This document describes the methods proposed to be used for the erection operations related to the air cooled condenser for any kind of plant project.
Method statement identifies the general steps, arrangements and precautions for the assembly and erection works of ACC.
This method statement also defines piping erection of all control equipment at the site which is developed for installation of steam condensed piping, extraction, cleaning systems and instrumentation.
ACC consists of modules with fan units and associated equipment which will be erected on top of the steel structures.
Scope of the ACC starts from the turbine exhaust steam turbine outlet with the main steam duct, which feeds to the Air Cooled Condenser (ACC). The latter is equipped with drain pot that collects the condensate to the condensate tank.
The steel structure will be erected at site according to the ACC Construction Manual, by means of crane and/or certified lifting equipment utilizing equipment specified, with competent personnel.
Works will also include the erection, installation and alignment of equipment above the steel structure as follows:
- fan screen and stack,
- motor bridge with drive and blades/impellers,
- condensate and steam manifolds,
- bundles (heat exchangers),
- associated steel structures,
- pipe works for steam recovery,
- and other amenities for access and walkways necessary for maintenance
The sequence of construction shall be by taking into consideration to specific requirement on the erection of condensate tank, steam ejectors and associated equipment which will be located with separate steel structure beneath the module as per the project drawings.
Scaffolding will be required during the duration of the works.
Scaffolding shall be inspected by HSE before work starts.
Periodic scaffolding inspection will be required.
HSSE Requirements
All works shall be in compliance with local laws and regulations, and International standards/codes, and client and contractor requirements and instructions.
All personnel will go through safety induction courses as well as other trainings as identified by their supervisor.
A Job Safety Analysis (JSA) specific for this work including a Risk Assessment is prepared and is attached for reference and implementation during the works. Such JSA addresses the hazards associated with each task within the scope of this Method Statement and introduces the controls that will be implemented to reduce the associated risks to acceptable levels.
The JSA will be used by the Site Supervisor as the basis of his TSTI / TSTO and Toolbox Talks.
All personnel will have PPE required for their specific tasks in addition to the minimum PPE (coveralls, safety goggles, safety shoes, high-visibility vests, gloves, double lanyard full body harness) at site at all times as required.
In the event of a release, fire or explosion, employees will secure their area and evacuate to the nearest muster point.
Once all employees are evacuated the supervisor will conduct a headcount to verify all employees are out of danger.
The supervision will report this to Contractor Emergency Contact numbers for client, contractor and consultant will be posted onsite.
All vehicles and equipment used for the subject work will be inspected and certified as required.
Drivers and operators will be competent and will have attended all required trainings set forth in the project procedures and specifications.
Abbreviations and Definitions
QCP: Quality Control Procedure
ITP: Inspection and Test Plan
QA/QC: Quality Assurance / Quality Control
HSSE: Health, Safety, Security and Environmental
JSA: Job Safety Analysis
SDM: Steam Distribution Manifold
CCM: Condensate Collecting Manifold
SS: Site Supervisor
ACC: Air Cooled Condenser
PTW: Permit to Work
LP: Lifting Plan
RA: Risk Assessment
NDT: Non-Destructive Test
TSTI: Total Safety Task Instruction
TSTO: Total Safety Task Observation
PPE: Personnel Protection Equipment
References and Codes
- ASME B 31.3: Process Piping
- ASME Sec II: Specification for Welding Rods, Electrodes & Filler Metals
- ASME SEC. IX: Welding And Brazing Qualification
- ASME SEC.V: Non Destructive Examination
- Technical Specification Steel Structures
- Piping General Requirements
- Specification For Traceability, Alloy Verification And Material Substitution
- Quality Control Requirement For Welding
- HSSE Plan Construction
- General Layout Plan Air Separation Plants
- General Arrangement Drawing
- Piping Tie-In Drawing And List
- Piping Layout – Condensate Piping
- Piping Layout – Air Take Off System
- Piping Layout – Cleaning System
- Support Condensate Piping
- Support Drain Piping
- Cleaning Water Piping
- Arrangement Steam Duct
Roles and Responsibilities
Site Manager will provide overall inputs to the project execution plan to ensure that strategies & philosophies of the project are properly addressed.
Mechanical Erection Manager is responsible for the overall management of the Project Construction team to ensure that safe and effective operations are conducted and properly documented.
Site Engineer is responsible for safe execution of the whole job including:
- Confirming the installation location from schedule of approved construction drawings.
- Organizing of equipment’s and tools needed for the job.
- Assigning skilled personnel for the job.
- Sequence of activities to be carried out for the work as per this method of statement.
- Conduct inspection and surveillance.
- Notify to Contractor engineer for inspection as applicable.
- Ensure that all Contractor and Company regulations are followed.
- Ensure that all personnel involved are in safe working condition at all times.
