What are the safety issues with tensile, pressure and universal testing opportunities?

What are the safety concerns of tension, compression and multipurpose testing machines? In the testing work of the test, the author has encountered safety incidents such as electric shock injury and oil pipe bursting. This article mainly analyzes and discusses these two problems.

Event 1: Multifunctional testing machine WE-100

The date of manufacture was June 1960. During the verification process, when the pressure rose to about 800kN, the oil pipe connecting the main body and the force-measuring mechanism burst suddenly, and the burst occurred at a corner of the oil pipe. And this test machine has been in use for more than 40 years. I think the fuel pipe burst because it reached the fatigue limit. If the service life of the testing machine is too long, will key parts such as columns and column bolts reach the fatigue limit and break? For this reason, the author once consulted an engineer of the testing machine manufacturer about the service life of the testing machine. He said that there is no limit to the service life of the test machine, as long as it passes the test, it can be used. However, the author believes that only verifying the indication error of the testing machine cannot test the safety performance of the testing machine. However, the testing machine verification regulations only require that the nameplate should have a production date, and no specific requirements are made. Therefore, the author suggests that the service life requirement be added to the testing machine verification regulations.

Event 2: Pressure testing machine YE-2000E

This testing machine is a type with a lower oil cylinder. There is a limit switch on the column to control the stroke of the oil cylinder. The lower part of the limit switch was damaged and the contact was lost. It was not found at that time. We generally clean the surface dust and garbage before verifying the testing machine. One time, when cleaning the concrete slag on both sides of the oil cylinder, I accidentally touched the limit switch and was injured by electricity. At that time, the testing machine was not turned on, and the testing machine was connected to the power grid through an automatic air switch. The distance between the two sides of the oil cylinder was narrow. When cleaning debris, the lower part of the travel switch was accidentally touched, and the current passed through the hand and the body column to form a circuit. If the testing machine is equipped with a suitable leakage protector, it will trip, and there will be no electric shock injury. The author has found that most of the testing machines are connected to the power grid with a knife switch or an automatic air switch in the verification of testing machines over the years, and there is no provision for how to connect them in the testing machine verification regulations. Therefore, the author suggests that the testing machine should be connected to the power grid after passing through the leakage protector and the knife switch.

The above are the problems encountered by the author in the verification of the testing machine. I hope that the relevant departments can consider adding relevant content when revising the verification regulations of JJG139-1999 "Tension, Compression and Multifunctional Testing Machines", and hope that the relevant manufacturers can further improve the testing machine. , in order to better guarantee the work safety of test and verification personnel.