Demonstration of Pulsed X-ray Machine Radiography

“Demonstration of Pulsed X-ray Machine Radiography
as an Alternative to Industry Radiography Cameras,
Demonstration Pilot Project”



Draft Final Report
SwRI® Project 14.12444




Prepared for

U. S. Environmental Protection Agency
Radiation Protection Division
1200 Pennsylvania Avenue, N.W.
Mail Drop: 6608J
Washington, DC 20460






Prepared by

Sensor Systems and NDE Technology Department
Applied Physics Division
Southwest Research Institute®
6220 Culebra Road
San Antonio, Texas 78238




November 2006


SOUTHWEST RESEARCH INSTITUTE
SAN ANTONIO
HOUSTON
DETROIT
WASHINGTON, DC

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TABLE OF CONTENTS

PAGE

1. BACKGROUND ........................................................................................................................ 1

2. TECHNICAL APPROACH........................................................................................................ 2

3. SCOPE OF WORK..................................................................................................................... 3

3.1
Isotopic Source and Pulsed X-ray Source....................................................................... 3
3.2 Work
Conducted ............................................................................................................. 4
3.3 Discussion ....................................................................................................................... 6
3.4
Impact to End-Users ..................................................................................................... 21

4. COMMERCIALIZATION PLAN............................................................................................ 22

5. CONCLUSIONS....................................................................................................................... 23

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LIST OF FIGURES

FIGURE PAGE


1
Illustration of double-sided pipeline radiography used to inspect pipeline welds........ 2

2
Photograph of a gamma ray camera.............................................................................. 3

3
Specifications for XRS-3 Pulsed X-ray Source ............................................................ 4

4
Illustration of source size and film/detector set used for the isotopic and pulsed
x-ray sources ................................................................................................................. 6

5
Photographs of portions of each pipe size showing some types of defects generated
in the welds ................................................................................................................... 7

6
Photograph showing isotopic source being used to take single-wall radiographs........ 7

7
Photograph showing isotopic source used for double wall radiographs....................... 8

8
Pulsed x-ray source with Vidisco real-time imaging used for double wall
radiographs.................................................................................................................... 8

9
Single wall isotopic radiograph on 16-inch-diameter pipe ........................................... 9

10
Double wall isotopic radiograph on 16-inch-diameter pipe ....................................... 15

11
Composite real-time images obtained using the XRS-3 pulsed x-ray source and
the Vidisco imaging system ........................................................................................ 15

12
Digital image on pipe showing six detectable wires on the IQI ................................. 19

13
Illustration of defects reported in the 4-inch-diameter pipe weld for both isotopic
and pulsed x-ray radiography...................................................................................... 19

14
Illustration of defects reported in the 6-inch-diameter pipe weld for both isotopic
and pulsed x-ray radiography...................................................................................... 20

15
Illustration of defects reported in the 10-inch-diameter pipe weld for both isotopic
and pulsed x-ray radiography...................................................................................... 20

