Work Method Statement xxx.xxx Fuel Storage Tank Design, Fabrication and Erection
Project
Construction Project of Three (3) Petroleum Depots in Chad Client
SHT–Chad National Hydrocarbons Company Contractor
Faber Insaat San. ve Tic. A.S. Istanbul, Turkiye
WORK METHOD STATEMENT FUEL STORAGE TANKS DESIGN, FABRICATION AND ERECTION
CONTENTS
SECTION
TOPIC
1.0
PURPOSE
2.0
SCOPE
3.0
REFERENCES
4.0
DEFINITIONS
5.0
RESPONSIBILITIES
6.0
RESOURCES
7.0
RISK ASSESMENT
8.0
HSE
9.0
QA/QC
10.0
WORK PROCEDURE
10.1
Detailed Engineering Design
10.2
Preparatory Works
10.3
Material Procurement
10.4
Fabrication
10.5
Packing and Shipment
10.6
Inspection of Tank Foundation
10.7
Erection
10.7.1
Annular Plates Laying
10.7.2
Bottom Plates Laying
10.7.3
Shell Course Erection
10.7.4
Stairway Erection
10.7.5
Appurtenances Installation
10.7.6
Roof Erection (Supported Fixed)
10.7.7
Roof Erection (Internal Floating)
10.8
Inspection and Testing
10.9
Calibration
10.10
Shot Blasting and Painting
WORK METHOD STATEMENT FUEL STORAGE TANKS DESIGN, FABRICATION AND ERECTION
PAGE
1.0
PURPOSE The purpose of this Work Method Statement is to ensure a safe and successful system of work has been identified and to communicate the responsibilities, work methods, sequence of working, and safety arrangements to all persons on, and off site during the activities listed herein. This document was prepared for following proper methodology to achieve the activities in a proper sequence for design, fabrication, erection and testing of the fuel storage tanks.
2.0
SCOPE xxx xxx for the Construction Project of Three (3) Petroleum Depots in Chad.
3.0
REFERENCES
3.1
International Reference Codes, Standards and Specifications -
API S 650 Welded Tanks for Oil Storage API RP 651 Cathodic Protection of Aboveground Petroleum Storage Tanks API RP 540 Electrical Installations in Petroleum Processing Plants API S 2000 Venting Atmospheric and Low-Pressure Storage Tanks API RP 2003 Protection Against Ignitions Arising Out of Static, Lightning, and Stray Currents ASCE 7-10 Minimum Design Loads for Buildings and Other Structures ASME B31.1 Power Piping ASME B31.3 Process Piping ASME BPVC II C Welding Rods Electrodes and Filler Metals ASME BPVC V Non Destructive Testing ASME BPVC IX Welding and Brazing Qualifications ASTM A283 Standard Specification forLow and Intermediate Tensile Strength Carbon Steel Plates ASTM A6 Standard Specification for General Requirements for Rolled Structural Plates ASTM A620 Standard Specification for General Requirements for Steel Plates for Pressure Vessels AWSSFA 5.1 Welding Consumables Classification NACE RP0193 External Cathodic Protection of On-Grade Metallic Storage Tank Bottoms NACE SP0285 External Corrosion Control of Underground Storage Tank Systems by Cathodic Protect. ISO 7507 Calibration of Vertical Cylindrical Tanks SIS 055900 SA 2 Surface Preparation for Under Side of Bottom Plate SIS 055900 SA 2½ Surface Preparation for Shell, Roof, Deck, etc. NFPA 11 Standard for Low-, Medium-, and High-Expansion Foam NFPA 15 Standard for Water Spray Fixed Systems for Fire Protection
-
3.2
National Reference Codes, Standards and Specifications -
xxx xxx xxx xxx xxx
-
3.3
Contractor’s Reference Codes, Standards and Specifications -
4.0
xxx
HSE Plan QA/QC Plan Approved Drawings xxx xxx
DEFINITIONS -
CLIENT CONSULTANT CONTRACTOR API ASCE ASME ASTM AWS BVPC DFT GSFCAW HSE ITP LPT MPI NACE NDT NFPA PQR PWHT QA/QC RFI RT SAW SMAW WPQR WPS
5.0
RESPONSIBILITIES
5.1
Project Manager
SHT - Chad National Hydrocarbons Company Xxx Faber Insaat San. ve Tic. A.S. American Petroleum Institute American Society of Civil Engineers American Society of Mechanical Engineers American Society for Testing and Materials American Welding Society Boiler and Pressure Vessel Code Dry Film Thickness Gas Shielded Flux Cored Arc Welding Health, Safety and Environment Inspection and Test Plan Liquid Penetrant Test Magnetic Particle Inspection National Association of Corrosion Engineers Non Destructive Testing National Fire Protection Association Performance and Qualification Record Post Weld Heat Treatment Quality Assurance / Quality Control Request for Inspection Radiographic Test Submerged Arc Welding Shielded Metal Arc Welding Welder Performance and Qualification Record Welding Procedure Specification
Project Manager; responsible in general coordination and ensuring that the necessary resources to implement the approved method statement have been allocated to the task also responsible in ensuring that all necessary safety and protective equipment are provided along with properly trained and qualified personnel.
