o Brief summary of reasons for replacement
o Replacement activities tentative plan
o Introduction to Urea Stripper E-4101
o History through inspection reports TA and
shutdowns after installation in 2006
o Motive for replacement
o Design Changes
o Current Status
o Replacement plan
o Replacement activities
o Rigging plan
o Vertical falling film shell and tube heat exchanger
o Strips out ammonia and carbon dioxide from urea
and carbamate solution at urea reactor R-4101 outlet
Inlet
Outlet Gas
Outlet Solution
Flow rate
238 tons/hr
56 tons/hr
182 tons/hr
Urea
31%
-
42.43%
CO2
14.56%
36%
8%
NH3
32.46%
58%
14%
Moisture
-Balance-
-Balance-
-Balance-
TAG
E-4101
TEMA TYPE
BEM Special Class R
Number of tubes
2388
Shell Side Fluid
MS
Tube Side Fluid
Urea Solution
Tube Pitch
31.75mm
Shell Working
Temperature/Pressure
226 C / 26.5 kg/cm2
Channel working
Temperature/Pressure
203 C / 148 kg/cm2
Weight
80 Tons
TAG
E-4101
Tube Material
25Cr-22Ni-2Mo tubes 2mm
THK internally lined with
Zirconium 0.7mm THK
CS + 6mm 25Cr-22Ni2Mo overlay
Tubesheet Material
Channel Heads Material
Shell Material
CS + 5mm 25Cr-22Ni-2Mo
lining
SA-516/70
Bellow Material
SA-516/70
Ferrule Material
25Cr-22Ni-2Mo
VAPOR OUTLET LINE
8”-99A
SOLUTION INTLET LINE
8”-99A
STEAM INTLET LINE
12”-13A/14”-13A
LINE TO PSV
6”-13A
PASSIVATION AIR INLET
CONDENSATE OUTET LINE
8”-13A
SOLUTION OUTLET LINE
6”-99A
• New Titanium Stripper Installed at
Commissioning
1992-2006
• Rehabilitated Bimetallic Urea Stripper
from
Plant
I
2006-2016
♦ Leakage of carbamate to MS
was reported
♦ Leaking tubes were indicated
and plugged. Total 5 tubes were
plugged.
♦ Dome lining petal welds were repaired on both top and bottom
heads
♦ One leaking tube was plugged. Leakage was from a pinhole in
seal weld of an already plugged tube
♦ 200 damaged ferrules were replaced due to thickness loss at
insertion ends
♦ 1600 ferrules replaced due to deformation. Evidence of solution
bypassing across ferrules was observed in the form of etching of SS
tubes from Zr removed area
♦ Top and bottom head petal lining welds repaired.
♦ Lining of top and bottom dish ends found deteriorated
♦ Replacement of stripper recommended due to overall
deterioration of the equipment.
♦ Major concerns include:
• Corrosion at tube ligament areas
• Pinholes and cavities in TTS. 74 (30%) out of a sample of
250 tubes had pinholes and cavities in them
• Corrosion cavities in tube internal surface in HAZ of TTS
welds.
• Top and bottom head lining thickness loss
Top Head
TA-2008
TA-2010
TA-2012
S/D-2014
TA-2015
Manhole
nozzle neck
Top Dome
Petals
Barrel
9.93 mm
9.90 mm
9.90 mm
9.87 mm
9.26 mm
5.42 mm
4.92 mm
4.74 mm
4.49 mm
4.96 mm
5.03 mm
4.55 mm
4.53 mm
4.50 mm
4.83 mm
Bottom Head
TA-2008
TA-2010
TA-2012
S/D-2014
TA-2015
8.90 mm
Manhole
nozzle neck
Bottom Dome 4.91 mm
Petals
Barrel
4.71 mm
8.90 mm
8.76 mm
6.54 mm
8.81 mm
4.32 mm
4.30 mm
4.44 mm
4.42 mm
4.07 mm
4.07 mm
4.35 mm
4.17 mm
o
o
Observations warrant serious shutdowns if replacement not
carried out
Replacement essential for plant reliability
o
o
o
The lining thickness of top and bottom dish ends to be
increased from 5mm to 6mm, keeping in mind the history of
thickness loss at these points
Set of two weep-holes to be provided in all HP nozzles of the
new stripper to ensure flushing/repair maintenance
Tube pitch may be increased from 31.75mm to 34 mm to
for TTS joints to be made with 17mm protrusion
o
Tube Protrusion
increased from
7mm to 17mm
o
Weld overlay
thickness increased
increased from
10mm to 13mm
o
o
o
o
o
Bimetallic stripper chosen
Cost the main reason for choice over Omega Bond
PO has been awarded to AlfaLaval Olmi
Drawings awaited for final technical review.
