FIELD OF THE INVENTION
The present invention relates to a method for evaluation of energy delivered
during the impact testing of tubular specimens using a ram, actuated by a
suitable powering mechanism, which delivers the impact energy. More
particularly, the invention relates to a method of determining quantity of energy
absorbed during impact testing of welded tubular specimen.
BACKGROUND OF THE INVENTION
Tubular components of boiler industries are fabricated using welding process for
producing coils like super heaters, re-heaters, economizers, water walls etc. Out
of the various available processes, the induction-pressure welding is preferred
because of being very fast and capable of producing butt joints of tubes with a
consistent quality and good integrity. Impact testing of tubes welded using the
Induction Pressure Welding process is an important quality control step in the
fabrication procedure. For the impact testing, a butt welded tubular sample of
length approximately 400 mm (weld joint in the centre) is taken and is subjected
to a cold impact loading by using a striking ram. If the joint does not break
under the impact load, then the entire tubular welded joints welded in a
production cycle, is accepted, otherwise, the joints produced in that production
cycle is rejected. Such a testing is carried out on the first joint produced in a
production cycle. The impact test of these tubular welded joints needs to be
done in accordance with the requirements of certain energy levels. The means of

evaluating the quantum of energy that is transmitted during the impact testing of
a tubular specimen, using a striking ram actuated by a suitable means is the
primary problem of the prior art.
US patent 4100617 states a method of compacting powders in a press using a
ram actuated by a toggle mechanism which in turn is actuated by a drive of the
press.
US patent 5694804 describes a method of forging and stamping of thin sheet
strips by using a ram with a tool that reciprocates backward and forward.
US patent 4418563 refers to a method of determining the impact fracture
toughness (KID) of construction materials including steels and plastics without
the need of performing the load measurement at the striking hammer.
US patent US 741280 discusses a method of delivering impact loads to test
material using a striking tup that moves along a rod falling like a projectile.
OBJECTS OF THE INVENTION
It is therefore an object of the invention to propose a method of determining
quantity of energy absorbed during impact testing of welded tubular specimen,
which eliminates the disadvantages of prior art.
Another object of the invention is to propose a method of determining quantity
of energy absorbed during impact testing of tubular specimen, the tubular
specimen being formed of both metal and non-metal.

A still another object of the invention is to propose a method of determining
quantity of energy absorbed during impact testing of tubular specimen, wherein
the impact load on the specimen is imparted by an electrically actuated ram.
SUMMARY OF THE INVENTION
A method for determination of the amount of energy absorbed by welded tubular
specimens when subjected to impact testing using actuated rams is disclosed in
this invention.
In another aspect of the invention, the present invention deals with a method of
calculation of energy delivered during impact testing of tubular welded
specimens, using a ram actuated by a suitable powering arrangement.
The present invention is enabled to quantify the energy that is absorbed during
the impact testing of tubular specimens.
According to the invention, the impact energy is delivered by a ram that is
actuated by an external powering arrangement, using a pre-determined
relationship between the impact energy and deformation.
In order to measure the energy delivered to the tubular sample during the
impact testing, a calibration graph is generated prior to the commencement of
the actual testing. The method of drawing the calibration graph is discussed
hereunder.

Tubular ring type of specimens are machined to suitable sizes and subjected to a
calibration step using a drop weight testing machine built according to ASTM
E208 specifications. This machine consists of a weight of mass which can be
linearly raised to various heights and the height can be measured by a metre
scale provided along the frame in which the weight raises. There are provisions
present in the machine to release the weight from such raised heights. The
machine is capable of imparting energy by way of dropping the weight onto the
specimens, and adapted for the calibration step. Means for firmly holding the
tubular ring specimens during the fall of the dropping weight that delivers impact
energy to these tubular ring specimens, was provided. Firstly, a tubular ring
specimen is placed onto the holding means and clamped. The weight is allowed
to fall over this specimen from a certain height. The impact energy delivered by
the falling weights is calculated by using the following formulae
Impact Energy = (M x g x H) Joules
Where M denotes the mass of the weight falling freely under the influence of
gravity in Kg, g refers to acceleration due to earth's gravitational field in metre
per squared second. H refers to height of fall in metres
The tubular ring specimen deforms and gets flattened at the impact location and
the deformed shape forms an ellipse. The major axis and minor axis of this
ellipse is measured and recorded. This procedure is repeated for multiple
specimens and two graphs are generated, one graph between the impact energy

