Proposed Revision to API Standard 1104, 20th Edition
Rev. 0
ID:
5/5.6/5.6.3
Section: 5 Qualification of Welding Procedures for Welds Containing Filler-metal Additives
Heading: 5.6.3 Nick-break Test
CURRENT TEXT
5.6.3 Nick-break Test
5.6.3.1 Preparation
The Nick-break test specimens (see
Figure 5) shall be approximately 9 in.
(230 mm) long and approximately 1 in.
(25 mm) wide and may be machine cut
or oxygen cut. They shall be notched
with a hacksaw on each side at the center
of the weld, and each notch shall be
approximately 1/8 in. (3 mm) deep.
Nick-break specimens prepared in this
manner from welds made with certain
mechanized and semiautomatic processes
may fail through the pipe instead of the
weld. When previous testing experience
indicates that failures through the pipe
can be expected, the external
reinforcement may be notched to a depth
of not more than 1/16 in. (1.6 mm),
measured from the original weld surface.
At the company’s option, Nick-break
specimens for qualification of a
procedure using a semiautomatic or
mechanized welding process may be
macro-etched prior to being nicked.
5.6.3.2 Method
The Nick-break specimens shall be
broken by pulling in a tensile machine,
PROPOSED TEXT
5.6.3 Nick-break Test
5.6.3.1 Preparation
…
5.6.3.2 Method
The Nick-break specimens shall be
broken through the weld by any
convenient method. The exposed area of
the fracture shall be at least 3/4 in. (19
mm) wide.
July 6, 2009
Page 1 of 2
JUSTIFICATION
During 2008, one large test laboratory in
Houston concluded that bending of nickbreak specimens in alternating directions
in a load frame was not permitted and
converted to breaking all nick-break
specimens in tension.
Breaking nick-break specimens in welds
of high-strength steel (i.e., Gr. X70 and
higher) in tension requires considerable
notching to avoid fracture through the
pipe material. The machine shop at this
lab frequently sawed deeper than the
permitted 1/16-in. below the original
weld surface and beyond the required ¾in. remaining width.
While breaking nick-break specimens
with a hammer may be practical for
relatively low-strength, thin-wall pipe,
breaking by manual hammering is
completely impractical for highstrength, heavy-wall pipe.
Explicitly permitting bending of
specimens in alternate directions in a
load frame, a common industry practice
for decades, will expose more fracture
surface for visual examination than
pulling in axial tension.
Proposed Revision to API Standard 1104, 20th Edition
Rev. 0
ID:
5/5.6/5.6.3
Section: 5 Qualification of Welding Procedures for Welds Containing Filler-metal Additives
Heading: 5.6.3 Nick-break Test
CURRENT TEXT
by supporting the ends and striking the
center, or by supporting one end and
striking the other end with a hammer.
The exposed area of the fracture shall be
at least 3/4 in. (19 mm) wide.
PROPOSED TEXT
July 6, 2009
Page 2 of 2
JUSTIFICATION