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- since 1996 -
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Technical Discussions
daniel iordache
daniel iordache
05:38 Apr-03-2004
Re: lamination evaluation

----------- Start Original Message -----------
: : hi
: : i am looking to find out how you be can evaluate a lamination area(spot laminations with variable depthes-fm. 3 to 7.5 -area size 300 x 600 mm starting fm. weld ) in a gas pipe line 16" -sch. 40 /700psi-30years old.
: : at ut the wall thickkness into that area shown echoes at 3 -5-7 mm and we seldom i found the 13-12.5
: : most of peaple said that is without inportance, but....
: : i want to know other opinions
: : thanks
: TOFD
------------ End Original Message ------------


i had still the same prolem and i found a new portion.


 
 Reply 
 
Steven Johnson
Consultant
USA, Joined Mar 2004, 16

Steven Johnson

Consultant
USA,
Joined Mar 2004
16
06:31 Apr-05-2004
Re: lamination evaluation
----------- Start Original Message -----------
: : : hi
: : : i am looking to find out how you be can evaluate a lamination area(spot laminations with variable depthes-fm. 3 to 7.5 -area size 300 x 600 mm starting fm. weld ) in a gas pipe line 16" -sch. 40 /700psi-30years old.
: : : at ut the wall thickkness into that area shown echoes at 3 -5-7 mm and we seldom i found the 13-12.5
: : : most of peaple said that is without inportance, but....
: : : i want to know other opinions
: : : thanks
: : TOFD
:
: i had still the same prolem and i found a new portion.
------------ End Original Message ------------


Hello,

I would write up the indication, and let the owner of the pipeline make the call. It our job to report, let them do the fracture mechanics.



 
 Reply 
 
N.Kuppusamy
Consultant, Level-III
United Testing Co. Pte Ltd, Singapore, Joined Jan 2003, 13

N.Kuppusamy

Consultant, Level-III
United Testing Co. Pte Ltd,
Singapore,
Joined Jan 2003
13
08:10 Apr-05-2004
Re: lamination evaluation
Dear Friend,

Herewith I suggest that the laminar indications observed at various depths can be evaluated accoding to AS1710-1986 (Table 5.1)as given below:

Maximum total area of discontinuity in any area 1m×1m:

Lamination (Sq.mm)
3 000
10 000
20 000

Inclusion cluster (Sq.mm)
5 000
16 000
40 000

This can be applied irrespective of depth (for plates).

From your description it seems that you encoutered service induced defects such as HIC or HSSC.

Regards,
N.Kuppusamy

----------- Start Original Message -----------
: : : hi
: : : i am looking to find out how you be can evaluate a lamination area(spot laminations with variable depthes-fm. 3 to 7.5 -area size 300 x 600 mm starting fm. weld ) in a gas pipe line 16" -sch. 40 /700psi-30years old.
: : : at ut the wall thickkness into that area shown echoes at 3 -5-7 mm and we seldom i found the 13-12.5
: : : most of peaple said that is without inportance, but....
: : : i want to know other opinions
: : : thanks
: : TOFD
:
: i had still the same prolem and i found a new portion.
------------ End Original Message ------------




 
 Reply 
 
John O'Brien
Consultant, -
Chevron ETC , USA, Joined Jan 2000, 280

John O'Brien

Consultant, -
Chevron ETC ,
USA,
Joined Jan 2000
280
01:41 Apr-13-2004
Re: lamination evaluation
Refer to API RP 579 Fitness For Service which has a section dealing with Laminations & Blisters. the size of the lamination may not be critical. the most critical dimension may be how close the lamination is to a structural discontinuity such as a weld.


 
 Reply 
 
Andrew Wilde
Andrew Wilde
05:06 Apr-14-2004
Re: lamination evaluation
Daniel,

In general, laminations found in pipeline steels are parallel to the surface of the pipe and therefore, do not affect its structural integrity. However, a lammination that has a sloping extent would be classed as a significant defect and its severity woud need to be assessed. Also, you say that the lamination is adjacent to a weld - you therefore need to be confident that there is no associated through-wall cracking at the weld toe (I'm told this can be difficult to detect with UT as the lamination can mask the weld crack). There has been very little research done on the assessment of laminations (even though there have been a number of recorded pipeline failures due to laminations), so any assessment method applied will be conservative. We tend to assess the lamination as a crack using BS7910 or API 579.

An internal inspection with a UT tool should really be considered if you suspect that the lamination problem may be extensive.

Hope that helps.

Andrew


 
 Reply 
 
morad merad
morad merad
04:40 Jan-15-2005
help
Hello Andrew,

I am a student at the norwegian state diving school and i have an exam on next wensday. I have some homework to do and one of the questions we got from the instructor is the following:

Wich NDT-method (non destructiv method) will normally show a lammination (defect) in steel:
- Ultrasound
- MPI
- Radiography or
- Eddy current

Actually i know the answer. The intructor says it is radiografy. But how does it work ? and i don´t really understand lammination. Could you please explain it to me ? how does a lammination occurs ? do you have any picture(s) showing a lammination ?

