SCOPE
OF WORK
The
work shall include complete design, furnishing, delivery on Site, erecting
stack and foundation with independent steel flue liner and accessories in
accordance with Book II refers to “Summary of Work” and refers to Book IIIA,
section 4.4.1 “General
Civil and Architectural Design Requirements” including but not limited to the
following:
Complete structural
steel structure to support the flues including :
§
Exterior carbon steel ladders and
grating platforms.
§ All
embedment that support ladders, and platforms, doors.
§ Lighting,
lightning protection, and grounding in accordance with the Electrical
Specifications included.
Two Carbon steel
plate liners (except top section stainless steel liner), including:
§ Stainless
steel rain hood, complete with stainless steel stiffeners and framing and the
gas monitoring ports.
§ Carbon
steel stiffeners and splice plates for the liner.
§ Mineral
fiber insulation of liner, complete with fasteners, wire netting etc.
§ The
flues and ducts shall be provided in accordance with the Mechanical
Specification included.
CODES
AND STANDARDS
The Contractor shall comply with the
requirements of Book II, Subsection “Codes and Standards”.
The codes and standards of the
following organizations extracted from Book II, Subsection “Codes and
Standards” are specifically applicable to the design, manufacture and testing
of the work included in this Specification:
AA Aluminum
Association, U.S.A.
ACI American
Concrete Institute
AISC American
Institute of Steel Construction
ANSI American National Standards
Institute, Inc. (Formerly United
States of American Standards Institute)
ASTM American
Society for Testing and Materials
AWS American
Welding Society
JIS Japan
International Standard
UBC Uniform Building Code
Applicable Indonesian Standard and
Guidelines.
DESIGN
AND DETAILED REQUIREMENTS
GENERAL
The stack shall be designed to serve
satisfactorily under the conditions indicated in refers to “General Civil and
Architectural Design Requirements”.
The stack shall consist of a complete
support structure for liner and foundation, with 2 (two) barrels of inner
flues. The flues shall be connected with framed steel girders and beams for
platforms located approximately every 25 m in height. Connection between the
flues and the girders shall consist of a sliding hinge against vertical force
(thermal expansion of flue) and a fixed hinge against horizontal force (seismic
force).
DESIGN REQUIREMENTS
Contractor shall design the support structure steel
system and foundation to resist stresses due to all dead load, live load,
seismic load, and wind load.
Stack liners shall be designed to
resist possible chemical reaction, and all stresses due to dead load, seismic
load, thermal load, and flexural loads, including loads induced by lateral
restraints and stack draft.
The stack liner shall be bottom
supported and free standing above. The liner may be extended to rest directly
on top of the stack foundation.
Alternatively the liner may be supported
at the breeching level by on independent steel framing or on independent
structures supported by the foundation.
Thermal expansion of each flues shall
be insulated; insulation shall be independent of the support system.
Lateral supports shall be provided each
stack flue near the top of the stack and at each platform. Lateral supports
shall resist horizontal displacements of the flue, but shall permit vertical
and radial expansion.
The portion of flues at and above roof
shall be constructed of stainless steel as shown on the Bid Drawing.
Rain cap shall be adequately stiffened;
and, shall slope down from the flue to overlap the outside face of the roof and
at each flue opening to compensate for unequal expansion of dissimilar material
during operation. Cap shall not be prevented from moving relative to the roof
curb.
The bottom plate of the liner shall be
fully protected from any acid attack with acid resistant glass blocks over a
lead pan.
Drains shall be provided at the bottom
to discharge any effluent to a designated location at the base of the stack.
All materials used and their
installations shall be suitable for the service conditions and possible acid
build-up.
DETAILED REQUIREMENTS
The minimum internal diameter of the
stack at the top shall be 9.0 m.
The maximum opening width in the stack
liner for breeching duct shall be 2/3 of the shell inside diameter at the level
of the opening.
All openings greater than 50 mm
diameter shall be reinforced around the opening with an area of at least twice
the cut out area.