5.2
Construction Manager
Construction Manager; responsible in ensuring the implement of construction procedure and method statement, the Quality Control of work, supervise the work and reporting the progress of work to Project Manager and must observe any hold-points and notify the Engineer for inspection.
5.3
Safety and Environmental Officer Safety and Environmental Officer; responsible in ensuring that all activities are carried out safety patrol at the site, establishing the site safety plan, conducting continuous safety inspection and stop any work deemed unsafe and a risk to personal, taking action to rectified the unsafe condition and report to project manager and preparing the notes of safety meeting.
5.4
QA/QC Engineer QC/QA Engineer; responsible to monitor the execution and performance of the works in relation to this method statement, approved drawings and material specifications; detect and report nonconformance; ensure that all nonconformance products or activities identified are reported; propose the corrective and preventive action where possible and appropriate and record the completion the nonconformance by report format.
5.5
Site Engineer & Foreman Site Engineer & Foreman; responsible in ensuring that the site preparation activities are conducted according to the approved method statement and all activities on site are carried out in accordance with the schedule and the construction drawing and take care all worker to be work with their responsibilities and make a decision when some nonconformance occurring their report to construction manager.
5.6
Worker It is the worker’s duties to properly wear the protective equipment provided and obey all safety rules. They must also perform the work as described in the method statement procedure.
6.0
RESOURCES
6.1
Equipment and Tools -
Generators x Air Compressors x Mobile Cranes Fork Lifts x Lifting Equipments Plate Plasma Cutting Machines Welding Groove Opening Machine Automatic ClosedShotblasting Machine Shop Primer Painting Machine
x x x x x x
-
6.2
Total
x x xx x x xx x x x xx x x XXX
Man Power -
7.0
Plate Bending Machine SAW Welding Machines Electric Welding Machines Electrode / FluxBakingOvens Electrode / Flux Holding Ovens Grinders Radiography Test Machine Vacuum Test Equipment Exhaust Fan Paint Guns Trailers Pick-ups
Project Manager (Mechanical Engineer) Site Managers (Mechanical Engineer) Safety & Environmental Officers QA/QC Engineers Site Engineers Administration Chief Accountant x Procurement Stuff Chief Surveyors Supervisor/Foreman Welders / Assemblers Skilled Labors Electrician Operators Drivers x Total
x x x x x x x x x xx xx x x
XXX
RISK ASSESSMENT 1. Hazards in the work area are identified, assessed and reported to designated personnel. 2. Occupational Health and Safety issues and risks in the work area are identified, assessed and reported to designated personnel. 3. Safe workplace procedures and safe work instructions are followed for controlling risks. 4. Occupational Health and Safety, hazard, accident or incident reports are completed according to workplace procedures and Chad Government legislation.
8.0
HSE
8.1
Health and Safety
1. As per HSE Plan, the following system to be followed. 2. In general all recommendations and suggestions advised in HSE Plan shall be strictly adhered by all personnel working at field and fabrication yard premises. 3. All relevant elements of HSE Plan shall be followed. 4. Emergency and Response Plan shall be followed in case of any emergency. 5. Road Transport Safety Procedure shall be strictly adhered while transportation of manpower or formwork materials by vehicles. 6. Safety signs and symbols are identified and followed. 7. Tasks are performed in a safe manner and in accordance with legislative requirements, company policies and procedures. 8. Organization of duties, tools, equipment and materials are performed in accordance with company procedures. 9. Daily Tool Box talk shall be conducted prior to proceed for the work. 10.Prior to the commencement of any activities, the workforce will receive an induction talk on the Project site safety requirements. This induction talk will include both activity safety issues, as well as general safety requirements. 11.Safety precautions should be followed during fabrication and erection. 12.Where work upon existing services may be required, the necessary work permits and safety equipment should be obtained prior to the activity commencement. 13.Personal protective equipment and clothing is worn, used and stored according to company procedures. 14.Tools and equipment guards are used manufacturer’s specifications and regulations.
in
accordance
with
15.Tools and equipment will be provided with back-up alarms, lights, and all other applicable safety devices. 16.Tested and certified lifting equipment should be used for lifting and shifting purpose. 17.Welding cables and power cables to be laid properly as per Occupational Health and Safety regulations. 18.Scaffolding shall conform to Occupational Health regulations and shall be designed by a civil engineer.
and
Safety
19.Provisions of adequate cool drinking water, shade, and salt tablets and or lemon will be in place. 20.Proper house keeping and clean condition shall be maintained in the fabrication shop and site as per requirement. 21.First aid arrangements shall be followed as per procedure.
