1. GENERAL
This specification defines minimum quality and technical
standards governing Non-Destructive Testing (NDT) during pipeline
installation. This specification is to
be used in conjunction with the following documents:
Note: This specification does not cover AUT of girth
welds. Specific requirements for AUT of girth welds are given in
84506-60-30-2L-440
•
Basis of Design
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 System (2000)
2. GENERAL NDT REQUIREMENTS
2.1
Contractor shall propose procedures and methods of NDT with due
regard to the conditions influencing the sensitivity of the methods. (Ref DNV
OS-F101 App D A300 ,A400)
2.2
Contractor shall provide third party inspection
services responsible for acceptance or rejection of all installation welding.
NDT of all installation welding shall be carried out to the requirements of DNV
OS F101 Section 9 A800 and App D.
2.3 CONTRACTOR
shall provide an exclusive workstation when on the laybarge for NDT inspection
of welds. More than one form of NDT may
be used.
2.4 Third
party NDT services shall include, but not limited to Visual Inspection (VI),
internal panoramic X-ray crawlers, external X-ray, Ultrasonic Testing (UT) Dye
Penetrant Inspection (DPI), and Magnetic Particle Inspection (MPI) including
all equipment, and a comprehensive spare parts inventory.
2.5 Third
party NDT services shall provide all the required personnel for 24-hour per day
inspection on offshore pipelay spreads.
2.6
For radiographic inspection, CONTRACTOR shall
furnish automatic film processing equipment to produce dry film for site
interpretation. COMPANY may also review
the radiographic inspection films of the pipe welds. If CONTRACTOR proposes a manual film processing
technique, in the event of automatic film processing failure, the manual
technique must be qualified prior to production.
2.7
Whenever
acceptance criteria for NDT are established by Engineering Critical Assessment
(ECA), the nondestructive testing method shall be by automatic ultrasonic
testing (AUT) in compliance with DNV OS-F101 and Company Specification for
Pipeline Automated Ultrasonic Weld NDT, 84506-60-30-2L-440.
2.8
Whenever Gas
Metal Arc Welding (GMAW) is employed and radiography is the primary NDT method,
a percentage of welds shall also be subject to ultrasonic testing. As a minimum the inspection frequency shall be
100 percent of the first 25 welds of each pipeline and 100 percent of one out
of every 20 welds thereafter. If a
defect is detected by UT and missed by RT, UT shall be conducted on the next
consecutive five (5) welds.
3. NON-DESTRUCTIVE TESTING PERSONNEL
3.1 All NDT
personnel shall be qualified to a minimum Level II proficiency in accordance
with DNV OS-F101, Appendix D, Section A600. Qualification papers on each
individual shall be submitted to COMPANY, for approval before the start of
welding.
4. EQUIPMENT AND PROCEDURES
All procedures used by CONTRACTOR for NDT and inspection
of welding shall equal or exceed those recommended in DNV OS-F101, Appendix D,
which shall be the governing standard except where more stringent requirements
are called for by this specification.
All procedures shall be submitted for COMPANY approval 60 days prior to
mobilisation and be qualified at least 30 days prior to mobilisation.
4.1 Approval
of intensifying screens shall be subject to satisfactory radiographic
qualification.
4.2 With
X-ray radiography, the film shall be fine grain, high contrast direct type and
preferably be used with lead screens.
4.3 CONTRACTOR
shall store all unexposed film in a clean and dry place where surrounding
conditions will not deteriorate the emulsion. If unexposed film condition is
questionable, sheets from the front and back of each package, or a length equal
to the circumference of each original roll, shall be processed in the normal
manner without exposure to light or radiation.
If processed film shows fog, the entire package or roll from which the
test film was removed shall be discarded unless CONTRACTOR takes additional
test film that proves the remaining film in the package or roll is free from
pre-exposed fog.
4.4 ISO wire
penetrameters shall be used with penetrameter placement in accordance with DNV
OS-F101, Appendix D, Section B200.
4.5 For
double wall single view radiography, at least four exposures separated by
ninety degrees (90o) shall be made for the radiographic inspection
of a complete weld.
4.6 A number
belt with numbers at 1-cm intervals shall be used to assure complete coverage.
4.7 The
following equipment shall be in the viewing area:
•
Densitometer with certified
density strip
•
Film viewer capable of
exposing densities up to 4.0 H&D
•
Magnifying glass (x 10
magnification)
•
Applicable code(s) for
inspecting the work
4.8 All
relevant job radiographs and reports shall be identified, filed and indexed in
compliance with a written procedure and stored in a lockable, fire resistant
cabinet or room.
