This specification is applicable to the engineering design of crude oil and natural gas pipelines crossing artificial or natural obstacles in areas where the basic earthquake intensity is less than or equal to 9 degrees. SY/T 0015.2-1998 Design Specification for Crude Oil and Natural Gas Pipeline Crossing Engineering Crossing Engineering SY/T0015.2-1998 Standard download decompression password: www.bzxz.net

1 General Principles
Petroleum and Natural Gas Industry Standard of the People's Republic of China Design Specification for Crossing Projects for Crude Oil and Natural Gas Pipelines Crossing Projects
Approval Department: China National Petroleum Corporation Date of Approval: 1998-04-26
Effective Date: 1998-08-01
SY/T 0015.2—1998
Replaces SYJ1.--1985
1.0.1 This specification is formulated to implement the relevant national policies and guidelines in the design of crossing projects for crude oil and natural gas pipelines, to achieve advanced technology, economic rationality, safety and applicability, and to ensure quality. 1.0.2 This specification is applicable to the design of projects for crude oil and natural gas pipelines crossing artificial or natural obstacles (rivers, lakes, swamps, gullies, reservoirs, railways, roads, etc.) in areas where the basic seismic intensity is less than or equal to 9 degrees. 1.0.3 The design of crude oil and natural gas pipeline crossing projects should comply with the following principles: 1. Handle the connection with oil and gas pipeline line projects, and the relationship with railways, highways, rivers, cities and water conservancy planning; adopt advanced technology and absorb new technological achievements at home and abroad; 2
3 Optimize the design plan to determine the location of the best crossing point and the best crossing structure type. 1.0.4 In addition to complying with this specification, the design of pipeline crossing projects should also comply with the provisions of the relevant mandatory standards currently in force in the country. 2 Terms
2.0.1 Pipeline aerial crossing engineering Pipeline aerial crossing engineering Construction projects in which crude oil and natural gas pipelines pass overhead over natural or artificial obstacles. 2.0.2 Girder pipeline aerial crossing A crossing that uses the transmission pipeline as a beam.
2.0.3 \ⅡI\-type frame pipeline aerial crossing A crossing that uses the transmission pipeline to form a "IⅡI\-type frame". 2.0.4 Truss pipeline aerial crossing is a crossing that uses pipelines and other components to form a truss structure. 2.0.5 Light truss pipeline aerial crossing is a crossing that uses pipelines as the upper chord and steel cables as the lower chord to form a bracket structure. 2.0.6 Single-line arch type pipeline crossing is a crossing that uses a single pipeline to form an arch. 2.0.7 Pipe-build up arch type pipeline aerial crossing is a crossing that uses pipelines and other components to form an arch. 2.0.8 Suspended cable and pipeline aerial crossing is a crossing where the pipeline is suspended on the load-bearing main cable in a suspended shape. 2.D.9 Suspended pipeline aerial crossing is a self-supporting crossing where the pipeline is suspended in a suspended shape. 2.0.10 Suspension cable type pipeline aerial crossing189
SY/T 0015.2-1998
A crossing where the pipeline is suspended in a straight shape on the load-bearing main cable. 2.0.11 Obliquely-cable stayed pipeline aerial crossingA crossing where the pipeline is connected to the tower and anchor pier by multiple oblique tensioned steel cables. 2.0.12 Pipeline bridge upper structureA general term for the overhead part of the pipeline bridge, i.e. the structure above the pipe bridge support or above the arch line of the pipe arch. 2.0.13 Pipeline bridge understructureA general term for the supporting structure part of the pipeline bridge upper structure, i.e. the tower, pier, foundation, anchor pier, etc. 2.0.14 Main span
The main spanning pipe section of the pipeline crossing project. 2.0.15 Elasticity failure When all the loads are removed, the structure or component cannot return to its original shape and size. 2.0.16 Plasticity failure When the load is applied, the structure or component does not increase and undergoes plastic deformation that does not conform to the elastic law. 2.0.17 Stability
After several cycles of load application, the structure or component does not undergo elastic, plastic or incremental non-elastic deformation. 2.0.18 Fatigue analysis fatigue analysis The analysis of the maximum dynamic stress that a structure or component can withstand under the specified number of repetitions and the amplitude of action changes. 2.0.19 Wind vibration
The dynamic response of a pipe bridge caused by the dynamic action of wind. 3 Basic provisions
3.0.1 Pipeline crossing projects should be divided into two categories, A and B, according to the geographical environment conditions of the crossing. Category A is the crossing of navigable rivers, and Category B is the crossing of non-navigable rivers and other obstacles.
