TPT May 2017

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AR T I C L E Rivit SpA
by Willy Goellner, chairman and founder – Advanced Machine & Engineering/AMSAW
80 MAY 2017
Figure 1: Finishing obtained
through the “HFree” process
– alloy UNS S32750
HFree Life Pickling – a new industrial
process that improves the environment
and productivity
By Loris Dal Santo, R&D Department, Rivit SpA, Italy
HFree Life Pickling, a project co-financed by the European
community through the instrument LIFE, represents the
synergy between Rivit, Henkel and the Province of Vicenza,
Italy, in the search for a new process that can help pickling
productivity and improve the environmental impact of the
process.
In the first stages of the project, Rivit provided Henkel
with various specimens of metal alloys to be heat treated.
Thanks to the ability to work on realistic specimens, Henkel
technicians were able to develop a new chemical solution
devoid of toxic substances that has achieved reductions
of more than 90 per cent in the laboratory yet still has the
technical features to achieve a surface finish comparable to
traditional pickling (see Figure 1).
The results achieved in this early stage confirmed the poten-
tial of the process from a production and environmental
viewpoint. However, it was necessary to verify the performance
during application with tubular geometries.
To this end Rivit implemented a pilot “mini-plant” in the
second stage by reduced scale in order to carry out tests on
specimens of tubes of a length shorter than one metre.
In recent years concerns about environmental issues have
increased considerably within manufacturing industries.
This is why the reduction of the environmental impact of
the processes involved represents a critical goal for many
companies. Interestingly, some of these environmental
improvements can also bring economic benefits for the
industry.
The tests led to excellent results, confirming in the large
majority of cases the results claimed by Henkel in the first
stage of testing.
However, during this stage some criticality connected to the
development of gases such as hydrogen and oxygen during
the application of electric current to the electrochemical cell
did emerge.
These gases in fact tend to collect on the upper inner surface
of the tube, giving rise to a volume of gas that prevents
the contact of the electrolyte solution with the surface to be
treated. Thanks to the plant changes, however, the problem
was completely solved, obtaining a complete removal of the
oxidised flake from the inner surface as well as from the
external surface of the tube.
During the tests, possible problems were identified connected
to the dragging of the particles of the bath by the gases that
develop during electrolysis.
For this reason Rivit – thanks to the support from ARPAV
and the Province of Vicenza – has identified a containment
system for the emissions that will be used in the industrial
pilot plant that is under construction in the Caltrano plant, a
long-standing production unit in the manufacturing industry
that produces stainless steel tubes.
Figure 2: Specimen of the Tube UNS S31803