1.
GENERAL
This specification defines the quality and technical
requirements for governing automated ultrasonic testing (UT) of girth welds for
offshore pipelines. This specification
shall be used in conjunction with the following documents:
•
Design of Basis 84506-60-00-2L-060
•
General Specification
84506-60-00-2L-000 - Definitions and Specification Directory
•
General Specification
84506-60-00-2L-010 - Quality Assurance / Quality Control
•
General Specification 84506-60-00-2L-020
- General Offshore Specification
•
DNV OS-F101 Submarine Pipeline Systems
(2000)
2. GENERAL REQUIREMENTS
CONTRACTOR shall provide Automatic
Ultrasonic Testing (AUT) services for acceptance or rejection of production
pipeline welds. COMPANY may provide
their own NDT personnel, to monitor CONTRACTOR testing.
2.1 CONTRACTOR shall provide exclusive
stations on the laybarge for the AUT System including the scanner and
calibration fixtures used for testing the pipeline production welds.
2.2 CONTRACTOR shall locate the AUT
control/analysis station as close as possible to the AUT scanner station. The
AUT control/analysis station shall accommodate a COMPANY Representative for
monitoring the AUT testing and analysis activities.
2.3 CONTRACTOR shall provide dedicated
communications and closed circuit video between the AUT scanner station and the
AUT control/analysis station.
2.4 CONTRACTOR shall provide COMPANY approved
personnel for 24-hour per day testing on offshore pipelay spreads.
2.5 Other NDT services that may be required
include: manual UT, Liquid Penetrant
Testing (PT) and Magnetic Particle Testing (MT). contractor
shall provide the qualified and/or certified materials, equipment and personnel
to perform these services.
3. PERSONNEL QUALIFICATION
Operators engaged in AUT weld testing shall meet the minimum
requirements specified in the DNV OS-F101, Appendix E (operators) and Appendix D A602.
Qualification records on each individual AUT operator shall be submitted
to COMPANY, for approval 60 days prior to mobilization. CONTRACTOR shall not substitute UT operators
without prior approval of COMPANY. Personnel performing manual or semi
automatic NDT shall meet the requirements of DNV OS-F101 appendix D A601.
4. EQUIPMENT AND PROCEDURES
CONTRACTOR equipment and procedures for AUT testing of butt
welds shall meet the requirements of DNV OS-F101. These DNV rules are the governing standard
except where more stringent requirements are called for by this specification. CONTRACTOR equipment and procedures shall be
submitted for COMPANY approval 60 days prior to mobilization and shall meet the
DNV OS-F101, Appendix E. CONTRACTOR
procedures shall also specifically address the following:
•
Pipe material grade, diameter and wall
thickness
•
Welding process and joint geometry
4.1 CONTRACTOR
calibration standards shall be made from a section of project pipe of the same
diameter and wall thickness that will be tested. A new calibration standard shall be made for
each change in diameter and/or wall thickness.
4.2 CONTRACTOR
calibration standard reflectors and the AUT system sensitivity settings shall
be in accordance with the COMPANY-approved CONTRACTOR procedure.
4.3 CONTRACTOR
shall perform a calibration scan for the first one-hundred (100) production
pipeline welds. After the first one
hundred (100) consecutive successful calibration scans, the frequency may be
reduced to a minimum of one calibration scan for every five (5) welds. In any case, calibration intervals shall not
exceed one (1) hour. Additionally,
calibration scans shall be performed for the following:
•
After change of UT Operators
•
After every barge meal break
Should a calibration scan be determined unsuccessful in
accordance with the COMPANY approved CONTRACTOR procedure, the CONTRACTOR shall
retest all welds to the last documented successful calibration scan.
Records of each calibration shall be included sequentially
with the weld testing data in order to facilitate the investigation of
unsuccessful calibration scans.
4.4 CONTRACTOR
shall demonstrate for COMPANY approval, the accuracy and maximum error of the
AUT system in accordance with the DNV OS-F101, Appendix E. This demonstration shall be performed no
later than 60 days prior to mobilization.
The Company approved AUT system shall not be modified without COMPANY
approval.
4.5 CONTRACTOR
shall submit for COMPANY approval, an AUT equipment spare parts list, 60 days
prior to mobilization. The spare parts
list may be detailed in the CONTRACTOR’s AUT testing procedure.
4.6 CONTRACTOR
shall submit for COMPANY approval, the AUT equipment maintenance schedule,
including but not limited to, transducer wear measurements and signal-to-noise
values. The maintenance schedule may be
detailed in the CONTRACTOR’s AUT testing procedure.
4.7
The AUT reports and records, both
electronic and hard copy, shall be identified, filed and indexed in compliance
with a COMPANY-approved CONTRACTOR written procedure and stored in a secure
manner. Additionally, reports and
records shall meet the requirements of DNV OS-F101, Appendix E.
5. STANDARDS OF WELD ACCEPTABILITY
Production welds shall meet the acceptability requirements
of DNV OS-F101. COMPANY shall approve
all testing results, and in the event of difference in opinion regarding weld
acceptability, COMPANY decision shall be binding and final.
5.1 COMPANY
may elect to use an engineering critical assessment (ECA) standard for weld
flaw acceptance to DNV Rules based on the CTOD properties of the weld. This criteria may replace, in whole or in
part, the acceptability requirements in the DNV OS-F101.
5.2 Production
welds shall be visually inspected by CONTRACTOR, and by COMPANY as required,
and shall meet the requirements of DNV OS-F101, Appendix D.
5.3 Production
welds shall be subjected to one hundred percent (100%) examination by AUT. COMPANY shall approve the testing results.
5.4 COMPANY
may review AUT scan data of pipeline welds.
COMPANY shall reject any weld which, in its opinion, does not satisfy
the criteria of acceptability defined herein.
5.5 COMPANY
reserves the right to examine any weld by manual UT, and/or other techniques
where the automated UT testing results are suspect. COMPANY may require additional manual UT weld
testing to define weld defect characteristic.
The manual UT equipment and the UT Operator qualification shall meet the
requirements of DNV OS-F101, Appendix D.
Acceptability of weld shall be according to the standards of
acceptability defined herein.
5.6
COMPANY shall approve CONTRACTOR weld
repair procedures and no weld shall be repaired without prior COMPANY
approval. Repaired welds shall be
subject to full weld testing, inspection and acceptance requirements as for the
original weld.
6. RECORDS
The automated UT system records shall be identified,
indexed, maintained, accessed, distributed, filed, and stored in accordance
with a COMPANY approved CONTRACTOR procedure and DNV OS-F101, where
applicable. All data shal be submitted
to the COMPANY in both hard copy and electronic format.
7. SAFETY AND HEALTH REQUIREMENTS
CONTRACTOR shall be solely responsible for safety concerns
associated with production weld testing.
7.1 CONTRACTOR shall familiarize itself and
its workforce with any testing safety concerns and shall comply with the rules
and regulations of the COMPANY.