TABLE OF
CONTENTS
1.
PURPOSE.......................................................................................................... 3
2.
SCOPE................................................................................................................ 3
3.
REFERENCE.................................................................................................... 3
4.
PROCEDURE.................................................................................................... 3
5.
DEMOULDING / DETENSIONING
STRENGH............................................ 5
6.
CONCRETE SAMPLING................................................................................. 5
7.
SANDBLASTING / ARCHITECTURAL
FINISH........................................... 5
8.
RESPONSIBLITIES.......................................................................................... 7
9.
SAFETY.............................................................................................................. 7
10. TRANSPORTATION......................................................................................... 7
11. ATTACHMENTS.............................................................................................. 10
1. Purpose
·
The purpose of this method
statement is to set guidelines and methodology to be followed during precast
concrete elements production.
2. Scope
·
The scope of this procedure is to
standardized method of the precast concrete elements production. Hence,
execution of the work shall be done be done as per the acceptable standards and
the relevant project specifications.
3. References
·
Project Specification
and Design Drawing
·
SAUDI ARAMCO Standards
4. Procedure
4.1.
Prior to Casting
Prior
to casting, the checks below are to be carried out to ensure that all items are
in accordance with standards, drawings and accepted procedures. In the event of
there being any variation the inspector is to ensure that it is corrected
before casting is authorized or that the matter is reported to his superior.
4.1.2 Mould Condition
Ensure that the basic table, plate or special mould is
level, robust and free from any inherent defects.
4.1.3 Mould Dimension
Ensure that the dimension of the mould conform in all
respect with the drawings. These must be checked prior to the initial cast in
the case of a new set-up or a mould change and thereafter, at intervals of not
more than 50 casts. A record, in the prescribed form, is to be kept of these
checks. Allowable tolerances on first set-up shall be half those detailed in
Appendix A to this manual.
4.1.4 Mould Fixing & Cleanliness
Ensure that all side closers and other formers are fixed
in such a manner that they will not move during the casting process. Ensure
that the mould of form-liner is clean and free from deleterious matters or
foreign substances.
4.1.5 Release Agent
Ensure that the type being uses is approved and that it
is being applied in accordance with the manufacturer’s instructions and in such
a manner that the mould surfaces are evenly covered.
4.2.
Casting
4.2.1
Placement of Reinforcement
Ensure
that the reinforcement is fabricated in accordance with the drawings. Ensure
that reinforcement is positioned in the mould, by means of spaces or any other
method, in such a way that, it remains in the correct position during casting.
Follow
the good practice for ensuring the correct concrete cover, correct hook length,
correct splice length.
4.2.2
Placement of Cast-in Items
Ensure
that cast-in items are of the approved type and size shown on the drawings and
that they are securely fixed in the correct positions.
4.2.3
Placing
The following test must be done prior to placing the
concrete:
-
Concrete
temperature should not be more than 32°C.
-
Slump
test as per mix design requirement:
Ensure
that concrete is placed in the manner most appropriate to the type of element
being cast. Where two different mixes are employed in the same element, as in
the case of some exposed aggregate finishes, particular care must be taken to
ensure that there is a satisfactory bond between the two mixes but that no
leeching occurs. In case of using two different mix for one element, e.g.
(facing mix and backing mix), time gap must be minimized.
4.2.3 Consolidation
Inspector
must ensure that adequate mechanical consolidation is carried out for the
concrete to form one homogeneous mass. Particular attention must be paid to
up-stands, recesses and other small cross-section areas. The method of
consolidation most suited to the mix and type of element is to be used.
4.2.4
Surface finish
All
non-mould surfaces are to be screeded level and trawled smooth. Inspectors are
to pay particular attention to the thickness of table cast elements and the
standard of the trowelled finish.
4.2.5
Movement
Sudden
or violent movement of any filled mould must be avoided between the times of
initial and final set of the concrete.
4.2.6
Curing
At sub contractor factory curing is done as per the factory set-up and sub contractorQMS Standard
Operating Procedure (Doc. No. 1.11) as one of the following:
• Steam Curing
• Indirect Heating
• Curing Compounds
No
need for continuous curing if the elements reach 70% of the 28 days compressive
strength.
Element
can be transported to the site after 3 days of casting date.
5. Demoulding / Detensioning Strength
The
needed concrete strength for demoulding / detensioning (cube strength):
• For
non-prestressed elements: 20 MPa
(or as specified on drawing).
• For
prestressed solid slabs: 25
MPa (or as specified on drawing).
• For
other prestressed elements: 35 MPa
(or as specified on drawing).
Special
instructions for striping strength can be submitted by Design Dept.
