Richter & Tomasi Ltd., Brazil, Joined Jan 2008, 29
AWS D1.1 versus Phased Array
Are the Acceptance Criteria of the table 6.2 and 6.3 ( statically and ciclically loaded) applicable to an inspection performed by PA system using sectorial or linear scan? The PA probes normally don't attempt to the characteristics established by AWS D1.1;
Thanks for any reply.
R & D, -
Materials Research Institute, Canada, Joined Nov 1998, 1252
Re: AWS D1.1 versus Phased Array In Reply to Manfred Richter at 21:03 Sep-11-2009 (Opening).
As I read the AWS D1.1, the rules are written for manual UT using the equipment and procedures described in 6.20 and 6.22. Clearly these rules belong to the old traditional methods using monoelement probes and the many restrictions AWS has maintained over the past 4-5 decades. The acceptance criteria methods it uses are similarly based on the old conservative workmanship standards.
For some time now, in paragraph 6.20.2, provision has existed to deviate from these old and restrictive methods. 6.20.2 states "Variations in testing procedure, equipment and acceptance standards not included in Part F of Section 6 may be used with the approval of the Engineer."
Using phased-array techniques is already a deviation from Part F. The Equipment does not conform to the AWS "standard" expectations for manual equipment so the Engineer needs to approve its use. The next issue comes with how to anayse data. Phased-array data is not "initially" evaluated like the old manual UT using A-scans. Instead, a colour display is used from which the operator will identify areas of concern. In order that it be treated with consistancy for the range of inspection there SHOULD be a TCG used to assure the operator uses the same colour identification method for all flaws of concern. This means that (at least for the initial assessment) the AWS Rating method is not practical. The guidance in Appendix S COULD apply. Table S1 is "recommended" acceptance criteria for the methods that would use TCG...but the entire Appendix S is not considered part of AWS D1.1 and is provided only for information. Again, the table S1 is based on conservative workmanship criteria. Even so, its use would requrie Engineer approval.
Alternatively, a full engineering critical assessment could be run and other acceptance criteria submitted to the Engineer for approval.
It has been my experience however, that many engineers do not want to do the engineering. This requirement for the Engineer to "approve" all deviations from the old methods is perhaps the greatest impediment to advanced UT being used on AWS work. (IMHO)
Canada, Joined Jan 2009, 31
Re: AWS D1.1 versus Phased Array In Reply to Ed Ginzel at 00:52 Sep-12-2009 .
Perhaps a way around the the problem of trying to asses indications to the criteria specified in AWS D1.1 while at the same time performing a Phased Array examination as may be allowed in Clause 6.20.2, would be to conduct a Phased Array examination to an ASME like procedure and to measure the length based upon the PA data, but to manually rate the defects using a standard AWS D1.1 rating procedure. Final defect assessment would be based on data from both methods, and when the location of the defects to be rated are known, the actual time spent rating them would not be that much extra.
NDT Inspector, API-510, 570, 653
MISTRAS, USA, Joined Jan 2009, 148
Re: AWS D1.1 versus Phased Array In Reply to Stan at 16:12 Sep-14-2009 .
As usual, Mr. Ginzel has cut to the heart of the problem. One possible suggestion, though:
You can point out to the structural Engineer that manual UT per D1.1 compares flaws to a 0.060 inch calibration hole, and that you can perform your PA calibration using the same 0.060" holes to build your TCG curve. This will give better correlation of deeper flaws to the calibration standard, instead of "add 2 dB for each inch of soundpath". A multipoint calibration with at least one point closer and one point farther away than the 'area of interest' will always be a more accurate calibration than a single-point calibration.
Further, if you show the Engineer the color pictures that a C-scan scope like the Omniscan can capture, you should have a customer for life. Personally, I have gotten tired of the scepticism I get at the end of a manual examination exam. I have nothing to show the Engineer but a chart listing indications, locations, and ratings. Some believe me, some remain sceptical until they get reports back from their welder that the flaws really were where I said they were, and what I said they were. "One picture vs 100 words"
The picture and data file is especially valuable to prove later that the indications judged as 'Acceptable" were indeed within the Code standards. On Bridge work especially, there is a lot of resistance to accepting any known defects, even when well within the Code limits.
consultant, Canada, Joined Sep 2006, 829
Re: AWS D1.1 versus Phased Array In Reply to Roger Duwe at 20:52 Sep-15-2009 .
I do agree with you, but it is not only in the bridge industry that acceptable indication are rejected by the client. We have the same situation with some of our clients. After seeing a few accidents happening 40 - 50 years after construction, can we blame the engineers?
Ultrasonic Testing Immersion Tanks with Unmatched Scanning Features
TecScan’s non-destructive testing Ultrasonic Immersion Tanks &
scanners are designed for high pe
rformance and demanding NDT testing
applications. Our Scan3D™ line of High Precision Immersion Tanks are
specifically designed for automated ultrasonic testing of complex
composites parts used in aerospace and industrial applications.
Pulse thermography is a non-contact test method that is ideal for
the characterization of thin fil
ms and coatings or the detection
defects. With a remarquable short test time and a high detection
sensitivity, the Telops TESTD-PT is the perfect tool for non-
destructive testing. With such high frame rates, it is even
to investigate highly conductive or diffusive materials.
High Resolution Industrial CT System for Small/Medium Size Parts Inspection
The YXLON FF35 CT computed tomography system is designed to achieve extremely precise inspection res
ults for a wide range of applications. Available in a single or dual tube configuration, it is perfect for very small to medium size parts inspection in the automotive, electronics, aviation, and material science industries.
Exertus Dual 120
The Exertus Dual 120 Projector has the ability to accept Iridium 192
sources or Selenium 75 source
s. This projector incorporates design
safety features that make it flexible, compact and lightweight.
The Projector is lighter than most of its competitors. It
incorporates an improved source channel, based on a new helicoidal
design, which makes maintenance easier. The helicoidal design also
allows smoother movement of the source assembly inside the device,
making it easier for the operator and improving safety. The
Projector also has a unique safety feature not found in competitive
The source assembly locking mechanism is triggered by the source
holder capsule at the front of the source assembly, thereby always
assuring the operator that the source has returned to the
safe position. The Exertus Dual 120 is ISO3999:2004 compliant.