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he American Petroleum Institute issued the 20th edition
of API Standard 1104, Welding of Pipelines and Related
Facilities, in November 2005. The standard covers the
welding of butt-joint, fillet, and socket welds in carbon and low-
alloy steel piping used in the compression, pumping, and trans-
mission of crude petroleum, petroleum products, fuel gases,
carbon dioxide, and nitrogen. Where applicable it also covers
welding on gas distribution piping.
In addition, API 1104 includes procedures for radiographic,
magnetic particle, liquid penetrant, and ultrasonic testing, as
well as the acceptance standards to be applied to production
welds tested to destruction or inspected by radiographic, mag-
netic particle, liquid penetrant, ultrasonic, and visual inspection.
The standard applies both to new construction and in-service
The CWI Test
Candidates for the AWS Certified
Welding Inspector examination who
choose the API 1104 open codebook
exam must use the 20th edition.
This change became effective June
1, 2006.
The new API 1104 exam consists
of 60 multiple choice questions
taken in the same two-hour format
as previous CWI tests. The new
exam is not compatible with any pre-
vious editions of the code.
Candidates are responsible for
purchasing the API 1104 20th edi-
tion and, if not in possession of a
bound copy of the standard, must
present proof of purchase for any
photocopies presented.
Changes to the Standard
Significant changes include a new revision in the radi-
ographic testing acceptance standard, the total elimination of
the use of hole-type penetrameters, removal of the nick break
testing requirement, and improved practices for welding on in-
service pipelines. These and other changes from the 19th edi-
tion are detailed as follows:
N Definitions have been added, corrected, and clarified.
N A new revision in the radiographic testing acceptance stan-
dards is in the area of “burn-through” (known as melt-
through in AWS terminology).
N A significant revision in the procedures for radiographic test
methods involves the total elimination of the use of hole-type
image quality indicators (IQIs/penetrameters) and will now
only allow the use of wire-type IQIs (either ASTM or ISO).
N The primary change to the Mechanized Welding section,
which was previously called “Automatic Welding,” was its
renaming, and in the Procedure and Welder Qualification seg-
ment, the requirement for nick break testing was removed.
The Qualification of Welders and Equipment was rewritten
for clarity.
N In Appendix A, the following was included: “Reference imper-
fection sizes (a*), which fall between the crack tip opening
displacement (CTOD) values of 0.005 in. to 0.010 in. can be
derived with an equation illustrated in the new edition of API
1104 as opposed to the graphical extrapolation method.”
NAppendix B improved the recom-
mended practices for welding onto
in-service pipelines. Significant
revisions include clarification per-
taining to discrepancies that exist
between Appendix B and the main
body of API 1104, the allowance of
trade-of fs that may be made
between the carbon equivalent of
the materials being welded and the
thermal severity of the pipeline
operating conditions without the
need for procedure requalification,
the revision of essential variable
requirements for welder qualifica-
tion and provisions for multiple
qualification of an in-service
welder, and additional in-service
welding guidance (welding sequence, time delay prior to
inspection, etc.).
Department of Transportation Use
This edition replaces the 19th edition (with 2001 errata).
However, the U.S. Department of Transportation (DOT) has not
yet incorporated the 20th edition into regulation by reference
into the Federal Register. This is expected to occur within the
next 6–12 months. Consult the DOT Office of Pipeline Safety
Web site,, for updates.
The 20th edition of API 1104 is 68 pages long and can be pur-
chased through World Engineering Xchange (WEX), Ltd., at
(888) 935-3464 or; and Global
Engineering Documents at (800) 854-7179 or Additional information is also available at
Based on information provided by the American Petroleum Insitute, Washington, D.C., (
What’s New in API 1104
The latest edition of the standard contains some significant changes
Significant changes
include elimination of
hole-type penetrameters
and removal of nick break
testing requirements.