Site Supervisor (SS)
Site Supervisor is responsible for safe execution of the following activities:
- Conduct TSTI with the concerned work force prior to start of work.
- Ensure that relevant work permits for the job are obtained prior to start of work.
- Conduct daily toolbox talks for the entire work force prior to start day work.
- Assigning a competent work crew for specific activities, details of activities and task information will be given to the work crew.
- Organizing tools and equipment needed to the work site.
- Inspection and supervision of work.
- Ensure that all Contractor and Company safety regulations are followed as applicable.
Piping Supervisor (PS) is responsible for the erection of pipes that will be performed in accordance to the method of statements.
Artisans: Group of skilled and semi skilled workers who will be responsible for the execution of works and other jobs related to the completion of construction of ACC.
QA/QC Officer / Inspector
QA/QC Officer/Inspector is responsible for:
Inspecting and Certifying of all foundations, alignments, etc. will be in coordination with the contractor representative as per conformance of the specifications.
Assurance that approved methods and materials are being used and conformance of the specifications.
Stage inspections and surveillance in accordance with ITP and assurance of quality of work as per specification and erection procedures.
Incoming material inspection and review of test certificates.
Equipment & Manpower
All equipment will be inspected and approved by the Contractor, when required, and all personnel will be inducted and trained before and during mobilization.
Equipment
- Crane – (1) each for 250 T, 120, 100 T, 80 T, 70 T and 50 T lifting capacities hydraulic or crawler type will be utilized
- Forklift – 15 and 5 T capacity
- Boom Truck – 5 T capacity
- Aerial Work Platform (man lift equipment) – capable to 45 meters reach, (2) numbers either telescopic and /or folding hydraulic type
- Man basket for 3 persons
- Trailer – for transport of materials from lay down area to assembly site
- Rigging and lifting equipment – approved, certified and color -coded
- Scaffolding – as per requirement
- Gas cutting torch with arrestors and welding machines
- Grinding machine with correct grinding wheels and tool speed
- Survey and level instruments
- Portable diesel generator and portable lights – to service night works
- Hilti DX 76 – Fastening tool
- Air compressor
- Hand and electric tools – Note: No prefabricated tools will be allowed and shall be in good working order
- Paints and accessories – Only for repair and touchup
Manpower
- Management
- Site Engineer
- Foreman
- HSSE personnel
- Certified Crane operator
- Certified Forklift operator
- Certified Articulated man lift operators
- Banks man and slingers
- Erectors
- Mechanical fitters
- Scaffolders
- Fire watchers
- Associated vendors
- Driver
If the above-listed equipment or manpower proves not sufficient for the timely completion of the facilities and project; additional will be provided to complete the works on time and in line with rules, regulations and specifications of contractor and client.
METHOD OF EXECUTION / SEQUENCE OF WORKS
This section explains the methods to be used for the erection of all structural steel works, piping and duct works, installation of air cooled condensers with associated equipment, and steam recovery at the site.
Pre-Commencement Works
Foundation Seats
Prior to works commencement, all seating foundations are checked for load bearing of all steel erection as per approved drawings issued by the vendor or the company.
Any deviations as per plan will be recorded and served as guideline during the execution of works and shall be within the tolerances recommended by the manufacturer.
Survey report on the main level references from civil will be generated and submitted before start up of construction to anticipate problems which can be encountered during construction and alignment stages.
Any deviations from the general arrangements, drawings shall be identified.
Logistical Materials and Equipment
Materials and equipment required for entire duration of works shall be available nearby and checked.
Lay down area for materials and equipment shall be located in such a place that double handling can be minimized or can be totally eliminated.
Due to space limitations at the assembly area, a minimum supply of materials or structures for at least three days will be maintained to assure continuous works without interruption.
This will also reduce risk for possible damage and distortion of materials from handling and during assembly
All the lifting procedures will be followed as per lifting plan.
Scaffolding will be provided and erected as per separate method of statement and PTW (permit to work) will be initiated before any works can commence.
The use of scaffoldings will only be at selected area where height and space have some limitations example as: pipe installation and welding works inside the A-frame with bundles structures, piping below the fan deck; installation and connection of condensate duct from turbine to the SDM.
Barricades and safety Sign Boards
All work areas are to be secured, barricaded, and posted with signboards indicating that works are in progress, and lifting operations are being conducted.
Only authorized personnel’s will be allowed to work within the perimeter.
All barriers will be kept in place during the progress of works, and/or until the works are completed.
Positioning and Lifting Equipment
Lifting and related equipment will be in position only by certified operators and banks man; ground foundation checked for stability before setting up the outriggers or tracks.
Correct color coded and certified slings are to be used only.
Aerial work platform/man-lift and construction cages are to be used for certified erectors.
