Polypropylene (PP) liquid end API675 pumps

[vjr0512]

For one of the Effluent treatment plant in a refinery complex, the EPC contractor is proposing to use PP Liquid end pumps for various chemicals like ferric chloride, flocculant, 48% caustic, 10% sodium Hypoclorite etc with the suction strainer, External PRV etc all in PP. As per API 675 2nd Edition the Materials clause does not provide any condition for minimum material to be complied with. Where as in API 675 Edition 3, it has been indicated that the Minimum Material of construction of Liquid end as Steel.

Eventhough EPC contractor is not contractually binded to follow latest API standard, the reason for including this condition in the latest edition gives us a change from the earlier edition that the Plastic head pumps would have giving problems in terms of reliability, main tenability or any other incidents that may include safety

Can anyone advise whether i can suggest for going for steel ( Materials should be selected for the chemicals used)? Do any one have bad experience on the PP make pumps and its accessories? Eventhough the pump pressure is around 2 to 3 barg, i would like to a reliable injection system for the client.

Thanks to advise

 

[bmw318be]

Is this outdoor or indoor application ?

 

[moltenmetal]

Why on earth would you force a vendor to supply a full-on API 675 compliant pump to pump water treatment chemicals?!

As an example, a ProMinent solenoid diaphragm pump can work for those services you described for decades without so much as a second look, much less any meaningful kind of maintenance.

It would be, in my view, totally idiotic to specify a (high alloy) metallic pumphead for concentrated ferric chloride being used as a water treatment flocculant.

 

[nickelkid]

I just went through a similar situation that confirms moltenmetal's post. Two water treatment metering pumps had been specified by Process as API compliant, skidded, with storage tanks, and control panels; nominal $100k. At the end of the day 2 diaphragm pumps, basically catalog items, did the whole job for a couple of thousand.

 

[DubMac]

Really no need to go with any kind of steel here; certainly not for reliability. Non-metallic fluid ends very acceptable, many more options, and most likely cheaper than exotic steels.

The key word is "refinery". API mandated steel for pump casings instead of cast iron or non-metallic so that in case of fire in the refinery, the pumps would not melt; a safety concern. This was the original intent, as API 610 refers to "critical service pumps".

So many spec'ing engineers are not aware of, or just ignore this original intent and take the easy way out by demanding all pump casings be made of steel. Your service in essentially an "offsites" application as it is not a part of the refining process and generally in a separate area.

No need for steel.

 

[moltenmetal]

Not only is there no NEED for steel, neither steel nor the normal stainless steel grades are at all tolerably resistant to either 10% hypochlorite or ferric chloride solution.

Fully API675 compliant metallic head pumps are inappropriate for your service. Full stop.

Water treatment vendors know what kind of pumps to specify for their water treatment equipment, because they're the ones who get the maintenance callbacks when they fail.