tank erection procedure

PROJECT: SUG FACILITIES UPGRADE, WAFRA

CLIENT: JOINT OPERATIONS, WAFRA

CONTRACT NO: JO/HC32/MP04

CONTRACTOR: ARABI ENERTECH KSC

DOCMENT NO: AE/C-911/QC/ME/030

FA 0 01/11/06 For ApprovalFA C 05/09/06 For ApprovalFA B 20/07/06 For ApprovalFA A 07/06/06 For Approval

Status Rev Date DescriptionBy

Checked

Approved JO

ARABI ENERTECH KSC CLIENT

FABRICATION AND ERECTION PROCEDURE FOR TANK

CONTENTS

1.0 Scope

2.0 References

3.0 Material & Marking

4.0 Cutting, Forming, & Fabrication.

5.0 Erection

6.0 Welding

7.0 Post Weld Heat Treatment.

8.0 Testing & Inspection

9.0 Health, Safety & Environment.

10.0 Attachments

1.0 Scope

1.1 This procedure shall supplement the requirements of API 650 10 th.edition for construction, shop fabrications, field fabrications, welding and erection of Tank (T-201) for SUG Facilities Upgrade project (Project No: MP-734) of Joint Operations at Wafra.

2.0 REFERENCES

2.1 API 650: Welded Steel Storage Tanks for Oil Storage.

2.2 AE/C-911/QC/ME/025: General Welding Procedure

2.3 AE/C-911/QC/ME/027: General Weld Repair Procedure

2.4 JO Technical Specs: Section 13208: Welded Steel Tank.

3.0 GENERAL

3.1 Materials & Markings.

* All plates & structural members shall be marked for traceability. * All plate material shall be shop primed for temporary protection during storage &

construction. * Tank plates shall be checked by TPI before receiving at site.

* Physical inspection & review of MTCs of all materials shall be carried by site TPI & JO for approval.

*Heat No. shall be stamped on these materials in the corner Approximately 6'' from either edge *Heat Nos. on each plates shall be highlighted for ease of correlation with mill certificates and shall be located on outside of the finished tank

* During fabrication & erection material identification & Heat No. shall be stamped on each part shall be cut.

* Fabrication may be carried out in AE work shop or at site.*Erection marks shall be painted clearly on plates and structural members in white paint and shall be at least 2'' height.

*

3.2 Foundation

Inspection of Foundationi)Before erecting the bottom plate the tank foundation shall be inspected visually for

evidence of cracks, damage etc.

ii) 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 shall be signed by AE, TPI & JO.

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iii) Spot level of the foundations shell be verified and tolerances shall be as per the limit’s specified in API 650 clause 5.5.5.2.

iv) Exact center point & orientation (0º, 90º,180º,270º) shall be marked.

4.0 CUTTING, FORMING & FABRICTION.

4.1 Plate material shall be straight and/or flattened by pressing or rolling audtties shall be done before the material is processed in any way.

Manual cutting shall not be utilized for containment parts without JO approval.

4. 2 Plate Edge Preparation

The edge of the tank plates shall be sheared, machine cut or bevelled with a machine operated gas-cutting torch. 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.

All shell plates shall be profiled to tolerance of ± 2mm in length and ±1mm in width. In addition, to ensure that plates are truly rectangular, the diagonals, measured across the rectangle formed by scrubbing lines 2'' from each edge, shall not differ by more than 3mm for lapped and welded roof and bottom plates, normal mill tolerances are acceptable.

Curved edges of roof, bottom sketch plates and annular plates shall be cut to shape by the machine operated gas torch. Various radius templates will be used for marking and cutting. Templates shall be approved by JO before using. The resulting surface shall be uniform, smooth and free from scale or slag accumulations. The beveled edges shall be ground to remove all the above accumulations.

Underside of tank bottom plates shall be blasted and coated as per KOC-P-001 system A1-2.