Insulation shall be completely cover
flues and all projecting elements. The Temperature of the exposed surfaces of
the insulation shall not exceed 600C at the operating expansion.
The flue liner shall be reinforced
using external stiffeners to give a rigid structure free from excessive
vibration under all operating conditions. The spacing between such stiffeners
shall not exceed 1.5 times the diameter of the liner or 8 m whichever is
smaller.
The minimum uncorroded liner plate
thickness shall be 6 mm.
An allowance of 1.5 mm thickness shall
be added to the computed thickness of the liner for corrosion.
Foundation shall be
supported by piles.
PERFORMANCE REQUIREMENTS
Stack shall be designed to produce a
minimum flue gas exit velocity of 30 m per second under the condition of
boiler operation with worst coal.
Stack shall be designed to produce a
required forced draft less than 50 mmAq at the breeching opening under the
condition of boiler operation with design coal.
Stack shall be designed for flue gas
flow and temperature characteristics specified in Table 4.4.2.13 - 1.
TABLE 4.4.2.13 -
1 EXHAUST GAS CONDITIONS
a.
Climate
condition
Ambient temperature 0C 32.8
Specific gravity of air 1.293
(at
0°C » 1,013 mb)
b. Exhaust gas
condition
ITEM
|
UNIT
|
WORST COAL
|
DESIGN COAL
|
Temperature
|
0C
|
130
|
126
|
Gas
volume
|
Nm3
/ h
|
410,000
|
396,000
|
(at gas temperature)
|
Nm3 /
sec.
|
113.9
|
110.0
|
Qq = m3 /
sec.
|
168.1
|
160.8
|
|
Specific gravity of gas (at gas
temperature)
|
Kg / Nm3
|
1.294
|
1.296
|
gg
= kg / m3
|
0.877
|
0.887
|
Gas
emission Dust
emission 0.046 t /
h
(Design coal)
Sulfur
dioxide 0.680 t /
h
Nitrogen oxide 0.189 t / h
Contractor shall guarantee that the
stack furnished will pass the specified flow rate with guarantee pressure loss.
DESIGN
LOADS AND LOAD COMBINATIONS
DESIGN LOADS FOR SUPPORT SYSTEM
The support system, ladders, platforms,
frames, embedded steel, inserts etc. shall be designed to resist the following
applicable loads acting upon them:
Dead Loads
Dead loads shall include the actual
weights of support system, platforms, doors and other accessories and shall
include the weights of liner, lining, breechings and other items supported by
the stack.
Live Loads
Live loads shall include basic live load
and construction loads. Each platform shall be designed for a minimum live load
of 350 kg/m2.
Wind Loads
The design wind pressure shall be equal
to the wind velocity of 120 km/hour, and other requirements in accordance with
American National Standards Institute (ANSI) A58.1-1982.
Wind pressure distributed around the
support system causes ovalling of stack horizontal sections, and produces
circumferential stresses which are added algebraically to the circumferential
temperature stresses. The wind-induced circumferential stresses shall be
calculated as specified here in.
Temperature Stresses
The vertical and circumferential
temperature stresses shall be calculated as specified here
in.
Seismic Loads
Zone of seismic for obtaining seismic
loads shall be as specified in the latest Indonesian Earthquake Standard
published by Ministry of Public Work. Detailed calculation of seismic load
shall be based on codes lates edition.
Minimum Load Combination
The minimum loads combined used in
design shall be those producing the maximum stresses based on dead loads, live
loads and temperature occurring inside the stack, combined with wind or seismic
forces, whichever are greater.
The stresses due to wind ovalling
effect on stack shall be considered alone, and shall be combined with
circumferential temperature stresses in checking the design of stack horizontal
sections.
DESIGN LOAD FOR STEEL FLUE LINER
Normal Loads
Dead Loads (D)
Weight of the structure, insulation,
flues and duct, platform, attachment etc.
Live Loads (L)
These shall include the following :
Operating Pressure Load (Pa)
Applied external and internal air or
gas draft pressures during normal operating conditions.
