SY/T 7318.3-2024 Standard test method for special properties of line pipe - Part 3.Full scale bending test English, Anglais, Englisch, Inglés, えいご
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ICS
E
Professional standard of the People's Republic of China
SY/T 7318.3-2024
Replaces SY/T 7318.3-2017
Standard test method for special properties of line pipe - Part 3: Full scale bending test
油气输送管特殊性能试验方法 第3部分：全尺寸弯曲试验
(English Translation)
Issue date: 2024-12-25 Implementation date: 2025-06-25
Issued by National Development and Reform Commission, P.R.C
Contents
1 Scope
2 Normative References
3 Terms and Definitions
4 Test Capability Assessment
5 Test Pipe
5.1 Test Pipe Properties and Dimensions
5.2 Test Pipe Fabrication
6 Test Equipment
6.1 General Requirements
6.2 Loading System
6.3 Measurement Devices
7 Test Method
7.1 General Rules
7.2 Test Pipe Preparation
7.3 Test Pipe Measurement
7.4 Test Temperature
7.5 Test Pipe Positioning
7.6 Testing
8 Data Processing and Test Report
8.1 Data Processing
8.2 Test Records
8.3 Test Report
Appendix A (Informative) Test Results
Appendix B (Informative) Test Report
Test Methods for Special Properties of Oil and Gas Transmission Pipes — Part 3: Full-Scale Bending Test
1 Scope
This document specifies the test pipe, test equipment, test methods, data processing, and test report for the full-scale bending test of steel pipes for oil and gas transmission pipelines.
This document applies to measuring the bending behavior of steel pipes (including pipes with girth welds) under static monotonic loading using the moment arm or four-point bending method. Full-scale bending tests of other similar steel structures under static loading may refer to this document.
2 Normative References
The following documents contain provisions which, through normative reference in this text, constitute essential provisions of this document. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 228.1 Metallic materials — Tensile testing — Part 1: Method of test at room temperature
GB/T 229 Metallic materials — Charpy pendulum impact test method
GB/T 232 Metallic materials — Bend test method
GB/T 13992 Bonded metal wire resistance strain gauges
GB/T 16825.1 Metallic materials — Calibration and verification of static uniaxial testing machines — Part 1: Tension/compression testing machines — Calibration and verification of the force-measuring system
3 Terms and Definitions
For the purposes of this document, the following terms and definitions apply.
3.1
test pipe
A steel pipe or pipe section containing a girth weld joint used for the full-scale bending test.
3.2
buckling
Instability or wrinkling of all or part of the pipe wall caused by bending or axial compressive loading of the pipeline.
3.3
four-point bending
Bending of the test pipe in the form of a simply supported beam, where the test pipe is placed horizontally in the bending test machine, the distance between the two support points supporting the test pipe is adjustable according to the specimen length, and there are two symmetrical loading points.
4 Test Capability Assessment
Before the test is carried out, test parameters shall be assessed and evaluated based on the capabilities of the test equipment. The design of test parameters shall not exceed 80% of the capacity of the test equipment.
5 Test Pipe
5.1 Test Pipe Properties and Dimensions
5.1.1 Before the full-scale bending test is carried out, tests on the test pipe should be conducted according to the content specified in A.1.
5.1.2 Tensile tests shall be carried out according to the provisions of GB/T 228.1, bend tests shall be carried out according to the provisions of GB/T 232, and the material ductile-to-brittle transition curve for the steel pipe body and welds shall be plotted according to the provisions of GB/T 229.
5.1.3 The length (test section) of the test pipe shall not be less than 6 times the pipe outer diameter D.
Note: Applicable to four-point bending.
5.1.4 The maximum wall thickness of the test pipe can be determined by calculation based on the test purpose, pipe diameter, material properties, and the maximum load capacity of the test equipment.
5.2 Test Pipe Fabrication
5.2.1 For moment arm type loading, both ends of the test pipe should be beveled mechanically and connected to end plugs by welding.
5.2.2 When conducting four-point bending tests with internal pressure, both ends of the test pipe should be beveled mechanically and welded to end caps for sealing.
5.2.3 The test pipe shall not have non-design defects.
5.2.4 When conducting bending tests with internal pressure, the water filling port and vent port of the steel pipe should be located at the end plugs or end caps.
6 Test Equipment
6.1 General Requirements
6.1.1 The test equipment shall include a loading system, measurement devices, accessories, etc.
6.1.2 During the test, the measurement devices shall continuously measure and record the following parameters:
—— Applied load;
—— Displacement in the load direction;
—— Strain at specific locations on the test pipe.
6.1.3 Load calibration shall be carried out according to the provisions of GB/T 16825.1.
6.2 Loading System
6.2.1 The main function of the loading system is to apply internal pressure and bending load. Its main components include load application devices, loading arms, supports, loading anvils, and an internal pressurization device. Schematic diagrams of the moment arm type loading system and four-point bending loading system are shown in Figures 1 and 2.
6.2.2 The displacement loading of the anvils in the four-point bending loading system shall be synchronized. The structural design of the anvils shall avoid generating additional stress.
6.3 Measurement Devices
6.3.1 Strain Measurement Device
6.3.1.1 During the test, the strain on the pipe body surface shall be measured.
6.3.1.2 The resolution of the strain acquisition instrument shall be better than 0.1 με, the acquisition frequency shall be greater than 10 Hz, and the measurement range shall be greater than 50,000 με.
6.3.1.3 The selection of strain gauges shall comply with the provisions of GB/T 13992.
6.3.1.4 The number of strain gauge points arranged within a range of 1 times the outer diameter on each side of the theoretically maximum strain position along the axial direction on the inner arc surface of the test pipe during bending should not be less than 4.
