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Has anyone experienced a phenomenon where their pumped fluid vaporises and condenses again, but does not actually cavitate. If so, what failures do you experience? What findings do you make on your pump internals (particularly your seals)? Etc.

JJPellin, I am encouraged by your previous post as that is my theory of what is going on. My suspicion is that we have significant quantities of products with density extremes, causing the thrust on the high-speed shaft to vary. If this is the failure mode: what damage would you expect to see...

We've measured the suction pressure and it is as per design - 10 bar. There are no strainers at the suctions of these points. Any significant obstruction would create an NPSH problem, which we do not see evidence of on the impeller, inducer or diffuser throat. The inducer is unchanged. There is...

My apologies we do have an external flush (plan 32) on this pump in addition to the plan 53B. We will do those specification checks as you recommended. With regards to the gearbox issues you raised, I doubt these will be the cause as the gearbox used in this service is used in multiple other...

Impeller Speed: 8,400 RPM There is no plan 11 or 31 on this pump; only 53B The barrier fluid pressure is 15 - 20 bar (measured operating stuffing box pressure is approximately 11 - 12 bar) The motor direction is correct The barrier fluid type has not changed. This barrier fluid is used...

Good day All We have a Sundyne LMV-322 pump with a Plan 53B seal system, operating in HF Alkylation service (product is a combination of propane, butane & HF acid). This set of pumps are our refinery's number 1 & 2 bad actors. We experience a high-frequency of failures on these pumps will...

Due to various reasons, our rod-drop measuring capabilities are not available. What would be the best way of tracking piston & rider ring wear for a study? Some have suggested using a feeler gauge to measure the top clearances but this only gives you the sizes of the outermost (crack-end) rings...

What is the impact (or consequence) of installing a pair of angular contact bearings (e.g. 7310BG) in a Face-to-Face orientation, vs. a Back-to-Back orientation? Similarly, what are the benefits & disadvantages of each configuration?

How do equipment manufacturers determine the journal bearing clearances for their pumps, compressors, etc.? Is there a rule-of-thumb for determining the optimal bearing clearances (metric)? Do manufacturers use 'hyper-theoretical' means of determining these clearances? By this, I mean, do they...

shvet2008 What failures do you experience? Have you identified the root causes of your failures? What is the average MTBF for these pumps? Do you use any other types of wash water or water injection pumps?

With such high differential pressures across a single impeller, is the machine not invariably exposed to discharge-to-suction internal recirculation and resulting cavitation? One would be inclined to say that if the API-specified min wear ring clearances are maintained this shouldn't be a...

JJPellin, I am looking for more detail on what systems are being used at refineries worldwide; "centrifugal" pumps is not sufficiently detailed. As I said in my intro, I am looking for pump manufacturers & models. I am also looking for details regarding the achieved MTBF, lessons learnt...

For those operating low flow, high pressure water injection pumps in crude oil refineries, can you please share with us: 1. What type of pump you are using (i.e. type, manufacturer, model) 2. Differential Head, Suction Head and Flow Rate 3. Average MTBF achieved I am operating a reduced crude...

An excellent suggestion, LittleInch. A foot valve at the suction line entry may be the simplest, and most cost-effective approach. There is minimal DP across the theoretical check valve; the only consideration will need to be the head loss across is, as the NPSHA is already very close to the...

Problem Statement: The pump (shown in the crude sketch attached) is a basic overhung, centrifugal pump which is required to pump out salt water from a pond (at approximately 20 m3/h). Due to the suction line extending over the bund wall to enter the pond, there is an accumulation of air in the...

Does a recip compressor (which takes suction from a header and discharges into a header) maintain a fixed differential pressure across the cylinder if the speed of the machine and suction temperature of the gas remain constant? Or does the compressor react to the pressure of the discharge...

I have a few questions regarding impeller trimming: 1. Many end-users attempt to use trimming of impellers as a strategy to reduce throttling the pump due to the pump being oversized. By reducing the impeller diameter, the efficiency of the pump is also reduced. Can this strategy of trimming...

TenPenny, The measured suction pressure of 0.6 bar was downstream of the obstruction - the reading was at the inlet flange of the pump. Hence my confusion regarding the obstruction as the rated suction pressure of the pump is 0.4 bar. This should have still been sufficient. LittleInch, The...

The pump is a Flowserve 400WUC-4H-5 pump. The failure included: shaft fracture, seal failure, bushes destroyed, all wear rings damaged, bearings were in a good condition, impellers were still in a good condition with no obvious cavitation indications such as pitting, etc. The recorded...

bimr, LittleInch The suction pressure reading was at the pump suction flange. The actual suction pressure is higher as the inlet is a further two metres below this (within the sump). I would agree with you to say it is first-stage cavitation, however, if the stated minimum suction pressure was...