How to avoid damage to the pump seal at the start of operation of the equipment
Thread Content
My installation is currently under construction, and based on past experience, mechanical seals tend to fail very frequently at the beginning of operations for newly built installations. Although construction quality is strictly controlled during the building process, it is still not possible to completely prevent impurities within the system from entering the equipment and causing damage to the mechanical seals. Therefore, I would like to use a startup seal during the initial water-cooled operation phase, that is, replace the mechanical seal temporarily with a packing seal, and then use a proper seal once the actual cold oil operation begins. I was wondering if any of you experts have any proven experience to share; I would be extremely grateful!
This is a really troublesome issue; when driving the machine for the first time, due to dirty pipes and excessive impurities, the mechanical seals get damaged frequently. The method suggested by the original poster also has issues; modifying all the gaskets requires a lot of work, and especially when it’s time to start using the machine again, there may not be enough time to replace them all with mechanical seals. I think the only solution is to control the installation process and perform more purging. Also, I was wondering if it’s possible to install a filter screen on the inlet side I haven’t tried it yet, so I don’t know if it has an impact on pressure or flow rate.
Pipeline purging, filters, pump turning, etc
For newly installed units, strict requirements are imposed in terms of project management, including strict control of impurities inside the pipes during piping, and the use of pipe caps at the pipe ends; however, these measures cannot resolve the problem at its root. Regarding the issue of installing filters mentioned on the 2nd floor, we have considered it. When the filters become clogged, it is easier for the pump to reach a vacuum condition, and mechanical seals are more prone to leakage. Although using packing seals requires more work, it is possible to discuss the cost-effectiveness with the manufacturer and maintenance personnel. I would like to know if everyone agrees with these views?
As mentioned on the 2nd floor, installing filters can lead to blockages, and the filling material requires a lot of work. Moreover, when building a system, it’s not just about one or two pumps but many pumps in total. If filters are installed everywhere and the filling material is changed in all cases, the costs will increase significantly, which seems impractical. The best approach is to carry out repeated purging before starting up the system. Special attention should be paid to the inlet and outlet pipes of some metering pumps; if the check valves get stuck, pressure cannot be generated. If time permits, it might be better to have the construction team pre-fabricate the pipes and then use TIG welding during on-site assembly
Damage to the pump while driving is mainly caused by incorrect operation – starting it without liquid. Another cause is mechanical impurities. Filters should be installed on the main pumps. :victory:
Pumps that have strict requirements regarding particle impurities in the medium are equipped with such features from the design stage; all that is needed is to pay more attention to cleaning the filters. For ordinary centrifugal pumps, cleaning can only be achieved through purging of the process pipelines. Using packing seals is not a viable option, as it involves a large number of components and high costs. Secondly, when impurities enter the filler, they may cause damage to the shaft or bearing sleeve, resulting in significant hazards. So there’s no need to do this!
We encountered cavitation on site; unfortunately, we don’t have any effective solutions for it. We removed 5 pumps and installed 3 in one day; it was extremely frustrating. Just one high-pressure seal costs 10,000 yuan. The simplest way is to use strong purging force (and tap the pipes during the purging process). Argon shielded welding should also be used to prepare the pipeline base. ), add a short section (or filter) at the pump inlet and perform more flushing. It still works. Also, fluctuations in the sealing water at the beginning of operation can be detrimental to mechanical seals; lastly, it is essential to maintain the proper gap for the mechanical seals.
A simple method is to disconnect the inlet and outlet of the pump during water flushing, and place iron sheets in place to prevent dirt from getting into the pump. During water circulation, a conical filter should be installed at the inlet; it is necessary to clean this filter regularly as well as to empty it frequently to avoid vacuum conditions.
As mentioned above: during assembly, the impurities inside the tube must be completely removed； Argon arc welding shall be used for root pass at the inlets of critical pumps ； Strengthen pipeline purging ； Install a filter screen at the inlet during water transport (preferably a Y-type filter screen) ； Pay attention to checking the sound of the pump when it first starts running ； Turn the disk during startup.