Abbrasion Resistant Cast Iron Pump Casing & Impeller on a C9+ Service with solid partticles

[Tilas]

I have a pump which is pumping C9+ and the process data sheet requires harness of the casing and impeller of a minimum 42 HC. The stream has hard nonmetallic solid particles to max 2500 microns thus requires the particular hardness.

The Pump Vendor has offered an abrassion ressistant cast iron with a minimum harness of 51 HC. Material designation 5.5609 (DIN 12513)

My question is : can cast iron casings and impeller be used for hydrocarbon service?

Is there any chances of spark during operation if the pumped stream has hard solid particles?

Thanks
Tilas

 

[EdStainless]

What have you used before?
These white irons are brittle, I am not sure that I would so that hard.

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P.E. Metallurgy, Plymouth Tube

 

[Tilas]

Hi,

To correct my post above, our process team needed at least 38- 42 HRC for the hardness of the casing and impeller for the new pumps.

We have used Stellite Gr.12 (for casing)HRC 30 and X30 CR13 Hardened (for the impeller) for the previous pumps but still the hardness was not enough and the casing and impeller wears our quite fast.

Now Vendor is proposing (Material Number : 5.5609; 0.9645 †; EN-JN3039 † ) DIN EN 12513 (05/2011) Abrasion Standards resistant cast irons. HRC 51

Pumped liquid is C9+ Liquid consists of 20% to 60% Hydrocarbons and rest is water. Mixture of oil and tar water. Presence of tar and coke particles, and or aromatics.Particles bigger than 180 micrometers, maximum size: 2.5mm; density: 1100 kg/m3

My question is : can cast iron casings and impeller be used for hydrocarbon service?
Is there any chances of spark during operation if the pumped stream has hard solid particles?

Thanks
Tilas

 

[EdStainless]

With you Stellite 12 + 13Cr combination which was wearing fastest?
Stellite 12 should hold up very well in this service.

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P.E. Metallurgy, Plymouth Tube

 

[LittleInch]

My question is : can cast iron casings and impeller be used for hydrocarbon service?
I would say they can. I can't see any issue with impurities and cast iron components are often used with hydrocarbons


Is there any chances of spark during operation if the pumped stream has hard solid particles?
No. A "spark" needs air / oxygen to become a "spark" which is really just very small particles or hot iron / steel oxidising rapidly in air.

If you're wearing out stellite and hardened 13chrome then I suspect abrastion "resistant" cast iron won't be much better. Where did your process group come up with a hardness of 38-42??

You might be better with a resilient lined casing ( rubber or similar and a flexible impellor) or look up some slurry pumps. Harder isn't always the best way to go.

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

 

[Tilas]

EdStainless,

Thanks for your response. Both wears almost the same.

LittleInch,

Thanks for your advice. Our process engineers might have indicated the hardness of 38~42 because the stellite and hardened 13chrome were still wearing.

As additional history of where this hardness of 38~42 requirement is coming from.

These pumps were originally purchased with A487-CA6NM + HVOF Tungsten Carbide (Impeller) & A350 - LF2 + HVOF Tungten Carbide :

But it weared off quickly so the Vendor proposed for an upgrade of the impeller and diffuser material to a harder material (which was the stellite and the hardened 13crome :

But it is still wearing off. Now we are totally replacing the pumps and we went to another Vendor and asked for a more harder material than stellite and hardened 13chrome. The Vendor then offered abrasion resistant cast irons :

I really am not sure if these will be any better than the other materials already tried. The pumps will come by this year and will start operation by early next year.

 

[Artisi]

You need to analyse why the wetted parts are wearing / eroding, just specifying harder materials is not necessarily the answer.}

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.)

 

[Tilas]

Hi Artisi,

I have pointed that out to our process engineer. But he also has not got any good answers.

He pointed out that a harder material might solve the problem.. Might...

In any case , it was already purchased and it is coming soon. So i guess we will just have to wait and see if it going to work.

 

[Artisi]

You need to look at the hydraulics as well.
What is the pump speed, is it running at or near to its BEP.
A few photos never go amiss.

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]

Artisi has the right track here.
You need a lower speed pump, and you have to make sure that it is running at BEP.
Both of the systems that you have tried are proven and should offer very good performance.
Their failure indicates to me that you have other hydraulic issues.

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P.E. Metallurgy, Plymouth Tube

 

[Tilas]

Hi Artisi / EdStainless.

The pumps are running near BEP.
Running at 2970 RPM

However, i do not have a picture of the wear parts of the pump.

The hydraulics of the wearing pumps for reference :

 

[Artisi]

I would think your excessive wear is related to the pump speed, unfortunately for the flow/head combination it is unlikely a suitable pump operating anywhere its BEP at 4 pole 50 Hz is possible,
Might be worth investigating a diaphram pump or a mono style pump, not my field of expertise but there are others here with experience in this area - hopefully you can get some input.

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.)

 

[Tilas]

Hi Artisi,

Thanks for the valuable inputs. Would definitely look on to the 4 pole 50 hz pump option from Vendor and see how it looks like on the proposal curve. I hope they have a suitable selection for that speed.

 

[LittleInch]

I'm with artisi here, as usual, especially his last para two above.

Basically just use a different pump - this is a low flow and low head and a Progressive Cavity pump would be ideal.

Basically anything which is actually designed to handle particles, not just "resistant"

Ever worn a water "resistant" coat vs a "water proof coat"??

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

 

[Tilas]

Hi LittleInch,

Thanks so much.