8.2
Environment 1. Refer to Environment Management instructions. 2. All activities shall comply with Environment Management Plan.
9.0
QA/QC This shall be followed and maintained with the compliance / adherence to the drawings, procedure and code specification. Records shall be kept in the relevant check sheet and formats duly signed by all the concerned departments.
9.1
Procedures / Reports -
Daily Progress Reports Weekly Progress Reports Monthly Progress Reports Document Transmittal Form Engineering Progress Report Accident Report Manpower Mobilization Schedule Equipment Mobilization Schedule Procedure Qualification Record Tank Erection Procedure - Conventional Material Identification Report Check Test Report Billing Status Report Welding Procedure Specification Sequence of Welding WPQR - Welder Performance and Qualification Record Inspection Report Radiography Procedure Radiography Inspection Report Vacuum Test / Air Test Procedure Liquid Penetrant Examination Procedure Post Weld Heat Treatment Procedure Magnetic Particle Exam Procedures Collapsible Test Procedure Hydrostatic Testing Procedure Flotation Test / Puncture Test Procedure Tank Calibration Procedure Blasting and Painting Procedure
10.0
WORK PROCEDURE
10.1
Detailed Engineering Design
Design of the storage tanks are based on API 650 and other relevant codes for construction of storage tanks. Following designs will be made for tanks in the project. -
10.2
Topographic Survey Works Construction Control Survey Works Geotechnical Engineering Report Meteorological and Seismic Design Data Tank Shell Calculations and Drawings Fixed Roof Calculations and Drawings Internal Floating Roof Calculations Foundation Calculations, Design and Drawings Annular Plates Layout Details Bottom Plates Layout Details Shell Plates Erection Details Anchor Detail Drawings Shell Manhole Detail Drawings Shell Nozzles Detail Drawings Stairway Detail Drawings Roof Platform Detail Drawings Roof Manhole Detail Drawings Roof Nozzles Detail Drawings Nozzle Orientation Weld Map External Cathodic Protection Calculations Internal Cathodic Protection Calculations Tank Bottom External Cathodic Protection System Layout Details Internal Cathodic Protection System General Layout Details Earthing Calculations and Detail Drawings Lighting Calculations and Detail Drawings Cooling System Details Fire Fighting Calculations and Detail Drawings Fire Fighting General Layout Foam Chamber Montage Detail Safety Devices Calculations ITP - Inspection and Test Plan WPS - Welding Procedure Specification Painting and Procedure Mechanical Installation Manual Electrical Installation Manual Installation and Commissioning Manual List of Material (Steel Plate, Bolt, Pipe, Paint Materials) Cathodic Protection Materials Earthing and Lighting Materials All Procurement Documents (Material Requisitions & Technical Specifications) Packaging and Shipment Details
Preparatory Works 1. Work instructions, including plans, specifications, quality requirements and operational details are obtained, confirmed and applied.
2. Safety requirements are followed in accordance with safety plans and policies. 3. Appropriate personal protective equipment selected, correctly fitted and used. 4. Signage/barricade requirements are identified and implemented. 5. Plant, tools and equipment selected to carry out tasks are consistent with the requirements of the job, checked for serviceability and any faults are rectified or reported prior to commencement. 6. The equipment, which requires regular calibration, will be calibrated prior to commencement as well. 7. Material quantity requirements are calculated in accordance with shop drawings and specifications. 8. Materials appropriate to the work application are identified, obtained, prepared, safely handled and located ready for use. 9. Environmental protection requirements are identified for the project in accordance with environmental plans and regulatory obligations and applied. 10.3
Material Procurement 1. Procurement will be made according to the approved project documents. 2. Specification and grades of all materials shall to bill of materials and fabrication drawing requirements. 3. Prior to procurement, conformed to.
Client’s
specific
requirements
shall
be
4. Conformance shall be checked at pre-order, receipt, inspection and inprocess stages. 5. All materials shall be bear manufacturer’s markings and shall correlate with Mill Test Certificates.