3.0.2 Pipeline crossing projects should be classified according to one of the conditions in Table 3.0.2. Table 3.0.2 Pipeline crossing project grades
Project grade
Total span length (m)
≥300
≥100～300
Main span length (m)
≥150
≥50～150
3.0.3 The strength design factor F of the crossing pipeline should comply with the strength design factor of the pipeline in the area and the provisions of Table 3.0.3, Table 3.0.3
Strength design factor F
Crossing project classification
Strength design factor F of the warning road crossing
Project grade
3.0.4 The selection of the pipeline crossing point should comply with the following The following regulations are set out: the large
crossing point should be consistent with the general direction of the line, and the local direction of the line can be adjusted according to the location of the crossing point; 190
SY/T0015.2-1998
2 The crossing point should be selected in a place where the river is narrow, the lateral scour and erosion on both sides are small, and there is a good stable stratum; when the river has a bend, the straight river section upstream of the bend should be selected; 3 The crossing point should be selected upstream of the dam or outside the influence area of ​​other hydraulic structures; the crossing point should avoid the section with developed gully heads; 4
The crossing point should avoid active earthquake fault zones; 5
There should be a certain construction and installation site and convenient transportation conditions near the crossing point. 6
3.0.5 When the crossing pipe section is connected to the buried pipeline, the following provisions shall be met: 1
The diameter of the crossing pipe section shall match the diameter of the buried pipeline, and the radius of curvature of the elbow used shall be greater than or equal to 5DN; 2 For large-scale crossing projects, cut-off valves shall be installed on both sides; The crossing pipe section and the buried pipeline shall be insulated at the connection point between the man and the soil, and shall comply with the provisions of the "Design Specification for Compulsory Current Cathodic Protection of Buried Steel Pipelines" SYJ36;
4 The connection point between the crossing pipe section and the buried pipeline shall generally be 10 m from the point where the buried pipeline enters the soil. 3.0.6 The design flood frequency (recurrence period) of the pipeline crossing project shall be selected according to Table 3.0.6 according to different project levels, and the design flood level shall be determined in combination with local hydrological data.
Table 3.0.6 Design flood frequency
Project level
Design flood frequency (1/year)
China type
3.0.7 When a pipeline crosses a navigable river, the clearance height of the lowest edge of its overhead structure shall comply with the provisions of the current national standard "Inland Navigation Standard" GBI139; if there are specific local requirements, they can be negotiated and determined. 3.0.8 When a pipeline crosses a river that is not navigable or has no streams, the lowest edge of its overhead structure should be 3m higher than the design flood level for large spans, and 2m higher than the design flood level for medium and small spans. 3.0.9 When a pipeline crosses a railway or road, the clearance height of the lowest edge of its overhead structure should not be lower than the provisions of Table 3.0.9. Table 3.0.9 Pipeline compliance with clearance height between crossing railway and road
Pedestrian road
Clearance (m)
Electrified railway
3.0.10 The distance between the crossing pipeline and the bridge shall be greater than or equal to the provisions of Table 3.0.10. Minimum distance between the crossing pipeline and the bridge
Table 3.0.10
Minimum distance (m)
Pipeline type
Oil pipeline
Gas pipeline
Bridge grade
Clearance height (m)
3.0.11 The signs for crossing projects on navigable rivers shall comply with the provisions of the current national standard "Inland River Traffic Safety Signs" GB13851.
3.0.12 For crossing projects near airports, if high towers are installed, the aviation department must be approved and signs must be installed in accordance with regulations. 191
SY/T 0015.2-1998
4 Pipeline crossing design
4.1 Materials
4.1.1 The domestic steel pipes selected for crossing pipelines shall comply with the provisions of the current national standard "Technical Conditions for Delivery of Steel Pipes for Petroleum and Natural Gas Industry Part 1: Grade A Steel Pipes" GB/T9711.1. The natural gas pipeline also requires that the ratio of yield strength to tensile strength should not be greater than 0.85.
4.1.2 Other steel materials used in the spanning project shall comply with the current national standards "Carbon Structural Steel" GB/T700, "Technical Conditions for Hot-rolled Carbon Steel for Bridge Construction" GB/T714 and "Hot-rolled Ribbed Steel Bars for Reinforced Concrete" GB1499. 4.1.3 Cement used in the spanning project shall comply with the current national standard "Medium-heat Portland Cement Low-heat Slag Portland Cement" GB200.