4.3 Rolling of Shell Plate.

Shell plates shall be shaped to the correct curvature of the tank. Rolling will be developed in place, in a fabrication shop designed and built for this purpose. Plate bending machine having rolling capacity 30mm thick and 2500mm wide size shall be used. Pre-bend 200mm of both ends, of shell plate edges to the required radius.

Plate shall be rolled within permissible localized variations as specified in ASTM A6 & A20 and shall be free from buckling, dents. excessive drawing, distortion or obvious imperfections. Templates shall be used to measure the rolled plates curvature. Rolling of shell plate giving required load stage by stage on rolling direction. Check radius using the above template stage by stage until the required radius is obtained. Rolled shell plates shall be stacked on radius cradles, which is same to roll for further process.

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plates dimensions shall be verified prior to the start of edge preparation or rolling operations.

4.4 Clean-out DoorC.O.D Plate cutting and marking only as per “Approved For Construction Drawing”. Machining of clean out door flange and cover as per drawings.

Stress relief shall be carried out according to API650 & Approved PWHT procedure.

4.5 Nozzles, Manholes and Other Appurtenances All nozzles, manholes and other appurtenances shall be fabricated & PWHT in the

shop, in accordance with the approved construction drawings.

A protective shelter shall be used. Pipe shall be pre-heated around its circumference and maintained on 12'' sections

on either side of the weld. Each weld shall be started (root pass) and finished while the preheat temperature is

maintained without interruption. Pipe shall be covered immediately after welding and be permitted to cool at

uniform rate.

5.0 Erection

5.1 Laying of Annular Plates

A backing plate shall be fixed to each annular plate. Each annular plate shall be placed in accordance with the approved project

drawings in correct orientation. The radius of each annular plate outer edge shall be measured. Fit-up between annular plates shall be adjusted as required. 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. The weld area (8'') upon which the shell plates to be erected shall be ground flush. All welds shall be inspected by vacuum and NDT techniques. The shell plate assembling line shall be marked. The lapping line of the bottom plates shall be scribed. Welding map must be (As Fig 9) check div before weld No.3 after that No.4 Last

Weld No.5 Start annular plate erect form clean out door. Check the dimension of Anchor bolt dia, if it’s not enough, we must cut around the

(slots) of the bolt.

5.2 Laying of Bottom Platesi) The bottom plates, starting from the center plate shall be laid progressively

towards the annular plates in accordance with the project drawings.

ii) Water draw-off sump shall be insulated and welded according to approved drawing JO-MP/AE-734-M-327 sheet 2 of 2 .

iii) Suitable fixtures shall be used to prevent warp age or buckling of the bottom plates when welding the longer side of each plate. (Ref. Fig.2)

iv) All plate cutting at site shall be with gas torch.

v) The bottom plates shall be welded in sequence mentioned before. (Ref. Fig.9)

vi) On completion of the welding of the bottom plates welding of the tank bottom to the annular plates shall be completed.

vii)The bottom plate welds shall be vacuum test inspected.

viii) The first shell plate start point shall be scribed.

ix) The center point of the tank bottom shall be scribed.

5.3 Tank Shell Assembling

5.3.1 Preparation before Assemblingi) The shell plates shall be placed around the tank foundation.

ii) All required fixtures shall be installed on the inside of the shell plates. (Ref. Fig.3)

iii) 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. (Ref. Fig.4)

iv) Bracket hooks shall be fitted inside and outside each shell plate before it is lifted into position. ( Ref. Fig.5)

5.3.2 Assemblingi) Each shell plate shall be secured on the annular plate and aligned by using guides

and wedges. (Ref. Fig.4)

ii) The first shell plate with its edge on the start mark shall be erected upright using a 100 mm channel support. ( Ref. Fig.3).

iii) 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. (Ref. Fig.6&7)

iv) The alignment fixtures shall be removed, all tacks cleaned and all vertical joints of the first shell course welded.

