TPT March 2007

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Inspection, Measuring, Testing & Marking
90 March/April 2007
Tube manufacturers need to accurately
weigh, measure, record and tally tube
weights and lengths for their own records,
and to stencil and stamp these tubes with
order information. These markings provide
identification and traceability. In the past,
measuring and marking systems for tubes
were typically manual operations, leading
to inevitably frequent errors.
The current application of the Weigh
Measure Stencil (WMS) system, from
Infosight, offers a number of minimum
automatic capabilities. These include
weight and length measurement, stenciling,
and report generation. In addition, optional
automatic capabilities are possible and
include stamping and colour banding.
The inline version of the WMS system
typically makes use of the user’s existing
tube conveyors to move the tube during
length measurement and stenciling. A
typical inline plan layout is shown in figure
2. Typically, weighing of a static tube is
performed at an upstream weigh scale. The
captured weight is then stored in the WMS
system memory.
Using the inline WMS system, length
measurement is performed as the tube
moves through the conveyor. An encoder
roller used in combination with a number of
sensors measures the tube length on-the-
fly. Length accuracy is typically guaranteed
at API (American Petroleum Institute)
tolerance of (30mm or 0.1ft). The captured
length value is stored in the WMS system
memory.
The system performs a tolerance check
of weight to length by comparing the
actual weight to the actual length and by
memorizing the theoretical weight per
foot. If the comparison falls outside of
allowed tolerances, the tube
is automatically marked as a
reject. A length range check
is also performed, to confirm
the tube length falls within a
programmable min/max length
range.
After a tolerance and length
range check, the good or
reject message is ‘compiled’
by combining the weight,
length, and stencil data into
one message for stenciling
onto the tube.
Stenciling is then performed
as the tube travels in the V-roll
conveyor. The tube approaches the stencil
jib and sensors detect the tube’s passage.
The stencil jib lowers the marking head, and
marks the compiled message onto the tube.
The marking head rises upon completion of
marking.
On the second system
version – the cross
transfer WMS system
– length measurement
is performed on the
tube in a set of idle
rollers. The tube is
pushed along by a
pusher cylinder and the
length is measured by
an encoder roller and
an array of sensors.
Length accuracy is
typically guaranteed at
a tolerance of 10mm
or 0.4". The captured
length is stored in the
system memory.
Weighing of a static
tube is performed on a
weighbridge supported
on load cells, with the
weight stored in system
memory. A tolerance
check of weight-to-length and length range
check are then performed. Following this,
the message is ‘compiled’ by combining
the measured weight, the measured length,
and either the good or reject stencil data
into a message for stenciling on the tube.
Stenciling is performed by lowering a
marking carriage to bear on the top of the
tube with a contact roller, with a marking
head then traversed longitudinally to mark
the stencil message along the tube’s axis.
Specialised logos such as the API logo can
then be marked.
Stamping is performed to mark up to 40
characters, with typical character height
ranges from 6mm (0.25") to 10mm (0.4").
Dot matrix character density typically
ranges from 5x7 to 7x9 (width x height).
For either geometry, a printed Tally report
is generated (showing totalized length
and weight by shift, day and order), while
a production report is also generated
(showing message data printed on each
pipe).
InfoSight Corporation – USA
Fax: +1 740 642 3777
Email:
Website :
Weigh measure stencil (WMS) system from
identification specialists
fi Figure 2 (below) a typical in-line WMS plan layout, and figure 1 (bottom) a
cross transfer walking beam WMS system
› Figure 3 (top) a typical cross section through walking beam WMS
system, and (above) highly advanced marking technology for
barcoding tube and pipe