Operating Thermal Load Effects
(Ta)
The most critical transient or steady
state thermal condition associated with the Operating Pressure Load which may
take place in different modes of operation.
Abnormal Loads
Abnormal Pressure Load (Pa)
Applied external or internal air or gas
draft pressure. This excursion pressure may take place due to boiler, fan or
damper failure.
Abnormal Thermal Load (Ta)
The thermal effects associated with the
Abnormal Pressure Load, Pa.
Severe Environmental Loads
Wind Load (W)
Wind loading shall be based on a wind
velocity of 120 km/hr per ANSI A58.1, exposure type D and appropriate shape
factor. The wind will be induced to the liner by the deflection of the stack
shell.
Seismic Load (E)
Seismic loading shall be as indicated
in Clause above. The seismic loads will also be induced to the liner by the
deflection of the stack support system.
Minimum Load Combinations
The minimum load combinations used in
the design of the stack liner shall be in accordance with Table 4.4.2.13 - 2
and the following:
Any load, other than dead load, shall be deleted from any
load combination if the effects of the combination are more severe without the
load.
For a liner in tension under construction and severe
environmental loadings, 75% of the dead load shall be used.
TABLE
4.4.2.13 -2 STEEL LINER LOAD COMBINATIONS
LOAD
COMBINATION
|
LOAD FACTOR
|
ALLOWABLE
|
|||||||||
Normal
|
Severe Environ-mental
|
Abnormal
|
|||||||||
D
|
L
|
Po
|
To
|
W
|
E
|
Pa
|
Ta
|
||||
Lf
|
Lm
|
||||||||||
Construction
|
1
|
1.0
|
1.0
|
1.0
|
1.5
AISC
|
||||||
Normal
|
2
|
1.0
|
1.0
|
1.0
|
1.0
|
1.0
|
0.25
|
1.33 AISC
|
|||
Severe Environmental
|
3
4
|
1.0
1.0
|
1.0
1.0
|
1.0
1.0
|
1.0
1.0
|
1.0
1.0
|
1.0
|
1.0
|
1.5
AISC
1.5
AISC
|
||
Abnormal
|
5
|
1.0
|
1.0
|
0.25
|
1.0
|
1.0
|
Note-1
|
||||
Note-1 :
Should be lesser of 1.6 AISC or 0.95
Fly for flexure; 0.95 Pcr. For compression (where Pcr is either elastic or
inelastic buckling whichever governs); 0.95 Fly/11.732 for shear.
SERVICE
CONDITION
The exhaust gas from the precipitator
into the stack will have the following approximate characteristics:
INPUT
Preliminary full load flue-gas flow
rate of 396,00 Nm3/h at 1260C and a velocity of 30
m/second. This will be confirmed during contract negotiation.
PRIMARY FUEL
Bituminous coal with a sulphur content
varying from 0.4% to 0.9% and a moisture content varying from 23.6% to 28.3%.
MATERIALS
GENERAL PROVISIONS
Unless otherwise indicated, structural,
architectural and miscellaneous materials shall be accompanied by
manufacturer’s certifications indicating that the materials meet the specified
requirements.
METAL AND EMBEDDED MATERIALS
All grating platforms and ladders of the stack shall be
carbon, hot dip galvanized in accordance with Technical Specification
Miscellaneous and embedded metal work.
Twisted closed-end type grating shall
be used and shall have minimum thickness 36 mm for operating floor, 32 mm for
floor, catwalk for crane access and platform, and 25 mm for stread of stair.
Ladders shall be vertical, not more
than 20 m long between rest platforms and with safety cage for full height.
Steel ladders, access platforms, and
miscellaneous steel secured to stack shell, shall be anchored thereto by means
of individual threaded inserts and anchor bolts.
The liner plates and other structural shapes shall conform
to the minimum requirements of Table 4.4.13 - 3 or approved equal.