v) 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.

vi) When checking is completed the second course of plates shall be placed into position together with the first shell course.

vii)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.

viii) On completion of assembling the shell plates handrail shall be installed on the inside of the scaffold

ix) Wall ladders shall be attached on the inside wall of the tank.

x) The second course vertical joints shall be aligned and welded.

xi)Aligning horizontal seam between 1st. & 2nd. Courses, as per Fig.8 and fit up check shall be carried out after tack welding.

xii)The alignment fixtures shall be removed, all tacks cleaned and horizontal joints shall be welded.

xiii) After completing welding of horizontal joint, 3rd. shell course shall be erected.

x) The same sequence shall be followed to complete the assembly of the remaining shell courses.

Vertical seams shall be located, as to clear all shell appurtenances and their reinforcing pads.

** Guying system shall be used during shell courses erection from 4th. Course and shall be moved up progressively. For details see. Fig.14

5.3.3 Tank Shell Plumbness To inspect the roundness of the first shell course, the distance from the auxiliary line

scribed on the tank bottom inside the tank shell, to each bottom shell plate, shall be measured. If the distance is not within tolerance it shall be corrected by means of the wedge guides and wedges.

The verticality of the first shell course shall be inspected by using an internal plumb line suspended from the course top and the distance between the plumb line and the inside of the tank shell at the bottom, measured at a minimum of two positions for each plate.

If the tank shell is found to be titled in excess of the tolerance limit, the temporary 100 mm channel supports shall be removed from the first shell course and the tank shell verticality corrected by means of a hand lever block.

To inspect the level of the first shell course top line, a graduated level shall be installed inside the tank at the center of the tank bottom, with its top aligned with the top of the shell course. The graduations shall be read at two or more positions per shell plate

The level shall be corrected by driving wedges between the foundation and the tank bottom where the tank shell is low. The space between the lifted tank bottom and the foundation shall be filled with non-shrink grout

5.3.4 Shell Manholes The manhole contour shall be marked on the shell plate in accordance with the

approved drawing. The client’s authorized inspector shall inspect the scribed manhole lines before the manhole is cut out.

5.4 Tank structure .

The installation of Tank roof supporting structural steel members and its attachment sequence with the last shell course prior to welding will be followed as described below:

5.4.1 The entire tank bottom plate will be accurately marked of the locations for one number central supporting Column (C2) and 8 numbers intermediate (inner) supporting columns (C1).

5.4.2 Erect column (C2) bearing plate on the Tank bottom plate, align and weld.5.4.3 Erect column (C2) base plate at the above bearing plate, align & tack weld.5.4.4 Erect column (C2) at base plate, align and tack weld along with stiffeners with the

column and the base plate. 5.4.5 Erect 8 Nos. columns (C1) as described at Sl. No. 5.4.2, 5.4.3 & 5.4.4 in sequence one

after another duly connecting the purlins beam between two columns as a bolted connection with due alignment.

5.4.6 Erect 8 Nos. Rafter beams (M2) between central column (C2) and inner column (C1) diagonally opposite in sequence duly aligned by bolting at one end and tack welding at other end.

5.4.7 Erect Rafter beams M4 & M6 between the ring beam of central column (C2) and the purline beam diagonally opposite, segment wise in sequential manner. One end of the rafter will be bolted with central ring beam and other end will be tack welded with gusset plate at purline beams with due alignment of each member.

5.4.8 The entire assembly of central column (C2), inner column (C1), purline beams main rafter beams (M2) and rafter beams (M4 & M6) will be finally checked for alignment as composite member and welded for full strength. The bolted ends of all above members will be fully tightened before full welding of various joints. The sequence of final welding will be diagonally opposite in each member to ensure that no distortion is taking place at any stage. Adequate restraints will be provided depending upon the prevailing situation.

