GB/T 50459-2017 Standard for design of oil and gas transportation pipeline aerial crossing engineering
1 General provisions
1.0.1 This standard is formulated with a view to implementing the national technical and economic policies in the design of oil and gas transportation pipeline aerial crossing engineering, thus ensuring advanced technology, safety and applicability, reliable quality and economic rationality.
1.0.2 This standard is applicable to the design of oil and gas transportation pipeline aerial crossing engineering in areas where the basic seismic peak ground acceleration is less than or equal to 0.40g.
1.0.3 A special design shall be submitted when the basic seismic peak ground acceleration is greater than 0.40g.
1.0.4 In addition to the requirements of this standard, the design of pipeline aerial crossing engineering shall also meet the requirements of the relevant current national standards.
2 Terms
2.0.1 pipeline aerial crossing engineering
construction engineering where a transportation pipeline passes above natural or artificial obstacles in an aerial crossing form
2.0.2 girder pipeline aerial crossing
form of aerial crossing structure that uses transportation pipelines or casing pipes as girders
2.0.3 truss type pipeline aerial crossing
form of aerial crossing structure that uses truss as the load bearing structure of pipeline
2.0.4 suspension cable type pipeline aerial crossing
form of aerial crossing structure in which the transportation pipeline structure is suspended from the main load bearing cables
2.0.5 obliquely-cable stayed type pipeline aerial crossing
form of aerial crossing structure in which the transportation pipeline structure is connected to the tower via multiple stay cables
2.0.6 single-line arch type pipeline crossing
form of aerial crossing structure that uses single transportation pipeline to fabricate arch
2.0.7 pipe-build up arch type pipeline aerial crossing
form of aerial crossing structure that uses transportation pipelines and other members to fabricate arch
2.0.8 light truss type pipeline aerial crossing
form of aerial crossing structure with a down-stayed composite girder composed of upper chord member (fabricated by pipelines) and steel cables or profile steel
2.0.9 “Ⅱ” type frame pipeline aerial crossing
form of aerial crossing structure in which the “Ⅱ” type frame is composed of transportation pipelines
2.0.10 suspended cable type pipeline aerial crossing
form of aerial crossing structure in which the transportation pipeline structure is suspended from the main load bearing cables in a hanging state
2.0.11 main span
bridge section with the maximum span in the aerial crossing engineering
2.0.12 cable
members that bear tensile force or connect the main girder (bridge deck structure) in the aerial crossing engineering, including wire cable and anchorage
2.0.13 wire cable
wire strand composed of multiple high-strength steel wires, steel wire ropes, etc., which is the main component of the cable
2.0.14 anchorage
component connecting two ends of the wire cable and the coupler, through which the tension of the wire cable is transmitted to the coupler
2.0.15 coupler
connecting components between cables and structures or between cables, including connecting screws, cable clamps, splay saddles and cable saddles
2.0.16 anchor block
structures supported on the foundation or embedded in rock masses to anchor the cables and bear the tension of cables
2.0.17 temperature compensator
pipe sections or devices with temperature compensation capabilities
3 Basic requirements
3.0.1 The pipeline aerial crossing engineering shall be classified into Class A and Class B. Class A shall include the pipeline aerial crossing of navigable rivers, electrified railways and highways; Class B shall include the pipeline aerial crossing of non-navigable rivers and other obstacles.
3.0.2 The grades of pipeline aerial crossing engineering shall be classified according to those specified in Table 3.0.2.
Table 3.0.2 Grades of pipeline aerial crossing engineering
Engineering grade Length of total span, L? (m) Length of main span, L2 (m)
Large-scale ≥300 ≥150
Medium-scale 100≤L?<300 50≤L?<150
Small-scale <100 <50
3.0.3 The strength design factor of aerial crossing pipeline shall meet those specified in Table 3.0.3.
Table 3.0.3 Strength design factor of aerial crossing pipeline
Engineering classification Engineering grade Gas transportation pipeline Oil transportation pipeline
Grade I area Grade II area Grade III area Grade IV area
Class A Large-scale 0.40 0.40 0.40 0.40 0.40
Medium-scale 0.45 0.45 0.45 0.40 0.50
Small-scale 0.50 0.50 0.50 0.40 0.55
Class B Large-scale 0.50 0.50 0.50 0.40 0.50
Medium-scale 0.55 0.55 0.50 0.40 0.60
Small-scale 0.60 0.60 0.50 0.40 0.65
3.0.4 In the design documents of pipeline aerial crossing engineering, the design service life of the structural engineering shall be specified, and the weld form, weld quality grade and weld inspection standards of the steel structure of the structural engineering shall be described.
3.0.5 The design service life of major structure of the permanent aerial crossing engineering shall not be less than 50 years, and the design service life of replaceable members should not be less than 25 years.
3.0.6 The design safety level of major structure of the permanent aerial crossing engineering shall not be inferior to Grade II specified in the current national standard GB 50068 Unified standard for reliability design of building structures.