When construction cages are being provided, dead man’s control & inspection certificate will be presented.
The personnel must rope themselves into the cage.
The cage must be suspended in an insulated manner when welding work is to be performed from the cage.
It is necessary to determine more or less the weights of the following sub-structures or equipment due to limitations on space and height at the assembly area for its respective lift, and they are as follows:
The assembly of two adjoining columns and braces (Step 1)
| Member Part no. Description Wt. No. Total Wt.
1 A0080123 Column 1 1864.4 2 3728.8 2 A0087913 Column 1 1920.8 2 3841.6 3 A0088074 Column 1 1164.4 2 2328.8 4 A0087511 Hor. Bracing 727.836 1 727.836 5 A0087512 Hor. Bracing 554.345 1 554.345 6 A0087506 Hor. Bracing 924.12 2 1848.24 |
|
| Weight of two adjoining columns & braces | 13029.621 Kg |
Note: This shows how weight of the steel structure is calculated.
Assembly of two adjoining columns & braces (Step 2)
| Member Part no. Description Wt. No. Total Wt.
1 A0087709 Column 1745.3 1 1745.3 A0087701 Column 1745.3 1 1745.3 2 A0088079 Column 1838.4 1 1838.4 A0088025 Column 1838.4 1 1838.4 3 A0088074 Column 1164.4 2 2329.8 4 A0087511 Hor. Bracing 727.836 1 727.836 5 A0087512 Hor. Bracing 554.345 1 554.345 6 A0087506 Hor. Bracing 924.12 2 1848.24 7 A0080136 Hor. Bracing 312.166 2 624.332 8 A0087493 Hor. Bracing 312.166 2 624.332 9 A0087495 Hor. Bracing 330.493 2 660.332 |
|
| Weight of two adjoining columns & braces | 14536.617 Kg |
The motor bridge with drive unit
| Member Part no. Description Wt. No. Total Wt.
1 A0087898 E. Motor 1700 1 1700 2 A0086149 Gearbox 1400 1 1400 3 A0091415 Motor Bridge Complete 5102.812 1 5102.812 Motor Bridge consists of the following: A0091417 Railings A0091360 Gear Support A0091352 Transversal Beam A0091358 Transversal Beam A0091357 Transversal Beam A0091398 Press Lock Grating A0091396 Press Lock Grating A0091395 Press Lock Grating A0091393 Press Lock Grating A0091394 Press Lock Grating A0091397 Press Lock Grating A0091399 Press Lock Grating 4 A0075068 Fan Impeller 126.88 7 888.16 |
|
| Wt. of Motor Bridge & Structure | 9090.972 Kg |
One section of A-frame
| Member Part no. Description Wt. No. Total Wt.
1 A0080285 A Frame 1568 2 3136 2 A0080291 A Frame 820 2 1640 3 A0080280 A Frame 2322.5 2 4645 4 A0080330 Bracing 260.215 8 2081.72 5 A0084581 Top Girder 938.37 1 938.37 6 A0088149 Top Girder 689.2 1 689.2 7 A0080320 Hanger 55.267 2 110.534 8 A0080316 Monorail 195.4 2 390.8 9 A0080302 Top Steam Header 237.63 1 237.63 Support Beam 10 A0080309 Outrigger 69.138 2 138.396 11 A0089231 Outrigger 61.81 2 123.62 12 A0089232 Outrigger 63.423 2 126.846 13 A0080338 Bracing 2 33.801 14 A0091097 Sealing Beam 95.801 1 95.801 15 A0091096 Sealing Beam 95.801 1 95.801 16 A0091101 Sealing Beam 95.801 1 95.801 17 A0091100 Sealing Beam 95.801 1 95.801 |
|
| Wt. of A Frame | 14675.121 Kg |
The sections of SM (Steam Manifold)
| Member Part no. Description Wt. No. Total Wt.
1 A0080519 Spool 5420 1 5420 2 A0080520 Spool 4700 1 4700 3 A0080521 Spool 3700 1 3700 4 A0086422 Spool 3650 1 3650 5 A0080522 Spool 3323 1 3323 |
|
| Wt. of steam Manifold | 20793 Kg |
- One assembly of support and parallel beams at the upper deck
| Member Part no. Description Wt. No. Total Wt.