5.4.9 Now the most critical installation/ attachment of structural members with the top shell plate course will be started segment wise diagonally opposite in sequential manner as follows :

5.4.9.1 Segment Starting from 355 0 to 45 0 :

5.4.9.1.1 Erect the pad plate item no. 23 with the tank top shell course and a gusset plate item no. 22 over the pad plate spaced at 7.5 degree interval from 0 degree to 45 degree.

5.4.9.1.2 Erect Rafter beam (M1) at 00 between inner column ring beam and top course of tank shell plate duly bolted at the tank shell side and tack welded at the rafter beam side.

5.4.9.1.3 Erect Rafter beam (M1) at 450 between inner column (C1) ring beam and top course of Tank Shell plate duly bolt at the tank shell side and tack welded at rafter beam side.

5.4.9.1.4 Erect 2 Nos. each rafter beams M3, M5 and 1 No. rafter beam M7 between central column ring beam and top course of tank shell plate falling with in segment from 00 to 450 duly bolting at one end and tack welding on the other end.

5.4.9.1.5 Align the above two rafters (at 00 and 450) & all other intermediate rafters between them and strengthen the existing tack weld at rafter beam end and tightened the bolts at other end.

5.4.9.2 Segment Starting from 175 0 to 225 0 Repeat the erection activities as per 5.4.9.1 diagonally opposite between the segment beginning from 180 degree to 225 degree.







5.5 Roof Framing and Roof Sheets

Temporary supports erected for the roof framing shall not be removed until the erection of the main and secondary framing is complete. The roof trusses shall be positioned very accurately to avoid misalignment .

Roof plates lifting shall be as per fig.13.

Roof sheets shall be assembled on the framing, with loads distributed as evenly as possible. Not more than three roof sheets shall be stacked at any one point. The roof sheets shall be assembled symmetrically, working from the center outward.

All attachments to tank shell, bottom & roof shall be continuous seal welded to prevent corrosion.

* Roof Supporting Structure shall be prefabricated, erected and welded according to approved drawing No. JO-MP/AE-734-M-332 sheet 1 of 2 , 2of 2.

5.6 SPIRAL STAIRCASE

Spiral Staircase shall be prefabricated, erected and welded according to approved drawing No. JO-MP/AE-734-M-333 sheet 1 of 3 , 2of 3 & 3of 3.

5.7 TOP HANDRIALING & PLATFORM

Top Hand Railing & platform shall be prefabricated, erected and welded according to approved drawing No. JO-MP/AE-734-M-334 sheet 1 of 1.

5.8 INTERNAL COLLECTOR.

Internal water & oil collectors shall be prefabricated, erected and welded according to approved drawing No. JO-MP/AE-734-M-335 sheet 1 of 2 & 2of 2.

5.9 INTERNAL SPREADER.

Internal spreader shall be prefabricated, erected and welded according to approved drawing No. JO-MP/AE-734-M-336 sheet 1of 2 & 2 of 2.

5.6 ANCHOR CHAIR

Anchor chair shall be prefabricated, erected and welded according to approved drawing No. JO-MP/AE-734-M-337 sheet 1of 1.

6.0 Welding

All welding of tank plates, steel framing, structural attachments and mountings in both the fabrication shop and in the field shall conform to welding procedures and qualifications per section IX of ASME BPVC.

6.1 Sequence of Welding

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The sequence employed for tack welding and final welding of the bottom, shell and roof plates shall be arranged to minimize distortion due to weld shrinkage. Ref. Fig. ( 9, 10 & 11 )

6.1.1 Annular plate: All joints shall fit-up except one and welding shall start either odd or even joints first. After that, welding shall start from any one joint to both directions i.e. clockwise and anti-clockwise. Before welding of the final joint make sure the annular plate outer diameter as required. Particular attention shall be given to the welding of butt-welded seams for the annular plates where these pass under the shell plates, to ensure that full penetration is obtained. (Ref. Fig. 10)

Necessary NDT shall be applied according to approved ITP, contract drawing & API650