10.4
Fabrication
10.4.1
Cutting Plates 1. Plate material shall be straight and/or flattened by pressing or rolling, before the material is processed in any way. 2. All shell plates shall be profiled to tolerance of ± 2 mm in length and ± 1 mm in width. 3. Plates shall be measured diagonally to ensure rectangularity. 4. Curved edges of roof, bottom sketch plates and annular plates shall be cut to shape by the machine operated gas torch. 5. Various radius templates will be used for marking and cutting.
6. Templates shall be approved by Consultant before using. 7. The resulting surface shall be uniform, smooth and free from scale or slag accumulations.
10.4.2
Marking 1. All plates and structural members, fittings or any other component shall be clearly identified by marking heat number on the parts using hard punching for traceability. 2. Heat numbers shall be stamped on these materials in the corner approximately 6'' from either edge. 3. Each weld joint shall be marked with joint number and welder number. 4. Heat numbers on each plates shall be highlighted for ease of correlation with mill certificates and shall be located on outside of the finished tank.
10.4.3
Plate Edge Beveling 1. The edge of the tank plates shall be sheared, machine cut or beveled with a machine operated gas-cutting torch. 2. Shearing shall be limited to plates less than or equal to 10 mm thick used for butt-welded joints and to plates less than or equal to 16 mm thick used for lap-welded joints. 3. According to the drawings, single or double welding groove will be opened to the proper corners of the plates using welding groove opening machine 4. The beveled edges shall be ground to remove all the above accumulations.
Horizontal joint beveling
Vertical joint beveling
10.4.4
Shot Blasting and Shop Primer Coating 1. All plate material shall be shot blasted and shop primed for temporary protection during storage and construction. 2. Any corrosions / mill scale shall be removed from the steel plates. 3. Plate surfaces should be blasted by the automatic closed blasting machine as per SIS 05 5900 SA SA2½.
4. Post shot blasting, the material passes to the shop primer coating. 5. First shop primer coating will be applied according to the painting procedure. 6. Drying of the paint will be ensured, and being ready, it will be placed on the carrying table.
10.4.5
Rolling of Shell Plate 1. Plate dimensions shall be verified prior to the start of edge preparation or rolling operations. 2. Shell plates shall be shaped to the correct curvature of the tank. 3. Rolling will be developed in place, in a fabrication shop designed and built for this purpose. 4. Plate shall be rolled within permissible localized variations as specified in ASTM A6 and ASTM A20 and shall be free from buckling, dents, excessive drawing, distortion or obvious imperfections. 5. Templates shall be used to measure the rolled plates curvature. 6. Rolling of shell plate giving required load stage by stage on rolling direction. 7. Check radius using the above template stage by stage until the required radius is obtained. 8. Rolled shell plates shall be stacked on radius cradles, which is same to roll for further process.
10.4.6
Shop Fabrication of Annular, Bottom and Roof Plates 1. Plate surfaces should be blasted by the automatic closed blasting machine as per SIS 05 5900 SA 2 and SA 2½. 2. Plates will be marked for each drawing. 3. Treated corners will be wrapped with masking tape. 4. First coat paint will be applied to both surfaces of plates according to the specifications. 5. Packaging of the items which are accepted by Consultant Examiner will be finished.
10.4.7
Shop Fabrication of Shell Plates 1. Plate surfaces should be blasted by the automatic closed blasting machine as per SIS 05 5900 SA 2 and SA 2½. 2. Dimensions of plates will be checked against the dimensions in the drawings, and they will be cut accordingly. 3. Plate surfaces and corners will be cleared of burrs. 4. Plates will be marked for each drawing. 5. According to the drawings, single or double welding groove will be opened to the proper corners of the plates using welding groove opening machine. 6. Shell plates will be bent at the bending machine (roller) with the help of temporary tools prepared for bending. 7. Surfaces of shell plates will be cleared of any oil or dirt and the treated corners will be wrapped with masking tape. 8. First coat paint will be applied according to the painting procedure. 9. Drying of the paint will be ensured, and being ready, it will be placed on the carrying table. 10.Packaging of the delivery items which are accepted by Consultant examiner will be finished. 11.The packages will the separated according to the destination stations and the package lists will be prepared.
10.4.8
Shop Fabrication of Roof Supporting Steel Structure 12.Middle section ceiling steel will be produced according to the drawings.
13.The ceiling beam will be cut and holes will be drilled on it according to the drawings. 14.The wind beam will be bent at the bending machine. 15.The arms of the ceiling support system will be manufactured according to the drawings. 16.Following surface preparation, the first paint coat will be applied in compliance with the painting procedure. 17.Its dimensions and DFT (dry film thickness) will be measured for ready-made package lists for each stage of the production and transportation to the work site. 18.Packaging of the items which are accepted by Consultant examiner will be finished. 19.It will be transported to the work site for assembly.