16
Photograph of isotopic source on pipe during radiography ........................................ 21


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1. BACKGROUND
The Radiation Protection Division of the Environmental Protection Agency (EPA) is dedicated
to minimizing incidences of lost radioactive sources that enter into consumer metal supplies and
the public domain. Industrial devices and consumer products containing radioactive sources
routinely fall out of regulatory control. Once out of regulatory control, these devices and
products may be subjected to harsh conditions capable of producing a breached source, with the
potential of harmful exposure incidents and significant economic impacts to industry.
Providing alternative technologies for devices and products which utilize radioactive sources is
one approach to minimize lost source incidences. The current focus of EPA’s efforts in this
regard is to conduct those studies and assessments necessary to support the implementation of
such alternative technologies in industrial practices – alternatives that are technologically and
economically advantageous.
The approach suggested by Southwest Research Institute® (SwRI®) is to identify an industrial
sector that routinely uses isotopic radiation sources and to demonstrate that an alternative
technology to isotopic sources can provide equivalent capability. One industrial sector that
regularly uses isotopic sources to perform radiography of pipeline welds is the pipeline industry.
The industry uses Co60, Cs137, and Ir192 which have gamma ray energy lines of 1.17 and
1.33 MeV, 0.66 MeV, and 0.31, 0.47, and 0.60 MeV. Ir192 is perhaps the most often used source
for pipeline welds because the pipe wall thicknesses usually range between 0.25 and 0.4 inches.
Ir192 has a half life of 74.3 days. Sources are usually purchased with an activity of
approximately 100 curies. The radiography conducted is usually double wall for detecting
cracks, inclusions, and porosity in the welds as illustrated in Figure 1. To verify the quality of the
radiography, the code that regulates the radiographic inspection usually calls for a
“penetrameter” or “image quality indicator (IQI)” and the image sensitivity required. In these
radiographs an IQI was used, and the quality requirement was that all the wires had to be
detected.
1

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Gamma
Rays
Film
Isotopic
Isotopic
Gamma-ray
Source

Figure 1. Illustration of double-sided pipeline radiography used to inspect pipeline welds
Isotopic radiography has been used for many years. The advantages of isotopic radiography
include portability, no need for electricity, no requirement for source cooling, and high energy.
The disadvantages of isotopic sources are the regulatory requirements, need for two licensed
radiographers to conduct the work, and the potential for mishandling/loosing radioactive source
material.
An alternative approach might be to use pulsed x-ray sources. These sources are now capable of
peak beam energies close to 300 KVP with sufficient intensity output to be used for radiography
of welds.
2. TECHNICAL APPROACH
The goal of this project was to demonstrate a radiography technology for inspection of pipe
welds that does not require the use of isotopic sources. The technical approach to be followed
included (1) developing procedures for inspection of schedule 40 pipe in the range of 3 to 16
inches in diameter, (2) producing radiographs with both an Ir192 source and a pulsed, battery
operated, portable x-ray source with a peak x-ray energy of 270 kV and (3) comparing the results
obtained as well as the operational issues associated with using the x-ray source compared to the
isotopic source.
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3. SCOPE OF WORK
The following sections describe the scope of work that was conducted to demonstrate the
feasibility of pulsed x-ray source technology.
3.1 Isotopic Source and Pulsed X-ray Source

Isotopic sources (called “pills”) are very small, often on the order of approximately ¼ inch
diameter by ¾ inch long. The pill is usually contained in a shielded housing usually called a
“camera.” Although these sources are highly regulated, because they are so small they can easily
be inadvertently or intentionally removed from the regulatory information stream.

Isotopic source technology has a number of advantages over existing large x-ray sources.
For example, the source technology employees a very compact geometrical envelop and does not
require any electrical power. Conventional x-ray sources, on the other hand, require 220V power
and room for a cooling system (often water based). In addition, Ir192 provides very good
radiographs, and this source has been used for many decades so that the knowledge base on its
use is well accepted.

However, recent advancements have been made in pulsed x-ray sources that operate using
14.4-volt battery power and have a geometrical envelop similar to the isotopic source shielded
housing. For example, a common isotopic source is shown in Figure 2 and the XRS-3 is shown
in Figure 3.
Camera
Guide tube
Drive Cable
Camera
Guide tube
Drive Cable
wi
w th
t Coll
h
imator
Coll
Crank Out

Figure 2. Photograph of a gamma ray camera

3

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Figure 3. Specifications for XRS-3 Pulsed X-ray Source

