erection procedure tanks

IMPROVED WATERSUPPLY QUALITY ATDHAHRAN PROJECT

TABLE OF CONTENTS

1 Scope…… ……………………………………………………………………………….…...….............5

2 Definitions…………………………………………………………………………………....……...........5

3 Reference …………………………………………………………………………………..……............5

4 Responsibilities............................................................................................................................6

5 Material Receiving.......................................................................................................................8

6 Welding Procedure......................................................................................................................8

7 Field Tank Erection.....................................................................................................................8

8 Quality Assurance and Testing...................................................................................................15

9 Health Safety and Environment..................................................................................................16

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1. SCOPE

This document provides the proper methodology and sequence of activities for tank field erection of

Storage Tank for Saudi Aramco – Improved Water Supply Quality – Saudi Aramco Project at

Dhahran. The scope of field erection tanks is follow:

1.1 Drinking Water Storage Tank (1 tank)

- 194-D-0001 1 Tank

2. DEFINITIONS

PURCHASER - Metals Services for Trading & Contracting Co. (MSTC)

VENDOR - Petrol Steel Company Limited (PSCL)

Shall - Denotes minimum requirements

Should - Denotes a recommendation

ITP - Inspection and Test Plan

WPS - Welding Procedure Specification

API - American Petroleum Institute

QA/QC - Quality Assurance/Quality Control

AFC - Approved For Construction

SMAW - Shielded Metal Arc Welding

SAW - Submerged Arc Welding

HSE - Health, Safety and Environment

PTW - Permit To Work

NDT - Non-Destructive Test

NCR - Non-Conformance Report

3. REFERENCE

xxxxxxxxxxxxxx

xxxxxxxxxxxxxx

4. RESPONSIBILITIES

The following are the responsibilities of personnel involved in the scope of this method statement:

4.1 Construction Manager

4.1.1 Shall report to the concern Project Manager

4.1.2 Shall be responsible for the overall site management, dissemination/execution of quality

procedures. Establish construction organization, monitor job quality, schedule control and

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overall construction management.

4.2 Construction Superintendent

4.2.1 Shall report to the Construction Manager.

4.2.2 Shall be responsible to supervise the construction activities required to complete the work

on time ensuring it meets the drawing’s specification requirements. Also ensure compliance

with quality procedures.

4.3 Construction Engineer

4.3.1 Shall report to Construction Superintendent.

4.3.2 Shall assist Construction Superintendent on daily construction activities including

monitoring of material delivery schedule; ensure approved drawings at site and other

construction matter.

4.3.3 Shall be responsible for coordinating with tank construction team and QA/QC Inspector for

inspection items. Shall take note and follow-up on the comments.

4.3.4 Shall monitor the tank assembly activities and update daily progress status to planning

engineer.

4.4 Tank Construction Supervisor

4.4.1 Shall be responsible for progress of works and meet necessary quality standards and

report to the Construction Superintendent.

4.4.2 His main duty is to direct actual day-to-day performance of work and to supervise the work

assigned under his charge.

4.4.3 He shall make arrangement for material request, work execution and coordinate with other

supervisor and subcontractors. Also monitor the safety of personnel under his charge.

4.5 Welding Supervisor

xxxxxxxxxxxx

Xxxxxxxxxxx

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4.6 QA/QC Inspector

4.6.1 Shall report to the QA/QC Manager.

4.6.2 Shall be responsible for inspection of tank erection activities. Assist and coordinate

with Construction Engineer or Construction Supervisor on daily work to make sure

it is line with quality requirement.

4.6.3 Shall coordinate with PURCHASER Inspection Representative or PURCHASER

approved/appointed third party for any inspection activity which is required as per

the ITP.

4.6.4 Keeps records of the inspection report.

4.7 HSE Officer

4.7.1 The HSE Officer is responsible for establishing and enforcing safety rules and

regulations adaptable to the site.

4.7.2 Shall ensure safe and healthy working conditions.

4.7.3 He is also responsible for conducting site safety meeting and other related training for

company workers and staffs.

5.0 MATERIAL RECEIVING, STORING AND DELIVERY

5.1 Receiving, storing and delivery of tank materials shall be done properly and accordingly.

5.2 Sufficient wood blocks shall be put under all elements and clearance from ground shall be

provided and maintained especially after sandstorm and other weather conditions.

