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

API 650 Shell Vertical

API 650 Shell Vertical

API 650 Shell Vertical

Dear experts,
API 650 storage tanks

My welding process is FCAW-G.
On the shell vertical seams, I am considering a single-vee joint, single side welding with ceramic backing.
Another option is single-vee, double side welding, which means I need to backgouge the second side.

I need advice on which option is better.
Thickness ranges from 7 mm to 13 mm.
With the double side welding, I think I can have a better shrinkage control also weld consumable may be less than welding single side with backing.

Not sure if API 650 allows to use temporary backing for shell vertical seams.

My welders are qualified on double side welding. Does this qualified them to weld on single side joint with temporary ceramic backing?

RE: API 650 Shell Vertical

Speaking from personal experience, with large tank construction you will not achieve the dimensional control of fit-up necessary for the successful use of ceramic backing.
Double sided is definitely favoured for managing angular distortion, although at sub-13mm there isn't much difference between single and double, but double-sided is more difficult to fabricate.
Transverse shrinkage is a function of the weld process and procedure but will definitely increase with larger root gaps. Fit-up is at least half the battle.

"Everyone is entitled to their own opinions, but they are not entitled to their own facts."

RE: API 650 Shell Vertical

Dear JXWu,

The second option is most prevalent (at least in the Indian sub-continent and the Middle-East).
However, SMAW is used instead of FCAW.


Kolkata, India

RE: API 650 Shell Vertical

Thanks to everyone for the advice!

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


Low-Volume Rapid Injection Molding With 3D Printed Molds
Learn methods and guidelines for using stereolithography (SLA) 3D printed molds in the injection molding process to lower costs and lead time. Discover how this hybrid manufacturing process enables on-demand mold fabrication to quickly produce small batches of thermoplastic parts. Download Now
Design for Additive Manufacturing (DfAM)
Examine how the principles of DfAM upend many of the long-standing rules around manufacturability - allowing engineers and designers to place a part’s function at the center of their design considerations. Download Now
Taking Control of Engineering Documents
This ebook covers tips for creating and managing workflows, security best practices and protection of intellectual property, Cloud vs. on-premise software solutions, CAD file management, compliance, and more. Download Now

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