Page 85 - Industrial Plants

and its pressure required the use of super duplex
stainless steel for the pressure components.
In fact, Termomeccanica had to reconcile the
mechanical features of the pressure components, that
pushed towards increasing thicknesses, with the
metallurgic difficulties of super duplex production that
grow in parallel to the increase of the material
thicknesses.

The choice of super duplex A890 gr.5A
for wet components was made in
agreement with the EPC engineering
team, considering the characteristics of
the pumped fluid, i.e. seawater, so as to
guarantee the best protection against
corrosion

The first technical challenge was the development of a
barrel casing with proper dimensions, without
unnecessary layers of material and, most important of
all, with regular and constant thickness along its entire
length.
Once the design of the barrel casing was finalized, the
second challenge consisted in adjusting it to make its
casting feasible, i.e. respecting the restrictions related
to the pouring of this type of material, finding the proper
and most suitable process and the right size and
position of risers and sprues to guarantee a successful
outcome. For Super Duplex material, this part of the
design is fundamental to prevent unwanted severe
T he four pumps are API 610 BB5 type achieve the proper final result in terms of mechanical
defects due to the formation of fragile phases and to

multistage pumps made of super
properties.
duplex stainless steel, characterised
The use of the most advanced computational tools and
by 300 m³/h flow and 2,160 m head,
a close collaboration with not only foundries and
and driven by a 3 MW motor rotating
pump crossover
at 3000 RPM.
experts allowed to perform a detailed analysis of this
area 1
specific design and to define the most suitable heat
Each pump is equipped with a double seal, an 11/62 pattern makers but also with NTC materials engineering CFD simulation in
plan system and an API 614 lubrication system. An API
671 coupling is fitted onto the skid, which is installed on
a 3-point base plate with gimbal-type ball joints. An API
661 air-oil heat exchanger will also be installed outside
the skid.
The choice of super duplex A890 gr.5A for wet
components was made in agreement with the EPC
engineering team, considering the characteristics of the
pumped fluid, i.e. seawater, so as to guarantee the best
protection against corrosion.
One of the main features of these pumps, however, is
the back-to-back impellers solution. This configuration
combines the advantage of the balanced hydraulic
thrusts derived from the back-to-back impellers with
the reduced thicknesses of the castings of the BB5
barrel solution in comparison to the usual split case
solution. The reduction of the castings thicknesses was
particularly critical given that the type of pumped water

IndustrIal Plants - May 2017
83