Industrial Pipe Welding Engineering
CJJ 28 Code for Construction and Acceptance of City Heating Pipelines
CJJ/T 81 Technical Specification for Directly Buried Heating Pipeline Engineering in City
JB 4708 Welding Procedure Qualification for Pressure Equipment
JB/T 4730 Nondestructive Testing of Pressure Equipment
SY/T 5257 Steel Bend for Oil and Gas Transmission
TSG Z6002 Examination Rules for Welding Operators of Special Equipment
API SPEC 5L Specification for Line Pipe
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
bonded insulation structure
structure of integrated insulating pipe (or insulating fitting) formed by bonding together the working steel pipe (or steel fitting) and the external protecting pipe via insulating layer
3.2
steel fitting
pipeline components such as steel reducer, T-branch, elbow, bend and fixed knot.
3.3
bend angle
central angle corresponding to the arc section of elbow or bend
3.4
heat-extruded elbow
elbow made of seamless steel pipe segment through pushing it with mandrel after heating
3.5
forge-welded bend
elbow fabricated through longitudinal welding after being formed by pressuring steel plate
Foreword i
Introduction ii
1 Scope
2 Normative References
3 Terms and Definitions
4 Product Structure
5 Requirements
5.1 Working Steel Pipe
5.2 Steel Fitting
5.3 External Protecting Pipe
5.4 Insulating Layer
5.5 Insulating Pipe
5.6 Insulating Fittings
5.7 Insulating Joint
6 Test Methods
7 Inspection Rules
7.1 Inspection Classification
7.2 End-of-manufacturing Inspection
7.3 Type Inspection
8 Marking, Transport and Storage
8.1 Marking
8.2 Transport
8.3 Storage
Annex A (Normative) Actual Continuous Operating Conditions and Accelerated Aging Test Conditions
Annex B (Normative) Calculation of Shortest Expected Life of Polyurethane Foamed-plastic Under Different Operating Temperatures
Annex C (Normative) Requirements and Tests for Insulating Pipe with Long-term Continuous Operating Temperature Between 120℃ and 140℃
Annex D (Informative) External Protecting Pipe Welding Guide
Bibliography
