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Technical Discussions
Martyn
Martyn
02:12 Jul-28-2006
API 1104 Manual UT

Can someone clarify the amplitude at which a signal would make an indication rejectable in accordance with API 1104 manual UT? Or does amplitude not play a factor, and the reference levels quoted are for detection and sizing only, and the indication length is the deciding factor regardless of amplitude?
Please provide some guidance and a reference if you have any.
Thanks in advance.


    
 
 Reply 
 
Ed
Ed
00:54 Jul-29-2006
Re: API 1104 Manual UT
----------- Start Original Message -----------
: Can someone clarify the amplitude at which a signal would make an indication rejectable in accordance with API 1104 manual UT? Or does amplitude not play a factor, and the reference levels quoted are for detection and sizing only, and the indication length is the deciding factor regardless of amplitude?
: Please provide some guidance and a reference if you have any.
: Thanks in advance.
------------ End Original Message ------------

An indication must exceed 50% of DAC/TCG to be considered relevant. Unless it is a crack, it can be considered nonrelevant if it is less than that. Once an indication exceeds 50% DAC/TCG then it is accepted or rejected based on length.
API-1104 11.4.7.2. UT Acceptance standards and classificaitons of indications can be found in 9.6.1 & 9.6.2.


    
 
 Reply 
 
Martyn
Martyn
04:38 Jul-31-2006
Re: API 1104 Manual UT
----------- Start Original Message -----------
: : Can someone clarify the amplitude at which a signal would make an indication rejectable in accordance with API 1104 manual UT? Or does amplitude not play a factor, and the reference levels quoted are for detection and sizing only, and the indication length is the deciding factor regardless of amplitude?
: : Please provide some guidance and a reference if you have any.
: : Thanks in advance.
: An indication must exceed 50% of DAC/TCG to be considered relevant. Unless it is a crack, it can be considered nonrelevant if it is less than that. Once an indication exceeds 50% DAC/TCG then it is accepted or rejected based on length.
: API-1104 11.4.7.2. UT Acceptance standards and classificaitons of indications can be found in 9.6.1 & 9.6.2.
------------ End Original Message ------------

Thanks Ed. That is pretty much how our company is operating at this point, but I still don't see where cracks are exempted from the 50% DAC criteria. Where do you get this exemption from? I believe some additional verbage ALA, ASME Sec. 3 or 8, with the words, "that exceed XX% FSH" should be added to the 1104 evaluation and acceptance criteria.



    
 
 Reply 
 
Ed
Ed
06:12 Jul-31-2006
Re: API 1104 Manual UT
----------- Start Original Message -----------
: : : Can someone clarify the amplitude at which a signal would make an indication rejectable in accordance with API 1104 manual UT? Or does amplitude not play a factor, and the reference levels quoted are for detection and sizing only, and the indication length is the deciding factor regardless of amplitude?
: : : Please provide some guidance and a reference if you have any.
: : : Thanks in advance.
: : An indication must exceed 50% of DAC/TCG to be considered relevant. Unless it is a crack, it can be considered nonrelevant if it is less than that. Once an indication exceeds 50% DAC/TCG then it is accepted or rejected based on length.
: : API-1104 11.4.7.2. UT Acceptance standards and classificaitons of indications can be found in 9.6.1 & 9.6.2.
: Thanks Ed. That is pretty much how our company is operating at this point, but I still don't see where cracks are exempted from the 50% DAC criteria. Where do you get this exemption from? I believe some additional verbage ALA, ASME Sec. 3 or 8, with the words, "that exceed XX% FSH" should be added to the 1104 evaluation and acceptance criteria.
------------ End Original Message ------------

Look at API-1104 Par 9.6.2.1. It states, and I quote, "Indications determined to be cracks (C) shall be considered defects.
Also look at 10.1.1. It states that Cracked welds shall be removed from the line unless a repair is permitted by 9.3.10 or authorized by the company. 9.3.10 addresses crater cracks. They are acceptable if they meet the size limits of 9.3.10.
ASME someties allows cracks under certain conditions, but they dont use the word crack. They call it an indication and it is evaluated based on its Aspect Ratio. a/l or vertical height / length.
ASME is a competely different code with different service conditions than a pipeline.