of falling weight versus the deformation along the minor axis, and the other
graph being impact energy of falling weight versus the deformation along the
major axis. These curves serve as calibration graphs for the actual measurement
of impact energy delivered to welded tubular specimens using an actuated ram.
The tubular ring specimens of the same grade and similar geometry as of those
used during the calibration step are taken. Firstly, one such specimen is placed
beneath the ram and clamped firmly, and the ram is actuated in order to deliver
impact energy to this specimen. The deformed specimen by virtue of the impact
energy delivered is taken and the major axis and minor axis deformation
measurements are made. By measuring the deformation and referring to the
calibration graphs earlier generated already between the energy and
deformation, the impact energy delivered by the ram is computed. The average
of the two impact energy values (one based on major axis deformation and other
based on minor axis deformation) are referred to the calibrated graph, and the
impact energy is calculated which was delivered to the welded tubular specimens
during the impact testing using the ram under the same actuating conditions and
stroke length of the ram.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Figure 1 - Holding means used for calibration curve generation
Figure 2 - A device for drop weight testing and means for holding tubular ring
specimen.

Figure 3 - Un-deformed tubular ring specimen kept under a striking ram
Figure 3 4- Tubular ring specimen deformed after impact energy delivered by
the striking ram
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
According to the invention, there is provided a method of determining energy
delivered to welded tubular specimens during impact testing by using a ram that
is actuated by any powering arrangement including mechanical and fluid
actuated types. As disclosed herein tubular ring type of specimens of a specific
material grade and a desired geometry are taken, and placed on a holding
means for clamping these specimens firmly. The details of the holding means are
presented in figure 1. The holding means consists of a base plate (1) of sufficient
thickness that withstands the impact energies caused by a falling weight. There
are two side-support blocks. The first side-support block (2) is fixed by means of
tack welding to the base plate (1), and is not movable. The second side-support
block (3) is movable and can be positioned nearer or farther from the first side-
support block (2). The tubular ring specimen is placed in a gap between the two
side support blocks (2,3). There are two fastening bolts (4,5) that can be easily
inserted into two threaded holes (6,7) provided in said two side-support blocks
(2,3). The threaded holes (6,7) in the two side support blocks (2,3) are coaxial in
nature for securing the fastening bolts (4,5). The tubular ring specimen is placed

in the gap between the two side-support blocks (2,3), and clamped firmly by
tightening the fastening bolts (4,5). This sub-assembly (10) is placed on a known
drop weight testing machine having a falling weight (8). The mass of the falling
weight (8) is fixed and the weight (8) is placed on a frame structure to allow the
weight (8) to be raised or lowered to required heights and subsequently drop
from that height when desired. A meter scale provided alongside the frame on
which the weight (8) is raised, which interalia exhibits the falling height of the
weight. The falling weight is now released from a desired height and the tubular
ring specimen (9) kept in the sub-assembly (10), deforms because of the impact
energy transmitted by the falling weight (8) by virtue of its free fall under the
influence of gravity. The impact energy delivered by the falling weights (8) is
calculated by using the following formulae:
Impact Energy = (M x g x H) Joules
Where 'M' denotes the mass of the weight falling freely under the influence of
gravity in Kg, 'g' refers to acceleration due to earth's gravitational field in metre
per squared second. 'H' refers to height of fall in metres.
The tubular ring specimen (9) gets deformed (flattened) because of the impact
received and forms a shape like an ellipse. The positive deformation and the
negative deformation experienced by this tubular ring specimen (9) along the
major and minor axis of this ellipse are recorded. The impact energy transmitted
by the falling weight (8) onto the tubular ring specimen (9) is calculated using