The stripper has to be replaced in TA-2018 of plant II
(1)
o Removal of portion of 4th platform
o Erection of scaffolding in place of 4th
platform
Activity Timing
Pre-Turnaround
(2)
o Opening of MS inlet flange (N2)
Activity Timing
0-2hrs (2hrs)
(3)
o Cutting and Rigging of MS inlet line for
Tee installation
Activity Timing
2-6hrs (4hrs)
(4)
o Beveling of MS line 02 faces
Activity Timing
6-14hrs (8hrs)
(5)
o Opening of condensate outlet line (N9)
Activity Timing
6-8hrs (2hrs)
(6)
o PSV-41012 and associated line
removal
Activity Timing
6-10hrs (4hrs)
(7)
o Expansion bellow locking
Activity Timing
14-20hrs (6hrs)
(8)
o Opening and Cutting of Vapor
outlet line (N5)
Activity Timing
14-22hrs (8hrs)
(9)
o Removal of HV-41006
Activity Timing
22-30hrs (8hrs)
(10)
o Opening of Soln inlet flange (N1) and
rigging of lines
Activity Timing
30-34hrs (4hrs)
(11)
o Opening of solution outlet line (N12)
and LV-41011 removal
Activity Timing
22-30hrs (8hrs)
(12)
o Removal of Passivation air line and
holding clamp
Activity Timing
34-40hrs (6hrs)
(13)
o Removal of HT-41011 and LT-41011
Activity Timing
40-44hrs (4hrs)
(14)
o S/F adjustment at 4th platform for
rigging of stripper
Activity Timing
44-50hrs (6hrs)
(15)
o Rigging arrangements for stripper
Activity Timing
50-56hrs (6hrs)
(16)
o Removal of Stripper
Activity Timing
56-62hrs (6hrs)
(17)
o Rigging Arrangements for New Stripper
Activity Timing
62-68hrs (6hrs)
(18)
o Rigging of New Stripper
Activity Timing
68-74hrs (6hrs)
E
R-4101
E-4102 A/B
W
5,900
E-4103 A/B
S
N
E-4101
OPERATOR CABIN
11,800
MAIN
CRANE LOCATION
TRAILING
CRANE
10,500
E-4105
HEAVY PAVED AREA
5,500
11,300
11,000
Main
Crane
• 300 tons capacity
• Shall be contracted out
Tailing
Crane
• P&H Crawler Crane
• Available at plant
• 80 tons maximum capacity
Activity
Weight to be Lifted
Boom Point Elevation
Removal of stripper
80 tons
45m
Installation of Stripper
83 tons
45m
Activity
Operating Boom
Radius
Length
Boom
Angle
Load
Capacity
Safety
Factor
Stripper
Removal
40 ft
150 ft
77 degree
91.5 tons
14.5%
Stripper
40 ft
Installation
150 ft
77 degree
91.5 tons
10.2%
o New stripper will be transported on a Low Bed
Trailer on Saddle
o Old stripper will be transported similarly
(19)
o S/F adjustment for flanges installation
Activity Timing
74-80hrs (6hrs)
(20)
o Erection of Structure at top Manway
Activity Timing
80-92hrs (12hrs)
(21)
o Rigging of New Tee Spool
Activity Timing
92-96hrs (4hrs)
(22)
o Tacking and welding of MS inlet Spool
and box-up of MS inlet flange
Activity Timing
96-124hrs (28hrs)
(23)
o Beveling of vapor outlet line
Activity Timing
94-102hrs (8hrs)
(24)
o Tacking and welding of vapor outlet
line flange
Activity Timing
102-118hrs (16hrs)
(25)
o Box-up of vapor outlet line
Activity Timing
118-120hrs (2hrs)
(26)
o Solution inlet line rigging and boxup
Activity Timing
124-132hrs (8hrs)
(27)
o Installation of HV-41006
Activity Timing
132-144hrs (12hrs)
(28)
o Box-up of solution outlet line
Activity Timing
144-148hrs (4hrs)
(29)
o Installation of PSV 41012
associated lines
Activity Timing
132-136hrs (4hrs)
(30)
o Box-up of condensate outlet line
Activity Timing
146-148hrs (2hrs)
(31)
o Installation of passivation air inlet
lines and its holding clamp
Activity Timing
138-146hrs (8hrs)
(32)
o Installation of LV-41011, LT-41011
and HT-41011 associated lines
Activity Timing
148-160hrs (12hrs)
o Change of ferrule design to gasketed ferrules may
increase ferrule life that is currently limited by
bypassing
o Tentative replacement plan
o Plan to be finalized after receipt of drawings
o Increase in shell size may force a change in activity
activity chart