SS 316 vs SS 2205 2

[efinol]

I need to specified a Plate and Frame Heat exchanger to use for water cooling with 30 ppm chlorides. I want to Know what percent is the increase in cost by using SS 2205 instead of 316.

thank for your help

 

[rmw]

Contact one or more PHE mftr's. They can give you that information. You have several things at play here, material costs vs heat transfer characteristics. They may be off setting or may be additive depending upon your design conditions.

rmw

 

[EdStainless]

Can you make the 2205 plates thinner?
Will this be welded or gasketed?
Why are you looking at 2205?

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[rmw]

EdStainless,

Most PHE plates are as thin as they can be and still survive the pressing process. Frame size and operating pressures/temperatures determine thickness as well, but heat transfer and mfg cost considerations drives any of the above to the thinnest plate possible.

P&F connotes gasketed although some versions have cassettes of welded plate pairs. Seawater wouldn't call for that degree of sophistication unless he was cooling the seawater with something exotic on the other side.

I, too puzzled as to why 2205.

Greetings,

rmw

 

[efinol]

I am cooling water from 150 C with 50 ppm Chlorides and i am worried about SCC.

 

[EdStainless]

OH, 150C. I would go with 2205. CSCC is a real possability.

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Rust never sleeps
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[mcguire]

The materials alternatives aren't 316L vs 2205. It's 316L vs. 2003, which has much better resistance to corrosion and CSCC. Don't neglect 2101, either. With $15/lb nickel, these alloys should also be cheaper than 316, which has 10% nickel, after surcharges are applied.

Engineers have to eliminate the use of excess nickel. It is the least useful element in stainless steel and the most expensive, after molybdenum, which while expensive is at least valuable.

Allegheny makes 2003 and Outukumpu makes 2101. Each has a good website to help with questions.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[TVP]

Mike,

I think I would qualify that note about Ni being the least useful element in SS...I believe you mean with respect to corrosion resistance in austenitic or duplex stainless steels. With respect to other properties (hardenability, toughness, etc.) in SS with other microstructures (martensitic/PH) Ni obviously is quite useful.

 

[mcguire]

Nickel has it's uses. But, it is still far overused. In martensitics it mainly lowers the austenite reversion temperature, hindering tempering. It is necessary in the PH grades to stabilize austenite and prevent delta ferrite. Nickel, like copper and moly, slow down active corrosion rates in super austenitics. This isn't much benefit for $15/lb.
My point is that you don't need very much of it in austenitics or duplex. 304, with 8%, is an economic disaster. I recommennd 201 and 439 (4% and 0%)all day long. I don't think you can overemphasize how much we need to get engineers to stop regarding 304 and 316 as the standard alloys. The mills aren't pushing 304 and 316 exclusivity anymore. It's the service centers who resist change...and the engineers who don't take the time to learn the alternatives.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[arunmrao]

mcguire,
I agree with your comments.Ni and Mo lobby have conditioned our minds in such a way that we are not willing to consider alternatives. If a component has to perform well just check,Ni and Mo presence . Now no one considers in say at times altering design,service conditions,there is a whole lot that can be done.

Please correct me if I am wrong regarding a news report about the future cost of Ni and Mo. It is predicted that the cost of these alloys is going to scale up to ridiculous levels with no rationale to justify like demand and availability.

lot of investment is going on in Ni mines in Central Europe and Africa.

I shudder to think of such a scenario as tiny guys like me will be wiped out.

 

[mcguire]

India has been a leader in adopting 201. Now China is moving that way. Europe has always used ferritics whenever possible. The US is the main culprit.

Try to get your customers to permit you to use lower nickel alloys. You'll be doing them and you as favor. I was able to get a lot of food service equipment makers in the US to switch. You can bet they are happy now.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[arunmrao]

Food and medical grade equipments here use only 316L and higher alloys as they adhere to USP norms I suppose.

 

[arunmrao]

mcguire
Please be careful with your comment on Ni and Mo users. atleast till your book is out else,your publishers may scale down the royalty and other benefits that go along .

 

[gvanbeek]

The orignal question was on increased cost. My cost info from July for unfabricated materials was:
2205 - $4.5 / lb,
2304 - $3.5 / lb,
316 - $3.5 / lb,
304 - $3.15 / lb,

This should get you in at least the parking lot of the ball park.

 

[unclesyd]

I'll have to take exception to some of the statements about the use of Mo.

In one of our processes where we oxidize alcohols with HNO3 at 110°C we have found that 304L SS, max C 0.015%, is the most economical alloy. No other material has show anything equal to or better than this material. As we approach 120°C Ti is the only choice. The product of this oxidation is an organic acid that carries essentially 0.0 corrosion rate on 304 SS until reaching it's melting point at 172°C where the corrosion rate is in excess of 100 IPY as it melts. The corrosion rate on 316 SS from 172°C-192°c is 0.0. At 192°C the rate will slowly increase to around 0.020-0.30 IPY at 210°C. Hastelloy C is the material of choice up to a temperature of around 225°C. Ti is the material of choice to around 240°C. Above this only Cu alloys will work. The reason for these temperatures was that the acid is reacted with NH3 to make a Nitrile. The Nitrile purification train is all 316 SS as again Mo is is essential for corrosion resistance. Rates on 304 SS are above 0.020 IPY through the purification train. Thank goodness the process that uses these temperatures is gone as we make the Nitrile by another process. The purification train for the new process is a lot simpler but the MOC is still has to be 316 SS.