TABLE
4.4.13 – 3
LINER PLATES AND OTHER STRUCTURAL
SHAPES REQUIREMENTS
ITEM
|
STANDARD
|
ADDITIONAL
REQUIREMENTS
|
(1)
Carbon Steel Liner Plates, structural
Shapes and Stiffeners
|
ASTM
A36
|
|
(2)
Stainless Steel Plates for liner,
rainhood and coping top.
|
ASTM
A240
Type
316L
|
Hot rolled,
annealed and pickled
|
(3)
Bronze Lubricated Bearing Plates with
Graphite Plugs, for sliding support.
|
ASTM
B22
Copper
Alloy
No.
911
|
3.1 Lubricated bearing plates for the duct
supports on stack shell shall have an allowable bearing value of 220 kg/cm2
(minimum) at a temperature of 4000C with a coefficient of
friction 0.15.
3.2 Plugs
shall be located on only one side of bearing plates and the plug side shall
be coated with graphite.
|
(4)
Anchor Bolts for support
|
ASTM
A36 or
ASTM
A193,
Grade
B7
|
Maximum bolt
diameter 62 mm.
|
(5)
Connection Bolts for supporting steel
|
ASTM
A325,
Friction
Type
|
All bolts shall
have a diameter of 22 mm unless otherwise indicated.
|
LINER INSULATION
Fiber-glass or equivalent insulation
shall be provided on all external surface of steel flues. Insulation material
having 50 mm in thickness shall be firmly affixed on the flues by means or 3.5
mmÆ nelson type studs, and shall be covered by 20# x 26 mm wire
mesh. The characteristics of insulation shall be as follows.
- Heat
transmission ratio : = 0.025 + 0.00018 Qg
- Heat
durability : more than 1300C
- Lagging : aluminum sheet 0.5 mm in thickness
FABRICATION
AND CONSTRUCTION
TOLERANCE AND MEASUREMENTS
Tolerance
Vertical Alignment: The stack shall be
constructed vertically and the centerline of the stack shall not to exceed the
following:
a.
Locally:
± 12 mm in any typical 2.2 of lift height, or a maximum of 25 mm differential
offset between any successive lifts.
b.
Overall:
± 25 mm in any 16 or 1/1800 of the stack height, with a combined maximum total
displacement not exceeding 75 mm.
Measurements
Contractor shall take all measurement and shall record them
in the “Stack Measurements Record”. This completed form shall be submitted to
Owner daily, prior to placing concrete.
All measurements shall be taken during
shell construction, at each lift at approximately the same time each day,
during the morning hours (7:00 AM to 10:00 AM), if at all possible. If the
measurements for any day cannot be taken during these hours, Contractor shall
verbally notify Owner’s representative on the site for resolution of this
deviation, and shall also confirm this notification in writing the same day.
Any resolved deviation shall be properly recorded in this “Stack Measurements
Record” Form.
Measurements for Vertical Alignment
a.
Vertical
alignment from top to base using a plumb bob or other suitable means shall be
taken before moving formwork from each lift.
b.
Vertical
alignment from top to base shall also be taken after formwork in moved to next
level and before making next pour.
Additional
Data
The following additional data shall be
included in the form “Stack Measurements Record”:
a.
The
elevation of the flue liner each pour and elevation of the top of the next part
of the flue liner for identification of the levels.
b.
A
cross-section of the stack showing the positions of the diameters measurement
azimuths in the circumferences.
c.
Time
at which the measurements is taken
d.
Weather
condition at the time of measurement, especially azimuth of sum is out,
temperature and wind speed and direction.
WELDING
Welding
for the fabrication and erection of the insulated steel liner work shall
conform to the ASW D1.1 requirements and Technical Specification 4.4.2.20,
unless otherwise indicated.
Extent
and Type Welding
The steel liner
work shall be of all welded construction, except where bolted connections are
required.
Complete
penetration groove welds shall be used for all vertical and horizontal joints
of main liner plates. When only one side of the liner plates is accessible, but
welding at one side with backing strips may be used. Intermittent groove welds
will not be permitted.
