FIFTH CANADIAN CONFERENCE ON NONDESTRUCTIVE ... - IAEA

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THE INTRODUCTION OF REAL-TIME RADIOGRAPHY FOR THE INSPECTION OF
BUTT WELDS IN OFFSHORE PIPELINES
T.E. Re.ynold& In.
Bfiown S Root Inc.
Houston, Texas, U.S.A.
This paper was presented at the 16th Annual OTC in Houston, Texas, May 7-9,
1984. The material is subject to correction by the author. Printed with
permission of the Offshore Technology Conference.
1. ABSTRACT
Real time radiography may significantly reduce the costs and efforts, improve
the reliability, and eliminate some subjectivity arising from the conventional
film radiographie inspection of butt welds in offshore pipeline
production. This paper describes this state of the art technology and discusses
its introduction to the production line of traditional pipe laying
barges.
2. INTRODUCTION
Traditional offshore pipeline installation operations involve an assembly
line process. Welding, inspecting, and coating the pipe occur simultaneously
along the assembly line. New weld methods and pipe handling systems are
being developed to speed this fabrication operation. In order to avoid
having the inspection station become the slowest, and thereby the controlling
station in the timing of this process, quicker inspection techniques must be
developed. Because conventional film radiography is currently being pushed
to its limits, other inspection methods were investigated. Furthermore, the
current mood among pipeline contractors' clients is to remain with radiography
and not stray into other non-destructive examination techniques such
as ultrasonics.
Real time radiography provides the required speed of inspection and helps
solve the problem of subjectivity in interpretation. This paper is the
result of efforts to bring a real time radiographie system to field testing
on a pipe laying vessel. Potential manufacturers of these systems were
contacted and encouraged to pursue development of this technology. Field
testing is to be conducted once successful prototype demonstrations have been
completed. This paper attempts to define the considerations to be made in
real time radiography systems by describing the function of the systems and
mentioning current applications of them. The current status of various codes
governing pipeline inspection is reviewed with respect to their acceptance of
real time radiography as a viable inspection method.
Interpretation of radiographs can be a subjective art. Disputes arise among
the three parties whose concern is weld quality: the client, the contractor,
and the inspector. Limiting the range of interpretability of radiographs is