Session 38 - Q&A Report (Both Sessions).xlsm

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1	Question Report Session 38 First Session
2	Report Generated:	1/30/25 3:41
3	Topic	Webinar ID	Actual Start Time	# Question
4	Session No 38 (Eastern): Start-Up, Commissioning & Troubleshooting of Centrifugal Pumps	844 8104 6744	1/30/25 1:50	30
5	Question Details				Ring Oil Lubrication	Oil Splash Lubrication
6	#	Question	Asker Name	Answer
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9	1	Is it possible to change the direction of rotation of Motor at site	Anonymous Attendee	Yes. If it has been connected the wrong way you just switch the live connections in the terminal box.
10	2	please explain a little about use of eccentric reducer, top side up or top side down. which configuration shall be used and where. secondly how far shall it be installed from pump suction nozzle.	Aamir Hasnain	In general you should install them with the flat side at the top. This will prevent any air separating out from the pumped fluid to be trapped in the suction piping. The exception to this general rule is if there are solids in the pumpage. In which case you want the flat side on the bottom so that the solids do not accumulate but get swept continuously through the pump
11	3	HOw does instrument Air contribute to low flow	FAIZ UL ISLAM	It is not instrument air we are concerned about, it is air in the pumped fluid. This will accumulate in dead spots and high points and prevent the pump pumping properly
12	4	How can "too much oil" provide high temperature on thrust bearing?	Gabriele Manenti	Bearings are not designed to be flooded with oil. The oil level should be at the level of the bottom of the bearing race for splash lubrication ; or lower still in the case of Ring Oil lubrication. Oil rings dip into the oil, rotate slowly, driven by the shaft, and transport the correct amount of oil to the bearings continuously. See pictures on the right here >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>
13	5	For BB3 pump and after perform complete OVH and install the pump, the vibration readings are all okay except the pump horizontal at inboard bearing it's reading is 0.55 ips at 1X (normal is 0.1-0.15), we rechecked alignment, retightened all base plate screws and perform impact test for the base plate. all are normal, what should cause such type of vibration?	Mohamed Mohamed	For 1 x Running Speed vibration it is likely to be Unbalanced Rotating assembly (or an element of the rotor) or a slightly bent shaft. See the Vibration Trouble Shooting Chart here on the right >>>>>>>>>>>>>>>> You have correctly checked the simple things that can be done without removing the rotor. You probably need to take the rotor back to the workshop for further anaysis. Depending on the expertise of your maintenance team it might be worth consulting a vibration specialist or the Pump OEM service team before proceeding too far.
14	6	Brief about open valve start and closed valve start up of discharge? and Significance of both starts?	Anonymous Attendee	Most pumps have rising power characteristic with increase in flow. So power is minimum at minimum flow and maximum at end of curve. But this does depend on the type of pump. Some large axial flow pumps have maximum power at shutoff and lower power at BEP or run-out. So GENERALLY it is kindest to start the pump against closed valve (or slightly open discharge valve). To start against open valve you need to be sure that the motor is suitably sized to cover the power at end of curve.
15	7	Please elaborate on pump reverse rotation impacts on pump and seal parts	Anonymous Attendee	Many mechanical seals are bi-directional and will work in either direction. But some are uni-directional and will only run properly in one direction. In particular the pumping ring (which circulates the seal auxiliary piping (Plan 11, 13, 52 etc) around the system my be uni-directional. A pump running backwards will not pump properly. Performance might be 30% of expected performance. A seal running backwards may not achieve the correct liquid film between the faces and the seal faces may crack.
16	8	Good presentation, thanks	Sergio Vidal	My pleasure. Thank you for attending.
17	9	How many pumps fail due to lateral and torsional analysis problems?	Ambrish Bajpai	Very few. Pumps that are at potential risk of lateral and torsional critical speed problems will have been identified at engineering stage and will have automatically have had analyses carried out at the early stages of engineering before manufacture to ensure no problems arise. Natural resonant frequencies can occur, particularly for vertical pumps. The pump on its own may be fine and will have tested OK in the factory test loop. But sometimes the combination of pump and support structure and piping system may hit a natural resonant frequency. Generally it is a straightforward operation to stiffen the structure or soften the structure to move the natural resonant frequency away for the running speed.
18	10	if you place a pump on say an FPSO you obviously don't have grouting, What alternative for that is there?	diederik ross	Correct. Those pumps will have a structurally stronger skid type baseplate that does not require grouting.
19	11	I will like to have the PDF of the presentation	Sunday Asubiojo	Everybody who registered for this Short Course will receive a PDF version of the Slideshow complete with my speaker's notes (the script) and additional notes. You will also get a You-Tube link to the video of the Presentation so you can download it and view it again at your leisure.