6. Concrete
Sampling
For
every concrete mix design that is currently used the frequency for take out of
test samples is once every, not less than once for every 120 m3 of concrete
(ACI 318.5.6.1). By every take out of test samples five (5) samples are taken
for test of strength as either cube specimens or cylinder specimens. By casting
on site only four (4) samples is taken for test of strength.
Sampling
of freshly mixed concrete shall comply ASTM C 172. It shall take place at the
place of casting and at the time of casting. The samples for strength tests
shall be taken at the same time in one work operation (ASTM C172:3.1). The
samples shall be taken in a way that ensures that the samples represent an
average of the mix (ASTM C172:4.2.1).
7. Sandblasting
/ Architectural Finish
Architectural
finish like sandblasting or exposed aggregate can be added to almost all types
of elements like wall panels, columns and slabs. Mostly that kind of finish is
done with special selected aggregates with white or colored concrete.
Before
starting the performance of the finishing work it is important to read the
fabrication drawing and clarify the kind of finishing wanted and on which parts
of the elements.
Sandblasted
finish is done with compressed air and sand blown in high speed through a
nozzle on to the element. The finish is depending on the degree of sandblasting
usually distinguishing between:
• Heavy sandblasting (HSB):
Leaves all stones exposed and in some
degree outstanding
• Medium
sandblasting (MSB):
Between hard sandblasting and light
sandblasting
• Light
sandblasting (LSB):
Leaves the stones only just visible.
However
any degree of sandblasting can be requested by the client.
The
quality controller marks on the elements the limits and the degree of
sandblasted wanted. By chamfered corners and by false joins it must be known
exactly where the limit for sandblasting goes, leaving no doubt whether the
chamfer or joint is sandblasted or not.
Exposed
finish is done by adding retarding chemicals before casting to the parts of the
mold where that finish is wanted. After curing the outer not hardened layer of
concrete is washed off with a strong water jet. Thereby the stones are exposed
giving the wanted surface finish.
The
finish quality is depending on how the retarder chemical is added in the mold
and how the casting is performed. The retarder chemical must be added evenly
and in correct thickness. It is also important that the correct limits between
exposed and not exposed areas is observed especially by chamfers and false
joints.
By
casting one must be careful by the non-horizontal parts of the mold, the
concrete must not slide on the mold moving the retarder and distributing it
unevenly. Generally bigger vertical mold parts with exposed finish should be
avoided because of the problems the to get the good finish.
Approved
sample must be available if the client requests a special finish. The approved
sample must be marked by the client and in addition marked clearly as approved
and for which elements and project it shall be used. If copies of the sample
are made then they must be marked clearly as well. All elements assigned for a
sample must be controlled to have the same appearance on the finish as the
sample.
By
all kinds of architectural finishing it is important that elements to the same
project have a uniform appearance. Seen together they must not stand out and
look different because eventually they will be installed on the same building.
Therefore all elements with the same finish must be compared with not only with
the approved sample but also with each other.
8. Responsibilities
a.)
QC
Manager have to ensure that the Plant QC section is provide by the necessary
facilities and cooperation from all supervisors, foremen and laborers to enable
satisfactory inspection and verification of activities performed by the civil
section.
b.)
Safety
Manager have to ensure that all safety requirements will be enforced by manners
to prevent injury to personnel, damage to plants and equipment's. He should
provide written instructions to established work methods; explain the sequence
of the operation, outline the potential hazards at each stage ad indicate
precautions to be adopted.
c.)
Production
Manager is solely responsible about casting of precast concrete elements
assuring all works being implemented are in
conformance with specifications.
9. Safety
a.)
All personnel shall wear personal protective equipment (PPE) and should
be instructed how to use the PPE correctly.
b.) Signs and barriers have been provided when warranted to isolate
the job site from public and unauthorized personnel.
c.) Conduct tool box meeting related to work activities. Safety
officer shall conduct the activities all the time.
d.) All equipment shall be inspected/passed Saudi Aramco requirements.
e.) All requirement operators must have their valid
license/certificate.
f.) Housekeeping.
10. Transportation
Precast
concrete element can be transported to site if its gain 70% strength of 28 days
of compressive strength.
10.1
Transportation of Wall Panel
For
transportation of wall panels the following type of trailers are used.
1.
A-
frame trailers (flat bed trailer fitted with steel frame having the shape of
letter “A”), to be used to transport elements which need to be transported
vertically, such as wall panels, claddings at normal height.
2.
Low
bed –A frame trailers fixed in such away to give more clear height to pass
under the bridges etc.
After
the loading is completed the loading supervisor will fill the dispatch delivery
note form which will be distributed as per the form. The dispatch deliver note
is to be signed and approved the QC Engineer and the driver.
10.2 Transportation
of Double Tee Slabs
For
transportation of Double Tee Slabs normal flat bed trailers 12m long, 2.5m wide
are used. If the length of Double Tee Slab is exceeding, long flat bed trailer
with length ranges between 13m ~ 22m long, 2.5m wide are used.
