Rigid polyurethane spray polyethylene winding prefabricated directly buried insulating pipes
1 Scope
This standard specifies the terms and definitions, product structure, general requirements, requirements, test methods, inspection rules, markings, transportation and storage of rigid polyurethane spray polyethylene winding prefabricated directly buried insulating pipe produced by polyurethane spraying process and polyethylene winding process (referred to as spraying and winding insulating pipe).
This standard is applicable to the manufacturing and inspection of rigid polyurethane spray polyethylene winding prefabricated directly buried insulating pipes with a medium temperature (long-term operating temperature) not exceeding 120°C and occasional peak temperature not exceeding 140°C.
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 3091 Welded steel pipes for low pressure liquid delivery
GB/T 6671 Thermoplastics pipes - Determination of longitudinal reversion
GB/T 8163 Seamless steel tubes for liquid service
GB/T 8923.1-2011 Preparation of steel substrates before application of paints and related products - Visual assessment of surface cleanliness - Part 1: Rust grades and preparation grades of uncoated steel substrates and of steel substrates after overall removal of previous coatings
GB/T 9711 Petroleum and natural gas industries - Steel pipe for pipeline transportation systems
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/T 29047 Prefabricated directly buried insulating pipes and fittings with polyurethane foamed-plastics and high density polyethylene casing pipes
CJJ/T 254-2016 Technical specification for leakage surveillance system of directly buried heating pipe
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
polyurethane spraying
process where polyurethane spraying equipment is used to continuously spray the uniformly mixed polyurethane raw materials onto the outer surface of steel pipe to form polyurethane insulating layer
3.2
polyethylene winding
process where the extrusion equipment is used to continuously wind the molten polyethylene sheet onto the outer surface of polyurethane insulating layer to form a continuous and dense polyethylene out casing
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Product structure
5 General requirements
6 Requirements
7 Test methods
8 Inspection rules
9 Marking, transportation, and storage
Annex A (Normative) Inspection method for circumferential thermal reversion of out casing
Annex B (Normative) Inspection method for circumferential shrinkage of out casing