20	12	What precautions we need to keep in mind when we are commissioning hot service pumps?	"Joshi, Jagrut Pratikbhai "	Any pump operating at 90C or higher should be warmed up before start-up. The GENERAL procedure is to slowly pass process fluid in through the drain connection and out therough the vent connection (or discharge connection on a self venting pump) such that the casing temperature slowly rises until it is close to the pumping temperature. This should be done over several hours. The hotter the pumped fluid the longer and slower the operation should take. The pump IOM will give detailed instructions for any pump that needs warm-up. Especially Hot-Oil pumps.
21	13	is it possible to replace double seal plan with single seal for a centrifugal pump	Sunday Asubiojo	Yes it is possible. Consult the seal vendor and the pump vendor. It will need a different auxiliary seal piping plan (perhaps Plan 11 instead of Plan 53)
22	14	for vertical pumps do we need to have any straight length at discharge of the pumps?	Anonymous Attendee	3 or 4 pipe diameters of straight pipe on the discharge before the first bend is desirable but not critical
23	15	What is normally the minimum differential pressure of mechanical seal chamber and discharge pump line ?	Hassan Zwida	Most mechanical seals will be working a little over suction pressure.
24	16	For horizontal pumps what is the straight length normally required at suction and discharge of the pump	Anonymous Attendee	Industry standard is 5 to 10 Pipe diameters on the suction side. Discharge side is not so critical. 3 or 4 pipe diameters of straight pipe on the discharge before the first bend is desirable
25	17	if pump is oversize could the pipe connetd to discharge rerouted by installing T and keep part of the flow to go to its direction and connect pat of the flow to the pump incharge line ?	Anonymous Attendee	Yes it is quite common to recirculate excess flow via a Tee or an Auto Recirc Valve back to the suction vessel or to the suction line as long as it is well upstream of the pump.
26	18	does RP have low flow high head model? like 100 gpm &1350 ft	Monis Akhtar	Yes we could do this with a VS6 pump or a BB3 or BB4 pump. For clean pumpage a Pitot Tube Pump (the RP "Combitube" pump might be suitable. Contact your local RP Sales Professional.
27	19	Can pumps start having vibration problems randomly during normal operation i.e. not during commissioning?	Anonymous Attendee	If there is a change to the operating condition somewhere in the entire pump system then this might be reflected in a pump problem. A change of system head will likely impact the flow rate and the pump could now be operating to the right of BEP or to the left of BEP.
28	20	Do you have any special recommendation for start-up of mag drive pumps?	Stefan Bachmann	Start up of mag drives is broadly similar but they are very vulnerable to dry running, proper venting etc is essential
29	21	Great Session, how could I register for the following sessions, am I going to recieve an invitation link	Mohammad Abu Shaala	If you received an invitation to this Session then you will automatically receive and invitation to the next one. If in doubt, send an email to marketing@ruhrpumpen.com
30	22	Customer need flow margin, usually ca 20%. Used throttle valve, to reduce this. How many margin can be?	maciej piotrowski	If the customer wants a 20% safety margin on flow (so for example the normal flow is 100m3/hr but he wants to size the pump for 120m3/hr) then try to "straddle" the BEP flow so that the Rated Flow is to the right of BEP and the Normal Flow is to the left of BEP
31	23	For high flow rate pumps, technically is it beter to install a single stage pump or it is better to install multistage pump ( please the answer from technical and maintanance POV)	Mohammad Abu Shaala	There is no short answer to your question A pump supplier will offer the best technical and best economical pump for any application. For example if it is a Process Pump application they will start by looking at an OH2 pump, then a BB2 pump, then a VS6 pump, then a BB3 pump then a BB5 pump (in increasing complexity and price)
32	24	Is plan 11 suitable for liquids with hot discharge temperatures? would it be more suitable to have cooling water connections? My pump supplier has specified plan 11 (discharge is water under pressure leaving at > 100 deg C)	Anonymous Attendee	The seal supplier will recommend the best piping plan for his seal selection. For the example you give I would have expected a Plan 23
33	25	Do vertical pumps , such as VS4 , need to undergo modal analysis if the length of the pump is around 4 m including motor ?	Ambrish Bajpai	Depends on the size of the pump and how established the design is. So it is a good idea on a large engineered pump, but probably not needed on a smaller standard, production line pump that is in regular production with a long installation list
34	26	what is the recommendation for systems where you require the pump to do a high flow to meet boiler regulations, but flow during normal operation is a lot lower. Multiple pumps that kick in at different flow requirements? or just high ARC flow rate?	Anonymous Attendee	No short answer. Any pump supplier would need to see the specific requirements to be able to answer. Pumps in parallel (one pump for the low flow, 2 pumps together for the high flow) might be a solution. If the pressure requirements for the two duties are different, variable speed might be an answer.
35	27	Thanks for presentation	Ambrish Bajpai	My pleasure. Thank you for attending.