4.1.4 Galvanized steel wire ropes used in spanning projects shall comply with the current national standard "General Provisions for Packaging, Marking and Quality Certificate of Steel Wire Ropes" GB/T2104, and steel cores should be selected in the design. 4.1.5 The selection of materials for rigging shall comply with the following provisions: 1 The selection of materials for rigging shall be determined based on environmental conditions, load conditions and the region where it is located, after technical and economic analysis and comparison; 2 The main rigging materials should be 16Mn, 20, 35, 45, 35CrMoA and Q235-A, Q235-B, Q235-C. General rigging can use structural steel;
3 Rigging materials with the possibility of fatigue damage must be killed steel smelted in acid open hearth or electric furnace, and belong to high-quality steel or forgings, with a material ≥40%;
4 When the ambient temperature is less than or equal to -20℃, an αkv test should be carried out and the requirement of αkv ≥ 20J should be met; 5 The carbon content of carbon steel for rigging to be welded shall not be greater than 0.25%; in addition to the carbon content not exceeding 0.25%, the carbon equivalent Ce of low alloy steel or alloy steel shall not be greater than 0.43%, and is generally controlled at around 0.38%. 4.1.6 Welding materials shall be selected based on the mechanical properties, chemical composition, pre-welding preheating, post-welding heat treatment and use conditions of the materials being welded.
4.1.7 Welding materials shall comply with the relevant provisions of the current national standards "Carbon Steel Welding Rod" GB/T5117, "Low Alloy Steel Welding Rod" GB/T5118, and "Steel Wire for Fusion Welding" GB/T14957.
4.2 Load and Load Effect Combination
4.2.1 When designing pipeline crossings, permanent loads, variable loads, accidental loads, pressure test loads, construction loads and seismic effects shall be considered. 1. Permanent loads shall include the deadweight of the transmission pipeline, wire rope, tower, foundation, anchor pier, railing and walkway board, connector, anti-corrosion and insulation layer, and the weight of the transmission medium and the condensate in the pipe, the pressure of the transmission medium, etc.; 2. Variable loads shall include pigging load, maintenance load, ice and snow load, ice-wrapped load, wind load, water-filled load, temperature stress, flood impact load, flow pressure, water buoyancy, ice pressure, etc.; 3. Accidental loads shall include the impact force of ships or drifting objects and the line break load; 4. Test pressure loads shall comply with the provisions of Table 5.3.2 of this Code; 5. Construction loads shall include temporary lifting facilities and operator loads during construction, and impact loads generated by lifting and pipeline delivery; 6. Seismic effects shall consider horizontal seismic effects and vertical seismic effects. 4.2.2 Load effect combinations shall be combined according to different stages, i.e., construction stage, use stage, test pressure stage, and pigging stage, and design calculations shall be carried out according to the most unfavorable combination.
4.3 Selection of pipeline span structure type and determination of geometric dimensions4.3.1 When selecting the pipeline span structure type, the transmission pipeline should be used as one of the structural system members4.3.2 According to the span, pipe diameter, and riverbed hydrological and geological conditions, the pipeline span structure type can be selected from beam, "I"-shaped rigid frame, single pipe arch, combined pipe arch, light bracket, truss, suspension, suspension cable, suspension cable, inclined cable and other structural types (see Appendix A). 4.3.3 When determining the span of the pipeline span, in addition to considering the stress conditions of the span structure and the stability of the pier (buttress), the construction site and other conditions should also be considered.
SY/T 0015.2-1998
4.3.4 For large and medium-sized pipeline spans using suspension, suspension cable, suspension cable, inclined cable and other structural types, a symmetrical structure should be adopted, and the side span length should not be less than 2/5 of the middle span length.
4.3.5 The cables of large-scale cable-stayed pipelines should be arranged symmetrically to the tower and suspended (or fixed) on both sides of the tower. The horizontal angle between the outermost cable and the pipeline should not be less than 22°. 4.3.6 The supporting structure of the pipeline span below the highest flood level should be made of concrete or reinforced concrete. 4.3.7 The anchor piers of large-scale pipeline spans should be made of gravity concrete or reinforced concrete. 4.3.8 Guardrails or duty guardhouses and other preventive facilities should be installed at both ends of the overhead pipeline. 4.4 Calculation of strength and stability of pipelines
4.4.1 The hoop stress caused by the internal pressure of the pipeline transport medium is calculated according to formula (4.4.1). pd
In the formula: oh--
-Annular stress caused by the internal pressure of the pipeline medium (MPa); d-.Inner diameter of the pipeline (mm);
---Pipeline wall thickness (mm);
pInternal pressure of the pipeline medium (MPa).
4.4.2 Calculation of axial stress of pipeline:
1 The axial stress caused by the internal pressure of the pipeline medium is calculated according to formula (4.4.2-1). dal = 0. 5ah
In the formula: ·.Axial stress caused by the internal pressure of the pipeline medium (MPa); dh
Annular stress caused by the internal pressure of the pipeline medium (MPa). 2 The bending stress caused by the combination of bridge deck load effects is calculated according to formula (4.4.2-2). Ca2 =
Where: 02 --
Bending stress caused by the combination of bridge deck load effects (MPa); Bending moment caused by the combination of bridge deck load effects (N·m); Net section resistance moment of the pipeline (cm).