5.3 Shell plates shall be placed on top of frame and curvature shall be maintained.

5.4 Materials shall be segregated as per material specifications and material grade. The plate ma-

terials shall be stored adjacent to the erection area for easy access during the time of lifting or

erection

5.5 Proper markings and barricades shall be provided properly.

6.0 WELDING PROCEDURE

6.1 Welding activities shall be performed in accordance with the approved WPS in accordance to

SAES-X-500

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6.2 Qualification and certification of welding inspector, NDT personnel and coating inspector shall

be in accordance with xxxxxxx.?

6.2.1 Welding inspector, NDT personnel and coating personnel qualification and

certification shall be reviewed and approved by Purchaser Quality representative

prior to starting work.

6.2.2 Welding inspector qualification shall be level I & II inspector and shall be approved

by Purchaser prior to proceed work.

6.2.3 The personnel responsible for interpretation of NDT operations shall be certified to

a minimum of Level II per the certifying organizations written practice.

6.2.4 Coating inspector shall be CSWIP/BGAS qualified and certified.

6.3 Welding shall not be performed when material surface to be welded are wet from rain nor

during period of high winds unless the welder and the work are properly shielded and as per

approved WPS.

6.4 The surface to be welded shall be cleaned and free from scale, oil, rust, water and other foreign

materials before commencing the welding work. When edges of plate are flame cut, the

resulting surface shall be uniform and smooth and shall be free from scale and slag

accumulation before welding.

6.5 Each layer of weld or multilayer welding shall be free from slag and other deposits before

applying the next layer.

6.6 All the visual inspection criteria will be followed as per API 650 code and approved ITP for

Tankage Construction (Fabrication and Erection).

7.0 FIELD TANK ERECTION PROCEDURE

7.1 Sequence of tank erection work.

7.1.1 On receipt of material for the tanks, its prefabricated shall commence.

7.1.2 The field erection of tank shall be led by field erection supervisors. Field tank

erection works shall be commencing upon approval of General Field Tank Erection

Procedure.

7.1.3 Civil tank foundation handover package pre-approved from (MSTC) shall meet

specification and procedure requirements. Slope of tank foundation and shape of

tank foundation shall be properly slope up or down as specified in approved

drawing.

7.1.4 The foundation level shall be measured at equal spaced points and confirmed that

is within the allowable tolerance.

7.1.5 Marking of center and orientation marks. The center point shall be determined

based on the four points 0°, 90°, 180°, and 270°.

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6” for position of shell plate

Annular PlateBacking strip

Figure 6.1


7.2 Erection of Annular & Bottom Plate.

7.2.1 Mark out the proper radius of the annular plates by marking from the tank center.

Annular plates shall be laid simultaneously in clockwise and counter clockwise

direction starting from a single point as per AFC drawing.

7.2.2 Any drain sump inserted in the tank bottom shall be firmly bedded on the

foundation, taking full care to eliminate any void under bottom of the sump itself.

7.2.3 Fit-up the annular plates in order to obtain the proper gap. Lay the plates at a

slightly larger radius than the given radius to compensate the welding shrinkage.

7.2.4 Fit-up shall be made for all the annular plate except last piece which shall be left

for make-up for dimensional adjustment.

7.2.5 Alternate annular joints shall be welded first and then balance joints shall be

welded (about 6” at shell plate location then grind flush – figure 6.1)

7.2.6 Fit-up, weld visual, welder ID number and radiography joint number shall be

maintained and recorded.

7.2.7 The portion of annular plate where shell plates shall be placed shall be

radiographic tested before the erection of shell will take place.

7.2.8 The portion of annular plate where shell plates shall be placed shall be

radiographic tested before the erection of shell will take place.

7.2.9 Lay the bottom plates by concentrating on the slope of the tank. Start the erection

of bottom plates as per the AFC drawing.

7.2.10 The required lap shall be provided on bottom plates as per the approved drawing.

7.2.11 Welding shall be done in a proper sequence to minimize distortion. In general,

welding shall be staged and shall be done in opposite direction simultaneously

from one point to avoid distortion.

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Bottom Plate

Cross seam

Long seam

1

3

5

2

4


7.2.12 Weld the cross seam (short seam) together of each plate layer first and kept the

next cross seam of each plate must be tack free during welding.

7.2.13 Back step welding method could be applicable as well as the distortion preventive

jigs shall be used.

7.2.14 After completing the cross seam welding, the long seams of the bottom plates will

be welded from center by following the sequence as one weld one left i.e. 1, 3, 5,

…. to compensates the shrinkage during welding.

7.2.15 After finishing the above sequence, start welding the remaining long seams i.e. 2,

4, 6,…. up to the sketch plate area.