Fillet
welds may be used in areas that are not subject to primary stresses, such as the rainhood,
breeching, ring stiffeners accessories etc.
Welding of Joints
The location of liner vertical joints shall be staggered.
Liner vertical joints
shall be welded before horizontal joints to avoid undue stresses and
distortions due to welding
Plates to be welded shall be matched
accurately and retained in position during welding operation. Misalignment in
completed vertical joints shall not exceed 20 percent of the plate thickness or
1.5 mm, whichever is the larger. The maximum offset in horizontal joints shall
not exceed 20 percent of the thinner plate thickness at the joint, with a
maximum of 3 mm, except that a maximum misalignment of 1.5 mm is permissible
for plates thinner than 8 mm.
The reinforcement for butt welds shall
not exceed 3 mm. The surface of the weld shall not be below or indented from
the surface of plates being jointed.
Welding of Stainless Steel
Shall performed with an interpass temperature not exceeding
1770C. ferrite contents of electrodes shall be 5 to 15 percent as
determined from the chemistry of the electrodes.
Surface preparation and other welding requirements shall
conform to the stainless steel manufacturer’s recommendations. Hard, brittle
martensitic weld is not acceptable.
Weld Cleaning
Shall conform to the applicable
requirements of AWS D1.1 Structural Welding Code and to the following:
a.
Where
joints are welded manually, tack welds used in the assembly of vertical joints
of liner shells shall be removed, unless otherwise indicated.
b.
When
the submerged arc process (for shop fabrication only) is used, tack welds need
not be removed provided that are sound and are thoroughly fused into the
subsequently deposited weld metal
c.
Tack
welds in the bottom, roof and circumferential joints of the liner shell need
not be removed if they are sound and are thoroughly fused into the subsequently
deposited weld metal.
STEEL FABRICATION
Fabrication of the curved
steel liner plates and other structural steel shall conform to the requirements
of Technical Specification ”Design and Fabrication of
Structural Steel”, unless otherwise indicated.
Contractor shall be responsible for
measuring and verifying the dimensions of the stack at the top before
fabricating the stack liner rainhood to ensure proper fit of the liner to the
stack. Any measurements which varies from the stack dimension indicated on the
design drawings shall be reported to Owner immediately.
Fabrication workmanship, straightening
of materials, finish of plate edges, shaping of shell plates and material
shipping shall conform to the applicable requirements of AISC Specification for
the design, Fabrication and Erection of Structural Steel for Buildings.
STEEL ERECTION
Detailed Requirements
Steel erection shall conform to the
requirements of related Technical Specification “Erection
of Structural Steel”, unless otherwise indicated.
The method and sequence of erection and
the details of temporary supports that Contractor proposes to use for the Work
shall be submitted to the Engineer, no later than 60 days after award of
Contract unless otherwise indicated.
Extra holes for erection purposed, made
in liner and other plates, shall be filled after use, with weld metal for small
holes and shall be removed by replacing the plates with materials meeting
specification requirements for large holes.
Temporary lifting lugs shall be placed
preferably on the interior side of a steel liner plate. After erection, these
lifting lugs shall be removed by burning off not closer than 6 mm from the
liner plate and grinding down flush with the liner plate. If lifting lugs are
placed on the exterior side of the steel liner plate, they shall be removed by
burning off not closer than 6 mm from liner plate and covered with the
specified insulation of required thickness, unless otherwise indicated.
Erection Tolerance
Out-of-Plumbness
The total out-of-plumbness (the maximum
displacements of the actual vertical center line from the theoretical vertical
center-line of the liner) shall not exceed one thousandth of the liner height.
The vertical misalignment in any 3 mm
height of liner shell shall not exceed 6 mm.
Overall Out-of-Roundness
The difference between the actual
maximum and minimum liner inside diameters shall not exceed 1% of the nominal
inside diameter at any cross section after erection, except at the opening,
where the difference may be increased to 2% of the nominal diameter of the
opening.