6.1.2 Bottom plate: Short seam joints fit-up and welding will starts first from bottom center to

side. After welding of short seam joints the long seam fit-up and welding will starts from center to towards side. Complete the welding both long joints adjacent to the center point, after that alternate joint. Finally complete all remaining long seam joints in the same manner. Keep open at least 8'' from open ends of long seam with annular plates. Annular plate to bottom sketch plates fit-up and welding shall start after completion of shell to annular welding. (Ref. Fig. 10)

Three lap joints shall be rounded and bent using horse shoe and wedge with hammering, direct hammering not allowed, and these joints shall be tested by DPI.(Ref. Fig 12)

6.1.3 Shell plates Vertical joints : Fit-up and welding shall start at alternative joints. After that, the remaining joints fit-up and welding shall start from any one joint in both directions i.e. clockwise and anti-clockwise. Before welding of the final joint the shell inner diameter shall be verified. All other shell courses shall be completed as above.

6.1.4 Shell Plates Horizontal joints: After completion of first and second shell course vertical joints, horizontal joint fit-up and welding shall start from any point in both clockwise and anti-clockwise directions. Welders shall be deployed at approximately equal distance, and welding progression shall be one direction. All other horizontal joints will be completed by the same method.

6.1.5 Roof plate: Prefabrication of rafters and roof frames will be complete as per approved drawing. Compression ring segments shall be fit up and welded as per fig.11. Short seam butt joints of each roof plate segments shall be completed first. After erection of roof plates the fit-up and welding of alternate long seam lap joints will complete. The remaining long seam welding will be completed in the same manner. (Ref. Fig.11)

Three lap joints shall be rounded and bent using horse shoe and wedge with hammering, direct hammering not allowed, and these joints shall be tested by DPI.(Ref. Fig 12)

6.1.6 Weather Conditions

Welding shall not be carried out during rain, sand storms or high winds, unless the welder and the work are properly shielded.

To avoid delayed cracking the base metal temperature is in between 0o

F to 32oF the

base metal joint shall be preheated to temperature warm to hand before starting the welding within 3 “ of welded area.

During inclement weather these following shall be considered;

A protective shelter shall be used. Pipe shall be pre-heated around its circumference and maintained on 12'' sections

on either side of the weld. Each weld shall be started (root pass) and finished while the preheat temperature is

maintained without interruption. Pipe shall be covered immediately after welding and be permitted to cool at

uniform rate.

6.2 Welding Procedure

6.2.1 General

The welding procedure shall be as follows: -

i) In multilayer welding, each layer of weld metal shall be thoroughly cleaned by removing all slag and other deposits before the next layer is applied. All completed welds shall be free from slag, brushed and thoroughly cleaned before final inspection.

ii) The reverse side of double welded vertical and horizontal butt joints shall be back-chipped, ground after the application of the first run of weld, in a manner which will leave the exposed surface accessible and satisfactory for the fusion of the weld metal to be added. Back gouging or grinding to bright metal is required.

iii) Undercutting and other weld defect shall be restricted to code permissible.

iv) The weld metal on both sides of all butt joints, except offset faces of horizontal joints of unequal plate thickness, shall be built up in the form of an overlay so that the finished face in the area of fusion extends above the surface of the adjoining plates to a height of not more than 1.5 mm.

v) The edges of all welds shall merge with the surface of the adjoining plates without a sharp angle.

vi) Automatic welding shall be used, subject to written approval from the client. When automatic welding is used, details of plate edge preparation shall be specified.

vii) Procedure qualification for shell- to-bottom joints shall be performed on the actual joint configuration, material and thickness to be used. The hardness of the heat affected zone shall not exceed 280Hv.

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ix) Vertical joints in bottom shell courses shall be at least 300mm clear of any

annular plate joint. Vertical joints in adjacent shell courses shall be off set by at least 1/3 rd. of the plate length but with a min. of 500mm where make-up plates are used.

x) Butt welds joining compression rings top angle or wind girder sections shall be at least 150mm away from any shell vertical seam.