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38	Question Report Session 38 Second Session
39	Report Generated:	1/30/25 12:04
40	Topic	Webinar ID	Actual Start Time	# Question
41	Session No 38 (Western): Start-Up, Commissioning & Troubleshooting of Centrifugal Pumps	868 5916 9891	1/30/25 10:50	18
42	Question Details
43	#	Question	Asker Name	Answer
44	28	Any recommenation for identifying whether a canned motor pump is rotating backward?	"Little, Nathan T "	Good question! Because you cannot see visually which way it is turning. The only way is to monitor the flow and head. If it is spinning the wrong way performance will be down to about 30% of expected.
45	29	Hi, Simon. Thanks for the nice and useful presentation! Maybe, if possible, it would be interesting if you could tell us the hydraulic causes that usually lead to blade pass frequency (BPF) vibration issues, regarding API-610 OH2 or BB2 pumps, for instance. Thanky you!	Fabio Ribeiro	Very simply put.... If you have a double volute pump it will have two volute lips on opposite sides of the pump (say at 3 oclock and 9 oclock). There will be a pulse every time an impeller vane passes a volute lip. If you have an impeller with an even number of vanes (say 4 or 6) then 2 vanes will be passing 2 volute lips at exactly the same time thus amplifying the vibration. With full diameter (or nearly full), the vibration pulse will be bigger. Most pump suppliers nowadays have modified their designs to have odd numbers of vanes so you don't get two impeller vanes passing the two volute lips at the same time. There are other methods of overcoming or mitigating the problem too. As I mentioned in the presentation Vane Passing Frequency is something you might see on a new installation or a retrofit. It is not something that will develop as a result of wear.
46	30	Is it healthy to commission a pump, which initaily desgined to be driven with VFD, in a temporary alternative loop line rather than its deginsted pipeline/piping system ?! Worhtmentioning, this temporary loop line will circulate to the buffer tank and a globe valve will be used to control the flowrate and create the required losses downstream the pump. Thanks and regards.	Abdalhakam Kamel	I am extending the answer I gave in the live presentation. The temporary loop has a globe valve in the discharge line so you will be able to replicate the sytem head and so ensure the pump is pumping at its rated duty point. This is good and so you will be able to check the performance of the pump. I am assuming the pump is on its baseplate and is properly installed on the concrete foundation and grouted in place. As this is a temporary piping loop you will not be seeing any impact of the final piping on the final installation. It is more likely, of course, that the temporary piping, which may not be so effectively anchored and supported as the final piping, may have an impact on the pump. Maybe a piping vibrations or loads will be transmitted to the pump. Will the VFD be connected? If not you will not be able to check any speed related symptoms.
47	31	more of a statement 90% of pumps problems are seal problems and 90% of seal problems are pump problems...90% of seal and pump problems are systems and operations problem	Alex Hitsman	Good call!
48	32	Thank you Simon for a very well presented bit of information that can be put to use immediately. Have a great day!	Kenny ONeal	My pleasure, thank you for attending.
49	33	Where can I find recommendations on time limits for operation against closed valve depending on the pump power?	Gennady Amusiev	You won't! All pump suppliers will say pretty much the same thing. "Only a few seconds." 15 to 20 seconds is a fair number for most average sized pumps. But don't try to apply that to a large axial flow water pump (which should probably be started agains open valve) or a high power mutistage pump.
50	34	Simon, your tie and waistcoat are very snazzy!	Kashif Uddin	Thank-you I will inform my wife!
51	35	When should alignment checks be done?	Jeff Berning	Several times. After intitial installation on the baseplate. After the baseplate is grouted. After the piping is connected. As part of Commissioning checks.
52	36	Is the symptom of cavitation due to low flow is same as cavitation due to NPSH? i.e.. 3% decrease in pressure head and acceleration spectra at VP frequency?	Ashker Rashid	Not identical no but similar. You will hear the same tell-tale sound of a handful of gravel in the pump, and performance will be down. But if it is low flow suction recirculation you are already operating well away from your duty point so you may not recognise any reduction in performance. Here is the crib sheet of potential solutions >>>>>>>>>>>>>>>
53	37	is there any special requirements/practices for placing the pump skid in the foundations ? like minimum distances for the Anchor bolts from the edge..any	Abdalhakam Kamel	This will be detailed in the Pump IOM.
54	38	are horizontal api pumps always installed on base plates with a concrete pad? or one or the other?	Samir Firfire	Most commonly in land based plants the baseplate is a bolted to a concrete foundation and filled with grout. Offshore installations and installations on steel structures will usually have a structural steel, skid type baseplate that does not require grouting.
55	39	epoxy grout?	charles bogert	Yes. Epoxy grout is more commonly used nowadays rather than the older cementitious grout
56	40	When a new pump is installed (replaced) and sees pump and piping vibrations, what could be possible causes	Samir Firfire	The two that immediately spring to mind are: Badly supported pipework putting excessive loads on the pump. Insufficient straight length of pipe on the pump suction.
57	41	Thank you Simon!	Anthony Farole	My pleasure, thank you for attending.
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