Axial stress caused by pipeline overhang is calculated according to formula (4.4.2-3). 3
4EDf×10-3
Axial stress caused by pipeline overhang (MPa); F----Elastic modulus of steel (N/mm\); DOuter diameter of pipeline (mm);
f---Vertical height (m);
1. Horizontal length of span (m)).
4Axial stress caused by cable is calculated according to formula (4.4.2-4). Qa
Where.·.…-Axial stress caused by cable (MPa); N-----Tension force of cable on pipeline (N);
A-Cross-sectional area of ​​pipeline (mm).
5 Temperature stress is calculated according to formula (4.4.2-5). N
dα = αEAt
Wherein..Axial stress caused by temperature deformation (MPa); ---Linear expansion coefficient of steel pipe (1/);
(4.4.1)
(4.4.2-1)Www.bzxZ.net
(4.4.2-2)
(4.4.2-3)
(4.4.2-4)
(4.4.2-5)
SY/T0015.2--1998
At——Temperature difference (℃);
E--Elastic modulus of steel (N/mm\). 4.4.3 Pipeline shear stress is calculated according to formula (4.4.3). Where: t—- shear stress caused by pipe bending (MPa); V——— pipe shear force (N);
A pipe cross-sectional area (mm).
4.4.4 Equivalent stress shall be calculated according to formula (4.4.4). V
a=Ve+,++(oa,+a.+aa)+3(t,+t+t) Where: α-equivalent stress (MPa);
o., o, α—-- stress in X, Y, Z directions (MPa); tay.tetx
shear stress in X, Y, Z directions (MPa)
4.4.5 Strength verification shall be carried out according to formula (4.4.5). aFa
Where:,--- yield strength of steel pipe (MPa); F—— strength design factor (see Table 3.0.3); g—equivalent stress of steel pipe (MPa). 4.4.6 Pipeline crossing structures should be verified for overall and local stability. 4.4.7 The wind dynamic response of large-scale spanning projects should be calculated by vibration mode decomposition response spectrum method or determined by wind tunnel simulation test. (4.4.3)
4.4.8 Pipeline spanning should avoid the resonance of bridge deck structure caused by wind vortex excitation, take effective anti-vibration measures, and perform structural fatigue verification. 4.4.9 The anti-sac design of pipeline spanning shall be carried out in accordance with the provisions of Section 4.10 of this Code. 4.5 Temperature compensation and bridge deck facilities
4.5.1 The spanning pipe section should utilize its own compensation capacity. When the thermal deformation requirements cannot be met, a compensator should be used. The compensator must meet the requirements that the pig and the detection instrument can pass smoothly. 4.5.2 When the last weld of the compensator and the straight pipe section is connected, welding should be selected under the local optimal temperature difference conditions. 4.5.3 The compensator elbow can be made of cold-bent pipe or hot-bent pipe, and the curvature radius of the elbow should be greater than or equal to 5DN. When the pipe diameter DN is greater than or equal to 400mm, it is advisable to use high-frequency bending pipes. 4.5.4 When the compensator is welded with a bend, the two bends should be connected by a straight pipe section. The length of the straight pipe section shall not be less than 1.5 times the outer diameter of the pipe and shall not be less than 500mm.
4.5.5 Where a compensator is used, appropriate pre-stretching (compression) measures shall be selected according to the difference between the construction environment temperature and the normal conveying medium temperature. 4.5.6 The navigation lights and transmission cables installed on the navigable rivers of the crossing pipe section shall be of reinforced insulation type, and the lighting fixtures shall be of sealed, waterproof and explosion-proof type.
4.5.7 If the overhead height of the crossing pipe section (including the tower height) exceeds 15m, lightning protection and grounding measures shall be considered. 4.5.8 A pedestrian inspection channel shall be set up for large and medium-sized crossings, and handrails shall be set on both sides of the channel, and the height shall not be less than 1.2m. 4.5.9 The support points of the crossing pipe section should be made into sliding bearings or elastic bearings. If both ends of the pipeline are pre-buried in the anchor piers on both sides, local reinforcement measures should be taken for the pipeline at the connection between the end face of the anchor pier and the pipeline. 4.5.10 When welding connectors on the crossing pipe section, they should be welded on the reinforcement plate and should not be welded directly on the outer wall of the pipeline. 4.6 Design and technical requirements for wire ropes
4.6.1 The design allowable tension of the wire rope should be 30% to 40% of the breaking tension of the wire rope, and the breaking tension of the wire rope should be 0.85% of the total breaking tension of the full-section steel wire.
4.6.2 The wire rope selected for the crossing project must be pre-tensioned before construction. The pre-tensioning force is 50% of the breaking tension of the wire rope. The stabilization time of the pre-tensioning shall not be less than 6h.
