team china lift 1 concerns - alta vista...

9/21/2009

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Team ChinaLift 1 Concerns

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September 22, 2009

VTAcceptableSec. 6.26.1,

AWS D1 5

Indication Defect CrackRejectable per Code

Verify by visual means

NDT Required

Defect

Acceptable

RT

AWS D1.5Repair

Defect

AcceptableSec. 6.26.2, AWS D1.5

RepairMT

SPs,Sec. 8-3

SPs,10-1.59

2

Requires Further

Evaluation

Defect Repair

UT Sec. 6.26.3, AWS D1.5

Table 6.3,AWS D1.5

Table 6.4,AWS D1.5

9/21/2009

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AWS D1 5



NDT Required

Defect

Acceptable

RT

AWS D1.5Repair

Defect


RepairMT

SPs,Sec. 8-3

SPs,10-1.59

3

Requires Further

Evaluation

Defect Repair

UT Sec. 6.26.3, AWS D1.5

Table 6.3,AWS D1.5

Table 6.4,AWS D1.5

For any welding, the Engineer may perform or direct the Contractor to perform NDT that is in addition to the visual inspection or NDT specified in the AWS welding codes, in the Standard Specifications, or in these special provisions to verify that the welds are free of

Special Provisions,Section 8-3.01 Welding

Potential issues that may affect Engineer’s decision to go down this path:

Should any welding defects be discovered by this additional NDT, all costs associated with the repair of the deficient area, including NDT of the weld repair and any delays caused by the repair shall be at the

provisions to verify that the welds are free of defects as defined by the AWS codes specified in this contract.

g p

• Unqualified Welders• Unapproved Welding

Procedures• Unusual NDT results• Defects observed during in-

process checks

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caused by the repair shall be at the Contractor’s expense.

9/21/2009

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AWS D1 5



NDT Required

Defect

Acceptable

RT

AWS D1.5Repair

Defect


RepairMT

SPs,Sec. 8-3

SPs,10-1.59

5

Requires Further

Evaluation

Defect Repair

UT Sec. 6.26.3, AWS D1.5

Table 6.3,AWS D1.5

Table 6.4,AWS D1.5

The extent of non-destructive examination is specified below, unless specified elsewhere in these special provisions.

All welds shall receive 100% visual inspection.

SPs, Sec. 10-1.59 Steel Structures, Inspection and

Testing, Pg. 330

Contract Requirements

Transverse splice welds 5% RT 100% UT

NDT Tables specify amount of NDT testing required for each weld type.

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9/21/2009

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AWS D1 5



NDT Required

Defect

Acceptable

RT / MT

AWS D1.5Repair

Defect


Repair

7

Requires Further

Evaluation

Defect Repair

UT Sec. 6.26.3, AWS D1.5

Table 6.3,AWS D1.5

Table 6.4,AWS D1.5


Testing, Pg. 330

SPs, Sec. 10-1.59 Steel Structures, Shop Welding, Pg. 325


Except as specified herein, welding, welder qualifications, and inspection of welding work shall conform to the requirements of AWS D1.5

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9/21/2009

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AWS D1 5



NDT Required

Defect

Acceptable

RT / MT

AWS D1.5Repair

Defect


Repair

9

Requires Further

Evaluation

Defect Repair

UT Sec. 6.26.3, AWS D1.5

Table 6.3,AWS D1.5

Table 6.4,AWS D1.5

6.26.3 UT6.26.3.1 Welds that are subject to UT

in addition to visual inspection shall be acceptable if they meet the following


Testing, Pg. 330



requirements:(1) Welds subject to tensile stress

under any condition of loading shall conform to the requirements of Table 6.3.

(2) Welds subject to compressive stress shall conform to the requirements of Table 6.4.

AWS D1.5-02, Sec. 6.26.3 UT, Pg. 151

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9/21/2009

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AWS D1 5



NDT Required

Defect

Acceptable

RT / MT

AWS D1.5Repair

Defect


Repair

11

Requires Further

Evaluation

Defect Repair

UT Sec. 6.26.3, AWS D1.5

Table 6.3,AWS D1.5

Table 6.4,AWS D1.5


Testing, Pg. 330



AWS D1.5-02, Sec. 6.26.3 UT, Pg. 151


Testing, Acceptance, Pg. 333

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For purposes of acceptance, all CJP welds shall be considered to sustain tension, except for those otherwise shown on the plans.

