×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Contact US

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!

*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

phosphate conversion coating for the cast valve bodies

phosphate conversion coating for the cast valve bodies

phosphate conversion coating for the cast valve bodies

(OP)
Hay there!

has somebody some experinces with phosphate conversion coating for the cast valve bodies used for valve applied in oxygen process. To use it as corrosion preservation. Some info if according to wha, aiga, and so on.
any input is welcim!

Thanks

RE: phosphate conversion coating for the cast valve bodies

Cast what (what alloy)?

Oxygen in what form (gas, liquid) at what temperature and pressure conditions, at what velocity, in what service (hospital, chemical plant, rocket engines...)

Sounds like you are looking at iron/steel low-alloy valves...which I have never heard of in oxy service.

RE: phosphate conversion coating for the cast valve bodies

Phosphate conversion coatings are meant to protect parts from corrosion in climate controlled environments until they can be assembled or installed in the field. Long term, phosphate conversion coatings are good for parts that will see service in oily environments or live their lives well protected under paint.

RE: phosphate conversion coating for the cast valve bodies

...and oil or paint plus oxygen = fire.

RE: phosphate conversion coating for the cast valve bodies

Aware of that, I was just giving examples of where phosphated coatings are successfully used. They work well for parts inside of engines or under paint. They offer a trivial amount of corrosion protection in any environment otherwise.

RE: phosphate conversion coating for the cast valve bodies

It is common practice to use zinc or manganese phosphate coating on carbon steel valve parts. Black oxide is also common. The corrosion resistance is limited and is mostly achieved with the oil dip at the end of the process. Since phosphate coatings are used on carbon steel, it is not used for liquid oxygen because temperature is too low. Only gas. I have seen phosphate coatings used for many years on oxygen cleaned valves with no issues. However, keep in mind that carbon steel can only be used for low pressures and velocities with no impingement possibility. Also, the oil at the end of phosphate process is removed during Oxygen cleaning. And when cleaning involves scrubbing, some of the coating is removed as well. I cannot find any document or standard that states phosphate coatings are ok, but have seen them used on Oxygen clean valves for over 30 years without issue.

RE: phosphate conversion coating for the cast valve bodies

Run away if you’ve got an oxygen service there, too higher risk of something going wrong.

Go solid metal, stainless, brass, Monel, inconel etc. so long as meets the velocity limits etc.

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! Already a Member? Login



News


Close Box

Join Eng-Tips® Today!

Join your peers on the Internet's largest technical engineering professional community.
It's easy to join and it's free.

Here's Why Members Love Eng-Tips Forums:

Register now while it's still free!

Already a member? Close this window and log in.

Join Us             Close