Frequent Bleach Pump Premature Failures with FRP Materials
Frequent Bleach Pump Premature Failures with FRP Materials
(OP)
The service is Sodium Hypochlorite 0.2 % and seawater. We experienced impeller vane fracture, and other vane cracking at leading edge and casing cracking. There are quality issues such as porosity, inclusions, deep cracks and coating pealing off at different location. Also, the vane inlet and outlet have sharp fillets 5 mm. The pump is quite large with flow is 3055 GPM, head is 98.4 ft, power is 90 kw and speed of 1800 RPM. We are currently conducting investigation to identify root causes of this failure but we welcome your input and feedback on possible causes in such application.
RE: Frequent Bleach Pump Premature Failures with FRP Materials
"FRP" is rather vague?
Who is vendor?
Any photos?
Was the pump operated in accordance with the data sheet?
Not much to go on here.
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RE: Frequent Bleach Pump Premature Failures with FRP Materials
Johnny Pellin
RE: Frequent Bleach Pump Premature Failures with FRP Materials
Where on the pump curve is it operating?
Do you have records for flow/pressure/power?
Do you monitor this pump (vibration, noise, other)?
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P.E. Metallurgy
RE: Frequent Bleach Pump Premature Failures with FRP Materials
RE: Frequent Bleach Pump Premature Failures with FRP Materials
RE: Frequent Bleach Pump Premature Failures with FRP Materials
https://www.affetti.com/en/horizontal-centrifugal-...
So what did the data sheet say about the fluid?
Why do you seem to have a material which is not compatible with the fluid?
Have you followed ALL the recomendations in the manual? http://www.europumps.sk/materials/files/affetti/Us...
Note page 22 where is states No solids of any type.
There are lots of warnings about not running dry so it is clearly quite sensitive to that. Did they ever run dry?
Also FRP materials are not great at resisting damage / over tightening etc.
If your technicians are used to metal units, there is a potential for damage. These things need to be handled and treated very carefully. They are not metal pumps and the material behaves differently.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Frequent Bleach Pump Premature Failures with FRP Materials
Johnny Pellin
RE: Frequent Bleach Pump Premature Failures with FRP Materials
We always insisted on testing new pumps at full speed across the entire operating range. If the performance was off or there was vibration we rejected the impeller. Static balance does not tell you much, but dynamics can.
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P.E. Metallurgy
RE: Frequent Bleach Pump Premature Failures with FRP Materials
Walt
RE: Frequent Bleach Pump Premature Failures with FRP Materials
Perhaps the NPSH needs to be higher than water alone would need it to be?
Keith Cress
kcress - http://www.flaminsystems.com
RE: Frequent Bleach Pump Premature Failures with FRP Materials
RE: Frequent Bleach Pump Premature Failures with FRP Materials
Could those inlet strainers have become bloodied and caused low NPSH? Where was that 0.5 barg measured? Upstream or downstream the filters?
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Frequent Bleach Pump Premature Failures with FRP Materials
Usually the cavitation point is anywhere from 1 to 5m ABOVE the NPSH curve.
You need to ask the vendor to give you the cavitation curve.
Typically like this
At cavitation initiation it is very difficult to hear it without very good microphones and you need to start from a high inlet pressure and then slowly reduce in order to identify the high frequency sounds of collapsing bubbles.
but having no answer about the materials is pretty damming so you might have a get out of jail card right there.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Frequent Bleach Pump Premature Failures with FRP Materials
RE: Frequent Bleach Pump Premature Failures with FRP Materials
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
RE: Frequent Bleach Pump Premature Failures with FRP Materials
OxyChem Sodium Hypochlorite Handbook
by Oxychem Corporation
FRP is allowed so it's probably not a material issue but a cavitation issue.
I think this is a lot lower than H2O but I could be wrong. It's kind-of over my head.. the water.. never mind.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Frequent Bleach Pump Premature Failures with FRP Materials
RE: Frequent Bleach Pump Premature Failures with FRP Materials
It's not the vapour pressure per se that we're talking about. It's whether when mixed with your seawater does it create micro bubble of gas due to the chemical reaction. This has caused bubbles and vapour locks in other similar systems.
It will be a transistory thing as the chemical reaction takes place so taking samples and testing them won't be simple.
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.