Bending test of steel pipe(Pipeline )
Bending test of steel pipe(Pipeline )
Pipeline bending tests deform the test pipes at the midpoint, resulting in concave or bending without fracture, and bending tests are usually performed to determine ductility or fracture resistance of the pipes. Pipe bending test is one of the basic methods for mechanical performance test of pipelines.
The purpose of pipe bending test:
Pipeline bending test is to deform the sample into a specific shape, which can determine the ductility, bending strength, fracture strength and fracture resistance of the pipeline. These characteristics can be used to determine whether the pipeline fails under pressure. If the pipeline begins to break or completely break during three or four point bending tests, it is assumed that the pipeline will fail under similar conditions in any application, which may lead to catastrophic failure.
There are four common types of bending tests.
1. In the steering bending test, the sample is placed horizontally on two supports, and then applied to the top of the point to deform the sample into a "U" shape.
2. in the semi guide bending test, the midpoint of the specimen is bent to a specific angle or radius.
3. in the free bending test, the end of the sample is pushed together, but no force is applied to the bending itself.
4. Finally, the common fracture toughness test (ASTM E399) consists of a sample with a pre-cracked actuator crack at the bottom of the midpoint and loaded into a three-point bending fixture so that the midpoint force is applied to the other side. Crack.
Advantages of bending test
1. Three kinds of circular, square and rectangle are suitable for the measurement of inconvenient brittle materials.
2. Tensile tests on brittle materials show little deformation. Bending tests can be used to express the plasticity of brittle materials with deflection.
3. In the bending test, the stress distribution on the section is the largest on the surface, so it is sensitive to the surface defects of materials.
4. For high plasticity material, bending test usually can not reach its failure degree, so bending strength test is not generally done.
5. Bending test is simple and convenient.