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Testing, Pg. 330



AWS D1.5-02, Sec. 6.26.3 UT, Pg. 151



Contract Plans General Notes No 4

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Contract Plans, General Notes No. 4, Sheet 426 of 1204

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AWS D1 5



NDT Required

Defect

Acceptable

RT / MT

AWS D1.5Repair

Defect


Repair

15

Requires Further

Evaluation

Defect Repair

UT Sec. 6.26.3, AWS D1.5

Table 6.3,AWS D1.5

Table 6.4,AWS D1.5

20mm

70 °

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• For indications that remain on the display as the search unit is moved, see 6.26.3.2

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Testing, Pg. 330



(1) Indications of discontinuities that remain on the screen as the search unit is moved towards and away from the

AWS D1.5-02, Sec. 6.26.3 UT, Pg. 151




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is moved towards and away from the discontinuity … may be indicative of planar discontinuities with significant flaw height dimension.AWS D1.5-02, Table 6.3,

Pg. 144


AWS D1.5-02,Sec. 6.26.3.2, Pg. 151

Contract RequirementsSPs, Sec. 10-1.59 Steel

Structures, Inspection and Testing, Pg. 330


AWS D1.5-02, Sec. 6.26.3 UT, Pg. 151

(3) When indications that exhibit these




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( )planar characteristics are present … a more detailed evaluation of the discontinuity by other means may be required (e.g., alternate UT techniques, RT, grinding, or gouging for visual inspection, etc.).

AWS D1.5-02, Table 6.3, Pg. 144


AWS D1.5-02,Sec. 6.26.3.2, Pg. 151

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AWS D1 5



NDT Required

Defect

Acceptable

RT / MT

AWS D1.5Repair

Defect


Repair

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May Require Further

Evaluation

Defect Repair

UT Sec. 6.26.3, AWS D1.5

Table 6.3,AWS D1.5

Table 6.4,AWS D1.5

• How do we move forward with the cracks in the Lift 1OBG Segment Splices?

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9/21/2009

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Possible Path Forwardto be Agreed Upon JointlyRemove, repair, and re-weld Lift 1 segment splices

Change fabrication process by implementing recommended fabrication improvements

Jointly agree on UT procedure w/ ABFgoing forward with Lift 2 and future segments

What do we do with Lifts 3 and 4?• Option 1: Recommend ABF assure the Department that Lifts 3 - 4

do not have similar defects

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do not have similar defects• Option 2: Pick a representative portion and re-examine by agreed

upon acceptance criteria• Option 3: Do nothing

From an engineering perspective, Team China recommends Option 2

Sequence of Events

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9/21/2009

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Meeting with ABF, August 19, 2009

Sequence of Events

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Meeting with ABF – August 19, 2009

Discussion of transverse defects

CT inquired about Lift 1 Segment Splice incident

McQuaid suggested ABF/CT corroborate on approach to identify potential defectsPerpendicular DeviationAlternate scanning patternsGrinding weld surfaces flush / Scanning Pattern D

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ABF / CT Joint

Sequence of Events

Investigation

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August 25 Joint Investigation of Lift 1 Transverse Splices

• ABF and CT identified transverse indications at transverse segment splices using a 70 ° transducer

• ABF performed a “more detailed evaluation of the discontinuity” with a 45 and 60 degree transducer

• Verbal agreement made by ABF and CT to excavate areas of concern

• ZPMC removed areas of concern without notification / or presence by ABF or CT

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9/21/2009

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ABF / CT Joint

Sequence of Events

Investigation

Incident Report #754

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UT indications later identified as Cracks by grinding

• QC discovered rejectable UT indication

• During repair of Class A defect, two additional UT indications were found to be cracks

• After QC acceptance of backgouged area, QA performed a routine MT inspection the backgouge

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9/21/2009

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UT indications later identified as Cracks

• QC discovered rejectable UT indication

• After QC acceptance of backgouged area, QA performed a routine MT inspection of backgouged

• Two transverse cracks were visually discovered after QC acceptance

• Cracks were identified by UT but not

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• Cracks were identified by UT but not rejectable per the code


ABF / CT Joint

Sequence of Events

Investigation

Inspection Request No 004185


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ZPMC requests “Green Tag” inspection of OBG Lift 1E Segment Splices on 9/7/09

No. 004185

9/21/2009

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“Caltrans Quality Assurance Inspector (QA) disco ered nineteen (19) class “A” rejectable


ABF / CT Joint

Sequence of Events

discovered nineteen (19) class “A” rejectable Transverse Linear Indications…”Investigation



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No. 004185

70 °

14 db more than required to be rejectable per the code

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9/21/2009

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ABF / CT Joint

Sequence of Events

“The indications exhibited planar characteristics with significant flaw height dimension as the search unit was moved toward and away from the indications and were not detectable during scanning patterns parallel to the weld axis.”