1 A0079847 Longitudinal Beam 328.664 2 657.328 2 A0079904 Longitudinal Beam 328.664 2 657.328 3 A0079900 Fan Deck Cross Beam 102.318 4 409.272 4 A0079896 Diagonal Beam 180.388 2 360.776 5 A0079898 Diagonal Beam 270.831 2 541.662 6 A0079904 Parallel Beam 225.28 2 450.56 7 A0079902 Parallel Beam 187.849 2 375.698 8 A0092946 Spring Support Beam 68.225 1 68.225 9 A0089654 Spring Support Beam 68.225 1 68.225 10 A0084106 Beam 21.705 1 21.705 A0082543 Beam 21.313 4 85.252 A0082456 Beam 21.313 4 85.252 A0084105 Beam 21.704 1 21.704 A0081962 Beam 472.99 1 472.99 11 A0089614 Column Head 520.149 2 1040.298 12 A0089588 Support Beam 85.534 1 85.534 A0089516 Support Beam 128.704 1 128.704 A0086912 Support Beam 171.993 1 171.993 A0079878 Platform End Profile 751.931 1 751.931 A0098394 Support Beam 274.061 1 274.061 A0086912 Support Beam 171.993 1 171.993 A0086911 Support Beam 128.704 1 128.704 A0086973 Platform End Profile 151.769 1 151.769 |
|
| Wt. of Fan Deck Structure | 7180.964 Kg |
Lifting of structures/members & equipment to the upper deck will be performed by the 250 T / or 120 T crane with counter weights.
For any single lifts greater than 10 Tons, individual rigging plans shall be provided and approved before lifting can commence.
Lifting procedures will be followed as per lifting method of statement documents.
Avoid related equipment operate over or near pre-installed and covered lines. Ensure such equipment access lifting area through identified access ways.
Avoid related equipment cause over settling of concrete pits resulting shears at the grip pipe connections.
Following the lifting operations, ensure proper condition of any nearby underground piping (with video cameras if necessary).
Main Erection Sequence of Work
Under Structure Erection
Two vertical column frames will be assembled on the ground, will be erected on the foundation plinths, using two cranes; and will be stabilized with 20 mm diameter wire ropes as temporary supports for verticality.
Minimum of two set of cables of hand operated winch will be used to serve as guy ropes for stability.
The bigger crane (100 T) will lift the load and the smaller one (80T) will support the tail load during mounting the structure to vertical position.
Temporary supports (ropes) will not be removed until twin column is erected and horizontal bracings and other diagonal braces are secured or bolted in; continue until one line/street is completed.
Proceed to erect the sub structures at the upper deck. The first street will be levelled and aligned before connecting any steel structures of another street.
Final bolt torque should be completed after thorough inspection has been performed and found acceptable, and they are to be color–coded indicating that bolts are properly checked and correct torque is applied.
All erection works will be done by competent and certified erectors, and banks man for all lifting operations.
Grouting will be done on steel structure foundation with approved materials as per site specifications after complete alignment and acceptance of fan deck assembly of each street.
See illustration for similar installation for a similar project by different agencies:
Upper Structure/Fan Deck Erection Method
The peripheral beams of the fan deck will be assembled on the ground and installed to form the support structure; assuring that all bolts are tightened correctly.
Temporary detachable railings will also be integrated and fixed to the structure prior to lifting, as safety measure for people to work at the upper deck later.
Aerial work platform (AWP) will be used by the erectors in connecting the structure to the built columns.
Proceed until the whole street is completed forming a complete working table.
Wherever necessary, man lifts will be also be used.
Inspection for the elevation and verticality will be done after it is determined and conditions are acceptable within the given tolerances.
It will serve as a guide or reference in foregoing installation of equipment and structure to the adjacent streets
After completing the erection of the fan deck structures at street 3, erect the columns and steel structures at N module of street 4 (south corner). Stairs and walkways will be assembled and will serve as access going to the fan deck or upper structure.
This will provide some leeway of maximizing the utilization of man lifts to other area and eliminate expensive scaffoldings.
One bracing is required to be temporarily removed to allow installation of condensate tank and steam evacuation unit.
Note: It is not permitted to proceed with erection of other equipment’s as motor bridge, A-frame, CCM and SDM until completion of condensate tank and steam evacuation unit and installation of temporarily removed bracing is complete
Deck plates and gratings are to be secured by Hilti fastening tool; catch nets to be provided and laid out on the fan deck screens to prevent materials, etc. from falling and other safety reasons.
Catch nets specification: PE or Polyester or PP perimeter debris netting for construction industry (Mesh size 2.5 x 2.5 mm, width 2000mm) subject to approval by client.
Subject to prevailing conditions at site, an alternative scheme can be devised to be able to install the fan deck plates at the fan deck structure.
After erecting the fan bell with screen into the structure, platform openings can only be closed by fan deck plates during the course of construction, hence additional safety measures for people working at height is mandatory.
Additional lifelines aside from the proposed will be provided i.e., lines installed midpoint from each cell. The latter will be used for people to be positioned inside the fan bell assembly during the laying out & fastening the fan deck sheets into the structure. They will be assisted by a third person riding in the man lift.
Lifting of the fan deck plates will be done according to approved procedure.
Lifting ACC fan deck plates & plate clamps lifter will not be allowed to be used.