    
 
 Reply 
 
Michael
Michael
06:40 Jul-31-2006
Re: API 1104 Manual UT
----------- Start Original Message -----------
: Can someone clarify the amplitude at which a signal would make an indication rejectable in accordance with API 1104 manual UT? Or does amplitude not play a factor, and the reference levels quoted are for detection and sizing only, and the indication length is the deciding factor regardless of amplitude?
: Please provide some guidance and a reference if you have any.
: Thanks in advance.
------------ End Original Message ------------

All indication that exceed 50% of DAC\TCG shall be evaluated and should be recored. Any indication that breaks evaluation level(ie: 100% DAC\TCG) and exceeds length for the that defect's classification in whole or part shall be rejected. Any indication that does not break evalution level but is 50% or greater in amplitude and exceeds classification length should be report to the company for accept or reject if not addressed in the procedure prior to inspection.



    
 
 Reply 
 
unknown
unknown
04:44 Aug-03-2006
Re: API 1104 Manual UT
Yes I agree, but I don't think it is the intent of the code to ignore a crack because of its amplitude. If an indication is determined to be a crack it shall be removed from the line. In my opinion and experience, a "good" UT hand should be able to identify a crack even at low amplitudes. So I still say that all cracks, regardless of amplitude are defects and shall be removed.


----------- Start Original Message -----------
: : Can someone clarify the amplitude at which a signal would make an indication rejectable in accordance with API 1104 manual UT? Or does amplitude not play a factor, and the reference levels quoted are for detection and sizing only, and the indication length is the deciding factor regardless of amplitude?
: : Please provide some guidance and a reference if you have any.
: : Thanks in advance.
: All indication that exceed 50% of DAC\TCG shall be evaluated and should be recored. Any indication that breaks evaluation level(ie: 100% DAC\TCG) and exceeds length for the thatdefect's classification in whole or part shall be rejected. Any indication that does not break evalution level but is 50% or greater in amplitude and exceeds classification length should be report to the company for accept or reject if not addressed in the procedure prior to inspection.
------------ End Original Message ------------




    
 
 Reply 
 
Kaveh Edalati
Kaveh Edalati
04:45 Aug-03-2006
Re: API 1104 Manual UT
HI,
I CHECK AN API STANDARD 1104 (1994) )18TH EDITTON.
iT SAY THAT AN INDICATION SHOULD BE EXCEED THAN 20% OF REFERENCE LEVEL TO BE CONCIDERED RELEVANT. YOU SAID ndication must exceed 50% of DAC.
WHICH ONE IS CORRECT IN NEW API VERSION: 20% OR 50%?
REGARDS
kAVEH


----------- Start Original Message -----------
: : : : Can someone clarify the amplitude at which a signal would make an indication rejectable in accordance with API 1104 manual UT? Or does amplitude not play a factor, and the reference levels quoted are for detection and sizing only, and the indication length is the deciding factor regardless of amplitude?
: : : : Please provide some guidance and a reference if you have any.
: : : : Thanks in advance.
: : : An indication must exceed 50% of DAC/TCG to be considered relevant. Unless it is a crack, it can be considered nonrelevant if it is less than that. Once an indication exceeds 50% DAC/TCG then it is accepted or rejected based on length.
: : : API-1104 11.4.7.2.UT Acceptance standards and classificaitons of indications can be found in 9.6.1 & 9.6.2.
: : Thanks Ed. That is pretty much how our company is operating at this point, but I still don't see where cracks are exempted from the 50% DAC criteria. Where do you get this exemption from? I believe some additional verbage ALA, ASME Sec. 3 or 8, with the words, "that exceed XX% FSH" should be added to the 1104 evaluation and acceptance criteria.
: Look at API-1104 Par 9.6.2.1. It states, and I quote, "Indications determined to be cracks (C) shall be considered defects.
: Also look at 10.1.1. It states that Cracked welds shall be removed from the line unless a repair is permitted by 9.3.10 or authorized by the company. 9.3.10 addresses crater cracks. They are acceptable if they meet the size limits of 9.3.10.
: ASME someties allows cracks under certain conditions, but they dont use the word crack. They call it an indication and it is evaluated based on its Aspect Ratio. a/l or vertical height / length.
: ASME is a competely different code with different service conditions than a pipeline.
------------ End Original Message ------------




