×
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

lamination and stress study

lamination and stress study

lamination and stress study

(OP)
in service LPG tank 3000 m3 ,18 bar mawp, sa516 gr.70 , i found lamination in more 5 shells , after return to API 510 to see assessment , it forwarding me to API 579 which say (lamination is acceptable regardless of sizes except(1- in case of no working in hydrogen charging service, 2-locate the lamination out of distance of( 1.8 √ D*t )from major discontinues 'manhole'

i want to make some study of effect of stress to lamination prolongation in case of P.V. working with lamination, and why avoid locate in the area near to manhole ?, wich type of stress may be run?

RE: lamination and stress study

Follow ALL of the requirements of API 579-1/ASME FFS-1, Part 13 "Laminations". All of the calculations necessary for any such study are contained there.

RE: lamination and stress study

INSP79:
Generally, laminations and non-metallic inclusions are planar irregularities/anomalies which lay parallel to the two faces of the plate. You can usually see them when you machine or cut through them, as you cut across the thickness of the plate. They do not usually change the cross sectional area of the plate appreciably. You can map their location in a plate by ultrasonic testing (UT) or radiographic testing (RT) through the plate. When your primary stresses are in the plane of the plate, as is usually the case in a PV, the lamination is not too critical as long as it is not too thick. The same applies to compressive loads or stresses perpendicular to the plane of the plate (radial loads/stresses in most PV’s), they just tend to compress the lamination. But, tension perpendicular to the plane of the plate is a different matter, since tensile stresses will tend to pull the lamination further apart, or make it grow at its boundaries.

I don’t have the API or ASME codes in front of me, so I don’t know exactly what restrictions and limitations those codes put on this situation. But, given the above general considerations, they will more than likely tolerate some lamination as long as they aren’t too large (thick) or extensive. The codes will be much more strict about their existence in locations where the actual stress patterns/fields are tri-axial. That is, where the likelihood of through plate stresses is high, such as at a nozzle or manway openings or other transitions and significant discontinuities, which distort the normal stresses and cause significant through plate stresses.

RE: lamination and stress study

TGS4:
We do seem to meet up at this topic periodically, don’t we? Have a nice holiday season.

RE: lamination and stress study

INSP79. Are you reading API 579 ASME FFS-1 edition 2016? The word “manhole” is not found here.

dhengr. RT is not adecuate to detect laminations

Regards
R6155

RE: lamination and stress study

Agree above, RT will not detect laminations because of orientation. Either shear wave UT or phased array UT are your best options for evaluating laminations.

RE: lamination and stress study

AET -Acoustic Emission Testing is the best, specially in large pressure vessel.

Regards
r6155

RE: lamination and stress study

Acoustic emissions is not appropriate for sizing any flaws for performing fitness for service evaluations. It can neither locate nor size flaws with sufficient accuracy. Particularly for laminations, it cannot provide information regarding the depth of the lamination.

The response provided by metengr is, as usual, spot on.

RE: lamination and stress study

INSP79. Please,can you tell us how did you found these laminations?
Was by chance during inspection of actual thickness?

Regards
r6155

RE: lamination and stress study

To detect laminations with AET see ASME V Table A-110. Once detected UT is used for more details.

Regards
r6155

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