the formula for potential energy of the raised weights. This procedure is
repeated for multiple specimens. The more is the number of the specimen,
greater is the accuracy of calibration curve that is generated. Two calibration
curves are plotted where the impact energy versus the deformations measured
in the tubular rings specimens (9) along the major axis and minor axis, is
plotted.
In order to evaluate the energy delivered to the tubular specimen (9) during the
impact testing done by an actuated ram, the tubular ring specimens (9) that are
similar in geometry and of the same material grade as those used for generation
of the calibration graph are taken. One such tubular ring specimen (9) is then
placed beneath the ram meant for delivering the impact energy. Then, the ram is
actuated by a powering mechanism. The impact energy is delivered by the ram
to the specimen (9). On receiving the impact energy from the ram, the circular
ring specimen (9) deforms into an elliptical shape. The deformations undergone
in the major axis and minor axis of this tubular ring specimen (9) are measured.
These measurements are used to infer the corresponding level of impact energy
that is delivered by the striking ram. This is done by locating the corresponding
levels of impact energy from the calibration graphs drawn between 'impact
energy and deformation along major axis' and 'impact energy & deformation
along minor axis'. These impact values are averaged to get the actual impact
energy delivered during the impact testing of welded tubular samples using the
actuated ram, provided the testing conditions like the height of placement of

specimen beneath the ram, the actuating conditions of the ram like stroke length
of traverse, oil pressure etc. or air pressure, as the case may be, shall remain the
same as that of the calibration exercise.
The disclosed invention as narrated herein above should not be read and
construed in a restrictive manner, as some modifications, adaptations and
alterations are possible within the scope and limit of the invention, as defined in
the encompassed appended claims.

WE CLAIM
1. A method of determining quantity of energy absorbed during impact
testing of welded tubular specimen, comprising the steps of:
- providing a known drop weight testing machine having a measuring
scale, a frame structure and a falling weight;
- constructing and placing a holding means having a base plate and at
least one each fixed and movable side support block;
- preparing a plurality of welded tubular specimen formed of identical
material with similar geometry;
- placing a single specimen into a gap between side support blocks of
the holding means and clamping the specimens;
- locating the holding means fitted with the specimen on the drop
weight machine and allowing the falling weight to fall on the specimen
from a height causing a elliptical deformation of the specimen by the
impact energy;
- calculating the impact energy delivered by the falling weight based on
the deformation of the specimen along the major and minor axis of the
ellipse;
- repeating the deformation step and calculating step for the plurality of
specimen and generating a calibration curve with deformation values

vs impact energy;
- placing a specimen of identical material and geometry beneath an
actuatable ram during a physical testing and delivering the impact on
the specimen of actuating the ram; and
- measuring the deformation of the specimen along major and minor
axes and interpolating the measured values based on the generated
calibration curve to determine the impact energy delivered by the ram.
2. The method as claimed in claim 1, wherein the impact energy of the
falling weight is determined based on the technical relationship: Impact
Energy = (M x g x H) Joules, wherein 'M' is the mass of the free falling
weight in Kg, 'g' is the acceleration due to gravitational force (mt/sec2),
and 'H' is the height of fall in meters.

ABSTRACT

A method of determining energy absorbed quantity during impact testing of welded tubular specimen, comprising the steps of providing a known drop weight testing machine having a measuring scale, a frame structure and a falling
weight; constructing and placing a holding means having a base plate and at least one each fixed and movable side support block; preparing a plurality of welded tubular specimen formed of identical material with similar geometry;
placing a single specimen into a gap between side support blocks of the holding means and clamping the specimens; locating the holding means fitted with the specimen on the drop weight machine and allowing the falling weight to fall on the specimen from a height causing a elliptical deformation of the specimen by
the impact energy; calculating the impact energy delivered by the falling weight based on the deformation of the specimen along the major and minor axis of the ellipse; repeating the deformation step and calculating step for the plurality of specimen and generating a calibration curve with deformation values vs impact energy; placing a specimen of identical material and geometry beneath an actuated ram during a physical testing and delivering the impact on the specimen by actuation of the ram; and measuring the deformation of the specimen along major and minor axes and interpolating the measured values based on the generated calibration curve to determine the impact energy
delivered by the ram.