7.2.16 The welding of the shell plates to the bottom shall be completed before final

welding of any bottom seam left open to compensate for shrinkage or pull of

bottom plate.

7.2.17 The initial weld pass of inner fillet weld of the shell to bottom joint shall be tested

for leaks (oil leak) prior to welding the outside fillet welds.

7.2.18 For conventional method, all bottoms to annular plate welding shall be done when

at least 60% shell courses are erected and welded so that it can restrict the

distortion of the plates due to welding.

7.2.19 When tank has annular plates, sketch plates shall be welded to annular plates after

welding of shell to annular plates. When tank has no annular plates, the sketch

plate shall be welded to bottom plates after welding of shell to bottom plates.

7.2.20 All tank bottom welds shall be tested by a vacuum box method.

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7.3 Erection of Shell Plate.

In general, bottom plates are assembled and welded first starting with the annular bottom

plates. The shell erection shall be carried out by conventional method. Course by course

erection will be carried out until the curb angle. Shell plates are erected and hold in place by

temporary jigs and fixtures.

7.3.1 Rolled shell plates shall be shifted to site with the help of trailers. The plates shall

be unloaded and placed in stacks along the periphery of tank using a crane.

7.3.2 Mark the shell inside diameter and erection diameter (inside diameter of tank plus

shrinkage tolerance) on the annular plate.

7.3.3 Mark the starting point of 1st shell course vertical seam as per approved AFC

drawing.

7.3.4 Tack-weld guide plates at equal intervals on annular plate. These guide plates

shall be set 10mm inward of the correct inside diameter so that wedge can be

inserted in the gap between the stopper plate and the shell.

7.3.5 Erect 1st shell course and secure it in the position on annular plate and taking care

to maching inside surface of the shell with erection diameter marked on the bottom

plate. Key plate shall be used to hold the two adjacent shell plates in the position.

After erection of 1st shell course, round the shell up by using wedges placed

between guide plate and shell.

7.3.6 Shell course shall not be added as long as the previous course is completely

welded and tested in order to prevent distortion and or buckling.

7.3.7 After all the shell plates for 1st shell course are erected in place, align the vertical

seam joint using key plates which have been fixed during erection and tack weld

the seams. Care shall be taken to avoid peaking in the vertical joint. Vertical

strengtheners shall be used and when required to maintain the individual

plumbness of the shell.

7.3.8 During erection, shell shall be safeguarded from distortion or damage due to wind

pressure. For this purpose, suitable steel wire guide, temporary girder or bracing

shall be provided.

7.3.9 Check plumbness of the shell course and provide temporary structure member at

every 4 meter interval to the base between shell and bottom plate to keep the shell

in perfectly vertical position while welding the 1st course vertical seams. Verticality

(plumbness) tolerance shall be 1/200 max (the maximum out of plumbness of the

shell relative to the bottom of the shell shall not exceed 1/200 of the total tank

height).

7.3.10 Check peaking at top, middle and bottom of vertical joint of shell using sweep

board of 900mm long, acceptance tolerance shall not exceed 13mm.

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7.3.11 The roundness of the tank shall be measured at 300mm above the bottom corner

weld shall not exceed the tolerances ±13mm for tank diameter <12 meter.

7.3.12 Shell plate 1st course – Complete welding of first course vertical seam as per

approved welding procedure specification. Care shall be taken to avoid peaking in

and peaking out of the vertical joint. The key plate/wedge shall be used to adjust

the peaking and banding in the respective joints as required.

7.3.13 Erect temporary working platform on the first shell from inside/outside for the next

shell course erection.

7.3.14 Manway shall be cut as soon as possible to break the wind vacuum.

7.3.15 Erect 2nd shell course plates on top of the 1st shell course plates by staggering the

vertical seam as per AFC drawing. 2-3mm thick spacer plates shall be kept

between 1st shell course plates and 2nd shell course plates to maintain horizontal

seam gap. The shell plates shall be held in position using jig plates and erection

channels.

7.3.16 Erection channels shall be placed at 3 places to align and hold the 2nd shell in

vertical position. This fixation of erection channels shall be done for every shell

plate being erected.

7.3.17 Same activities will repeat where need to check plumbness, peaking and

roundness.

7.3.18 Shell plate 2nd course – Complete welding of 2nd course vertical seam as per

approved welding procedure. Fit-up and tacking 1st horizontal seam. Welding can

be start after this. Remove the spacer and tack weld shall be grind smooth before

covered by weld beads.

7.3.19 Weld 1st horizontal seam from outside by SMAW/SAW as applicable. The outside

welding shall be completed first and then inside weld will be after the inspection of

gouged/grind groove has been completed.