    
 
 Reply 
 
Ed,
Ed,
04:48 Aug-03-2006
Re: API 1104 Manual UT
----------- Start Original Message -----------
: HI,
: I CHECK AN API STANDARD 1104 (1994) )18TH EDITTON.
: iT SAY THAT AN INDICATION SHOULD BE EXCEED THAN 20% OF REFERENCE LEVEL TO BE CONCIDERED RELEVANT. YOU SAID ndication must exceed 50% of DAC.
: WHICH ONE IS CORRECT IN NEW API VERSION: 20% OR 50%?
: REGARDS
: kAVEH
------------------

I'm looking at the 19th Edition.


    
 
 Reply 
 
Martyn
Martyn
06:06 Aug-03-2006
Re: API 1104 Manual UT
Thanks again Ed. I understand the crack criteria, and the difference between ASME and API in their applicability to various equipment. I am still somewhat concerned about other types of indications though. It does not state in 11.4.7.2 that indications that exceed 50% of reference shall be considered relevant, only that, and I quote "All indications that exceed 50% of DAC/TCG screen height shall be evaluated"
This is where I think a statement such as (taken from ASME VIII)
"(b) Other imperfections are unacceptable if the indications exceed the reference level amplitude and have lengths which exceed:
(1) 1⁄4 in. (6 mm) for t up to 3⁄4 in. (19 mm);
(2) 1⁄3t for t from 3⁄4 in. to 21⁄4 in. (19 mm to 57 mm);
(3) 3⁄4 in. (19 mm) for t over 21⁄4 in. (57 mm)."

would be very beneficial to the API standard. Of course, the actual lengths and such from 9.6.2 would apply.

Oh, and by the way, ASME does indeed use the word "cracks" in its acceptance critera ;)
"(a) Indications characterized as [i]cracks,[/i] lack of fusion, or incomplete penetration are unacceptable regardless of length."

----------- Start Original Message -----------
: : : : Can someone clarify the amplitude at which a signal would make an indication rejectable in accordance with API 1104 manual UT? Or does amplitude not play a factor, and the reference levels quoted are for detection and sizing only, and the indication length is the deciding factor regardless of amplitude?
: : : : Please provide some guidance and a reference if you have any.
: : : : Thanks in advance.
: : : An indication must exceed 50% of DAC/TCG to be considered relevant. Unless it is a crack, it can be considered nonrelevant if it is less than that. Once an indication exceeds 50% DAC/TCG then it is accepted or rejected based on length.
: : : API-1104 11.4.7.2. UT Acceptance standards and classificaitons of indications can be found in 9.6.1 & 9.6.2.
: : Thanks Ed. That is pretty much how our company is operating at this point, but I still don't see where cracks are exempted from the 50% DAC criteria. Where do you get this exemption from? I believe some additional verbage ALA, ASME Sec. 3 or 8, with the words, "that exceed XX% FSH" should be added to the 1104 evaluation and acceptance criteria.
: Look at API-1104 Par 9.6.2.1. It states, and I quote, "Indications determined to be cracks (C) shall be considered defects.
: Also look at 10.1.1. It states that Cracked welds shall be removed from the line unless a repair is permitted by 9.3.10 or authorized by the company. 9.3.10 addresses crater cracks. They are acceptable if they meet the size limits of 9.3.10.
: ASME someties allows cracks under certain conditions, but they dont use the word crack. They call it an indication and it is evaluated based on its Aspect Ratio. a/l or vertical height / length.
: ASME is a competely different code with different service conditions than a pipeline.
------------ End Original Message ------------




    
 
 Reply 
 
J. Mark Davis
Teacher, And Consultant
University of Ultrasonics, Birmingham, Alabama, USA, Joined Mar 2000, 85

J. Mark Davis

Teacher, And Consultant
University of Ultrasonics, Birmingham, Alabama,
USA,
Joined Mar 2000
85
00:40 Aug-03-2006
Re: API 1104 Manual UT
I am currently writing Phased Array Procedures for API 1104, 19th Edition, Sep. 1999.