10.4.9
Shop Fabrication of Internal Floating Roof 1. The cutting of plates according to the approved fabrication drawings. 2. Cleaning of the surfaces for production. 3. Preparation for welding for floating roof, verification of external panel dimensions for all in accordance with approved fabrication drawings. 4. Preparation of the central section of the floor in accordance with approved drawings, separation from its corners, welding at the work site with approved WPS of qualified welders. 5. Marking of floating roof panels, cleaning of burrs and applying masking tape. 6. Repeating the same operations for the central section and performing the cleaning activities. 7. Application of the first paint coat to the finished and cleaned parts according to the painting procedure. 8. All produced parts will be examined according to Consultant approval. 9. The visual inspection dimensional check and package lists of the produced parts should accompany the delivery. 10.The preparation and production of the permeation of support pads of the floating roof will be performed as per approved drawings and approved by Consultant. 11.The production of these parts will be completed and following the examination, the burrs will be cleared off. 12.It will be ensured that surface preparation is performed and first coat of paint is applied according to the procedure. 13.Packaging of the items which are accepted by Consultant Examiner will be finished.
14.Examination reports for package lists and compliance transportation boxes for transportation will be prepared.
of
15.Delivery to the work site for construction
10.4.10 Shop Fabrication of Stairs and Handrails 1. Components of the tank (controlled plates, pipes, guardrails and steel constructions) will be placed to their positions according to the approved shop flow fabrication drawings. 2. All the structural items shall be straightened before marking and cutting. 3. Mark the components as per drawing. 4. All the cutting operation, as per requirement shall be carried out after getting the clearance from inspection authority. 5. Components of the structure will be processed using the cutting and bending machines. 6. All the cutting operation shall be carried out by gas cutting method. 7. Grind the cut edges smooth to remove burrs and slag. 8. Fabrication such as fitting, welding, drilling, etc. shall be carried out as per drawing and after the clearance from inspection authority. 9. Dimensions of the parts which are cut of welded with approved WPS will be verified. 10.Welded areas will be cleared of burrs. 11.After fabrication all these structural items shall be blasted as requirement. 12.Components will be delivered to the galvanizing unit. 13.Hot dip galvanizing will be performed according to the procedure. 14.All stages of the plant production for each tank inspection shall be performed in accordance with Consultant’s Procedure and the company records will be completed without error. 15.Preparation of package lists for all parts and the placed layers. 16.Packaging of the parties which are accepted by ConsultantExaminer will be finished. 17.They will be delivered to the work site for construction.
10.4.11 Shop Fabrication of Manholes, Nozzles and Other Appurtenances 18.A protective shelter shall be used.
19.All manholes, nozzles and other appurtenances shall be fabricated and PWHT in the shop, in accordance with the approved construction drawings. 20.The produced components will be cut at full scale when they are placed into their locations, for instance, flanges and metal parts, and they will be prepared and joined according to the drawings. 21.Before joining, welding burrs will be cleaned by grinding and with a brush and these parts will be transported to the painting area for surface preparation. 22.Each weld shall be started (root pass) and finished while the preheat temperature is maintained without interruption. 23.The prepared parts will be joined according to the fabrication drawings using a tack welding. 24.After dimensions are verified, the actual welding will be performed according to the approved fabrication drawings. 25.Pipes shall be pre-heated around its circumference and maintained on 12'' sections on either side of the weld. 26.Pipes shall be covered immediately after welding and be permitted to cool at uniform rate. 27.Primer and final paint coats will be applied. 28.Examination reports will be provided; packaging lists and packages suitable for transportation will be prepared. 29.Packaging of the items which are accepted by Consultant Examiner will be finished.