4.7 Rigging design and technical requirements
SY/T 0015.21998
4.7.1 Rigging in pipeline crossing projects includes components such as turnbuckle bolts, anchor heads, tie rods (U-shaped rings) and cast steel saddles. 4.7.2 Rigging design calculations generally include the following: 1. Strength design calculations with elastic failure as the failure criterion; 2. Limit design calculations with plastic failure as the failure criterion; 3. Structural instability caused by changes in structure or shape requires stability design calculations using stability criteria; 4.
Fatigue damage caused by load changes requires fatigue analysis and verification design calculations. 4
4.7.3 The safety factor, allowable stress and calculation criteria of rigging design shall comply with the following provisions: The safety factor of important components shall be selected in accordance with the provisions of Tables 4.7.3-1 and 4.7.3-2; The limit design allowable stress with plastic failure as the failure criterion shall be 1.5 times the basic allowable stress: 2
3 The allowable stress value and calculation criteria of stability design criteria and fatigue failure analysis design shall be implemented in accordance with the "General Principles of Analysis and Design" in "Steel Pressure Vessels-Analysis and Design Standard" JB4732-1995 and Appendix C "Design Based on Fatigue Analysis" (Supplement) respectively;
Allowable stress of cast steel The value is equal to the basic allowable stress multiplied by 0.8 to 0.9 times the casting quality coefficient; Table 4.7.3-1 Safety factor of steel materials
Carbon steel, low alloy steel,
Ferritic high alloy steel
Austenitic high alloy steel
Carbon steel
Low alloy steel,
Martensitic high alloy steel
Austenitic high alloy steel
Minimum
Tensile strength at room temperature
Bolt diameter
AM22,
M24~M48
M22,
M24~M48
≥M52||tt| |M22,
M24~M48
Yield point or
Table 4.7.3-2
Bolt safety factor
Endurance strength αp after 10×10°h
fracture at design temperature
Average value
Sub-yield point at design temperature
Heat treatment state
Hot rolling, normalizing
ans
Minimum value
Endurance strength after 10×
10'h fracture at design temperature
Average value of products㎡
Welded parts The allowable stress should be multiplied by the weld coefficient. The Φ value is selected according to the provisions of 1.8 in GB150-1989 of "Steel Pressure Vessels" 5
;
The allowable stress value under instantaneous load should be less than 0.9 times the yield limit of the material at that temperature; 6
SY/T0015.2-1998
7When the temperature is lower than 20℃, take the allowable stress at 20℃: 8The bolt strength reduction coefficient is greater than or equal to 4.0. 4.7.4 The manufacture and inspection of rigging shall comply with the following provisions: 1The manufacture and inspection of rigging shall be carried out in a factory with a qualification certificate; 2For the materials used in the manufacture of rigging, the manufacturer shall provide the raw materials In addition to the quality certificate, the materials used must also be re-tested. 4.7.5 The manufacture and inspection of important parts with fatigue damage such as basket bolts and tie rods shall comply with the following provisions: 1 Forgings should be killed steel, and the steel ingots used for forgings should remove sufficient pouring and risers; 2 The chemical composition, mechanical properties and heat treatment of forgings should comply with the current national standards "Technical Conditions for High-quality Carbon Structural Steel" GB/T699 or "Technical Conditions for Alloy Structural Steel" GB/T3077. 3 The grain size inspection shall be carried out in accordance with the current national standard "Method for Determination of Average Grain Size of Metals" GB/T6394, and ensure that it reaches level 6 or above:
4 The inspection of non-metallic inclusions shall be carried out in accordance with the current national standard The forgings shall be inspected in accordance with the provisions of GB/T10561 "Microscopic Evaluation Method for Non-metallic Inclusions in Steel", with oxides not exceeding level 2, sulfides not exceeding level 2, and the sum of oxides and sulfides not exceeding level 3.5; 5 The macroscopic inspection of forgings shall be carried out in accordance with the provisions of the current national standard "Macroscopic Structure and Defect Acid Etching Test Method for Steel" GB/T226, ensuring that the general looseness does not exceed level 2, the central looseness does not exceed level 2, and the segregation does not exceed level 1.5. White spots, cracks, pores and other defects are not allowed inside the forgings;
6 Forgings shall be inspected by ultrasonic testing, and the results shall comply with the provisions of the current national standard "Ultrasonic Testing Method for Forged Steel Bars" GB/T4162 A-level regulations;
7 Parts should be subjected to magnetic particle inspection. The inspection is carried out twice, that is, after rough machining and fine machining respectively. The results should ensure that there are no defects such as cracks, holes and gaps on the inner and outer surfaces and threads of the parts; 8 The basic tooth shape and basic dimensions of the thread should comply with the current national standards "Basic Tooth Shape of Ordinary Thread" GB/T192 and "Basic Dimensions of Ordinary Thread (Diameter 1~600mm)" GB/T196. The tolerances shall comply with the provisions of "Tolerances and Fits of Ordinary Threads (Diameter 1355mm)" GB/T197. The limit deviations of other dimensions without tolerances shall comply with (Unindicated Tolerances of General Tolerances Linear Dimensions" GB/T Processing according to the requirements of m level in 1804;
