×
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

API 653 FFS Evaluation for Hydrotest

API 653 FFS Evaluation for Hydrotest

API 653 FFS Evaluation for Hydrotest

(OP)
We were recently considering a hydrostatic test exemption, following API-653.  The repair of the annular plate was considered major and did not fall under the shell repair or minor shell jacking sections.  This left the fitness for service evaluation for hydrotest exemption.  Although the ultimate decision was made to hydro the tank, I was having difficulty with the concept that a fitness for service evaluation could be used instead of a hydrotest.

A hydrotest stresses the system and is primarily used for detecting quality issues with welds that were not detected using NDE.  Presumably, a flaw found with NDE that was large enough to result in a leak during a hydro would have been repaired.

FFS assessments are used to determine if degraded or flawed equipment is suitable for continued operation.

Has anyone had experience with using FFS to exempt a hydrotest on a tank?

I appreciate any info.

RE: API 653 FFS Evaluation for Hydrotest

I'll sidestep your exact question, and go to hydro's after repair. If I had my annular ring [or any other major component] repaired, I'd put a good Inspector on the job, too.  Waaay cheaper than a hydro.  

Tank was originally hydro'd after construction
Annular ring degraded, without the tank failing
Bad sections of ring were removed and replaced
My API-653 & CWI Inspector evaluated the removed areas, and had any further questionable areas replaced.
Inspector observed 100% of the welding & welders, and assured that no sloppy or marginally competent welders worked on my tank.
Inspector 'signed off' on the Visual Examination of the welding, and the proper and complete replacement of all the degraded areas.
Inspector specified the type and extent of NDT testing required to further assure that the replaced areas are as good [or better] than the original construction.  NDT passed.

Why would I not want to waive hydro?  What will it tell me that my Inspector hasn't?  

Keep in mind that to have a hydro failure, the tank has to be below the strength of the *actual* material -- below *all* the combined Safety Factors.  This means that my tank is now less than 1/4th of the Design Strength.  Remember also that the tank did not fail with the degraded ring in place.  There is no credible scenario that would cause my tank to fail during hydro after witnessed and tested repair/replacements.  
  

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