The Sequence will be repeated until the cell is covered by deck plates.
See illustration for similar installation by other agencies:
Erection of Fan Screen and Fan Ring
These foregoing activities can commence in parallel with the above sequence.
Sectional screens will be pre assembled at ground level with timber cribbage or fabricated supports below the corresponding location or module where they will be lifted into their final position.
Each section will be supported underneath and levelled to prevent distortion and possible damages on the wire mesh during the assembly of the fan stack or bell.
Fan stack segments will be assembled on top of assembled fan screen.
After the guard grill is pre-assembled, the stiffening plates need to be installed on the connection plates on the outside edge from the guard grill. Here the fan bell segment can be connected into their position. The connection bolts have no torque value. They need to tighten in the most tightly possible way by hand, to consider that the fan bell material is fragile FRP glass fibre. The inspector for the bolt tightening needs to check every bolt for its tightness by hand.
Before lifting; check the roundness and diameter of the fan bell on the top edge from the bell. In the positions from the stiffening plates they can use slings to adjust the roundness and diameter.
Then lift the fan bell & guard grill into its position on the fan deck level. Attach stiffening plates to the small supports in the fan deck steel structure.
The bolts which keep the fan bell in position can just be hand tight, because in later stage from the erection the fan bell needs to be aligned with the fan blades. This is the moment the connection bolts will be tightened according to the correct torque value.
Then install the fan deck plates on the fan deck level.
Drill holes at the top of the fan stack using the sealing angle plate as template, and install the sealing angle.
Lifting of the assembled fan stack and screen will be performed using four point soft slings taking note on the correct and final orientation of the fan screen assembly which is 45 º offset from the axis.
Final alignment of the fan stack with screen will be carried out once the motor bridge with the drive unit installation is completed.
Lifting will be done by certified and competent riggers and banks man.
See illustration for similar installations:
Assembly of Motor Bridge with Drive unit and Fan Blades
Pre assembly of motor bridge with drive unit will be done by mechanical fitters at the adjacent streets respectively to limit movement of lifting equipment. The latter structure will be laid horizontally and levelled along with fabricated support beams at 1.2 meters height.
This will assure mobility of people working underneath for fan blade erection
Secure and align the gearbox with correct bolts and shims for correct levelling on the motor bridge structure; then fasten the motors, taking note the orientation of the motor control box. At this stage, gearbox will not be filled with oil; this will be done during the commissioning stage.
Railings, grating materials and walkways will be installed before lifting the whole structure with blades at the upper deck. The fan blades will be installed in vertical position temporarily; to prevent damages during erection of other parts above the deck
Observe correct torque value for bolts on the gearbox shaft coupling to motor plus the flanged connection to the fan hub plate, and then install and assemble the fan blades.
Torque bolts on joints, blades for flange with 70% torque value.
Prior to lifting, additional fasteners and/or soft ropes will be required to prevent movement and rotation of the fan blades during the lifting operation to the upper sub structure
Lift the structure assembly and secure into final position at the upper deck.
Lifting of the motor bridge with drive unit and fan blades will be done by certified and competent riggers and banks man.
Following the erection, ensure proper preservation of rotating equipment (e.g. 4 weekly vertical shaft rotation, oil top-up/greasing) and refer to equipment manuals as necessary, for protection against heat, dust and humidity.
See illustration for similar installation:
Following the erection, ensure proper preservation of rotating equipment (e.g. 4 weekly vertical shaft rotation, oil top-up/greasing) and refer to equipment manuals as necessary, for protection against heat, dust and humidity.
Alignment of Fan Ring
After the motor bridge is aligned and levelled to its position, alignment of the fan stack with angle sealing plates will be done accordingly, and fixing the fan deck plates permanently.
The blades pitch angle will be set to 12.7 ° as recommended by the manufacturer; and the gap between stack and fan tips will be noted.
Alignment will be done by mechanical fitters.
Final settings of the blade angle will be performed prior to trial operation & bolts torque to 100%.
See illustration for similar installation by other agencies:
Upper Structure: Pre assembly and Erection of A – Frame
Pre assembly of the A – frame will be done on the ground with complete support, with partition walls sub structure, with cladding, supports and braces are lifted to the upper deck and fastened to the main steel structure.
Alignment of the upper and lower sections of the A – frame for the street will be controlled with shims to obtain same elevations.
Structures like the sliding and fixed supports at the top of the beam, bracings between A – frame and motor bridge, and hoisting beams will be installed before any installation of the foregoing structures.
See illustration for similar installation by other agencies:
Assembly of CCM, Bundles, SM, Piping Works and Wind wall
Erection of the remaining structures will be as follows: –
Condensate Collecting Manifold (CCM) first, secondary bundles and primary bundles, and Steam Distribution Manifold (SDM) as third step
Assemble and weld two CCM spool on the ground, temporarily fixed with bolts after lifting them at the upper deck.
