04_Walter Tosto_Fossataro.pdf

8th
Dillinger
Pressure
Vessel
Colloquium

Advanced
techniques
in
CrMoV
reactors
fabrica<on
30th September – 1st
October 2015
Authors : G. Fossataro – D. Quintiliani

The Company
340.000 sqm Workshops
500+ Employees
Average Turnover 100 ml. €
Sea Front Workshop
Wide Machine Park
50+ Years Experience

Facts and Figures
Turnover:

100,000,000
euro

Employees:

500
more

Assets:

75,000,000
€

Investments:

50,000,000
€
in
3
years

Equity
and
Reserves:

70,000,000
€

Orders
PorEolio:

220,000,000
€


Company Products

HYDROCRACKING
REACTORS
ARE
BETWEEN
THE
MOST
CRITICAL
ITEMS

OPERATING
IN
A
REFINERY.

CRITICALITIES

COME

FROM:

-‐ SEVERE
OPERATING
CONDITIONS
:

-‐ CHALLENGES
IN
FABRICATION,
WITH
SPECIAL

CONSIDERATION
TO
FORMING,
WELDING

AND
HEAT
TREATMENT.

Pressure
(Design/Opera<ng):

165÷200
Bar
/
150÷180
Bar

Temperature
(Design/Opera<ng):

360÷454
°C
/
360÷430
°C

H2
Par<al
Pressure:

140÷175
Bar

MDMT:
-‐29°C

TYPICAL
MATERIAL
SELECTION
IS

:
SHELL:
Plates
in
SA542DCL4a
or
Forging
SA336GrF22V

HEADS:
Plates
in
SA542DCL4a

NOZZLES:
Forging
SA336GrF22V


SHELL
COURSES
FABRICATION
CAN
BE
DONE
STARTING
FROM
A

MACHINED
FORGING
OR
BY
PLATES
ROLLING


TYPICAL SHELL COURSES FABBRICATION

Forming
of
heavy
plates
requires:

-‐ Powerful
rolling
machine
(9000
tons
in
Walter
Tosto)

-‐ Forming
control
“near
to
numeric
control”
to
obtain
and
guarantee
proper
roundness

-‐ Furnace
in
proximity
of
the
rolling
machine
to
perform
warm
preheaWng.

CAN
HEAVY
PLATES
(35-‐40
TONS)

BE
USED
AS
AN

ALTERNATIVE
TO
HEAVY
FORGINGS
(70+
TONS)
?

Longitudinal
weld
followed
by
warm
rolling

-‐ Special
tools
for
plates
handling
to
avoid
stress
in
the
weld
region
during

plates
posiWoning
and
rotaWon
with
parWal
welding
compleWon

-‐ ISR
to
stress
relieve
the
weld
and
to
achieve
acceptable
toughness

-‐ Grind
ﬂush
of
the
weld
to
reach
a
regular
surface

-‐ Uniform
preheat
(350°C)
before
rolling.


Lower rolls clearence (up to 2500mm) allow to have
progressive stress increase in rolled plates

This
process
has
been
qualiﬁed
with

several
PTP
that
have
been
rolled
and

than
subject
to
severe
mechanical
tests

(tensile
and
impact
test
at
compressed,

neutral
and
stretched
ﬁber,
Z
test
in
fusion

line
and
in
HAZ,
step
cooling
test)

Several
reactors
have
been
fabricated

by
Walter
Tosto
with
this
technique

and
are
in
operaRons
since

years


SHELL
BARRELS
WITH
CATALYST
BED
SUPPORT
RING.

When
shell
courses
are
made
by
heavy
forging,
the
support
ring
is
an
integral

part
of
this
forging;
this
is
frequently
used
in
producWon
but

unfortunately

with
a
negaWve
impact
in
the
project
costs.

