API X70 vs. Lean Duplex

[BTF83]

Hi Guys,

I have been asked to compare the two materials mentioned in the title. Could someone please help me come up with a list of the key differences between these two materials.

Any Help would be greatly appreciated

I'm looking for info regarding

1. Price
2. Hot Bending potential
3. Yield and tensile strength
4. Welding potential
5. Corrosion

Cheers guys!

 

[EdStainless]

1. Will depend on product form. Per pound the LDX will be a lot more, but you can use less material and have significantly longer life (maybe).
2. You cold bend SS, not hot. It will take serious forces to form LDX, but that is how it is done.
3. Look them up in the specs
4. common, fillers available and no issues
5. Define an environment. If we are talking about wet, CO2, HS2, and some minor amounts of chlorides then the LDX will have significantly better corrosion resistance, as in multiple times the life.

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Plymouth Tube

 

[SJones]

One is a carbon steel pipe grade, the other is a generic name of a stainless steel. Come on - help us out and be a lot more specific as to the application and what you are trying to achieve! If it is a pipeline, the first thing to check is does the pipeline design code specifically address 'lean duplex' or, if not, does it allow the inclusion of additional grades and detail the work that has to be done to get them accepted.

Steve Jones
Materials & Corrosion Engineer

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

 

[BTF83]

Sorry for the lack of info. This isn't really my field but I was aksed to make a comparison. I was only told that a dicision has to be made between API Grade 70X and Lean Duplex - I realised that lean duplex is just a type of steel. But I thought that maybe this type of steel would be so much different to X70. It's for wet gas with a CO2 concentration between 0.7-0.8% at a deisgn temperature of 70 C and design pressure of 220 bar.

I have been searching around our databases and can't find any mechanical info for any lean duplex steel. In fact, I could only find three lean duplex steels through this forum.

 

[SJones]

One could say "if it isn't your field you shouldn't have been asked" but that's another issue. What you are looking at is technical comparison and life cycle cost analysis between two very different materials. The basic tenet of materials selection for oil and gas pipelines (and piping) is that carbon steel is ALWAYS the base case until it is demonstrated not to be viable. The first data that you should have been given is the corrosion study that has identified the necessary corrosion allowance for the carbon steel X70. The 'lean duplex' is a corrosion resistant alloy (CRA) and will not require any corrosion allowance - so there is a starting point in the comparison. The corrosion study should have also identified whether chemical inhibition will be required to protect the X70 so there is another point: what will the chemical cost over the design life of the pipeline versus not having to buy chemical for the CRA? The X70 will require corrosion monitoring (possibly intelligent pigging); the CRA pipeline will not. And so on - you see where we are going with this?

Another key point is: what specification will the 'lean duplex' be manufactured to and is it allowed by the adopted design code? For example, a subsea pipeline designed to DNV-OS-F-101 could not use 'lean duplex'.



Steve Jones
Materials & Corrosion Engineer

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

 

[EdStainless]

The lean duplex stainless steels are known by their tradenames, LDX2101, AL2003, and a couple of others. The older 2304 is not in the same league, neither is D19.

good luck

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Plymouth Tube

 

[strider6]

here you can find some informations of lean duplex:

http://www.outokumpu.com/26807.epibrw

http://www.outokumpu.com/pages/Page____42266.aspx

http://www.alleghenyludlum.com/pages/al2003/docs/AL 2003 - ASME Code Case 2503.pdf

the corrosion resistance of ldx 3101 is similar to SS 316

S

Corrosion Prevention & Corrosion Control

 

[BTF83]

Thanks very much!