The camera is approximately 15 inches in diameter by 4 inches wide and weighs
approximately 40 lbs. This camera holds the isotopic source. It is connected to a drive cable that
allows the isotopic source to be cranked out of the camera into a collimator placed on the pipe.
The collimator is approximately 1 inch in diameter and 1½ inches long. The conventional
300-KVP x-ray unit is approximately 36 inches long, 14 inches in diameter, and weighs
approximately 100 lbs. In addition, a cooler is needed, which is an additional box. The XRS-3 is
14 inches by 4.5 inches by 7.5 inches and weighs 12 lbs. The specifications for the XRS-3 are
also provided in Figure 3. Since it is a pulsed source, it does not require a coolant system.
However, the pulsed x-ray source must be used with a real-time imaging plate. The real question
is “will a pipe inspection company be willing to utilize this technology for actual inspection
work?”
3.2 Work
Conducted

Procedures for both the isotopic and x-ray inspection techniques were developed and
formalized. The procedures developed for each pipe size for double wall isotopic radiography are
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in Appendix 1. The procedures for double wall pulsed x-ray radiography are contained in
Appendix 2.

Approximately five pipe samples were used in this project (shown in Table 1).
Table 1.
Pipes Used for Pilot Demonstration
NOMINAL
PIPE
PIPE
WALL
PIPE
DIAMETER
THICKNESS
LENGTH
LOCATION OF WELD
(inch)
(inch)
(inch)
AND TYPES OF DEFECTS
Weld located mid-length, lack of
4 0.225
24
penetration, porosity
Weld located mid-length, lack of
6 0.200
24
penetration, porosity
Weld located mid-length, lack of
10 0.250
24
penetration, porosity, lack of fusion
Weld located mid-length, lack of
14 0.350
24
penetration, porosity, lack of fusion
Weld located mid-length, lack of
16 0.200
24
penetration, porosity, lack of fusion


The welds were made so that naturally occurring flaws were produced in each weld
including porosity, slag, lack of penetration and lack of fusion. Ground truth data were collected
using a panoramic x-ray technique where the source is placed inside the pipe and single wall
radiographs were obtained.

Isotopic, double wall radiographs were obtained for each pipe using the procedures
provided in Appendix 1.

Double wall radiographs were obtained (by SwRI) using the XRS-3 x-ray source and the
x-ray procedures are provided in Appendix 2 with the Vidisco real-time imaging system. Glenn
Light (SwRI Level III RT), Steve Winterberg (SwRI licensed radiographer and Level II RT) and
Mr. Bryan Lancon of All American Inspections (licensed radiographer and Level III RT)
compared the radiographs and realtime images obtained.

This report serves as the progress report that provides details of the work conducted and
the results obtained. A conference call with the contracting office representative and other
project representatives will occur in November 2006.

The following sections of this report provide a discussion of how the pulsed x-ray source
worked and a comparison of images obtained with that system with respect to the industry
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standard (double wall isotopic) and the impressions of a vendor in the field of pipeline
inspection. Key issues discussed include time required to obtain the images, density of the
radiograph, detection of defects, and general image quality.
3.3 Discussion


The approach suggested by SwRI was to demonstrate the capabilities of a 270KVP pulsed,
battery powered x-ray unit and to compare the double wall pipe radiographs generated using the
pulsed x-ray source with the real-time imaging device to radiographs generated with Ir192 and
film. The demonstration application was double wall radiography (where the source is placed on
one side of the pipe and the film or imager is on the other side of the pipe) for a variety of pipe
welds (ranging in diameter from 4 to 16 inches) as illustrated in Figure 4. The pipes were
fabricated with intentionally placed defects. The welders intentionally used poor welding
techniques to generate regions of lack of fusion, lack of penetration, porosity, and slag. The
intent was to develop a number of regions where natural defects occurred as well as a number of
regions where there were few or no defects. Examples of the pipes and the types of defects are
illustrated in Figure 5.

Figure 4. Illustration of source size and film/detector set
used for the isotopic and pulsed x-ray sources
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Figure 5. Photographs of portions of each pipe size showing some types of defects generated in the welds

Photographs showing how the single wall and double wall radiographs were obtained with
the isotopic source and the pulsed x-ray source are shown in Figures 6-8.

Figure 6. Photograph showing isotopic source being used to take single-wall radiographs
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