9 The thread surface shall not have burrs, scars, depressions and other defects, the thread root shall be smooth, and R shall be 0.625~0.72mm10 In addition to the inspection by the manufacturer, the parts shall be re-inspected and sampled before on-site installation, and the sampling rate shall be 10%20%; if unqualified parts are found, the sampling percentage shall be increased or all shall be re-inspected, and the sampling results shall be based on the test data;11 All parts must have a complete quality inspection certificate, which shall include chemical composition, mechanical properties (including low temperature Akv value), inspection results during the processing of parts and final inspection results, and sampling data before on-site installation. 4.8 Selection and design of tower structure type
4.8.1 According to the hydrological conditions, engineering geological conditions, the height of the supporting structure itself, the force characteristics and construction conditions, etc., the supporting structure of the pipeline spanning can choose steel tower or reinforced concrete support. 4.8.2 Depending on the environment, the connection method with the pier or buttress, etc., the steel tower frame can be a self-supporting steel tower frame or a pole-type steel tower frame. The reinforced concrete support should be a four-column support with diagonal braces. 4.8.3 In order to increase the lateral stiffness of the pipe bridge, a rectangular steel tower frame should be used. A conical steel tower frame can also be used, but the top width of the conical steel tower frame perpendicular to the pipe bridge direction shall not be less than 3m. 4.8.4 The ratio of the height of the steel tower frame to the bottom width should not be greater than 5. 4.8.5 The steel tower frame should adopt a "K"-shaped web member system, and a transverse partition should be set at the main horizontal web member. 4.8.6 The columns, main web members and horizontal web members at the top of the steel tower frame should be made of steel pipes, and the remaining members should not use combined sections. 4.8.7 An inspection platform must be set at the top of the steel tower frame and at the compensator of the transmission pipeline. For steel tower frames with a height greater than 50m, a rest platform should also be added in the middle.
4.8.8 The top of the tower frame should reserve a position for the construction of load-bearing cables. 4.8.9 When calculating the natural vibration period of the tower frame, the vertical load of the pipe bridge superstructure under normal use should be considered. 196
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4.8.10 When analyzing the internal forces of a self-supporting steel tower, the entire tower shall be analyzed and calculated as a spatial truss. When analyzing the internal forces of a pole-type steel tower, a plane truss may be connected for analysis and calculation. 4.8.11 The strength and stability calculations, node connection calculations, and structural requirements of steel tower members shall be carried out in accordance with the provisions of the current national standard "Code for Design of Steel Structures" GBJ17.
4.8.12 When analyzing the internal forces of reinforced concrete supports, the entire support shall be analyzed and calculated as a spatial structural system. 4.8.13 The strength, crack width, and structural requirements of reinforced concrete supports shall be carried out in accordance with the provisions of the current national standard "Code for Design of Concrete Structures" GB310. The thickness of the concrete cover shall not be less than 35mm, and the crack width shall not be greater than 0.2mm. 4.9 Foundation and base design
4.9.1 The hydrological and engineering geological survey reports of pipeline crossing projects shall meet the design requirements of pipeline crossing projects. 4.9.2 When constructing pipeline crossing projects in areas with a basic earthquake intensity of ? and 7 degrees or above, it shall be determined whether there is a liquefied soil layer in the foundation, and the liquefaction identification and foundation liquefaction level shall be determined in accordance with the provisions of the current national standard "Code for Seismic Design of Buildings" GBI11. 4.9.3 The foundation type of pipeline crossing projects shall be selected based on various factors such as engineering geology, hydrogeology, pipeline crossing structure type and construction conditions.
4.9.4 The foundation depth of pipeline crossing projects shall meet the following requirements on the premise of meeting the foundation strength and deformation requirements: 1 The foundation depth shall meet the requirements of anti-slip and anti-overturning; 2 When the foundation is set in the frozen soil layer, the base shall be buried below the freezing line. Not less than 0.3m; 3 When the foundation is set in the scour stability layer, except for the rock foundation, the base is buried below the design scour line. The large pipeline crossing project should not be less than 2m. The medium-sized pipeline crossing project should not be less than 1.5m, and the small pipeline crossing project should not be less than 1m; 4 When the foundation is set on the rock foundation, the weathered rock layer should be removed, and the base should be embedded in the rock to a certain depth according to the anti-scour force and bearing capacity of the bedrock.
