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Selection of Better Material for Vessel Construction 2

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rifa92

rifa92

Mechanical
Apr 17, 2020
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Hi everyone,

We are using a horizontal rotating vessel/mixer made of SA-283 Grade C. Due to erosion the vessel shell needs to be replaced every two three years. How do I select a better material with higher hardness, economical and that can easily fabricated. Any standard for selection of vessel material. The medium temperature is approximately 100C and pressure is atmospheric.
 
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Yu could try a 80ksi UTS C-Mn steel but it might not provide much more service life or you could use a high hardness liner like A400 and weld to the shell or a high hardness overlay/coating.
 
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Clad or weld overlay is the best route.
Selecting a material will require a lot of details.

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P.E. Metallurgy, consulting work welcomed
 
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6 ft is possible with weld overlay, depending on length.

Look into something like a Stellite or similar hard-facing weld overlay.

The devil is in the details; she also wears prada.
 
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You are really asking a very complex question that is best suited to a specialist in material handling.... !!

How is your assembly failing/eroding ? ...We reallyhave zero information ...

What are the skills of your field fabrication team ? .. Have they ever welded anything but carbon steel (SA283 Grade C)... How long is your "vessel" and how is it rotated ? ... What is inside and what is the Process ???

Can you send pictures of the failure and describe the process ? ... More details would be helpful !!!

Since it is a rotating assembly, the overall weight is imporatant and means of engagement to the vessel.

A long lasting replacement vessel could be made thicker, but that may not be your best choice ..

Much more detail woud help !!!

MJCronin
Sr. Process Engineer
 
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The vessel is rotating and used for mixing of CaO and H2O to form Ca(OH)2 also known and milk of lime. Corrosion is also involved.

Total length of vessel is 34ft.

Weld overlay or coating would result in increase in weight so other things would also be need to considered like driving motor.

We are thinking of using SS316, its density is similar so weight would not be an issue.

What other options can we go for. There is not much data related to corrosion due to Milk of lime available.
 
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Internal rubber coating?

Maybe something like inconel for the hard wearing surfaces of the mixer?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.
 
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There is a ton of info on corrosion in lime slurries.
And on its own it is basically non-corrosive.
Minor impurities (esp Cl) matter a lot.
But what happens to steel is that the minor rust layer gets worn off and metal keeps being lost.
While 316 would be an improvement I might suggest something like Nitronic 50 (XM-19) as it will work harden more under abrasion and should wear better.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, consulting work welcomed
 
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"Metallic parts are manufactured to withstand certain levels of stress. However, even at lower stress levels, sometimes metal parts can fail during the use for which they were intended. This can be caused by wear. There are numerous types of wear including the following: corrosion, heat, metal to metal contact, impact, and abrasion. The strength of metal pieces can be severely compromised by all of the above. Spray and diffuse hardfacing is a technique which, when applied to a component or surface, can prolong the life of metal pieces and help lessen the types of wear just mentioned." You can mantain your material and apply over it a an hardfacing material addapted to your working condictions

regards
 
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This is starting to sound really bad ...

When this spinning can fails (1mm corroded thickness, 6 ft diameter and 34 ft long) I will bet that it is spectacular !

--- Let us continue the long and tortuous process of prying tiny bits of information from the OP !!!

Carbon steel generally works in high pH "Milk of Lime" service ..... excepts when it doesn't and a painted surface is constantly eroded !!!


Industry experience on storage of "milk of lime" indicates that tanks can be made of long lasting stainless steel or short-lived Carbon steel


I believe that the OP should price out two alternatives:

---1) Replacement rubber-lined Carbon Steel "can" along with acomplete turning motor/gearbox upgrade... (there will be a much heavier weight to turn)

---2) Complete replacement of "can" with new 10 mm 304L/316L materials

But, Najeenb, .... we don't really know if these are good alternatives because you won't share complete descriptions of your problem !

Anybody else out there have comments ?



MJCronin
Sr. Process Engineer
 
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MJcronin, thanks for the input. Can you kindly let me know details you require further?

The erosion/corrosion is local and not uniform. At the feed end CaO and H20 enter vessel and start getting mixed. Most of the thickness loss is at the discharge side. The 34ft length is divided into 8 lengths axially. So last three to four shells are more affected. It’s mostly erosion that is causing the thickness loss.
 
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The feed of CaO and water is done in the sense of vessel rdaius? Or tangencial? Tangencial with a baffle and wear plate would improve the design and minimize the erosion.
 
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How about a dimensioned overll sketch showing all segments and areas of metal loss ? (this will take 5 minutes)

Show where the can is supported along it's length

How about pictures of the assembly and close-ups of metal loss ?

Describe and show the rotational drive ....

MJCronin
Sr. Process Engineer
 
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