Homogenizers - material of construction

[Nitzey]

I am reviewing bids from four companies for homogenizers. The homogenizer block represents 1/3rd the cost of the homogenizer, and is obviously of great importance. Three bids indicate duplex stainless steels, either 2205 or 2507, as the material of construction. The other company uses just 316 grade stainless steel. The price for this company is half the others. The formulation we will start with has no chlorides and proceesing conditions are mild. However, I am concerned about just using 316.

 

[Latexman]

Is there any previous experience in the application for 316 and the duplex SS's? If so, contact those production sites for their knowledge and experience.

I have experience with a 316SS homogenizer in a dairy application (ice cream). It has run for years and years with no major issues.

Without knowing more, that's all I got.

Good luck,
Latexman

 

[Nitzey]

Thanks for the reply. I have a lot of experience with homogenizers in chemical plants and all were either duplex stainless steel or precipitation hardened grades. Some were involved with hot applications including chlorides and I never heard directly of problems with the block. The company who manufactures out of 316 ss has customers in SE Asia, and so far I have held off trying to contact any of them. Ice cream; is that a low pressure application? We will be running at least 200 bar.

 

[Latexman]

About that. It runs 2000-3000 psi depending on the mix.

Good luck,
Latexman

 

[Nitzey]

Thanks. What we are making is AKD (alkyl ketene dimer) dispersion in water, a paper chemical. Most AKD is made at 3000 psi, but some companies use much higher according to the homogenizer manufacturers.

So, it would seem 316 ss is fine if we stick with a non-chloride formulation. The homogenizer cost is about half.

 

[SJones]

The 316L is a lot easier to procure correctly and to weld. However, the cost differential is surprising since the duplex will have nearly twice the yield strength of the 316L requiring a thinner vessel. What is the design temperature?

Steve Jones
Materials & Corrosion Engineer

http://www.linkedin.com/pub/8/83b/b04

 

[Nitzey]

Operating temperature is only 70°C.

The company offering the lowest cost is from India. Frankly, their offer is so low, it is amazing to me.

 

[micalbrch]

I have similar experience as Latexman with homogenizers for food applications. All 316ss and pressures up to 2000 psi.

Ask the other two bidders why they do not quote 316ss. Nobody bids something expensive without a certain reason and I cannot imagine that the two expensive bidders cannot make a homogenizer out of 316ss. They might not meet the price of the Indian manufacturer but that is another story. You need a technical explanation.

 

[Nitzey]

I talked to someone I know at a homogenizer manufacturer and here is what I got from our discussion. This company tends to use 15-5 PH in No. America but duplex ss in Europe (2205). Both are twice as strong as 316 ss. However, 15-5 PH is less corrosion resistant than 316 ss. They do make homogenizers in 316 ss and in No. America 316 ss is often used when the pH is low, for example ketchup. However, duplex ss are both stronger and more corrosion resistant than 316 ss. There was mention of the ability to use shot peening to relieve stresses, but I am not sure how this enters the equation. My friend speculated that 316 ss is available at very low cost in India.