We also have another process where we take dibasic acids and make esters where the MOC is 316 SS due to corrosion, mainly H2SO4. The MOC separation and purification for the DBA's has to be Ti or 316 SS depending on the temperature.

As for changing MOC's we were constantly evaluating different materials in every process on site. We started using Ti in the early 60's and tested it in every process stream in the oxidation trains, both air and acid with samples from DuPont. We very aggressively approached the material problems from the bench scale through the pilot plant and continued through the process implementation.

In a plant as large as ours the selection of a MOC is based on a lot factors. Not the least is material mix ups process wise especially from all the contract people involved, where Stainless is Stainless.

 

[mcguire]

No disagreement. Moly is terribly expensive, but irreplacable. Nickel is terribly expensive and able to be reduced in most austenitic applications at no loss of performance.

Michael McGuire

http://stainlesssteelforengineers.blogspot.com/

 

[EdStainless]

gvan, There is something wrong with your numbers. They don't scale right.
Current sheet prices, base + surcharge
304L $1.05 + $1.10 = $2.15
316L $1.25 + $1.85 = $3.10
201 $0.90 + $0.66 = $1.56
2205 $2.00 + $1.55 = $3.55

I don't have current 2101 and 2003 numbers.
I would guess that 2101 is about $1.45 + $0.40 = $1.85 and 2003 is roughly $1.65 + $0.90 = $2.55

These are estimates based on what I have seen recently for sheet pricing.
Remember, stainless is price in effect. Place your order now and you will pay whatever the base price and surcharge is in 16 weeks. The wills will not hold a base price.
I expect to see another 10-15% increase before the end of the year.

Mac, Yes, the lean duplex grades are the preferable options, but availability will be the driver here.

My favorite example of substitution is a 4%Mo, Mn rich alloy with tons of N. It has the same pitting and crevice corrosion resistance as traditional 6%Mo supersutenitic grades.

I have seen some very bad '201' out of Asia. It was not a stable austenitic alloy. Come on, use a little Ni.


= = = = = = = = = = = = = = = = = = = =
Rust never sleeps
Neither should your protection

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[rolledalloy]

Pricing is a little on the low side on LDX 2101 and probably 2003. LDX 2101 and 2003 now with nickel hitting $16 this week has dropped with respect to 304 and 316 which have more nickel. I can't comment on 2003 specifically but Allegheny has been promoting it more strongly as an alternate to 316L so it likely very competitive price wise at this point where originally it was slotted as a cost down from 2205. I think it is closer to $3.00/lb than $2.50.

In the case of LDX 2101 it originally was maybe 10-15% under 316L but the surcharges in effect have it today a little below 304L, but still above $2.00/lb

Something to bear in mind. Be aware that these price differentials could be temporary. If you consider lean duplex just on cost savings bear in mind that today youmay save money vs. 304L by switching to LDX 2101 however if nickel comes down to $8/lb say the LDX 2101 will no longer be cheaper. The only way to get a permanent savings in such a scenario is to redesign with a thinner section with any duplex if that is possible.

 

[moltenmetal]

I love the idea of reducing our nickel dependency by using alternative alloys of similar or superior resistance. But when you're considering breaking our slavish tendency to use austenitic stainless steels, you have to think about the person actually spec'ing and using the material a little more. The availability in the desired finished form article is the key here. No point in spec'ing an alloy that you can't get your hands on in the form you need. Plate and billet are fine if you're building massive vessels, but no comfort to me when I'm selecting materials for piping!

Duplexes are difficult to weld while retaining the desired metallurgy. Especially when you're working on small sections that heat up rapidly, resulting in increased ferrite content and a welded article which has nowhere nearly the same corrosion resistance of the parent metal. Duplexes are not impossible to weld, surely, but no picnic either. The austenitics are dead easy in comparison.

And even 2205, as ubiquitous as it seems to be in the imaginations of corrosion engineers, we have found in practice to be very tough to get your hands on in the form of smaller-diameter pipe fittings etc. These problems go away somewhat if you want to order $1 million worth on a single purchase order and can afford to wait for a mill run, but the situation is a might tougher when you want $10k worth for a small job. Forget about 6 moly stainless grades or the so-called super-austenitics- they're next to impossible to find in the forms we want.

The alloy price ratios people are talking about are applicable only for raw materials (ie. plate and bar again). The pricing for small lot orders of pipe and fittings tend to follow pricing which is very different than what you'd estimate based on their alloying contents. Though recent rapid metals price changes have altered the formulae somewhat, our experience has been that for small lot orders of pipe and fittings, 304 is 1 unit of cost, 316 is 1.2-1.5 units of cost, and anything else is 5 to 15 units of cost!