7.3.20 NDT should be completed immediately after completion of welding from both sides

to ensure the SMAW/SAW welding is progressing satisfactory. This shall help in

progressive checking of welds during the process of welding.

7.3.21 Lugs, clamps and any other devices used to assist in lifting the plates shall be

removed after use in proper manner without any hammering and shall be ground

flush.

7.3.22 Maximum care in order to avoid damage to the plate surface. For minor damage,

recap by filling the gap with approved material and later ground smooth is

applicable.

7.3.23 Plumbness, peaking and banding shall be checked for each course as explained

above and tolerances archived as per API code QC record shall be maintained.

7.3.24 The erection of stair, ladder, nozzles, manholes or other accessories shall be in

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accordance with AFC drawings and according to the applicable codes and

standards.

7.3.25 Reinforcement pads shall be pneumatically tested with 15 Psi pressure.

7.3.26 Erect succeeding shell courses 3,4,5,6 and 7 using the same sequence from shell

course 1nd 2.

7.3.27 For Cone Roof w/ Internal Rafter

7.3.27.1 Roof rafters shall be constructed first as per AFC drawing to be

assembled inside tank.(see figure 6.4.1)

7.3.27.2 The completed roof structure is now ready to lift by crane as per

proposed roof construction and erection plan.

7.3.27.3 Lift and erect the roof rafter assembly to its permanent location on

tank. (see figure 6.4.2)

7.3.27.4 Once the roof rafter is secured, start lifting the roof plate piece by

piece.

7.3.27.5 Lay the roof plates or roof plate assemblies after then fit and weld.

7.3.27.6 Mark the 0°, 90, 180°, 270°, the orientations/locations of roof

nozzles, platform and other roof attachments.

7.3.27.7 Install the roof nozzles, platform and other roof attachments

including lifting lugs for lifting.

Figure 6.4.1 Roof with Internal Rafter

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ROOF STRUCTURE AS-SEMBLY INSIDE THE

TANK

TANK LOCATION

CRANE

CRANE


Figure 6.4.2 Lift and erect the roof rafter assembly

8.0 QUALITY ASSURANCE AND TESTING

8.1 All tanks & tank components shall be inspected by PURCHASER/VENDOR Inspector at the

field in accordance with approved ITP and Inspection Sequence and Checklist is as per

approved ITP also.

8.1.1 Vacuum box testing of tank bottom welds shall be as per Vendor procedure

reference number PSC-QAQC-PRO-008.

8.1.2 Oil penetrant leak testing for shall to bottom plate joint shall be as per Vendor

procedure reference number PSC-QAQC-PRO-007.

8.1.3 Dye penetrant or wet fluorescent magnetic particle for inside fillet welds of the

shell-to-bottom shall be as per third party.

8.1.4 Radiographic and NDT required testing will be performed by third party.

8.1.5 Coating requirements including applications, approval personnel qualification and

inspection and testing shall be as per Vendor document reference number PSC-

QAQC-SPEC-001 (Painting Specification for Field Erected Tanks) and PSC-

QAQC-PRO-001 (Blasting & Painting Procedure for Field Erected Tanks). Need to

submit

8.2 VENDOR QC Inspector shall verify and record the data of the inspection items before

requesting PURCHASER Inspector for any field inspection.

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ROOF STRUCTURE LIFTING AND POSITIONING ON TOP AN-

GLE OF SHELL

CRANE


8.3 During production welding, the VENDOR QC Inspector shall carry out patrol inspection of the

welding process, checking on consumable and welder qualifications.

8.3.1 Welding Control Procedure shall be as per Vendor document reference number

PSC-QAQC-PRO-004 (Welding Control Procedure for Tankage).

8.3.2 Welding processes to be use during tank field erection are Shielded Metal Arc

Welding (SMAW), Gas Tungsten Arc Welding (GTAW) and Submerged Arc

Welding (SAW).

8.3.3 Welding consumables (electrodes, filler metals, fluxes) shall conform to the project

requirements and shall bear proper identification as required by the applicable filler

metal specification. Welding consumables shall be used only for the primary

material and process applications recommended in the ASME/AWS material

specification or by its manufacturer.

8.4 On completion of welding, the inspector shall examine the relevant percentage of welds

completed and the surrounding area 100% to confirm the acceptability:

8.4.1 Contour

8.4.2 Width and size

8.4.3 Undercut

8.4.4 Overlap

8.4.5 Reinforcement

8.4.6 Cleanliness (spatter, slag, etc)

8.4.7 Stray arcing and scar areas

8.4.8 Any visible flaws

8.4.9 Satisfactory removal of temporary attachments

8.5 On successful completion of visual inspection, the inspector shall give clearance to conduct

required level of NDT in accordance with the relevant ITP, procedures and specifications.