Investigation



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No. 004185

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• For indications that remain on the display as the search unit is moved, see 6.26.3.2

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ABF / CT Joint

Sequence of Events

Investigation



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(3) When indications that exhibit these planar characteristics are present… a more detailed evaluation of the discontinuity by other means may be required …

No. 004185

Additional transverse indications have also been detected in the welds that do not exceed the threshold of the code for rejection, but are characteristic of crack indications nonetheless.


ABF / CT Joint

Sequence of Events

The Department would like to collaborate with ABF to jointly examine and confirm that these welds do not contain cracks.

“Please provide grinders to excavate portions of the welds … as directed by the Engineer”

Investigation



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No. 004185

Team China Letter #28

9/21/2009

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Additional Events

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ABF / CT Joint

Sequence of Events

CT inspectors identify portions of the weld for the Contractor to excavate and grind.

Investigation



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No. 004185


Incident Report

9/21/2009

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September 15, 2009• After CT Inspectors identified portions of the

weld, ZPMC personnel began gouging out the area from underneath the weld.

• CT Inspectors observe linear defects in the


ABF / CT Joint

Sequence of Events

• CT Inspectors observe linear defects in the gouged area

• Department’s technical staff believe defects in pictures are cracks and not “fusion type defects” suggested by ABF

Investigation



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Crack. A fracture type discontinuity characterized by a sharp tip and high ratio of length and width to opening displacement. See Figure 33.

No. 004185


Incident Report


ABF / CT Joint

Sequence of Events

Investigation



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No. 004185


Incident Report

6.26.1.1 The weld shall have no cracks.

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Two Issues• How do we move forward with the cracks in

the Lift 1OBG Segment Splices?• How do we jointly address the cause that

got us here?

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Talking Points1. Lift 1 segment splices require a more detailed examination2. Team China believes there are cracks in the Lift 1 Segment splices3. The current QC/QA inspection process is not adequate to find such

cracks4 There are cracks in other fabrication work; however the current4. There are cracks in other fabrication work; however, the current

QC/QA inspection process is finding these cracks5. The Department should not re-inspect material that has been “green-

tagged” 6. If concerns are identified with “green-tagged” material, they should

be communicated to ABF and only the “repaired areas” verified by CT QA

7 The Contractor’s QC inspection process is not identifying all of the

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7. The Contractor s QC inspection process is not identifying all of the current issues

8. The labor subcontractors are not uniformly implementing recommended fabrication improvements

9. If recommended fabrication improvements are not implemented by each labor subcontractor, then Team China recommends a temporary suspension of those operations

9/21/2009

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Technical Material

• 45 Degree Transducer infoDeviation from perpendicular diagramMagnitude of UT readings in Seg SpliceScanning Patterns

• Commentary2008 Commentary

• Team China Letter #20

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Sound Path and Defect Detection

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9/21/2009

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45 °As high as 12 db more than required to be rejectable per the most lenient criteria in the code

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AWS D1.5 2008 Section C6.26.3.2

Discontinuities that may lead to failure are reliably detected by the prescribed scanning procedures buy may not accurately be identified as rejectable.

When a defect is normal to the surface of the joint and completely surrounded by sound metal, there is a likelihood that it will be difficult to detect. Almost all of the sound may be reflected away with essentially non reflected back to the transducer.

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If there are indications of flaw height, regardless of amplitude, a crack may be present and soundness should be verified by other wedge angles and locations or alternate inspection methods or tests.


“increased incidence of cracks and relevant MT indications found by the Department’s QA METS inspectors on welds previously inspected and approved … by … QC”

• OBG: 63 Missed MT Indication since May 30, 2009• Tower: 22 Missed Indication by QC since April 15, 2009

4848

“Please investigate why these indications have gone undetected during the Magnetic Particle Inspection Procedure, and provide the Department of your findings.”

team china lift 1 concerns - alta vista...

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