These bolts can be removed once the alignment and tack welding of the CCM is done.
Lift the next two joined spools, and join to the latter spools.
Final alignment of the joined spools and welding will be done at this stage, then proceed to complete the street.
Final welding on the manifold will be done as soon as all the alignment of the manifold is achieved
Before erecting the bundles onto the A-frame, thorough inspection will be done for any damages.
The inspection shall be recorded and noted whether bundles are acceptable, or require repairing
Lifting up of the bundles starts first with secondary, then the primary. Installation of lifeline for people working in the bundle erection will be performed. Refer document attached
Lifting up of the bundles will be alternate (to Left & to right side) to avoid unbalancing on the structure.
Bundles shall be lifted at the required A-frame slope, using offset sling lengths.
Join two (2) opposite primary bundles with plate (A0080412) by welding after aligning the bundles; taking into consideration on special procedures to avoid overheating of the tube sheets. After welding completion and alignment, the steam distribution manifold (SDM) will be installed.
The weight of the complete steam manifold exceeds 10 Tons, hence it is necessary to have at least three (3) lifts; starting lift of spool 3 (A0080521) at the fixed point, which is located on the top of the secondary bundle structure.
Spool 4 (A0086422) & spool 5 (A0080522) will be assembled & welded on the ground prior to lifting; similarly with spool 1 (A0080519) & spool 2 (A0080529).
They will be joined with spool 3 after erection at the structure.
Lifting lugs will be provided for its joined spools, taking into consideration of the centre of gravity.
Seal plates at the end of manifold (spool 5) are to be adjusted at the site after the bundles assembly & steam manifold installation is completed and stitch welding of the manifold & bundle will commence.
Ensure all heat exchanger pipe protection covers removed before installation.
Ensure pipes are internally clean before lifting into the structure (visual, air blow, lifting- up at one end).
Ensure all open ends capped after work interruption or day end.
Condensate tank and structure will commence for erection after fan bell is erected at module N of street.
Condensate tanks, steam ejectors, the drain pump station and associated equipment and instrumentation will be erected and piping will follow as soon as the upper structures are done, then continue to work on the remaining streets.
At this stage, the steam duct connecting the turbine exhaust and the ACC can commence simultaneously with other works in the ACC; and it is necessary to start works at each fixed points.
Installation of walkways and rails at street 4 going to the upper deck will be done to minimize utilization of man-lift equipment during installation of structures on the remaining streets.
Soon as the entire street installations are completed, panel sheeting of the interior will be done.
The pre-assembly of the wind wall will be done on the ground level, lifting and installation will be parallel and commence with A-frame erection at the upper structure.
Wind wall section will be connected and bolted to the main structure (fan deck) and connected to the steam manifold bracings.
See illustration for similar installation by other agencies:
Steam Ducting
The steam ducting will be assembled and installed between the connection of the turbine exhaust and the ACC with the construction sections as per drawings.
Steam ducting section – certain sections are fabricated with additional fitting lengths.
These fitting lengths will be used for adjustment to site conditions.
By means of a cutter or blow torch; the sections will be cut to the exact length required during installation, the cut edge will be ground smoothed, cleaned and prepared for welding in accordance with specified WPS.
The expansion joints and ducting sections will be assembled and welded together to a great extent at the ground level, before lifting them into position; however the weight of the assembled parts and crane lifting capacity and the reach will be considered and planned accordingly.
During installation of the expansion joints and the vane elbows special care and attention will be taken to ensure that they are installed correctly for the direction of the steam flow.
Beginning at the turbine, the remaining main steam ducts and risers are installed up to the top steam distribution manifold.
The Steam ducting installation will start at the duct fix point. Sequence refer sketch as given below in (illustration A & A1):
The steam ducting has to be assembled and installed starting from the turbine outlet at machine house to the air cooled condenser inlet joining streets 3/4 and streets 2/1 respectively.
The expansion joints and ducting sections can be assembled and welded together to a great extent at the ground level before lifting them into position.
Spool 1 a and expansion joint to be welded on site to the turbine piece before turbine installation.
Install complete part to the turbine flange and lift together with turbine into the turbine table.
After adjustment at spool 1, fabricated duct part-01 DN3820 to be welded with the expansion joint.
During installation of the expansion joints and the vane elbows, special care and attention shall be taken to ensure that they are installed correctly for the direction of steam-flow.
Additional stiffening brackets may have to be welded to the steam duct risers in the area of expansion bellows for safeguarding and preventing damages on the rings – convolutions of the expansion rings.
All sections of the ducting must be connected together free of any “forces and moments” by means of using the correct procedure and respectively, the planned sequence of erection.
