Recently asked questions in Kochi mmd and Class 2 Numerical solutions

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26 October 2018

30.Centrifugal pump overhaul procedure

October 26, 2018 Posted by AK 1 comment
1 Isolate pump electrical circuit breaker on main switch board and attach a warning notice. (Do Not Operate-Men at Work).
2. Switch off and lock pump supply at its local supply panel. Attach a warning notice to pump local supply panel.
3. Close suction and discharge valves, chain and lock hand wheels.
4. Open pump suction and discharge pipe drain valves to bilge and when water ceases to flow; crack open the pipes / pump flange joints carefully to ensure that pump has drained off and is safe for opening.
5. Fix a shackle to lifting pad eye above pump and hang chain block; ensuring SWL of block, slings and shackles are satisfactory.
6. Use a center-punch to match/mark coupling and casing, then remove the coupling bolts.
7. Disconnect, fix i/d tag and remove motor supply cables; taping over bare ends with insulating tape.
8. Connect shackle and sling to motor eyebolt and lift motor clear of pump using overhead chain block. Lay motor on its side out of harm’s way, protecting machined surfaces on both pump and motor coupling halves against damage. (Cardboard and masking tape is quick and efficient method.)
9. Disconnect all external fittings from pump casing e.g. cooling pipe, pressure gauge, oil reservoirs and air cock.
10. Remove bolting from top cover and remove cover. Scrape off old gasket and check mating surfaces, and renew gasket on assembly. (Light smear of grease on gasket / faces)
11. The pump shaft with impeller can be lifted out of casing.
12. Dismantle the impeller, and remove the wear ring.
13. Remove the gland packing and disregard; replacing it on rebuild. Remember to cut ends of packing at 45° and stagger joints when repacking gland.

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