Issues related to pump draining
Thread Content
This post was last edited by Tieszi on 2015-9-7 08:45. Question: 1. A drain port is generally required at the bottom of horizontal centrifugal pumps; should this drain port be fitted with a plug, or is a isolation valve along with a blind flange necessary? Are there any specific regulations? 2. The following is excerpted from PIP: Pumps shall be provided with a boss on the lowest part of the casing capable of accommodating a case drain, which shall not be drilled or tapped unless a drain is specified. As for how to translate this “boss”, and also if drilling or tapping is not allowed for the drain outlet, then what method is used to create it? 3. The following is excerpted from API 610, version 11, section 7.5.2.6: Unless otherwise specified, threaded vent and drain connections shall be plugged. Carbon steel plugs shall be used with cast iron casings. API 610 requires that these connections be “plugged” to prevent leakage; but can plugs meet the requirements under high pressure conditions?
These are all silk plugs, and they rarely need to be adjusted. Before maintenance, drainage is done from behind the pump inlet valve.
In my opinion, it depends on the toxicity and hazard of the pumped medium. If the medium being pumped is something like clean water, using a thread plug is no problem. However, if flammable or toxic liquids are being transported, valves must be used, as the process requires connection to an open or closed discharge system.
For pump maintenance, it is necessary to clean the chemical substances inside the pump; merely discharging them through the inlet drain may not be sufficient to remove them completely. Therefore, the drain port of the pump body also needs to be drained. It’s just a plug, which is inconvenient to use and may cause splashing. Furthermore, the pump body vibrates during normal operation; how can it be ensured that the plug does not come loose and cause leakage due to these vibrations?