It is not acceptable to assemble or install together by force as this would lead to lateral deformation or misalignment of the supports.
Even in such cases; uncontrolled forces and moments can occur to the turbine connection.
After full completion of the ducting and piping systems; all temporary stiffening or locking devices must be removed.
Separate Method statement for ducting will be prepared and got approved prior to commencement of the erection of ducting.
Preservation of ACC
Preservation of the Installed ACC. Due to the local conditions at Pearl site and long period between the mechanical erection and final commissioning preservation methods on site need to be considered.
All parts, components and auxiliaries are to be preserved after installation in accordance with the general instruction listed in operation and maintenance manuals.
The scope of this procedure is to describe the measures to be undertaken for the preservation of ACC (Air Cooled Condensers).
Measures will be undertaken in order to preserve the equipment & reticulation’s in order to maintain the ACC performance to high degree.
The measures to be undertaken are divided into three gradations, each presenting different level of protection, as the length of shut down in cases, a higher level of protection will be required and economically justified.
Categories:
Short Term Shutdown
Short term shutdown is considered a period less than one week, with respect to preservation of ACC, no specific requirements are to be fulfilled.
Medium Term Shutdown
Medium term shutdown is considered a period of more than one week and less than 6 (six) weeks, dry air connection is to be made into the manhole (20”) on steam duct near to hot weld, Air evacuation to atmosphere through the hogging ejection silencer & holding ejectors.
Precautions:
- All valves on steam, air extraction & condensate shall be open (except for vents and drains)
- Vent & drain on condensate tank can be partially open to improve air circulation in the tank
- Condensate pumps to be removed to create air circulation of dry air
Preservation with hot air cannot be considered for the ACC tube bindles since cooling surface is high and air will cool down immediately, hence efficiency is limited.
The condenser, tanks, vessels and tubes to be drained.
Condenser will be preferably blown dry with air; if possible to be maintained under vacuum
Long term Shutdown
Long term shutdown is considered a period more than 6 weeks.
Alternative A: Dry air preservation All condensate shall be drained in:
- Condensate tank
- Hot weld on Steam Duct
- Vacuum ejector units
- Condensate pumps
- After draining of all components, immediate drying of complete ACC will start
- Dry air shall be blown into the steam duct and evacuated at hogging and holiday ejector
- A continuous dry air injection is to be foreseen
Alternative B: Preservation with Nitrogen
This alternative is theoretically possible, but not practical due to huge quantity of nitrogen requirement.
Blanketing plate is provided in part 1 of the steam duct, hence steam turbine connection is isolated
Condenser, the steam duct, the vessels, exchangers and all connecting piping’s will be drained and filled with nitrogen
The purging of nitrogen will be controlled within 0.05 barg and 0.25 barg over pressure. When it exceeds, the nitrogen has to be blown off
Note: Complementary to preservation; following interventions are especially required:
- Condensate Pump – Weekly by hand rotation
- Gearboxes – Rotation of gearbox every 3 weeks
- Greasing – Check every 3 months
In addition to the above a separate procedure on preservation will be presented and approved.
Piping Erection Order
Condensed steam piping, air extraction piping, cleaning system and instrumentation with related support and hangers will be erected according to approved SPX reference drawings, only certified welders will be performing based on existing WPS Welding Procedure Specification.
Basic consideration will be given before any erection works can start and are as follows:
- Steel structure will be built so far that the main pipe supports will be
- Main pipe supports will be made and assembled in right positions and
- Equipment and devices will be available, assembled and fixed in right position where pipe connections will be
- Required tools and materials will be made available so the works can continue without
- Blind plates and plugs have to be kept in place during the progress of
- Bigger and technically difficult pipes will be erected first before the small Non – Destructive Test (NDT)
This activity is performed to check the correctness and soundness of the welded joints performed at the site.
A number of test can individually or in combination be applied which includes but not limited to visual inspection; ultrasonic inspection, dye-penetration check, magnetic particle check, eddy current check, radiography etc. the test will be performed in accordance to NDT Procedure; ASME code Sec. V and related specifications.
Leak Test and Cleaning of Pipes.
A separate method of statement will be prepared for the above test and procedure.
Special Technical Procedures
Bolting
The bolting applies for all subsequent description:
All high strength joints will be tightened to the specified torque indicated on the drawings or attachments to manufacturing instruction respectively.
Correct bolt torque will be applied in accordance with the instruction given and will be color-coded to mark completion.
Task completed will be recorded in site construction records.
Employees doing bolt tightening shall bear a unique number in a similar manner to the welder numbers and shall be certified appropriately.