10.5
Packing and Shipment 1. Packing of the goods will be done according to professional standards and in a safe manner in order to prevent damage during transportation. 2. Materials will be packed by engineering ID number system. 3. Bolts, nuts, nipples, and other small parts shall be boxed or put in kegs or bags for shipment. 4. All flange faces and other machined surfaces shall be protected against corrosion and from physical damage. 5. The packages will the separated according to the destination stations. 6. Examination reports will be provided; packaging lists and packages suitable for transportation will be prepared. 7. Plates and tank material shall be loaded in a manner that ensures delivery without damage. Packing for bottom, roof and shell steel plates will be done in following forms;
10.6
Inspection of Foundation 1. Before erecting the bottom plate the tank foundation shall be inspected visually for evidence of cracks, damage etc. 2. Before proceeding to the assembly, ensure that necessary survey of topographic measurements and labeling of the ground on the tank will be mounted have been performed, and that the elevation and axle settings of the assembled anchorages have been correctly fixed. 3. Spot level of the foundations shell be verified and tolerances shall be as per the limit’s specified in API 650 Section 7.5.5.2. 4. A check of the dimension, level and reference point shall be carried out prior to takeover of the foundation and all QA/QC required documents should be signed by Consultant. 5. Level and direction of the foundation shall be confirmed and accepted by Consultant. 6. Camber and flatness of foundation surface shall be confirmed and accepted by Consultant prior to erection of the tanks. 7. Exact center point shall be marked. 8. The tank should be oriented on the tank circle whose 0, 90, 180 and 270 degree points are drawn on the concrete ground.
10.7
Erection (Conventional Method and Internal Floating Roof) Erection sequences of tanks will be as follows: -
Laying of Annular Plates Laying of Bottom Plates Erection of Shell Plates, Wind Girder and Top Curb-angle Erection of Stairway Assembly and Installation of Internal Floating Roof
-
10.7.1
Erection of Structural and Appurtenances Installation of Tank Internal Piping Assembly and Installation of Roof Tank Hydrostatic Test Shot Blasting and Painting Installation of Seal Box-up Handing-over
Annular Plates Laying 1. Welding map must be checked before starting welding. 2. Check the dimension of anchor bolt diameter, if it’s not enough, cut around the slots of the bolt. 3. A backing plate shall be fixed to each annular plate. 4. Start annular plate erect form clean out door. (If any) 5. Each annular plate shall be placed in accordance with the approved project drawings in correct orientation. 6. The radius of each annular plate outer edge shall be measured. 7. Fit-up between annular plates shall be adjusted as required. 8. Upon completion of erection and prior to welding of annular plates, a final check of the joint fit-up welding gaps and radius shall be made. 9. The lapping line of the bottom plates shall be scribed. 10.The shell plate assembling line shall be marked. 11.The weld area (8'') upon which the shell plates to be erected shall be ground flush. 12.All welds shall be inspected by vacuum and NDT techniques.
10.7.2
Bottom Plates Laying
1. Welding map must be checked before starting welding. 2. All plate cutting at site shall be with gas torch. 3. The bottom plates, starting from the center plate shall be laid progressively towards the annular plates in accordance with the project drawings. 4. Root pass welding will be done by back step method with 30 cm intervals parallel from inside to outside. 5. Laps shall be maintained while the fit-up of short seam and long seam as per drawing.
6. Temporary tack weld to be carry out on the long seam to avoid uneven movements and distortion while the fit-up and welding of short seam. 7. Short seam welding will be carried out alternatively to avoid distortion. 8. To prevent welding distortion, restraint jigs or reinforcing beams shall be used. 9. After the completion of short seam welding, remove the temporary tacks on the long seam by grinding to facilitate the long seam fit up. 10.Long seam welding will be carried out alternatively to avoid distortion. 11.Suitable fixtures shall be used to prevent warp age or buckling of the bottom plates when welding the longer side of each plate. 12.Minimum laps shall be maintained while the fit-up of long seam as per approved drawing. 13.Joggling shall be carried out by hammering wherever it necessary. (Three plate joining junction) 14.On completion of the welding of the bottom plates, welding of the tank bottom to the annular plates shall be completed. 15.Sketch to annular plate joint shall be welded only after shell to bottom joint welding. 16.After completion of the welding works, the gauges are removed and point welding places are cleaned thoroughly by wire brushing and grinding. 17.Water draw-off sump shall be insulated (installed olması gerekmiyormu izolasyon değil) and welded according to approved drawing.
18.The first shell plate start point shall be scribed. 19.The center point of the tank bottom shall be scribed. 20.All the bottom plate's joints vacuum box test shall be carried out as per approved process and code specification. 21.If any defect found the defect weld shall be removed by grinding and re-weld and conduct the vacuum box test. Repeat the sequence until the defect cleared.