Local Out-of-Roundness
Local deviations from a true liner
circular from shall not exceed the minimum liner shell thickness at any cross
section.
Weld Reinforcement At Welded Horizontal
Seams
Shall not exceed 3 mm from liner
surface as specified in AWS D1.1, unless otherwise indicated.
Measurement And Recording
Contractor shall measure and record the
liner alignment and circumferential dimensions at every horizontal joint of
liner.
A copy of the measurement record shall
be submitted daily to the Owner. The temperature, weather conditions, wind
speeds and direction and the time of measurement shall be recorded.
INSULATION INSTALLING
Cleaning of Lines
The liner plate and breaching surfaces
shall be cleaned at locations where welding pins (insulation holding pins) are
to be fastened. This cleaning shall be done by wire bushing, peening,
prick-punching or grinding to remove any scale, rust or other injurious material,
just prior to welding of the pins.
Blanket Insulation Installing
Insulation
holding pins shall be welded to the liner plates and breechings at maximum
spacings of 450 mm on centers horizontally and 300 mm on centers vertically.
Not less than 10% of the pins shall be verified and tested by Contractor for
soundness of welds.
Insulation shall be impaled over the
pins and a speed washer shall be driven home over each pin to hold the
insulation in continuous contact with the liner plate. Care shall be exercised,
however, not to reduce the thickness of insulation by stretching or squeezing
the insulation or by excessive driving of the speed washers. All edges of
insulation shall be tightly butted to ensure complete continuity of insulation
at all joints and to ensure a complete blanket of insulation continuous over
the entire area of the liner and breeching. The use of adhesives of any kind
will not be permitted.
Wire netting shall be applied over the
insulation and shall be continuous around the liner and breeching. All joints
in netting shall be lapped minimum 150 mm and either wire tied or secured to
the pins by speed washers. Wire ties, if used, shall be 1.58 mm diameter
galvanized soft annealed wires. Laps in netting must be tied not greater than
150 mm on centers, or secured under speed washers, lacing of tie wires will not
be permitted. Tie wires shall be bent down or out of way to a safe position.
The second speed washer (over each pin) shall be driven home to hold then were
netting securely in position. Care shall be exercised not to reduce the
thickness of insulation by excessive driving of this second speed washer. Excess length of a pin shall be bent over and
shall not be cut.
CLEANING
AND PAINTING
Cleaning and painting shall conform to
the applicable requirements of related Technical Specifications and to the
requirement that the following materials shall be properly cleaned but shall
not be painted unless otherwise indicated.
Galvanized Steel
Stainless Steel
All other Nonferrous Metal
The supporting steel, such as beams,
columns, bracings etc. shall be cleaned and painted in the shop in conformance
with the applicable requirements of related Technical Specification for Prime
Coat Painting and Field touch-up painting shall be provided for supporting
steel.
The steel liner plates, breechings and
their stiffeners shall be cleaned and prime coat painted or coated with rust
preservative suitable for the sea water environment.
INSPECTION
AND TESTING
GENERAL PROVISIONS
During the course of the Work and after
its completion, Contractor shall be responsible for all inspection and testing
works as required or as needed, unless otherwise indicated. Owner may, during
the course of the Work, observe the various phases of the Work at Contractor’s
plant and at the Site, for full compliance with all requirements of this
Specification and the design drawings. Contractor shall provide conveyance
between ground and stack top at all times for inspection and observation purposes.
INSPECTION AND
TESTING OF STEEL WORK
Shall conform to applicable
requirements of Technical Specifications of ‘Design and Fabrication of
Structural Steel’ and ‘Erection of Structural Steel’.
INSPECTION AND EXAMINATION OF WELDING
Shall conform to applicable
requirements of Technical Specifications of ‘Welding in Steel Structures’.
INSPECTION OF BOLTING
Shall conform to applicable
requirements of Section 6 of AISC Specification for Structural Joints using
ASTM A325 or A490 Bolts.
Shall
conform to applicable requirements of Technical Specifications.