TPT July 2017

82 / 96

MEA SUR I NG & MARK I NG
80 JULY 2017
Pipe and tube marking and measuring
By Walter N Arth, Jr, director of automation and engineering, InfoSight Corporation, USA
THERE are many different needs for
marking and measuring pipes and tubes
for the OCTG industry. These needs
continue to grow as API, customer and
internal requirements become more
demanding for proper identification,
tracking and improved quality.
Fortunately, the various technologies
implemented to meet these changing
needs also continue to evolve and can
be used to reduce initial investment
as well as downtime and maintenance
costs. Specifically, advancements in
lasers, robotics, sensors, machinery
and automated stencil equipment as
well as barcode marking and reading
can improve accuracy and simplify
implementation.
To save on equipment cost, in-
line equipment can be used. Length
measurement and stencil marking are
easily accomplished ‘on the fly’ (Figure
1), while weight can be measured on
approaching ‘roll-by’ gravity transfer
rails. Alternatively, if conveyor space
is limited and/or cycle time is critical,
cross-transfer equipment can be
implemented to perform various
functions simultaneously in a small
footprint (Figure 2).
The above are only examples. In
either case, the equipment is used to
first measure the pipe, and then perform
tolerance checks, followed by marking
as needed, and then finally to report the
information on a per-pipe or per-order
basis.
Measurements include both length
and weight, followed with associated
tolerance checks and calculations to
meet various API or customer-driven
requirements.
Length measuring methods including
lasers, photo-eyes, proximity sensors,
encoders, etc easily meet the API
required ±0.1 foot accuracy, with typical
actual length accuracies approaching
±0.03 foot (0.375"), and can be
accomplished with contact or non-
contact distance measuring devices.
Accurate weight measurement can
be performed via lift-and-weigh devices,
cross-transfer equipment or even
roll-by methods by installing the load
cells beneath the support structure.
The measurements are then used to
validate, and report (tally) each specific
pipe by performing weight-to-length
calculations and comparing those to the
API acceptable tolerances.
Once the specific pipe measurement
information is gathered
and combined with the
remaining message that
has been downloaded from
the host, the markings can
be applied to a large variety
of locations via numerous
methods. The two most
common methods are OD
stencil and/or OD stamp
marking of man-readable
text and/or logos, followed
by the need for OD colour
bands.
Additionally, barcodes
(either 1D or 2D) can be
utilised, not just to meet
customer or end-user
requirements, but also
for manufacturers’ own
internal tracking and traceability needs.
Beyond that, interest in defect marking
and thread engagement verification (3/8"
triangle) is also growing.
The specific marking processes can
be performed in a number of automatic
or manual methods, including stencilling,
stamping, application of labels/tags, and
line/band spraying.
OD and ID stencilling can be on just
one end of the pipe, both ends or even
full-length, and can be achieved with in-
line, cross transfer or overhead beam
equipment.
Variations of the above methods and
requirements can often be combined
into a single integrated machine
commonly referred to as weigh measure
stencil (WMS) equipment that utilises
a multi-station cross-transfer machine
to process multiple pipes at once. For
example, the first station can process
weigh and length measure functions,
the second station can stamp, and the
third station can stencil.
The specific designs generated vary
greatly based on needs and plant
geometry. For example, equipment
can include cross-transfer walking
beams to move the pipe from station to
station, or robots may be better suited
for the variability of pipe dimensions
associated with both ID and OD
marking needs of stationary pipes.
Individual requirements along with
ingenuity and technology will drive the
specific solution.
InfoSight Corp – USA
Fax:+1 740 642 5001
Email:
Website: Figure 1: In-line length measure and stencil
Figure 2: Cross-transfer weigh, measure, stamp and stencil