Sea Water Pump for Middle East 1

[Hilal1984]

Hello Engineers,

I would like to know what is the cost-effective and durable construction material for pump used in pumping large quantities of seawater. This pump is of vertical turbine type and will be installed in Arabic Gulf Region.

Should we insist also on certain PREN rating?

I heard also that Ceramic Bearings are bad due to failure and long time required to get replacements. I need your opinion on that.

Thank you in advance,

Regards

 

[Artisi]

Depending on life of the project, you could use cast iron, zinc free bronze or stainless steel or a combination of these materials.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[pumpingtips]

Hi Hilal,
Try the attached documents. The spec comes straight off our recent seawater intake pump spec for a desal plant.

 

[pumpingtips]

The two documents didn´t seem to attach to the response. Here is the other.

 

[georgeverghese]

There are reports of seawater pump failures due to increased localised contamination of the seawater, so siting of the pump is critical if there is disposal of other contaminated return water streams from refineries and sewage treatment plants nearby. Also, as the article from the ITT man says, hypochlorite injection beyond low concentrations ( which is what some operating companies do when they find barnacles and molluscs growing on HX tubing)in to the pump suction can wreck the pump over the long term.

 

[EdStainless]

It is now common to see SuperDuplex alloys specified, with both PREN requirements, and validation of the annealing process with A923 and G48 testing.
See papers by Roger Francis at NACE conferences.
Wetted bearings are always an issue. I have seen good life out of ceramics, but regardless of material I would have spares on hand.
Chlorination control will be critical for any alloy. More chlorination will not stop growth of difficult species. Only other chemicals (like chlorine dioxide) can do it.

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P.E. Metallurgy, Plymouth Tube

 

[Hilal1984]

Dear All,

your replies were helpful.

Pumpingtips, can you share word copy of your specifications. I feel they are much detailed than mine.

Thanks

 

[LittleInch]

Warm aerated seawater eats everything unless it is plastic, aluminium bronze or super duplex.

Bearings in these type if units are always a big issue. Sealed units or one where you supply a filtered clean water supply to the bearings will have a risk of damage.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[Artisi]

pumpingtips, ref your spec you supplied.
First up 4.3.2 Pump casing -- if I was quoting, that would have a big red mark along side it, casing designed to carry misalignment, come on now - a very open ended requirement, a little bit or 50mm of misalignment?, secondly 4.3 casing is not compatible with 4.5 shaft and column - two different pump styles.
Needs correcting and would suggest the whole spec. is vetted for similar errors.


It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[EdStainless]

Hilal,
You can hire an expert to draft you a specification. It will probably only cost you $20-40,000.
There is a lot of work in doing one of these correctly, and people make their living doing just that.

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P.E. Metallurgy, Plymouth Tube

 

[DubMac]

Try to get the temperature and salinity of the seawater where these pumps will be installed. It does vary around the world and should be a consideration in material selection.

Once you find a material suitable for the native water, whether Nickel aluminum bronze, CD4MCu, or another from the Super Duplex family, you must make sure the pump manufacturer selected has good experience with it for THEIR pumps.

For instance, casing wall thicknesses vary on different models and if too thin, some materials will crack easier than others. Super duplex is not the easiest material to machine due to hardness. If a company is not experienced with it, the machining costs and leadtimes can vary widely.

Don't try to make a "one size fits all" specification for your service. Be flexible enough to listen to the pump manufacturers metallurgists; they are typically VERY knowledgeable on seawater materials and how they fit their pump designs.

 

[pumpingtips]

Hilal1984... The specification is from a marine port designer company that also does engineering for desalination plants. The seawater intake pump specification I included was for desalination plant feed water on the west coast of Sth America. The company that prepared the specification has headquarters in Nth America. Hope this helps. I can provide you with more specific information 1-2-1 if you email me @gmail.com