It states in Paragraph 9.6.2.1 "Indications determined to be crack (C) shall be considered defects".

If a crack is found it is rejectable; but maybe through Fracture Mechanic Analysis (FMC) it can be left in and monitored with crack growth analysis.

You will have to utilize Crack Sizing Methodolgy like Creeping Waves, Tip Diffraction, etc. to determine the crack defect to support FMC.

J. Mark Davis


----------- Start Original Message -----------
: : HI,
: : I CHECK AN API STANDARD 1104 (1994) )18TH EDITTON.
: : iT SAY THAT AN INDICATION SHOULD BE EXCEED THAN 20% OF REFERENCE LEVEL TO BE CONCIDERED RELEVANT. YOU SAID ndication must exceed 50% of DAC.
: : WHICH ONE IS CORRECT IN NEW API VERSION: 20% OR 50%?
: : REGARDS
: : kAVEH
: ------------------
: I'm looking at the 19th Edition.
------------ End Original Message ------------




    
 
 Reply 
 
David
David
02:25 Aug-04-2006
Re: API 1104 Manual UT
20th Edition - Definitions -Defect: An imperfection of sufficient magnitude to warrant rejection based on the stipulations of this standard.

9.6.1.5 - Relevant indications are those caused by imperfections. Relevant indications shall be evaluated at the evaluation levels given in 11.4.7 to the acceptance standards given in 9.6.2.

11.4.7.2 - Manual ultrasonic examination shall be performed at a scanning sensitivity of DAC/TCG plus 6dB minimum. All indications that exceed 50% of DAC/TCG height shall be evaluated.

9.6.2.1 - Indications shall be considered defects should any of the following conditions exist:
a. Indications determined to be cracks(C)
b. Individual indications with a vertical height (through wall) dimension determined to be greater than one quarter of the wall thickness.
c. Multiple indications etc.

Note the statement ...Relevant indications shall be evaluated at the evaluation levels given in 11.4.7....
Does this mean that you first use the 50% DAC criteria and ignore anything below? Definitions says ....based on the stipulations of this standard.
The stipulation is 50% DAC so any indications below this can be ignored????
It also states ......Indications shall be considered defects should any of the following conditions exist:
a. Indications determined to be cracks...
Indication is not referenced to DAC in definitions "evidence obtained by nondestructive testing" - so if you have evidence of a crack it is reject???????
Also in the linear indication acceptance standards they constantly state "....other than cracks..." So cracks are obviously a special case and should be rejected to 9.6.2.1 a.

That's my opinion anyway.


----------- Start Original Message -----------
: Yes I agree, but I don't think it is the intent of the code to ignore a crack because of its amplitude. If an indication is determined to be a crack it shall be removed from the line. In my opinion and experience, a "good" UT hand should be able to identify a crack even at low amplitudes. So I still say that all cracks, regardless of amplitude are defects and shall be removed.
:
: : : Can someone clarify the amplitude at which a signal would make an indication rejectable in accordance with API 1104 manual UT? Or does amplitude not play a factor, and the reference levels quoted are for detection and sizing only, and the indication length is the deciding factor regardless of amplitude?
: : : Please provide some guidance and a reference if you have any.
: : : Thanks in advance.
: : All indication that exceed 50% of DAC\TCG shall be evaluated and should be recored. Any indication that breaks evaluation level(ie: 100% DAC\TCG) and exceeds length for the that defect's classification in whole or part shall be rejected. Any indication that does not break evalution level but is 50% or greater in amplitude and exceeds classification length should be report to the company for accept or reject if not addressed in the procedure prior to inspection.
------------ End Original Message ------------




    
 
 Reply 
 
Ed Ginzel
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1268

Ed Ginzel

R & D, -
Materials Research Institute,
Canada,
Joined Nov 1998
1268
07:26 Aug-06-2006
Re: API 1104 Manual UT
I am not sure who has been posting replies in my name but I have not had adequate access to internet to participate in this thread until now.

The reply by David Davies is by far the best and most comprehensive so far. The manual UT acceptance criteria in API 1104 are based on "workmanship". Effectively this is from an old tradition (based on RT) of what a good welder can consistently weld.