5. RADIOGRAPHIC QUALITY
5.1 Exposed radiographs are to have an average H&D density at
the sound weld metal image of minimum 2,0.The maximum density allowed is to be
not more than 3,5
5.2 All films
shall be interpreted by CONTRACTOR appointed Level III or Level II
radiographers to the acceptance criteria in DNV OS-F101, Appendix D, Section H,
immediately after developing of each film is completed, and with the aid of a
high intensity viewing screen light. All
defects not meeting or questionably meeting standards of acceptability shall be
recorded and promptly brought to COMPANY attention by the radiographer. Acceptance or rejection of any defective weld
shall initially be made by CONTRACTOR’s appointed person.
5.3 COMPANY
shall specify approve the film identification system, prior to mobilization.
5.4 CONTRACTOR
shall furnish COMPANY a daily written record of inspected welds, at the end of
each day. The record shall include:
•
Number of welds inspected,
whether or not welds meet specified acceptance standards.
•
Number and approximate
location of unacceptable defects observed.
•
Start and finish times for
each joint.
5.5 All film
shall be capable of maintaining their quality as per requirements of DNV
OS-F101, Appendix D, Section B210.
5.6
All radiographs produced or digitally copped in
an approved manner shall be delivered to COMPANY at the end of job, and shall
become COMPANY property.
All NDT reports shall be
submitted to the company in both hard copy and electronic format.
6. STANDARDS OF WELD ACCEPTABILITY
Welds shall meet the requirements of DNV OS-F101,
Appendix D, Section H. COMPANY shall
approve all examination results, and in the event of difference in opinion
regarding weld acceptability, COMPANY decision shall be binding and final.
6.1 Repair
or Removal of Welding Defects: COMPANY shall approve weld repair
procedures. No weld shall be repaired
without prior COMPANY approval and then only as directed by COMPANY. Repaired welds shall be subject to the same
testing and inspection requirements as the original weld.
6.2 Examination:
All production welds shall be visually inspected by CONTRACTOR, and by COMPANY
as required, and shall meet the requirements of DNV OS-F101, Appendix D, Table
D-3 and requirements of 84506-60-30-2L-330.
6.3 All
pipeline welds shall be subjected to one hundred percent (100%) NDT
examination. COMPANY shall approve
examination results.
6.4 COMPANY
may review radiographic films of pipeline welds. COMPANY shall reject any weld which, in its
opinion, does not satisfy the criteria of acceptability defined herein, or
lacks proper workmanship.
6.5 COMPANY
reserves the right to examine request further NDT of any weld by RT,UT, DPI or
MPI techniques where radiographic original examination results are deemed
suspect. COMPANY may require additional
UT weld inspection to define weld defect height. Equipment calibration, operator
qualifications, and definition of acceptability shall be referenced to the DNV
OS-F101, Appendix D.
6.6 Inspection
of Weld Repairs: Repaired welds, made by grinding and welding, shall be subject
to visual and non-destructive examination, in strict accordance with the
preceding Sections.
6.7 CONTRACTOR
shall re-NDT all weld repairs, and the examination shall cover the repair area
and a minimum additional 50-mm each end of the repair area.
6.8
Additional UT and / or MPI may be required, when
radiographic examination results are suspect and / or to determine defect depth
and size.
6.9 Records of non-destructive testing, including X-ray film, shall be filed to comply with sequential weld completion, and shall be available for COMPANY review upon request during construction. Upon Work completion, CONTRACTOR shall submit all records to COMPANY for permanent retention, as specified in the Contract Documents. All records shall be clearly identified and traceable to the physical weld.
All data records will be supplied in
a hard copy and electronic format
7. SAFETY AND HEALTH REQUIREMENTS
CONTRACTOR shall be solely responsible for safety
concerns associated with radioactive materials or methods used for weld
inspection. CONTRACTOR radiographers
assigned to each field unit shall protect and monitor each person working with,
or in the vicinity of, the radiation source.
Protection and monitoring shall be in compliance with the rules and
regulations set forth by the AUTHORITIES.
Each radiographer shall have a film badge and / or pocket ionization
chamber, with all inspection equipment retained by CONTRACTOR and made available
to COMPANY upon request.
7.1 CONTRACTOR
shall familiarize itself and its workforce, and shall comply with the rules and
regulations of the AUTHORITIES having jurisdiction over the handling, storage
and use of radioactive materials. This
shall include safety of its personnel and the public, posting of required
notices in radioactive areas and any other condition arising from CONTRACTOR
handling and / or use of radioactive materials.
CONTRACTOR shall collect, store, transport and dispose of
all used developing chemicals so as to avoid release to the environment.