As
an
alternate,
when
barrels
are

made
by
plates,
this
support
ring
may

be
fabricated
with
weld
build-‐up

Welding build up in progress

TO
PERFORM
THIS
ACTIVITY

IS
IMPERATIVE
TO
HAVE:

-‐ Proper
weld
parameters
and
temperature
control

-‐ Large
preheaWng
zone
during
welding

-‐ Immediate
ISR
(typ.
670°C
6H)
without
allowing

the
weld
deposit
to
cool
below
approx.
180°C

-‐ Scale
1:1
mock
up
for
UT
calibraWon


TYPICAL HEADS FABBRICATION

TO
OPTIMIZE
THE
HEADS
FABRICATION
AND
TO
GUARANTEE
THE
BEST
PERFORMANCES
IN

QUALITY/PRODUCTIVITY
DURING
WELDING
IT
IS
IMPORTANT
TO
PERFORM:

-‐ Very
careful

warm
calibraWon
in
order
to
have
petals
in
precise
shape
and
to

avoid
extra

ﬁt
up
acWviWes

-‐ Petals
machining
before
ﬁt
up
to
reach
a
narrow
gap
bevel


WELDING

WELDING
IS
A
CRITICAL
ACTIVITY
USING
CrMoV
MATERIALS,
AS
IT
IS
WELL

KNOWN
THEIR:

-‐ CRACKS
SUSCEPTABILITY

-‐ LOW
TOUGHTNESS
IN
AS
WELDED
CONDITIONS

MECHANICAL
PROPERTIES
ARE
REACHED
ONLY
WITHIN
VERY
SPECIFIC
WELDING

PARAMETERS
AND
AFTER
A
PROPER
POST
WELD
HEAT
TREATMENT.


WELDING
ACTIVITIES
SHALL
BE
CONDUCTED
FOLLOWING
A

ROBUST
AND
RELIABLE
PROCESS:

-‐ STATE
OF
THE
ART
IS
TO
IMPLEMENT
NARROW
GAP
WELDING

WITH
SPECIAL
CONTROL
OF
THE
BEAD
SEQUENCE.

-‐ NOZZLES
EQUAL
OR
GREATER
THAN
4
INCHES
SHALL
BE

WELDED
WITH
NARROW
GAP
SAW
PROCESS

-‐ LOCKED
WELDING
PARAMETERS
AND
PROPER
ROTATING

EQUIPMENTS
ARE
MANDATORY
TO
PERFORM
PRODUCTION

WELDING
CONSISTENT
WITH
THE
QUALIFIED
ONES

300
mm

-‐ Proven
welding
consumable
management
system

Good management of filler metal means, guaranteeing that the filler metal in all phases from Goods-In to welding has
negligible hydrogen absorption. In addition the flux is dried and stored at temperatures indicated by the filler metal
manufacturer, typically 350°C for drying and 150°C for storage, in special distribution equipment, prior to use.
“Drying
and
ﬂux
feeding

system
designed
and

manufactured
in-‐house.”

-‐ Intensive
training
of
all
involved
personnel


WELD

OVERLAY
IS
TIPICALLY
PERFORMED
IN
ONE
LAYER
WITH
ESW
PROCESS

USING
TANDEM
90mm
STRIP
WELDING
EQUIPMENT
Weld overlay
by double heads ESW process type 347

Weld
overlay
of
nozzles,
usually
performed
with
FCAW
process
can
be

opWmized
implemenWng
automaWc
robot
welding

(2
or
3
layers
depending
on
different
project
specificaWon
or
different
locaWon)


FOLLOWING
SPECIFIC
QUALIFICATION
PROCESS
ROBOT
WELDING
IN
LIEAU

OF
MANUAL
OVERLAY
WELDING,
BRINGS
IMPROVEMENTS
IN
:

-‐ FERRITE
CONTROL
(uniform
readings
of
FN
between
5
and
7)

-‐ COSTANT
OVERLAP
BETWEEN
WELD
PASSES

-‐ SIGNIFICANT
INCREASE
IN
PRODUCTIVITY


HEAT
TREATMENT

ISR
(intermediate
stress
releaving)
is

typically
performed
in
fournace
for
reactor

secWons
(heads,
shell
courses
with
nozzles)

while
circunferencial
welds
are
subject
to

DHT

When ISR is requested also for
circunferencials weld, to avoid potential
detrimental eﬀects on base metal due to
multiple ISR + max PWHT, Localized ISR
can be performed.

POST
WELD
HEAT
TREATMENT

Example
of
reactor
treated
with
temperature
range
710°C
+/-‐5°C.

It
is
essenWal
to
have
a
reliable
PWHT
procedure,
state
of
the
art
furnace
&
skilled
personnel
to

guarantee
precise
temperature
(+/-‐5°C)

Thanks
for
your
aUenRon


04_Walter Tosto_Fossataro.pdf

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