8.6 Unacceptable discontinuities detected during visual examination shall be repaired according to

applicable WPS and the repaired area shall be re-inspected by the same NDT method. After

completion of the Corrective action, PURCHASER Inspector & VENDOR QC Inspector shall

jointly inspect and shall agree for the close out of the NCR.

8.7 After completion of field erection, all the inspection reports as per approved ITP shall be

submitted to PURCHASER for review/approval.

8.7.1 Welder performance data shall be tracked and recorded on a daily basis and

reported to Purchaser Quality representative.

8.7.2 Total number of welds made and rejected shall be reported to Purchase Quality

representative.

8.7.3 Reporting format shall be submitted by Vendor to Purchase Quality Representative

that includes the list of the minimum requirements that shall be included in the weld

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tracking and welder performance report.

8.8 After inspection and acceptance of tank construction, testing shall be in accordance with RT9S-

2500-01.

8.8.1 Field erected tank settlement measurements during hydrostatic testing shall be in

accordance with the requirements of xxxxxxxxxxx???

8.8.2 Field erected tank hydrotesting shall be as per Vendor procedure reference number

PSC-QAQC-PRO-002 (Hydrotest Procedure)

9.0 HEALTH, SAFETY AND ENVIRONMENT (HSE)

The Safety Procedures shall be strictly followed by all VENDOR personnel. The site area will be

covered by VENDOR’s Health, Safety and Environmental Management System.

9.1 Hazard Identification & Counter Safety Measures

Work Activity Hazard Safety Measures

Gas Cutting

Gas leakageUse soup liquid to check any leakage on cutting hose before ignite the torch.

Body injuryMust put on hand glove, face shield & full PPE.Provide proper training to the workers.

Fire hazardKeep away combustible material.Fire extinguisher placed nearby.

Fit-up Plates Pinch pointsUse proper hand tools.Hand gloves required.

Welding Activities

Electrocution

Ensure power cables are in good condition & double insulated.Make sure the welding machine have proper grounding.

Arc eye/ sore eye when exposed to the rays

All welders must use welding shield.Inform other workers not to directly look at the arc strike.

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Fire hazard Keep away combustible material.Fire extinguisher placed nearby.

Grinding & Gouging

Flying particles or pieces

Face shield, hand glove & safety glasses must be worn.

Loud noise emitted Ensure ear plugs are worn by workers.

Changing grinding disc

Accidentally activation of grinder

Ensure power supply is disconnected at every disc changing period.

Working at height

Falling from height Use fall protection & secure when working at height.Proper access & handrail on the working platform.Toe board need to install to prevent falling object from heightProper training to worker.

Lifting/Rigging Falling object hazardCrane failure hazardPinch Points

Use proper rigging equipment and tools which are duly inspected.Hand gloves required.Use appropriate crane.Competent crane/equipment operator required.Competent rigging personnel required

Confined space activities

Suffocation, Lack of air/oxygen deficiency, Fire hazard, electrocution, tripping hazard

No confined space training no entry policyNo confined space permit no entry policyGas testing prior confine space entryConfined space rescue planProper illuminationProvide adequate air flow

9.2 Environmental Risk & Mitigation Measure

9.2.1 Construction Activities – Loud noise produced during the fitting up process of the tank plates, so all the workers working within the vicinity must wear ear plugs and proper safety signage are to be put up.

9.2.2 Welding Activities 9.2.2.1 It will cause welding fumes and it should be performed in open air areas where possible (ventilation should be providing in confine space welding).9.2.2.2 Welders should stand at a correct location to position their heads to avoid the fumes plume flow direction. 9.2.2.3 Remove or protect combustible materials from welding sparks and slag. Welding sparks and slag should be contained by welding cloth/fire blanket.

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9.2.2.4 Alert other colleagues within the vicinity before welding to prevent any arc on eye.

9.2.3 Power Tooling & Painting Activities9.2.3.1 Will cause rusty dust and it should be cover with canvas for the particular area. (JERS H001 R5 does not allow for power tooling as a method for surface preparation prior to coating)

9.2.3.2 Painting will cause strong solvent smell and enriched flammable gas environment. Should have ventilation for internal painting and no hot work is allow in the vicinity where painting is commencing.

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erection procedure tanks

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