3.0.7 The pipeline aerial crossing position shall meet the following requirements:
1 It is necessary to properly handle the connection with oil and gas transportation pipeline engineering, as well as the interrelationships with railway, highway, river, power, city and hydraulic engineering planning, etc.
2 It shall conform to the overall direction of the line, and the local direction of the line may be adjusted according to the aerial crossing position.
3 It shall be away from areas with important ground or underground facilities.
4 It should be away from environmental sensitive area, historic reservation and airport clearance area.
5 It should be away from developing gully/gully head, active seismic fault zones, areas with landslides, debris flows, karst, and other areas with adverse geological development.
6 It should be away from areas of river channels with frequent dredging and deepening, severe bank erosion, or intense changes in beach erosion and siltation.
7 It should be located in areas where the river is relatively narrow, there are mountain spur or highlands on both banks, the lateral scouring and erosion are relatively small, and the strata is quite stable. It should located be in the straight section upstream of the bend if the river has a bend.
8 It should be located upstream of the sluice gate or dam or outside the affected area of other hydraulic structures.
9 Certain construction and installation sites as well as relatively convenient transportation conditions should be available near the position.
10 The aerial crossing position and scheme shall meet the requirements of the relevant assessment report for the pipeline engineering.
3.0.8 In case aerial crossing pipe sections and buried pipelines are connected, the following requirements shall be met:
1 The diameter of the aerial crossing pipe section shall match that of the buried pipeline, and the curvature radius of the elbow used shall meet the requirements for the passage of the pigging equipment.
2 For large-scale pipeline aerial crossing engineering, the shut-off valves shall be installed at both ends.
3 In case insulating joints are added at the ground-soil connection points between aerial crossing pipeline sections and buried pipelines, the relevant requirements of the current professional standard SY/T 0086 Electrical isolation of cathodically protected pipelines shall be met.
4 The connection point between the aerial crossing pipeline and the line section pipeline should be located 10m away from the support pier or anchor pier at the point where the aerial crossing pipeline enters the ground.
5 Measures shall be taken to prevent mutual influence between buried pipelines and aerial crossing pipelines.
3.0.9 The design flood frequency (recurrence period) of the aerial crossing engineering shall be selected according to different grades of the aerial crossing engineering specified in Table 3.0.9, and the design flood level shall be determined in combination with local hydrological data.
Table 3.0.9 Design flood frequency
Crossing engineering grade Large-scale Medium-scale Small-scale
Design flood frequency 1% (once every 100 years) 2% (once every 50 years) 2% (once every 50 years)
3.0.10 When crossing the navigable rivers, the clearance dimension of the span shall meet the requirements of the navigable impact assessment. The clearance height at the lowest edge of the pipeline aerial structure shall meet the relevant requirements of the current national standard GB 50139 Navigation standard of inland waterway.
3.0.11 When crossing non-navigable rivers unavailable for rafting, the lowest edge of the pipeline aerial structure shall be 3m above the design flood level for large-scale aerial crossing engineering and 2m above the design flood level for medium-scale and small-scale aerial crossing engineering. If the accurate hydrological data is unavailable, the aerial height should be increased and the requirements of relevant departments for clearance shall be met.
3.0.12 When crossing railways or roads, the clearance height at the lowest edge of the aerial structure shall not be lower than those specified in Table 3.0.12. Height limit signs shall be set up on both sides of the aerial crossing engineering, and the height limit structures should be set up.
1 General provisions
2 Terms
3 Basic requirements
4 Measurement and investigation
5 Materials
5.1 General requirements
5.2 Durability
5.3 Design index
6 Structural analysis
6.1 General requirements
6.2 Design methods
6.3 Linear elastic analysis
6.4 Non-linear elastic analysis
6.5 Structural dynamic response analysis
7 Classification and combination of actions
7.1 Classification of actions, representative values of actions and effects of actions
7.2 Permanent action
7.3 Variable action
7.4 Accidental action and earthquake action
8 Structural design
8.1 General requirements
8.2 Structural deformation
8.3 Calculation of pipeline strength and stability
8.4 Temperature compensation and deck installation
8.5 Cable
8.6 Anchorages and couplers
8.7 Steel tower and truss
8.8 Concrete tower
8.9 Anchor block design
9 Pier design
9.1 General requirements
9.2 Pier ground and foundation design
9.3 Detailing requirements of pier foundation
10 Detailing requirements
10.1 General requirements
10.2 Structure protection
10.3 Cables, anchorages and couplers
10.4 Anticorrosion of structure
11 Seismic design
12 Welding, pressure test and anticorrosion of aerial crossing pipe sections
12.1 Welding and inspection
12.2 Pigging, gauging and pressure test
12.3 Anticorrosion and thermal insulation
13 Construction supervision and health monitoring
13.1 Construction supervision
13.2 Health monitoring
Explanation of wording in this standard
List of quoted standards