4.9.5 The foundation of various types of pipeline crossing projects should be calculated according to various load combinations and foundation conditions, and in accordance with the provisions of the current national standard "Code for Design of Building Foundations" GBJ7 for foundation bearing capacity, foundation settlement and the strength and stability of the foundation itself. 4.9.6 The anti-overturning and anti-sliding stability of the foundation shall be calculated according to formula (4.9.6-1) and formula (4.9.6-2). FRm ≥1. 3
MRM ≥1.5
Wherein: FR滑——anti-sliding force;
Fs滑——sliding force;
K滑——anti-sliding stability coefficient:
Mr傻——anti-overturning moment;
Ms\\——overturning moment;
K anti-overturning stability coefficient.
4.10 Earthquake-resistant design
4.10.1 The anti-slip design of various pipeline crossing projects shall comply with the following provisions: (4.9.6-1)
(4.9.6-2)
1 When the seismic fortification intensity is 7 degrees or above, the effect of the ground on large pipeline crossing projects shall be calculated according to the seismic motion parameters specially studied.
2 The effect of earthquakes on other types of pipeline crossing projects shall be calculated according to the basic seismic intensity of the local area. When the basic earthquake intensity is 6 degrees or less, no earthquake action calculation is required. 3 Pipeline crossing projects should adopt corresponding earthquake-resistant measures. 4.10.2 Earthquake-resistant structures should comply with the following provisions: 1 The structure should have a clear force transmission system and a reasonable transmission path for earthquake action; 2 It is advisable to set up multiple earthquake-resistant lines;
SY/T 0015. 2--1998
3 It should have the necessary earthquake-resistant strength, good deformation capacity and shock absorption capacity. 4.10.3 The earthquake-resistant calculation and construction measures of pipeline crossing project structures should comply with the provisions of the current national standards GBJ11 and GB50191 "Code for Seismic Design of Structures".
4.11 Anti-corrosion and thermal insulation
4.11.1 The surface of steel pipes and other steel materials used in pipeline crossing projects should be coated with an anti-corrosion coating that is resistant to environmental corrosion, sunlight, cold and ultraviolet rays. In the design of components, dead corners and grooves that are difficult to inspect, clean, and accumulate moisture or dust should be avoided. 4.11.2 The surface oil film and sludge of the steel wire rope used in the pipeline crossing project must be cleaned, and the surface of the steel wire rope and rigging must be wrapped or hot-coated with a protective layer. The anti-corrosion material used must not flow at high temperatures and crack at low temperatures under local temperature conditions. It must be a neutral material that does not contain acid or alkali and has good bonding performance with the steel wire rope. 4.11.3 All rigging connectors (including main cable splints, basket bolts, U-shaped pull rings, pulleys, cable saddles, pull rod bolts, etc.) should be coated with anti-corrosion oil after installation and commissioning, and sealed and wrapped with self-cross-linking adhesive tape to prevent rain erosion. 4.11.4 When the transportation process requires insulation, the crossing pipe section should use insulation materials with good insulation performance and light weight, and a waterproof protective layer should be set on the surface of the insulation layer.
5 Technical requirements for construction
5.1 Assembly of spanning pipe sections
5.1.1 Before processing the pipe sections, their length and diameter shall be selected. The minimum length of each steel pipe shall not be less than 8m. The allowable deviation of the outer diameter of the steel pipe shall be ±3.0mm, and the allowable deviation of the wall thickness shall be ±10% of the wall thickness. 5.1.2 The processing type and size of the pipe groove shall comply with the provisions of Table 5.1.2. Table 5.1.2 Processing type and size of pipe groove Type
Upward welding
Downward welding
Upward welding
Downward welding
Upward welding
Downward welding
Gap 6
1. 5~~2. 5
1. 0~1. 5
1. 5~2. 0
Blunt edge P
1.0～1.5
1.5～2.0
Groove angle α
60°±5°
60°5″
60°±5°
60°±5°
60°±5°
5.1.3 When assembling pipelines, the length of the pipe section should be accurately measured, and the brackets or other connectors should be welded at the designated positions in the design, with obvious numbers marked. During construction, pay attention to checking and correcting at any time.
5.1.4 When butt-jointed, the longitudinal welds of the two pipes (including the longitudinal welds of the elbows) must be staggered, and the spacing must not be less than 100mm.5.2 Welding and inspection of crossing pipe sections
5.2.1 The construction unit shall conduct an assessment in accordance with the design documents and the provisions of the current national standard "Oil and Gas Pipeline Welding Process Assessment Method" SY4052 before welding.
5.2.2 The preheating of the weldment and the post-weld heat treatment shall be determined based on the mechanical properties, chemical composition, weldment thickness, welding conditions and climatic conditions of the material.
