Yearbook 2013/2014 - ehedg

Material and design optimisation calculated by EHEDG: Tubing systems 105
The orbital welding method enables tubing to be connected
with a continuous 360º welding seam (Figure 5). To
accomplish this task, Dockweiler AG uses orbital welding
equipment, among other tools, with welding electrodes
positioned on the inside of the tubing. The result is a
continuous, high-quality welding seam that prevents dead
space, ridges, etc., and thus fulfils hygiene requirements.
At the same time, narrow dimensional tolerances are
maintained and the branches from manifolds and special
parts can be designed to be extremely short. This method is
used to engineer a variety of manifold designs for food and
pharmaceutical production.
Figure 6. Thermowell: Tube section with immersion rod for ‘inline’
measurement in product flow.
Example: Optimising design during
engineering phase
Another example: A manufacturer with a complex system
desires two individual valves for the material feed and two
valve blocks, each with three hand-operated shut-off valves,
which need to be mounted directly onto the respective entry
and outlet openings on the backside of the system. Dockweiler
AG’s engineering team determined that the valves, which
must be regularly controlled during system operation, would
be too inaccessible. An alternative was developed that
allows an operator to control all eight fittings from one central
station that is also at an easily accessible height (Figure 7).
Additional functions can be included with this basic concept,
for example, a sequence for each of the eight lines.
Figure 5. Orbital welding enables the optimal design of hygienic
tubing components.
Special components for sensors under
EHEDG conditions
Dockweiler AG also develops and produces customised
tubing components for EHEDG-compliant sensors, for
example, for detecting the temperature of media in tubing
systems. This includes, among other things, a tube section
with an dip tube where the sensor is housed (‘thermowell’).
The medium flows past the dip tube and is subject to the
strictest hygiene requirements. The entire construction
should be designed so that disruption of flow and turbulence
are avoided (Figure 6). Measurement results that are actually
reproducible are obtained in this way.
Figure 7. Clearly better results can be achieved through optimisation
of design during the engineering phase.
Strict requirements for documentation
The ‘correct’ production methods and engineering
competency are important when it comes to putting EHEDGcompliant
special constructions into practise. These examples
demonstrate the importance of designing and producing
tubing that meets the highest standards of hygiene. This
applies not only to basic processes like drawing, boring,
expanding and welding, but also surface treatments that
employ processes like grinding, honing, pickling and electropolishing.
All production steps are documented in detail so
that the traceability of each individual component as well as
the reproducibility of the processes is possible. Using this
holistic approach means that manufacturers and operators of
EHEDG-compliant systems can ensure and credibly document
that their tubing meets the highest quality standards.