Regarding the overspeed test of the compressor unit
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It is well known that a speed test must be conducted before a new machine is run for the first time. But for units that have been in operation for a while, for example, after maintenance or when they are shut down for other reasons, is an overspeed test conducted when they are restarted?
This post was last edited by xlxuiin on 2015-7-14 at 14:38: http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=1192341&highlight=%B3%AC%CB%D9%CA%D4%D1%E9. The emergency safety device is one of the most important protections for steam turbines; it must be tested regularly to prevent the flywheel from rusting or to avoid a decrease in the elasticity of the springs over time, which could lead to a reduction in the activation threshold or even no activation at all. Tests help to identify any hidden defects in the emergency safety device. It is worth noting that some turbines contain high levels of turbine oil along with impurities, which can cause corrosion and sticking in the various components of the speed control system, thereby threatening the safety of the equipment. However, since the overspeed test imposes excessive stress on the blades, conducting it too frequently is also detrimental to the equipment. Typically, manufacturing plants require the unit to undergo a test every 2,000 hours of operation. Based on actual conditions, our factory conducts tests every six months under normal circumstances, or after major repairs; in special cases, the testing interval can be shortened appropriately, such as when there is a large amount of water in the oil or when the speed control system is corroded.
http://bbs.hcbbs.com/forum.php?mod=viewthread&tid=266432&highlight=%B3%AC%CB%D9%CA%D4%D1%E9 JB/T 6445-2005 Over-speed test for industrial ventilator impellers
Strictly speaking, this should be done, especially after major repairs, but nowadays some factories rarely do it to save trouble.
We’ve never seen our turbines do this!
No need, la la la. PS: I’ve never seen our company do it
After maintenance, an overspeed test is usually carried out when starting the machine; it may not be done if the unit does not need to be operated. Generally, this test is not performed if the machine is started right after the fault has been resolved
Well, it depends on which part of the compressor is being repaired. If it’s a minor part, then there’s no need for testing. But if it’s a more important part that could affect the compressor’s operation, it’s better to conduct tests, such as on components like bearings, which are crucial. If it’s just a matter of changing the oil and air filter, then testing isn’t necessary. It’s just an example; the decision should be based on the actual situation, taking into account the compressor’s model and the part that needs repair
After a major overhaul, it is generally necessary to conduct an overspeed trip test, aimed at determining whether the turbine’s safety systems and flyweights can function effectively as protective mechanisms. If it’s just a minor repair, then it’s not necessary. Overspeed represents a challenge for steam turbines every time; in particular, components such as the blades can suffer from fatigue and fracture due to overspeed. But they’re not that fragile – my turbine is 40 years old now and still performs excellently!