– Leak Tightness Test
– Bending Test
Tubes are an essential part of many industrial applications, and it is important that they be able to withstand certain loads and stresses. One such test is the bending test, which determines a tube’s ability to resist fracture or failure under duress.
• Tubes ≤ DN50 – The test is carried out by placing the tube in a bending machine, with the weld at a 90 degree angle to the plane of bending. The tube is then bent cold around a former with a radius that is appropriate for the particular tube being tested. For ungalvanized tubes, this radius should be equal to 6 times the outside diameter of the tube; for galvanized tubes, it should be 8 times the outside diameter of the tube. If the tube does not crack or show any signs of failure during this process, it is considered to have passed the test.
• Tubes ＞ DN50
– According to the given specifications, for finished tubes that are larger than DN50 in diameter, rings cut from the end of the selected tubes must be at least 40mm in length and be able to be flattened between two parallel plates. The weld, if there is one, should be at a 90 degree angle in relation to the point of maximum bending. Additionally, no opening or fracture should occur in the weld until the distance between the plates is less than 75% of the original outside diameter of the tube. There should also be no cracks or breaks in the metal occurring elsewhere until the distance between the plates is less than 60% of the original outside diameter of the tube. As appropriate, test rings may have their inner and outer edges rounded.