Carbon Steel A105 vs H2S

Cant give you a full account here, but I am pretty sure you will get to answer the questions:

- in what environment,

- at which temperature

- and with what sort of Chemicals you maybe dealing with.

Give us a bigger picture of what you trying to do and we can hopefully give you better advice.

IS

Hi,

Thank you for your reply,and here is the detail:

union joint of carbon steel ASTM A105 to resist HIC corrosion

union joint of carbon steel ASME SA106 Gr.B to resist H2S corrosion

Tell me if it is possible for the upper situation to happen, if so, how?

Penny, sorry to ask more questions, but the environment these joints will be in is not clear. The effect of the said corrosions are different at different Temperatures. And I also only get half the story of the application of said Union Joints. What material is the Pipe made of that the Joints join? What is the reason that only the joints seems to be a problem? Generally I would make the joints from the same material that the pipe is made off. More generally making material suit a certain corrosive environment means making new material. One normally does choose the correct material for the specified environment.

Your Original post suggests that you want to do it the other way around. How permanent is your installation, what environmental parameter (like Temperature) are in your control?

Need more input about the application. Check the material datasheets what manufacturer recommends.

Best regards

IS

Havent covered all that is probably needed to say.

two things just pooped to mind:

1. Concentration of H2S plays a role

2. www.NACE.org is a starting point when talking about corrosion

IS

Hi,

Thank you so much, and now i am so confused. In fact we normally use SS316 to do this kind of union joints for pipes, and the reason why we choose Carbon steel is that our customer asked us to do this for him. You know what, if carbon steel does not work out, I will just suggest him to choose SS316.

Been there, done this. Customer wants to save some money and wants supplier to get him the less costly material which shall perform the same way as the high spec material. Proove has to come from Supplier and if anything goes wrong its Suppliers fault.

If it be my project I would supply SS316 as the material of obvious choice.

Gives you better sales and keeps everyone happy.

:-)

So long

Thank you so much, you are so nice!

This is the best solution !!

To add; you could choose thinner walls (as Stainless steel YP is twice as stronger

than A105 Carbon steel ). Add also that no paint required!!

This will lower the price quite strongly!!

Use the 316.

The H2S will destroy the carbon steel, and you'll be using the 316 eventually anyway.

According to my data, SS316 is only mildly resistant to H2S. Hastelloy C or Titanium would be a better material. You did mean HCl didn't you? SS316 is not resistant to 37% HCl. You need to use Titanium. If you can use plastic, PVC and PE are resistant to both.

In the left corner, wearing black trunks: A105!
In the right corner, wearing white trunks: H₂S!

15 rounds later....And the winnah--HCl! (Wait a minute, how did he get here?)

There are several materials compatibility databases on the 'net.

It sounds like this particular customer needs a crazectomy.

Well, I do not know they manage to do it, but the head of our department just told me that in China now, carbon steel can resist H2S.

Can you get that in writing?

I wish that I could， but it is done by one of the head research institutions in China, and they sure are not going to give it out anyhow.

My skin can resist H2S, just not for very long. Carbon steel can resist H2S, but not as long as stainless. The one question to ask: "How long do you intend to use this?"

Marketing advice: Supply carbon steel per customer's requirement but adjust your warranty period way way down.

I suspect that if the Chinese gentleman really can make carbon steel as resistant as stainless, his process is too costly to justify its use. (I have a method of making carbon steel as resistant as stainless. It begins by using the carbon steel as one of the inputs to the regular stainless steel production process.)

I'm assuming the piping is also SS316 and that the acids are transported in these pipes (or is it a splash/temporary exposure risk)

If the customer wants these then make them aware of the risks and alternatives and then give them what they want. It's their rap.

What secondary risks are there if the union fails?

Why does the customer want this?

If there is a corrosion resistant A105 Carbon Steel then it isn't A105 Carbon Steel anymore is it?

If SS316 has functioned in the past, why risk the liability associated with an unknown material. The downtime incurred from one failed joint would more than justify the additional cost. It's good to save money, but it's bad to have a costly accident.

You forget, its only expensive to have accidents in countries that have codes against such "accidental" releases or actively pursue, prosecute, and fine pollution generating entities. Lest we forget why the jobs went West. It had very little to do with labor costs and everything to do with environmental restrictions, safety codes, and all those wonderful regulations that make working safer and more earth friendly in advanced countries.

So true; we have an investigation to determine the cause of an accident, and hopefully prevent future misshapes. In China the only investigation will involve finding a replacement person (we got more where that one came from). Supporting a communist nation and destroying US jobs simultaneously, all for profit.

My source for chemical resistance is: www.usplastic.com