After
the loading is completed the loading supervisor will fill the dispatch delivery
note form which will be distributed as per the form. The dispatch deliver note
is to be signed and approved the QC Engineer and the driver.
Speed
Limit
-
Inside
Factory not to exceed 20 KM/H
-
On
high way to site: speed limit as per traffic police instructions
-
At
site as per site instruction but should not exceed 20 KM /H
Securing
the Loads
-
Use
steel chain with come along hook to tighten the DTT slabs
-
Use
protection at the touching point between the chain and DTT slab such as rubber
sheet, steel or plastic angles.
-
Be
aware not to use excessive force while tightening the chain to avoid damage to
DTT flange.
-
The
line of chin should be along wooden donnage under the DTT slabs.
Transport Permit
ARA or their Transport subcontractor will
secure the required permit to transport DTT slab from ARA Factory in Riyadh to
job site in Jubail City as per trip rout between the two cities.
Safety Convoy Vehicle
ARA or their transport subcontractor will
provide pilot Vehicle as needed by Transport Authority and will coordinate with
highway police as needed.
Access to Site
Upon approaching to the site, drivers will
call site supervisor to specify waiting location near by the site in safe
public Area.
Site super visor or his assistance will meet
the drivers at that point and give them instruction on when to come to site in
certain sequence as per erection sequence at site.
Also he will explain to them how to enter to
the site and where to park near to offloading crane.
Site supervisor should assign signal man of
Flag man to help and guide the drivers to the unloading place near to crane.
Driver
maneuvering inside the site should be minimum in straight line without the need
to make Turing unless it is Must.
Trailer conditions and Maintenance
Sub contractor will make sure that all Trailers used in
delivering DTT Slabs and maintained well and in running safe conditions.
Unloading of DTT Slabs
Driver should use safety hard hat, gloves and
safety shoes and reflecting jackets.
Driver should not leave or come down from his
tractor head unless he receive instruction from unloading Foreman to un-tight
the chains for unloading. He should go back to his cabin till receiving
instruction to leave the site or any other instruction from site supervisor.
11. Attachments
11.1 Design Process Flowchart
11.2 Production Process
Flowchart
11.3 Sub Con Quality Assurance
11.4 Hot Weather Concreting
11.5 Equipments Calibration
Summary
11.6 Raw Material Frequency
Test Plan
11.7 QCIR Forms
11.8 ITP
ERECTION TABLE OF
CONTENTS
1.
PURPOSE.......................................................................................................... 3
2.
SCOPE................................................................................................................ 3
3.
REFERENCE.................................................................................................... 3
4.
PROCEDURE.................................................................................................... 3
5.
DEMOULDING / DETENSIONING
STRENGH............................................ 5
6.
CONCRETE SAMPLING................................................................................. 5
7.
SANDBLASTING / ARCHITECTURAL
FINISH........................................... 5
8.
RESPONSIBLITIES.......................................................................................... 7
9.
SAFETY.............................................................................................................. 7
10. ATTACHMENTS................................................................................................ 7
1. Purpose
·
The purpose of this method
statement is to set guidelines and methodology to be followed during precast
concrete elements erection at site.
2. Scope
·
The scope of this procedure is to
standardized method of the precast concrete elements erection. Hence, execution
of the work shall be done be done as per the acceptable standards and the
relevant project specifications.
3. References
·
Project Specification
and Design Drawing
·
SAUDI ARAMCO Standards
4. Procedure
4.1.
Storage of Precast Concrete Elements at site
4.1.1.
Wall Panels
Wall panels shall be
stored vertically in fixed or moveable racks supported by dowels in top and
dunnages down under (see Fig 1.0). Any wall panel rack must either be fixed by
bolts or welding or it must be designed for moveable use.
By the use of a
moveable rack the wall panel must always rest on the foot beam of the rack.
No moveable rack with
damaged or missing foot beam must be used.
Special attention
must be paid to wall panels with cutouts at the bottom line (see fig. 2.0).
Following is important:
The wall panel is
turned with the cutout away from the supporting dowels as shown on Fig 2.0.
The support at the
panel end with the cutout is stabilizing horizontally. Do not use a simple
stud.
For insulated panels
always place the dunnages under the structural skin (see fig. 3.0). Never place
dunnages under delicate parts of wall panel (see fig. 4.0.)
Panels with architectural
surface must be paid special attention to avoid damaging by handling.
Architectural surfaces should be directed so that they do not get direct
sunshine.
Transport of wall
panels takes place in trucks with A-frames. Note that the rules given under point
2 for placing of dunnages under insulated panels also counts for transport.
Fig. 1.0
Fig. 2.0
Fig. 3.0 Fig.
