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Evaluation
of Ultrasonic Inspection Techniques for the Root Region of
Girth Welds
| Category: |
Materials
|
| Project Number: |
PR-220-9123 |
| Catalog Number: |
L51734 |
| eBook Version Available:
|
Yes, L51734e
|
| Publication Date: |
January 01, 1996 |
| Author(s): |
van der Ent, J.; Dijkstra,
F.H. |
| Research Agency: |
RTD Quality Services (Rontgen
Technische Dienst bv) |
| Pages: |
523 |
| Binding Type: |
GBC |
| Software Included: |
Yes |
| System Requirements: |
32MB RAM, 10MBHD, Pentium
PC, Windows 95/98/NT |
 Click
here to view Table of Contents
Abstract:
Need: A system for mechanized ultrasonic inspection of girth
welds during pipeline construction, the RTD Rotoscan, has
already been available for almost twenty years. In fact, its
development started back in the seventies, after initial trials
going as far back as the fifties. First commercial use started
in the beginning of the eighties. Today, RTD Rotoscans are
being used all over the world whereby, for a number of pipeline
projects, it replaces radiography as a sole girth weld inspection
technique. It has been known for many years, that the main
difficulty in mechanized ultrasonic inspection of pipeline
girth welds is in a reliable inspection of the root region.
On one hand, the possibility exists that serious planar defects
are over-looked (missed defects) because they are interpreted
as geometry signals, on the other hand geometrical echoes
(caused by e.g. hi-lo) can easily give rise to interpretation
as defect signals false calls). This difficulty is mainly
caused by the fact that defect signals and geometry echoes
are received with only very small differences in transit distance,
and thus are difficult to separate by means of a gating system.
Benefit: This project was initiated to evaluate
the performance of the existing system(s) / method(s) and
the improvements contemplated. It was decided to build the
project around a number and variety of representative test
welds. These were inspected with Rotoscan 1990, also using
improvements and radiography, and then destructively tested
for correlation with the NDE results. This document reports
improvements to the RTD mechanized ultrasonic inspection
system for pipeline girth welds. Describes how the addition
to the ROTOSCAN 1990 system of ROTOMAP AND ROTOTOFD have
led to improvements in the accuracy of the inspection of
the girth welds in the root region.
Result: The work done within this project
shows, that by proper implementation of improvements such
as Rotomap and RotoTOFD (here still used in early prototype
versions) the initial drawbacks of mechanized ultrasonic
inspection in the root can be overcome. Together with the
technology and experience that form the basis for the existing
Rotoscan 1990, mechanized ultrasonic inspection of pipeline
girth welds can now be considered as a mature technique,
capable of replacing radiography in many cases.
Price: $1,495.00
L51734
is included in the Ultrasonic
Pipeline Reports Compendium
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