GB 242-82 Metal Tube Expanding Test Method
This document provides requirements and procedures for expanding metallic tubes conforming to GB 242. This method relies on the properties of traditional thermally treated or mechanically formed metal tube components to expand under pressure. For this reason, it is necessary to use properly selected test materials and tools in order to achieve accurate, reliable results.
Test materials must be either specially prepared for the test or obtained from a standard catalog. Care should be taken to ensure that the test materials conform strictly to the specified standards. Any variation from these standards may cause the results to be inaccurate.
In order to properly expand a test tube for evaluation, the proper expanding tools must first be selected. A mandrel and die must be selected according to the specified diameter of the test material. The mandrel should be chosen such that it is slightly larger than the test tube in order to provide a degree of time flexibility when expanding the tube. The die should be chosen such that the pressure exerted is uniform along the length of the tube.
Once the test material and proper expanding tools are selected, it is necessary to properly secure the test tube to the expanding tools. This is necessary in order to achieve even distribution of the forces applied to the tube during expansion. The tube should be held in place by either a vice or by clamps. If the tube is held in a vice grip, care should be taken to ensure that the grip does not damage the tube in any way.
Once the test tube is secured, the expanding tools should be positioned in place. The mandrel should be used to push the expanding die onto the test material in a steady, low-pressure manner until resistance is felt. The test tube should then be expanded at a rate of approximately one tenth of a millimeter per second until it has expanded to the desired amount.
Once the tube has been expanded to the desired amount, the expanding tools should be carefully removed. The expanded test tube should then be inspected thoroughly to ensure that the expansion process was successful. It is important to check for any signs of cracking, deformation, elongation, or other abnormalities that may have occurred during the process.
Once the inspection is complete, the performance of the test tube should be evaluated against the specified standards. This evaluation can include determining the strength, ductility, and permanent set of the tube as well as evaluating any other properties that were specified for the test. The results of this evaluation should be recorded for future reference.
This document sets out the requirements and procedures for expanding metal tubes conforming to GB 242, which are used in various industrial applications. Following these procedures and requirements closely will help to ensure that accurate, reliable results are obtained from the expanding test process.
