Page 47 - Impiantistica industriale

and final regenerator position was 65 meters.
The large gap between the crane and fi-
nal lifting positions along with the increased
equipment weight required a new 3,000 tons
load capacity crane selection versus the usual
1,350 tons crane.
The turnaround optimisation process brought
to the pre-assembly of the new isolation valve
with top and bottom spools of new flue gas
line in the replaced section.
The configuration of the isolation valve and flue
gas line spools required the system preassem-
bly to use a temporary steel support structure.
The available area for the module preassem-
bly was approximately 90 meters from the final
isolation valve position in the FCC unit. The
availability of the 3,000 tons crane selected for
the FCC regenerator lifting became an oppor-
tunity for the lifting of the preassembled isola-
tion valve from the module area to the instal-
lation position.
The FCC regenerator and isolation valve with FCC regenerator lifting - 3D simulation and real case
flue gas line section replacements represented
FCC unit turnaround critical path. The identi-
fied constructability solutions enabled the tur-
naround duration to be reduced by four wor-
king days.
• Equipment dressing during pre-turnaround
phase
Topping distillation and alky depropanizer to-
wers were pre-dressed with piping, platform
and ladders and internals during the pre-tur-
naround phase.
In this case, the upfront decision for the pre-
dressing approach enabled specific enginee-
ring dedicated solutions for design of piping
isometrics and support, towers internal sup-
port configuration etc.

• 3D simulations and fabrication/construction/
exiting infrastructures interferences constraints
A key success in the project was Wood’s
extensive use of laser scan and 3D modelling
for the design and plan of the pre-turnaround
and turnaround works.
Wood carried out detailed simulations stu-
dies of potential mutual interferences during
equipment lifting operation including cranes
rotations/translation, booms and superlifts
movement using the 3D laser scan of the exi-
sting infrastructures combined along with cra-
nes and equipment 3D models.
• Site fabrication and laydown areas logistic as-
sessment
FCC, topping, alky units’ accessibility areas 3D infrastructures interferences studies and Construction Execution Plan instructions
were very limited due to existing pipe rack ele-
vations, roads dimensions and infrastructures assembly of final equipment combined with
along the refinery access roads. Preassembly the temporary storing of removed existing
and laydown areas next to units were also qui- equipment took a fundamental role in schedu-
te narrow. ling activities and dictating the delivery on site
The operation sequences of new equipment of the shop fabricated material.
elements translations and lifting during the Wood’s construction execution plan collected all

Impiantistica Italiana - Novembre-Dicembre 2020 45 45