One noteable exception to the rejection of cracks does exist in API 1104. Cracks in RT are permitted in API 1104, provided they are star or crater cracks with a "length" that does not exceed 4mm. UT is not likely to be able to discriminate a crater crack from surface geometry and if it is even a suspect crater crack it is clearly possible to see this on the surface as a visual flaw so the exercise reduces to one of visual follow-up of the manual UT response.

If it is kept in mind that the concept of a good workmanship UT criteria are mostly applicable to manual welding methods, then the discovery of a crack indicates some significant departure of the welder's welding pratice from proper welding procedure.

Although the wording of API, as noted by David Davies, suggests that no lower threshold exists for "crack" analysis, I would merely caution that jumping to the conclusion that the echo dynamics of a flaw are indicative of a crack when using very low amplitude resposes may risk an overcall (i.e. un-necessay rejection).

Ed

----------- Start Original Message -----------
: 20th Edition - Definitions -Defect: An imperfection of sufficient magnitude to warrant rejection based on the stipulations of this standard.
: 9.6.1.5 - Relevant indications are those caused by imperfections. Relevant indications shall be evaluated at the evaluation levels given in 11.4.7 to the acceptance standards given in 9.6.2.
: 11.4.7.2 - Manual ultrasonic examination shall be performed at a scanning sensitivity of DAC/TCG plus 6dB minimum. All indications that exceed 50% of DAC/TCG height shall be evaluated.
: 9.6.2.1 - Indications shall be considered defects should any of the following conditions exist:
: a. Indications determined to be cracks(C)
: b. Individual indications with a vertical height (through wall) dimension determined to be greater than one quarter of the wall thickness.
: c. Multiple indications etc.
: Note the statement ...Relevant indications shall be evaluated at the evaluation levels given in 11.4.7....
: Does this mean that you first use the 50% DAC criteria and ignore anything below? Definitions says ....based on the stipulations of this standard.
: The stipulation is 50% DAC so any indications below this can be ignored????
: It also states ......Indications shall be considered defects should any of the following conditions exist:
: a. Indications determined to be cracks...
: Indication is not referenced to DAC in definitions "evidence obtained by nondestructive testing" - so if you have evidence of a crack it is reject???????
: Also in the linear indication acceptance standards they constantly state "....other than cracks..." So cracks are obviously a special case and should be rejected to 9.6.2.1 a.
: That's my opinion anyway.
:
: : Yes I agree, but I don't think it is the intent of the code to ignore a crack because of its amplitude. If an indication is determined to be a crack it shall be removed from the line. In my opinion and experience, a "good" UT hand should be able to identify a crack even at low amplitudes. So I still say that all cracks, regardless of amplitude are defects and shall be removed.
: :
: : : : Can someone clarify the amplitude at which a signal would make an indication rejectable in accordance with API 1104 manual UT? Or does amplitude not play a factor, and the reference levels quoted are for detection and sizing only, and the indication length is the deciding factor regardless of amplitude?
: : : : Please provide some guidance and a reference if you have any.
: : : : Thanks in advance.
: : : All indication that exceed 50% of DAC\TCG shall be evaluated and should be recored. Any indication that breaks evaluation level(ie: 100% DAC\TCG) and exceeds length for the that defect's classification in whole or part shall be rejected. Any indication that does not break evalution level but is 50% or greater in amplitude and exceeds classification length should be report to the company for accept or reject if not addressed in the procedure prior to inspection.
------------ End Original Message ------------




    
 
 Reply 
 
Harry T. Blain
Harry T. Blain
17:46 Mar-01-2012
Re: API 1104 Manual UT
In Reply to Ed Ginzel at 07:26 Aug-06-2006 .

One thing I did not see addressed here is the specific wording of 11.4.7.2 that is "Evaluation sensitivity for manual ultrasonic weld testing should be DAC/TCG reference sensitivity plus 6 dB with an evaluation level for all indications at 50% of DAC/TCG screen height."
50% of DAC/TCG screen height with the instrument set at "DAC/TCG reference sensitivity plus 6 dB" would actually be 25% of the original reference level. That is the way it is worded whether it was their intent or not.

    
 
 Reply 
 

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