Thank you

Morad




 
 Reply 
 
Walter
Engineering, -
Innovative Test Systems, Inc., USA, Joined Jul 2002, 4

Walter

Engineering, -
Innovative Test Systems, Inc.,
USA,
Joined Jul 2002
4
08:32 Jan-15-2005
Re: help
----------- Start Original Message -----------
: Hello Andrew,
: I am a student at the norwegian state diving school and i have an exam on next wensday. I have some homework to do and one of the questions we got from the instructor is the following:
: Wich NDT-method (non destructiv method) will normally show a lammination (defect) in steel:
: - Ultrasound
: - MPI
: - Radiography or
: - Eddy current
: Actually i know the answer. The intructor says it is radiografy. But how does it work ? and i don´t really understand lammination. Could you please explain it to me ? how does a lammination occurs ? do you have any picture(s) showing a lammination ?
: Thank you
: Morad
------------ End Original Message ------------

Actually, the answer is Ultrasound. A lamination is typically a disbond in the steel caused during the rolling process when an edge is rolled over onto the surface. It is generally parallel to the surface. As it basically has no thickness, the radiograph will not see a density change. The Ultrasound will show a refelction from the disbond and/or a reduction in backwall signal.


 
 Reply 
 
DJ Kallhof
DJ Kallhof
03:43 Jan-17-2005
Re: help
----------- Start Original Message -----------
: Hello Andrew,
: I am a student at the norwegian state diving school and i have an exam on next wensday. I have some homework to do and one of the questions we got from the instructor is the following:
: Wich NDT-method (non destructiv method) will normally show a lammination (defect) in steel:
: - Ultrasound
: - MPI
: - Radiography or
: - Eddy current
: Actually i know the answer. The intructor says it is radiografy. But how does it work ? and i don´t really understand lammination. Could you please explain it to me ? how does a lammination occurs ? do you have any picture(s) showing a lammination ?
: Thank you
: Morad
------------ End Original Message ------------
Morad,
Laminations are impurities in the parent metal, metallic and or non-metallic. They originate from the solidification of the material when the alloyoing components of the material partially segregate. That is not mix well. Sulphur is a good example. When the steel is further processed, as in rolling plate or extruding seamless pipe, the impurities are elongated with the rest of the material. They get sandwiched inbetween the rest of the steel. I am sorry to say you might have a problem with your instructor. I hope you misunderstood him. Radiography will not be able to identify this condition. Ultrasound is the best method available to find laminations in plate or pipe. Hope this helps.

DJ Kallhof





 
 Reply 
 
LUIS MARQUES
LUIS MARQUES
05:27 Jan-17-2005
Re: help
----------- Start Original Message -----------
Morad

To detect a lamination into a steel piece, ultrasound technique is the best choice. You can also detect it by radiography; in that case you must be sure that your lamination is normal (not perpendicular) to your X ray source emission. As the other poster says a lamination is a sandwiched impurity, which lays parallel to lamination sheet surfaces direction inside steel material.

Regards

Luis Marques



 
 Reply 
 
ANSHUL SANGHI
ANSHUL SANGHI
08:48 May-16-2012
Re: help
In Reply to DJ Kallhof at 03:43 Jan-17-2005 .

Dear DJ Kallhof and Andrew

Thanks.. it was good and very simple to understand..

 
 Reply 
 
sanjay
sanjay
10:44 Sep-22-2017
Re: lamination evaluation
In Reply to daniel iordache at 05:38 Apr-03-2004 (Opening).

Is lamination crack on plate will able to detect by UT 100 %. Or may chance to UT can't identify lamination. One of the reason that UT waves will not transfer through vacuum / air gap area of lamination.
Pls. advise.

 
 Reply 
 
S V Swamy
Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex , India, Joined Feb 2001, 787

S V Swamy

Engineering, - Material Testing Inspection & Quality Control
Retired from Nuclear Fuel Complex ,
India,
Joined Feb 2001
787
19:04 Sep-22-2017
Re: lamination evaluation
In Reply to sanjay at 10:44 Sep-22-2017 .

Detection of any discontinuity depends on several factors and laminations are no exceptions. Thus, asking for a 100% detection is idealistic and impractical.

The reason we can detect laminations using UT is precisely because ultrasonic waves are reflected by the lamination interface and thus we get an echo much before the back echo. Back echo may drop slightly or disappear all together depending on the area of the lamination, the frequency and diameter of the probe, thickness of the plate etc.

For thinner plates / sheets, it is better to look for a change in the screen pattern instead of looking for reduction of back echo. The echo pattern gets lifted up because of multiple echoes generated by the lamination.

In practice, it is always good to create natural / artificial standards to help the operator get the correct idea of interpreting the presence of a lamination.

 
 Reply 
 
James Scalf
NDT Inspector,
Global Integrity, Canada, Joined Oct 2012, 273

James Scalf

NDT Inspector,
Global Integrity,
Canada,
Joined Oct 2012
273
21:04 Sep-22-2017
Re: lamination evaluation
In Reply to sanjay at 10:44 Sep-22-2017 .

Sanjay,

Swamy is correct in that UT Will not always detect laminations. While UT will detect most forms of laminations, there are situations where a lamination may go undetected.

Laminations at or very near the far surface may go undetected due to its proximity to the actual back wall.

Another common defect in composite and laminated materials are "Kissing Bonds" these are laminations (and true defects) which have an air gap that is so minimal that the vibrations emanating from one side of the lamination are still able to cause sonic vibrations to emanate beyond the lamination and continue to the far surface and return. There are tricks and means to discriminate these but it takes skill and a profound understanding of how the sonic waves propagate in the materials being examined.

Hopefully this provides you with a little more understanding. Cheers...

James Scalf

 
 Reply 
 

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