×
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

What weld Process is suitable

What weld Process is suitable

What weld Process is suitable

(OP)
Hello All

The user's specification indicates that weld shall not be anodic with respect to the base material.

The material in question is API 5L X 65.

Welding is done with SAW and GMAW combination.

What flux (If SAW is used) will result in Cathodic Weld.

If GMAW is used fully, whether changing the gas composotion result in change in Cathodicity/Anodicity? If so what is the recommended Gas composition.

Suppose the potential measured of the pipe base material is "- 0.5" and the potential of the weld is "-0.4" (I persume it is the potential that will be determined as the measure of Anodicity or Cathodicity), is the Weld Anodic with respect to Pipe.



RE: What weld Process is suitable

Anodic, I believe in reference to your specification, refers to the filler metal chemical composition in relation to the pipe base metal chemical composition. Flux is selected based on filler metal chemical composition. So, select the filler metal that matches as close as possible to the chemical composition of the pipe and provides similar mechanical properties.

RE: What weld Process is suitable

If the user's specification indicates that the weld shall not be anodic... it should also say how that is determined and what is the limiting acceptable result.
Otherwise it does not appear to be a meaningful requirement.
Fluxes for SAW are not designed to control anodic condition.

http://www.welding-advisers.com/

RE: What weld Process is suitable

I have not heard about anodic. I presume the spec may be mentioning of job being anode while welding. Generally GTAW process requires straight polarity (Electrode negative and job positive).

Vainala

RE: What weld Process is suitable

metengr,
Your post makes perfect sense, I'm wondering if there also may be a concern over hardness?

RE: What weld Process is suitable

I suppose that whichever the welding process you use, if you chose the proper filler metal it has to match the base metal with the same composition or very similar, so the question of being cathodic or anodic doesn´t make sense.

RE: What weld Process is suitable

The Owner's specification may make sense depending on the process fluid's corrosivity. Deposited, matching chemistry, weld filler metals are often more susceptible to corrsion than the base metal, even in carbon steels.   The Owner or its Engineer should also specify the filler metal(s) that will provide acceptable corrosion resistance. Filler metals with higher chromium, molybdenum or copper contents than the X65 pipe base material may provide better corrsion resistance and extended service life.

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