×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Valve's trim in H2SO4 service
4

Valve's trim in H2SO4 service

Valve's trim in H2SO4 service

(OP)
Hi
In H2SO4 services (98% - 85c) the contractor want to use PTFE as body seat ring and trim but we think it is not proper. also we have another choice, carbon steel. but seems high corrosion will be happened in aforementioned temperature.
could you please help me to select the best choice.

RE: Valve's trim in H2SO4 service

What type of valve and valve body material?

RE: Valve's trim in H2SO4 service

(OP)
Globe valve, Body material is A105

RE: Valve's trim in H2SO4 service

2
Carbon steel is ONLY resistant because it forms a layer of ferrous sulphate on the surface. Even MODEST velocities will destroy that surface layer and the parent material will be destroyed rapidly. A carbon steel plug in a globe valve would be eaten like candy.

Alloy 20 has a hope, but I'm not near my references. You'd need to review the NACE sheets and see what it says for pipe- then increase the alloy selection in the direction of additional resistance because you're dealing with material exposed to high velocity and potential erosion-corrosion.


RE: Valve's trim in H2SO4 service

And I hope that you are looking at a high Si Stainless for the piping.
Even though 98% acid isn't all that corrosion resistant the combination of high temp and flow make this a delicate application.
You need to own a copy of MS-1 on Sulfuric acid and Oleum printed by MTI.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

RE: Valve's trim in H2SO4 service

That A105 body will be toast in no time. Not only the trim need to be A20- the body does too.

RE: Valve's trim in H2SO4 service

Please bear in mind that Alloy 20 was developed specifically for sulfuric acid service. If carbon steel could sustain this service, Alloy 20 would probably not exist.

http://www.rolledalloys.com/alloys/nickel-alloys/a...

Since this seems to be your first acid system, and since Alloy 20 is expensive in a huge globe valve, perhaps this large, expensive type of valve is not your best choice...???

Consider the use of butterfly valves for flow control and plug valves for on-off control.

XOMOX Series 9000, or the cheap Chinese knock-off, may be a good choice .....

http://www.sulphuric-acid.com/techmanual/strong%20...

Like most of these posts, we never get enough information without asking several times ...

What is the strength of the H2SO4 ????

MJCronin
Sr. Process Engineer

RE: Valve's trim in H2SO4 service

(OP)
Tanx guys, thank you so much

RE: Valve's trim in H2SO4 service

The size hasn't been mentioned, but if it's "huge", the all-lined Xomox or Durco plug valves are a good option. We've fitted them with gear operators and find them adequate for coarse control. They will be corrosion immune, which in this service beats mere corrosion resistance hands down.

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources