The quality inspection of reinforced mechanical joint is divided into type inspection and on-site inspection. In accordance with the requirements of building the type of inspection to joint uniaxial tensile performance, high stress and tension and compression performance and large deformation pressure performance test repeatedly, the extrusion sleeve joint and taper thread joint based on the differences of joint performance index is divided into A, B two performance level, type test is more complex, workload is big, therefore, After determining the performance grade of a joint product through type inspection, only on-site inspection can be carried out on the site under the condition that the production technology and main raw materials do not change significantly. However, the technology provider is required to submit a valid type inspection report and conduct joint process inspection on each batch of steel bars before and during the construction of the steel bar connection project.
Site inspection is also called construction inspection, generally only for appearance quality inspection and tensile strength test. Under the same construction conditions, 500 joints of the same grade, type and specification of the same material shall be used as one acceptance batch. Ten acceptance batches have been continuously inspected on site, all of which are qualified in one sample of unidirectional tensile test. The number of joints in the acceptance batches can be doubled. During appearance quality inspection, 10% of sleeve extrusion joints and 10% of taper thread joints are randomly selected from each acceptance lot. During the tensile strength test, 3 specimens must be randomly selected from the engineering structure for each acceptance batch of joints.
The quality of mechanical joint depends on the management and operation level of the site to a large extent, especially the taper thread joint, so adhere to random sampling in the project can greatly promote the responsibility of construction personnel to operate, improve the quality of joint. When threaded joints cannot be made after being cut in the field, welding, lap joints or other types of joints are allowed to replace the cut joints, because the proportion of the cut joints to the total number of steel bars in the member is usually small, so local substitution will not cause damage to the overall strength of the structure. Insist on random sampling in the project will bring some trouble to the construction, but the quality of the project concerns the safety of people’s lives and property, so we must insist. Tensile samples for on-site inspection of mechanical joints should be randomly sampled in the project to ensure the quality of the project.
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