Refinery - II M&I SD Oct-Nov 2018

Chennai Petroleum Corporation Limited (A group company of Indian Oil)
Chennai Petroleum Corporation Limited (A group company of Indian Oil)
Technical - Inspection
Technical - Inspection
Constraints & issues in the present Reactor setup:
210 mm
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10” pipe
492 mm
230 mm
1380 mm
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2016 mm
3000 mm
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5
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FCC was commissioned in the year 1985. First FCC revamp was taken up in
the year 2004. The old ‘T’ arm design was modified to VSS design at the
riser termination point. Other critical jobs like replacement of Reactor top
head along with both cyclones, High efficiency stripper baffles, Riser with
cold wall design were also taken up.
During the revamp proposal itself, recommendations were given from
inspection side for replacing the reactor with a larger size reactor as a part
of revamp project; however the activity could not be taken up because of
budget constraint & time constraint. Reactor shell was retained and
internals were modified at that point of time.
Present Issues & constraint:
1. Reactor Shell internal ARL: It was recommended to remove the reactor
shell internal ARL (considering limited access after VSS set up
installation), eventually only bulged/ loose ARL alone was removed.
Subsequent to revamp shutdown, chipping out of internal ARL was also not
taken up due to space/time constraint & left as such. Over a period of time,
the deteriorated/loose hexmesh anchors accelerating further coke
deposition tendency (since coke is easily sticking onto the exposed hexmesh
at random locations). In the current M&I shutdown, damaged ARL was
rectified at few locations.
2. Stripper section shell Bulges: Shell bulges were reported (during the
2004 revamp shutdown) at two areas in the stripper section. No micro
structural degradation was observed through IMG test in the last M&I
shutdown (2012), however degradation level-IIIL was observed in the
current shutdown.
3. Reactor Cyclone internal ARL erosion: Reactor cyclone has given a life of
14 years subsequent to the replacement in 2004 revamp shutdown. Partial
replacement/repair on the cross over duct plates was carried out during the
current M&I due to severe ARL erosion (followed by perforation). Similarly
reactor cyclone internal ARL erosion (up to a depth of 10 mm) has occurred
on the barrel section in a pattern, but recommended portion of ARL
replacement job could not be carried out because of time & space
constraint. Based on the condition, it is recommended to replace both the
cyclones along with cross over duct during next M&I.
4. Cyclone dip leg space constraint: Reactor cyclone dip leg is located in a
very constrained location for which inspection & repair works is extremely
difficult.
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5. VSS Chamber & transfer pipe internal erosion: Frequent erosion pattern
has been observed in the VSS chamber to transfer pipe joining location &
transfer pipe elbows. Same is being replaced in a frequent interval (all M&I
shutdowns).
6. Expansion bellow inspection constraint: Similarly transfer pipe (Riser-
Reactor termination) expansion bellow is also located in a space constraint
location. Complete health assessment of the subject bellow could not be
carried out in the M&I shutdowns.
7. Riser: Riser internal refractory damage was noticed at many locations in
the form of vertical grooves for a depth up to 2” against the original
refractory thickness of 5” (with many exposed anchors). It was
recommended for refractory relining for about 8.0 m 2 . However it was
extremely difficult to break the refractory lining in such space constrained
location. Breaking & relining of refractory was done only for about 3.0 m 2 in
15-20 days.
8. Stripper baffle cleaning & inspection issue: Stripper baffles were
replaced with high efficiency type in the 2004 revamp shutdown. However
with space constraint & inaccessible location, it has become extremely
difficult to clear the chocked (plugged with hard coke deposits) baffle holes
in the subsequent shutdowns. Cleaning & inspection was done only from
accessible locations (near both manway) & from top/bottom.
9. Internal chamber assessment: Space
constraint is also being faced while
approaching the gap between the riser &
internal chamber. Similarly, the disengaging
arm support locations are also located in a
very constrained location. The locations are
very difficult not only for inspection, but also
a time consuming process in case of
repair/replacement.
The above observations & key points were noted during the
current M&I shutdown.
Recommendations are furnished along with the
recommendation summary.
492 mm
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FLUIDIZED CATALYTIC
CRACKING UNIT (FCCU – PLANT 16)
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Refinery - II M&I S/D Oct-Nov 2018 - Inspection Report
Refinery - II M&I S/D Oct-Nov 2018 - Inspection Report
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