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  1. CheemaJ

    Load bearing capacity of concrete slab - for vessels on legs

    HTURKAK - this is the intention. I just wondered if there was a rough calculation to provide an indication of whether the slab will be suitable for supporting this sort of load.
  2. CheemaJ

    Load bearing capacity of concrete slab - for vessels on legs

    Hi, There is an area where we would like to install a number of steel vessels, supported off legs, for storing liquids. Some core sampling was carried out last week (attached a couple of photos) and we managed to get a measurement of the slab thickness in a couple of different locations. It is...
  3. CheemaJ

    Pickling of stainless steel - to polish welds or not

    @EdStainless: there are several welds which cannot be accessed to use pickling paste. There is a supplier nearby which specialises in immersion pickling. Rather than do some by hand and immerse others it is cost effective to send all pipework to their works for immersion pickling. I am not 100%...
  4. CheemaJ

    Pickling of stainless steel - to polish welds or not

    Hi, The plant I am working in has experienced some very rapid and localised corrosion on 316 stainless steel process pipework. It is almost entirely around the heat affected zone. See attached document showing some photographs of this. The duty is a clean in place return line. To mitigate the...
  5. CheemaJ

    Seal failure on hot water application

    Hi Johnny, The pump is horizontal overhung. The impeller is semi-open. It doesn't appear to have wear rings nor balance holes. I am assuming the seal chamber is running at discharge pressure - given the rapid leak that developed when the seal failed. I've attached a very basic exploded view of...
  6. CheemaJ

    Pressure spike damage to heat exchanger

    Apologies I forgot to add set points. During commissioning we adjusted the backpressure regulator spring to it's lowest setting. We ran the water pump and found that we had sufficient return flow to the hot water tank when the pump was running at around 30 hZ. The pressure transmitter was...
  7. CheemaJ

    Stainless steel in chloride environment

    Just thought I'd add to this discussion. We have recently experienced issues with MIC on newly installed process pipework in 316 stainless. This was using UV treated towns water that was left in the pipework for only a few weeks during commissioning. Almost all of the corrosion sites were on or...
  8. CheemaJ

    Seal failure on hot water application

    Johnny, thanks for the prompt response and offer to help on this. According to the pump supplier the mechanical seal faces supplied are Carbon graphite/stainless steel. The pump used is quite a basic industrial centrifugal and having had a look at the API seal flush plans (in this table...
  9. CheemaJ

    Pressure spike damage to heat exchanger

    Hi all, thanks for the prompt replies. I've attached a snippet of the P&ID for this which should hopefully address a few of the questions you had asked. The maximum velocity in the 2" header is 2.2 m/s. It is much lower than this when hot water is not being called for. The valve closure...
  10. CheemaJ

    Seal failure on hot water application

    Hi, We're running a duty/standby hot water (180oF) centrifugal pump arrangement on our plant hot water ring main. A mechanical seal failure occurred over the weekend on one of the pumps. The seal faces are silicone carbide. The pumps have been running for less than 6 months continuously. I am...
  11. CheemaJ

    Pressure spike damage to heat exchanger

    Hi, We're running a hot water ring main and have experienced some issues with pressure spikes bursting gaskets on a plate and frame heat exchanger. Water is pumped from a 20,000L tank via. centrifugal pumps that are powered by variable speed drives. There is a 100m pipe run before the water...
  12. CheemaJ

    Heating/cooling jacket air elimination

    Hi, I've two jacketed pressure vessels which are serviced by both cooling water and low pressure steam. There is a compressed air blowdown inbetween cooling/heating duties. I need to be able to eliminate air from the jacket when heating and cooling. At the moment there is a thermostatic air...
  13. CheemaJ

    Air entrainment/cavitation/vortexing issue

    Thank you all for your replies. There is not currently a minimum flow bypass installed around the pump however I think this would be beneficial. Based on the curve, could you recommend the best method for sizing this and type of valve for controlling the flow? Also, it would be easier from...
  14. CheemaJ

    Air entrainment/cavitation/vortexing issue

    I'd have to remove a flange on the top of the tank to get a good look but will try this. Also I've realised that the inlet strainer is less than 5 diameters from the suction flange. Considering getting a spool piece made up to put in it's place. With the spool piece in place there'd be about...
  15. CheemaJ

    Air entrainment/cavitation/vortexing issue

    When returning into the tank there is definitely free-fall which would lead to air entrainment as you say. But when the pump is delivering flow to the rotary spray jet, there is no return back to the tank and yet the issue persists. I've just tried closing valves on both suction and discharge...
  16. CheemaJ

    Air entrainment/cavitation/vortexing issue

    Hi, I'm having some issues with a centrifugal pump which is being used on a CIP tank. Pump is 18.5 kW and is on a frequency inverter drive. Tank capacity is 2,500L Pump suction pipework diameter is 3" NB Pump suction pipework length is ~ 1m There is a full bore ball valve in the suction line...
  17. CheemaJ

    Fluid pass through centrifugal pump

    Is it possible to pump through a centrifugal pump without unintended consequences such as damage to pump (when the pump is idle)?
  18. CheemaJ

    Hot water ring main design question

    Hi, I am installing a hot water ring main to serve a number of end users in a factory. The main is fed via. a 20 m3 buffer tank with a centrifugal pump on an inverter drive, it returns back to the same tank. The average demand I have calculated will be 15 m3/h. The pump will be spec'd to...
  19. CheemaJ

    Non newtonian pipe sizing

    Latexman, another question I have thought of: During a product transfer there is a pause which results in the transfer pump stopping for a period of time. The line is left primed with product that is now stationary. When the pump is re-started, will there be a considerable spike in discharge...
  20. CheemaJ

    Non newtonian pipe sizing

    Power law is something that I had come across, but I wasn't sure if this was something I'd be able to compile from the data that I have - do you know if it would be possible to do so or not? I did happen upon that thread you posted but wasn't sure I had sufficient data to be able to work out...

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