5.2.3 When welding two materials with different preheating or post-weld heat treatment requirements, the material with the higher requirement shall prevail. 5.2.4 The minimum ambient temperature during welding should be ~20°C for low-carbon steel, -15°C for low-alloy steel, and 5°C for low-alloy high-strength steel.
SY/T 0015.2-1998
5.2.5 Effective protective measures must be taken when welding in rainy or snowy weather, when the wind speed exceeds 8.0m/s, or when the relative humidity exceeds 90%. 5.2.6 After welding, the weld should be inspected in time for appearance. Nondestructive testing shall not be conducted for welds that fail the appearance quality inspection. The appearance quality inspection of welds shall comply with the provisions of the current national standard "Specifications for Construction and Acceptance of Petroleum and Natural Gas Pipeline Crossing Projects" SY4070. 5.2.7 Nondestructive testing of welds shall comply with the following provisions: 1 100% of the circumferential welds across the pipeline shall be subjected to radiographic testing. 2 For individual circumferential welds where radiographic testing is difficult, ultrasonic testing may be used instead of radiographic testing after joint agreement by relevant departments, but the number shall not exceed 10% of the total number of circumferential welds in the pipeline. 3 Radiographic testing shall be carried out in accordance with the provisions of the current national standard "Radiographic Transmission Process and Quality Classification of Circumferential Fusion Welded Butt Joints of Steel Pipes" GB/T12605, and the qualified level is Level II. Ultrasonic testing shall be carried out in accordance with the provisions of the current national standard "Manual Ultrasonic Testing Methods and Classification of Testing Results for Steel Welds" GB/T11345, and the qualified level is Level I. 5.3 Pressure Testing and Pigging
5.3.1 Pressure testing and pigging shall be carried out after the pipeline is assembled, welded, and inspected. The overall purge, pressure testing, and pigging of the pipeline shall be carried out after all the crossing pipelines are completed.
5.3.2 The test pressure medium should be water or air. The test pressure and qualified standard shall comply with the provisions of Table 5.3.2. Table 5. 3.2 Test pressure, stabilization time and qualified standard Item
Test pressure
Pressure stabilization time
Qualified standard
Note: p is the design pressure (MPa).
Where: △p---pressure drop rate (%);
Strength test
Pipe section pressure test
Tightness test
Water or air
No abnormal deformation, no leakage
No leakage
pNatural T) × 100
PStart TEnd
TStart---Thermodynamic temperature of the medium in the pipe at the beginning of the test (K); T. Thermodynamic temperature of the medium in the pipe at the end of the test (K) p. "· Reading value at the beginning of the test (MP a); p---Read the meter value at the end of the test (MPa). Overall tightness test
5.3.3 The strength test pressure should rise evenly and slowly. When the test pressure is greater than 3.0MPa, it is advisable to increase the pressure in three steps, that is, when the pressure is 30% and 60% of the test pressure, the pressure should be stabilized for 30 minutes respectively, and the pipeline should be fully inspected before continuing to increase the pressure to the final test pressure. When using air medium for pressure testing, the pressure increase shall not exceed 1.0MPa per hour. If any leakage is found during the pressure stabilization period, After the pressure relief repair is passed, the pressure test shall be carried out again according to the regulations until it passes. 5.3.4 After the strength test is passed, the pressure in the pipe shall be reduced to the design pressure. After the temperature of the medium in the pipe and the temperature of the air around the pipe are balanced, the tightness check shall be carried out according to the provisions of Table 5.3.2. 5.3.5 Before the pipeline is pressure tested in sections, the soil and debris in the pipe shall be cleared. Before the overall pressure test, the pipe must be cleaned. When cleaning the pipe with water, the water flow rate shall not be less than 1~1.5m/s; when cleaning the pipe with air, the air at the outlet shall not be less than 1~1.5m/s. The flow rate shall not be less than 20m/s until all the dirt is swept away. 5.3.6 Before connecting large and medium-sized crossing projects with line pipelines, temporary cleaning and sending facilities and vents shall be set up. It is strictly forbidden to pass dirt and accumulated water in the line pipeline through the crossing pipeline.
5.3.7 When testing the pressure with water, an exhaust valve shall be installed at the highest point of the pipe top of the crossing pipeline. 5.3.8 For pipeline crossing projects that transport hot oil, a hot water test shall be carried out before oil is passed. After checking that the displacement of each node is normal, oil can be passed for transportation. 199
SY/T 0015.2—1998
Lhh 4]
Beam-type pipeline span
Combined pipe arch span
Appendix A
Schematic diagram of various spanning structures
“IⅡI” type rigid frame pipeline span
Light bracket-type pipeline span
Suspended pipeline span
Figure A8 Cable-suspended pipeline span
Single pipe arch span
Truss-type pipeline span
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