The following table will be implemented for ACC Steel structure:
| # | dimensions | nominal preloading force (kN) | Torque control Method (Nm) | Torque value (KN) |
| 1 | M 12 | 35 | 70 | 40 |
| 2 | M 16 | 70 | 170 | 80 |
| 3 | M 20 | 110 | 300 | 120 |
| 4 | M 22 | 130 | 450 | 145 |
| 5 | M 24 | 150 | 600 | 165 |
| 6 | M 27 | 200 | 900 | 220 |
| 7 | M 30 | 245 | 1200 | 270 |
| 8 | M 36 | 355 | 2100 | 390 |
Refer relevant document for Grade 8.8, hot dip galvanized and lubricated nuts and bolts from the vendor.
The following table will be implemented for Motor & Gear Box, coupling’s, fan blades and other machine components:
| # | dimensions | Strength class 8.8 | Strength Class 10.9 |
| 1 | M 6 | 10 Nm | 14 Nm |
| 2 | M 8 | 25 Nm | 35 Nm |
| 3 | M 10 | 49 Nm | 69 Nm |
| 4 | M 12 | 86 Nm | 120 Nm |
| 5 | M 16 | 210 Nm | 295 Nm |
| 6 | M 20 | 410 Nm | 580 Nm |
| 7 | M 24 | 710 Nm | 1000 Nm |
| 8 | M 30 | 1450 Nm | 2000 Nm |
| 9 | M 36 | 2530 Nm | 3580 Nm |
| 10 | M 42 | 4070 Nm | 5720 Nm |
| 11 | M 48 | 6140 Nm | 8640 Nm |
| 12 | M 56 | 9840 Nm | 13850 Nm |
| 13 | M 64 | 14300 Nm | 21000 Nm |
Refer Document provided by vendor.
Any other bolts of different grades, the torque values will be followed in line with the vendor’s recommendations.
Site Welding Principles
On structures and parts of structures as well as all the items that are protected by hot dip galvanization, welding is not allowed.
Repair and/or adaptation of assembly parts are subjected to a concession authorized by vender site representative prior to proceeding.
Welding will be performed by certified welders with approved WPS (Welding Procedure specifications).
NDT shall be carried out on areas of lifting lug removal after dressing of affected area.
Welding map; each weld should be itemized with particular reference number and recorded in the welding map drawing and listed on record sheets with location and WPS that are done.
In case of bad weather conditions, special protection during welding must be taken to avoid weld failure; such prevention will be listed before starting main welding operation and must follow general welding recommendations.
Galvanized structures need to be shielded off during welding and/or grinding activities in close proximity to avoid contamination or damage.
Whenever the galvanized portion or portions is damaged on the structure or corrosion exist; repair can be done with the following procedure;
- corrosion or damage shall be removed using light sweeps of an orbital grinder
- 25 mm band of sound galvanizing around the damaged area shall be carefully feathered down to bare steel
- residual oil or grease shall be removed with degreaser
- on surface preparation completion, scrub and rinsed with fresh water
- the area shall be coated with rich zinc paint (or approved equal paint) for at least 100 microns, or
- the repair coating shall overlap onto the feathered edge of the existing
Ensure welding of valves is carried out with closure member in open position as required by Appendix 3, DEP 31.38.01.31 to avoid small bore valve internals be damaged during welding.
Ensure received rotating equipment drain connections are free of screwed and seal welded screwed connections.
Ensure adequate supervision/QC during lifting & lug removal to avoid pin holes at Column walls.
Apply GTAW (TIG) root run welding for all pipe welds on process piping works (no internal slag generation) unless access to back weld is possible, (i.e.> 36″ diameter) to avoid instrument toppings and small bore piping plugged with weld slag.
Have tight control on GTAW root run backing gas dams. Avoid paper dams with sticky tape.
Ensure thorough inspection on internal cleanliness when any form internal dams for backing gas are being applied.
Root bulge of weld between nozzle and flange has to be removed by grinding to ensure correct ID of manhole walls.
Ensure the cleanliness be preserved after welding, cutting or grinding operations as per “Quality Control Procedure for Cleanliness”.
Ensure the cleanliness be preserved after welding, cutting or grinding operations as per “Quality Control Procedure for preservation of Piping Material and Equipment”.
Proper screening and training of the personnel shall be performed in accordance with the “Training and Orientation”.
Record of Deviation and Tolerance for Construction
Deviations and tolerances have to be strictly followed as per requirements specified by associated Vendor’s.
Necessary records & protocols will be recorded, kept & maintained.
QUALITY ASSURANCE
A Quality Assurance System will be operated conforming to related standards and vendor’s recommendations.
Controls and checks will be established and documented through relevant quality control procedure QCP.
ATTACHEMENTS
- Job Safety Analysis
- Installation of Life Line for Bundles Erection at ACC
- Lifting of Fan Deck Plates
- Design Calculation Notes for Horizontal Lifeline System