Bottom plates welding sequence
10.7.3
Shell Course Erection 1. Welding map must be checked before starting welding. 2. The shell plates shall be placed around the tank foundation. 3. All required fixtures shall be installed on the inside of the shell plates. 4. All required fixtures shall be installed on the inside and outside of the annular plates to ensure that the shell plates are aligned with the scribed line. 5. Bracket hooks shall be fitted inside and outside each shell plate before it is lifted into position. 6. Each shell plate shall be secured on the annular plate and aligned by using guides and wedges. 7. The first shell plate with its edge on the start mark shall be erected upright using a 100 mm channel support. 8. Strong back plates shall be employed to secure adjacent shell plates. An alignment and width check of joint gaps shall be carried out before tack welding the vertical seams. 9. The alignment fixtures shall be removed, all tacks cleaned and all vertical joints of the first shell course welded. 10.The shell course dimensions shall be checked for roundness at the bottom and top levels, vertically at a minimum of two points and for level at the shell plate top-level line. 11.When checking is completed the second course of plates shall be placed into position together with the first shell course. 12.For the erection of the second and subsequent courses, scaffold brackets and plates shall be attached to the shell plates and secured with rope. The shell plates shall then be lifted into position. 13.On completion of assembling the shell plates handrail shall be installed on the inside of the scaffold. 14.Wall ladders shall be attached on the inside wall of the tank.
15.The second course vertical joints shall be aligned and welded. 16.Aligning horizontal seam between 1st and 2nd courses, and fit up check shall be carried out after tack welding. 17.The alignment fixtures shall be removed, all tacks cleaned and horizontal joints shall be welded. 18.After completing welding of horizontal joint, 3rd. shell course shall be erected. 19.The same sequence shall be followed to complete the assembly of the remaining shell courses. 10.7.4
Stairway Erection 1. Pad location for the stair case support shall be marked on the shell plates. 2. Pad shall be welded and appropriate QC check to be done. Weep hole shall be provided on all pads. 3. All stair-treads, handrails must be bolted to stringer in segments up to the intermediate landing platforms. 4. Assembled lower segment of spiral stairway shall be lifted and installed. Following the lower segment, first intermediate platform shall be erected. 5. After welding of the lower segment, further portion shall be erected in similar way. 6. MPI shall be carried out on all temporary attachment removal areas.
10.7.5
Appurtenances Installation 1. After completion of bottom shell course welding shell manholes and nozzles shall be marked as per drawing. 2. Orientation, elevation and projection shall be maintained as per drawing and offer for the inspection clearance. 3. Cut the openings by gas cutting after proper inspection by Inspection Authority. 4. Install the reinforcing pads wherever required as per drawing before erection. 5. Erect the prefabricated manholes or nozzles as per the orientation and the elevation shown in the drawing. 6. Suitable jigs and fixtures shall be provided to prevent the distortion during the welding. 7. Welding shall be as per WPS and to be welded by the qualified welder. 8. Manhole neck shall be fabricated and the longitudinal joint shall be radiographed.
9. All RF pad weld shall be pneumatically tested at an pressure of 1.05 kg/cm2. 10.Reinforcing pad pneumatic test shall be carried out to the satisfaction of the Consultant. 11.All the shell manholes or nozzles final weld from both sides and reinforcing pads welds shall be inspected by visually and by LPT, to the satisfaction of the Consultant. 12.Flanges to pipe joint shall be prefabricated and required NDT shall be completed before erection.
10.7.6
Roof Erection (Fixed Supported) 1. Shell plate and roof structures shall be protected by heavy wind during the erection using guy wire rope method. 2. A detailed execution procedure and/ or plan including the detailed dimensions of the device shall be prepared and submitted to Consultantfor approval, prior to commencement of shell construction work. 3. Roof structure shall be assemble on the ground in section or completed depending on size and weight. 4. Assembled roof structure shall be erected inside the tank after completion of bottom plate and annular plate. 5. Roof of outer rafter shall be assemble on the ground in section or completed depending on size and weight. 6. Assemble the roof plate on the temporary support. 7. Assemble and welding the center ring and center plate complete with stiffener and rib plate. 8. Fit the ring on the roof plate. 9. Install the rafter and girder on the roof plate. 10.Erect the outer rafter on the temporary support after completion of bottom plate and annular plate.
10.7.6
Floating Roof Erection (Internal)
1. When half portion of the bottom plates are welded, including annular plates segment plus the internal welding between 1st shell course and annular plates, vacuum box test shall be conducted and cleared for internal float roof assembly. 2. Internal floating roof lower deck plates shall be laid and welded in same sequence of bottom plates.