** All shell vertical joints shall be welded by manual Arc Welding.

Progressive RT & other NDT required shall be carried out as per contract & code requirements.

6.2.2 Bottom Plate jointsAll lap joints on bottom plates shall be full fillet welded on the topside only.

The annular plate's radial seams shall be butt-welded and shall have complete penetration for the full thickness of the annular plate, with a backing strip of 6 mm thickness. Special attention shall be given to the required gap between the plates to ensure full penetration

6.2.3 Bottom to Shell Plate JointsThe shell plates shall be continuously welded on both sides to the annular plates with the leg length of both fillet welds equal to the thickness of the annular plate.

6.2.4 Shell Butt JointsShell butt joints shall be made as follows & as per API 650 last edition as applicable.

i) All seams shall be butt welded from both sides of the plate.

ii) All vertical butt joints, whether square, single “V “or double “V’, shall have complete weld penetration through the full thickness of the parent plate.

iii) All horizontal square and single bevel butt joints shall have complete penetration through the full thickness of the parent plate.

iv) All horizontal double bevel butt joints shall have complete penetration through the full thickness of the parent plate.

6.2.5 Roof Plate Joints

All Roof plate joints shall be full fillet welded on the welded side. All roof lap joints and nozzles penetration shall be seam welded and weld spatter shall

be removed to give smooth internal surface.

7.0 POST WELD HEAT TREATMENT. (PWHT).

a) Stress Relieving for clean out door, nozzles and fittings shall be carried out according to API 650, Approved PWHT procedure & JO specification.

b) Stress Relieving shall be furnace stress relieved prior to installation. No. local stress relieving is permitted for shell fittings.

8.0 Testing & inspection.

8.1 Welded Joints

a) If any tack welds are to be incorporated into horizontal shell seams these shall be dressed to the satisfaction of the JO representative.

b) Fillet welds that cross horizontal or vertical shell seams shall be subjected to 100% MPI.

c) One spot radiograph shall be taken of each radial joint.

d) 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.

e) When roof truss main supporting members are made up from 2 shorter length, the penetration of these welds shall be examined by radiography.

8.2 Tank Bottom and Roof Plates

*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. Test shall be done after at least 4days of welding.

*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.

*Annular plate joints shall be tested by RT & MPI according to API 650 Sec. 6.

Tank Shell

* Applying NDE on shell joints shall be according to approved ITP of tank & API 650, Sec. 6.

* On completion of the tank construction, inspection of all welded seams and dimensional check according to API 650 sec.5 and acceptance by the client, a hydrostatic test shall be conducted in accordance with the approved procedure to demonstrate welding quality and foundation stability.

Hydrostatic testing shall be carried out according to approved hydro-test procedure .AE/C-911/QC/ME/044.

* Dimensional control.

Dimensional check including Peaking, Banding, Plumbness and Roundness shall be according to API 650 Sec. 5. & approved ITP of tank.

9.0 HEALTH, SAFETY & ENVIROMENT.

9.1 In general all recommendations and suggestions advised in HSE Plan. shall be strictly

adhered by all Personnel working at field and fabrication yard premises.

9.2 Necessary Personnel Protective safety equipments shall be provided to the all the

personnel working in the field as well as yard.

9.3 Equipments used shall meet the safety requirements of Joint Operations Fire & Safety

regulations

9.4 Scaffolding shall conform to OSHA1910.28.and shall be designed by a civil engineer.

10.0 ATTACHMENTS.

Attached to this procedure the forms of the following reports.

Fit up Check. Peaking . Banding. Roundness. Plumbness. Dimension Check.

tank erection procedure

Documents

arabi enertech ksc

erect rafter beam

rafter beam side

full fillet welded

plate edge preparation

tank shell side

ring beam

rafter beams