3. Mark up on the lower deck plates, the location of outer rim, Intermediate rim, compartment plates, structures, leg supports and accessories. 4. Positioning, fit up and welding of outer rim, intermediate rim plate, center rim plate and rafter. 5. Complete welding of vertical and all joints to the lower deck plates 6. Welding of the compartment of the floating deck shall be done starting from the opposite side of the entry ramp. 7. When total assembly and welding of the floating roof without roof plates is completed, including sleeves supporting legs, all manholes and nozzles of 1st shell course shall be closed. 8. Temporary ladder positioned in two locations of the 2nd or 3rd shell course shall be provided to enter in the tank. 9. Closing of the 1st, 2nd and, in case, 3rd shell course will be done in steps, in order to complete at the same time the assembly of the floating roof (still without roof plates). 10.Water shall be pumped inside the tank trough one nozzle and slowly float roof will be lifted up. 11.Water shall be pumped until the float reaches the height allowing the insertion of the pins into the legs. 12.Check the orientation of the floating roof, as per floating roof layout drawing. 13.Water shall be drained. 14.Tank shall be cleaned with high pressure water jet. 15.Floating deck roof plates shall be installed. 16.Foam dam shall be installed. 17.Manholes, drainage, internal piping, etc. shall be installed. 18.Roller ladder shall be installed. 19.Primary shoe and seal shall be installed after final hydrotest and internal painting, as per supplier instruction.
10.8
Inspection and Testing Also see Field Inspection and Test Procedure xxx.xxx
10.8.1
Welded Joints 1. If any tack welds are to be incorporated into horizontal shell seams these shall be dressed to the satisfaction of the Consultant Representative. 2. Fillet welds that cross horizontal or vertical shell seams shall be subjected to 100% MPI.
3. One spot radiograph shall be taken of each radial joint. 4. The shell to bottom weld shall be inspected by wet MPI on the inside and outside after the 1st pass each side and after hydro test on the completed welds. 5. When roof truss main supporting members are made up from two shorter length, the penetration of these welds shall be examined by radiography.
10.8.2
Tank Bottom and Roof Plates 1. All tank bottom and roof plate welds shall be tested, before hydro-test & painting, using vacuum box soapy water shall be applied to all joints. 2. Test shall be done after at least 4 days of welding. 3. Roof plate shall be tested applying internal air pressure not exceeding the weight of the roof plates and applying to the weld joint a soap solution for the detection of leaks.
4. Annular plate joints shall be tested by RT and MPI according to API 650 Section8.
10.8.3
Tank Shell 1. Applying NDT on shell joints shall be according to approved ITP of tank and API 650 Sec. 6. 2. On completion of the tank construction, inspection of all welded seams and dimensional check according to API 650 Section 8 and acceptance by the Consultant, a hydrostatic test shall be conducted in accordance with the approved procedure to demonstrate welding quality and foundation stability. 3. Hydro test shall be carried out according toapproved Hydrostatic Testing Procedure. See Field Inspection and Test Procedure xxx.xxx
10.8.4
Nozzle Reinforcement Pad Test 1. Nozzle reinforcement pad will be pneumatically tested at 1.05 kg/cm 2 with soap solution.
2. This test shall be carried out before filling the tank for hydrostatic testing. 10.8.5
Fixed Roof Test 1. After filling the tank up to curb angle, all openings in the roof shall be closed and internal pressure shall be applied equivalent to the weight of roof plates, all welded joints in roof shall be checked with soap-suds for detection of leaks. 2. For tanks with small internal pressure, the test pressure shall be equal to 1.25 design pressure.
10.8.6
Dimensional Control 1. Dimensional check including peaking, banding, plumpness and roundness shall be according to API 650 Section 8 and approved ITP of tank.
10.9
Calibration See Tank Calibration Procedure xxx.xxx
10.10
Shot Blasting and Painting 1. Before application of paint, the surface shall be cleaned of dust etc. by wire brushing / sand blasting by SA 2 for under side for bottom plate and SA 2 ½ for shell, roof, deck etc. 2. All paints shall be stirred up not be carried out if the atmospheric temperature is less than 5 °C, above dew or if the temperature exceeds 40°C, in the shadow or if relative humidity exceeds 85% or any other adverse weather conditions such as rain, fog, dust storm etc. 3. Coating media shall be applied in uniform thickness. 4. All slots, recesses, grooves, corners, angles and interstices shall be distributed or removed and new paint shall be applied uniformly. 5. All paint containers shall only be opened prior to utilization and shall be carefully closed immediately after withdrawal of material. 6. Material, which become unserviceable during storage shall not be applied. 7. All painting material shall be kept in weatherproof barracks and shall be kept cool and dry. 8. Paint shall be applied by brush or by spray. 9. During spraying the paint shall be maintained thoroughly mixed in the spray gun. 10.The paint shall be sprayed uniformly.
11.Surface impossible to be coated by spraying shall be painted by brush. 12.Painting work shall be done in day time only. 13.Check dry film thickness (DFT) with standard paint thickness measurement instrument such as Elcometer. 14.Tank number and capacity shall be painted on each tank with suitable size letters and numbers.