4.0
4.1.2.
Double Tee Slabs
The DT-slabs must only be placed on a
plain and stable surface so that no twisting can occur. Dunnages type 1 shall
be used, they shall be placed as close as possible to ends of element.
The DT-slabs can be stacked in up to
3.5 meters, number of elements accordingly. The number of dunnages needed
increases downward in the stack. The two elements on the top needs one dunnage
under each leg in both ends of element, the next element under needs two, the
next element three, and so on downwards. Note: The dunnages must be placed in
one layer only, never pile them.
By transport of max. cantilever is 2
meters.
Fig. 1.0
4.2.
Erection of Precast Concrete Elements
4.2.1.
Wall Panels
The installation of the precast wall
panel shall be done according to the following methodologies:
·
Before
the installation the area should be properly barricaded with visible sign postings
indicating that installation operation is going on.
·
A
watcher should be posted in the area to warn unauthorized persons or vehicles
that may suddenly enter the area.
·
Prior
to lifting the crane must be located in a level and well compacted ground immediately
adjacent to the building and the vehicle carrying the precast elements or
storage area.
·
Top
surface must be flat and even.
·
Check
that no obstruction for erection.
·
Layout
Wall Panels position marking out width of each Wall Panel on the surface of the
beam.
·
Place
plastic shims on the location of wall panels.
·
As
soon as the hooks are lowered by the crane operators, the erection crew will
attach these to the precast elements making sure it is properly latched before
making a hand signal to the rigger to start lifting.
·
The
riggers will make a hand signal to the crane operators to start lifting, and
blow a whistle or by any means to warn everyone that lifting process is going
on.
·
The
crane operator will slowly lower the element and the erection crew will pull
tag line (if necessary) to bring the element in its proper position.
·
The
rigger will give hand signals to crane operator to make small adjustment to fit
element in its final position.
·
For
the panel, once the panel is fitted in correct position, the erection crew will
fix the adjustable props and install the necessary anchor bolts to hold the
panel element in its position.
·
As
soon as the anchor bolts and adjustable props are properly fixed the erectors
crews will unlatched the crane hook, and the rigger will signal the crane
operator to raise the crane chain out of the panel element.
·
Anchor
Bolts hole with Non Shrink Grout will commence after the alignment of wall
panels.
4.2.2.
Double Tee Slabs
·
Conduct
survey of the structure and check the following:
- Top surface must be
flat and even.
- Measure distance
between the supports, the distance should within the required length of DTT
slabs including tolerances.
- Check that no
obstruction for erection.
- Layout Double Tee
Slabs position marking out width of each slabs on the surface of the support.
- Install neoprene pad
on the location of Double Tee legs.
·
Crane
should be positioned to the nearest distance against the position of the last
elements according to the crane position plan.
·
The
main hoist of the crane is used to lift the PC elements on its lifting points.
·
Lifting
cables must be at minimum 45 degrees angle from the horizontal.
·
DTT
Slab will be lifted directly from the trailer to its proper position.
·
Release
the DTT Slab from the crane when the elements is properly aligned and leveled.
·
After
erection completion, start welding the adjacent double tee slab plates, as
required by the approved shop drawing and approved WPS.
4.2.3.
Post Erection
Once the lift has been safely completed and the load has
been secured in its final position:
- The rigging crew shall remove all tag lines, rigging and temporary
barriers.
- Equipment operators shall remove all transportation, positioning or
manoeuvring and lifting equipment from the area (if no longer needed).
- The responsible superintendent shall restore the work area for future
construction work.
- Rigging supervisor shall ensure that transporting, positioning or
manoeuvring and lifting equipment that is no longer required for the project is
safely disassembled, loaded on to transport equipment, and removed from the
construction site.
5. Responsibilities
5.1
Main Contractor Engineer
Site Engineer or his representative is the overall
in-charge of the site, and coordinates all activities related to storage and
installation of all pre-cast panels. His responsibilities are, but not limited
to the following:
§
Inform all persons involved in the lifting
and installation of the schedule for storage or installation of pre-cast
element, making sure of their presence during the operation.
§
Prepare the site for the installation,
ensuring that there are no objects or other activities going on in the site
that will disrupt the lifting the lifting and installation of the pre-cast
elements.
§
Provide an area in the site for the storage of
pre-cast element which is safe from other on-going activities hard well
compacted.
§
Coordinate equipments and manpower as
necessary for the safe and successful lifting and installation of pre-cast
element.
5.2 Erection
Supervisor / Foreman (Sub contractor)
The Erection Supervisor / Forman are directly responsible for the receiving,
stocking, lifting and installation of the precast elements. They directly
supervise all persons involved in the operation. Their responsibilities are as:
§
Full coordination with client’s engineers.
§
Receive all precast elements arriving to the
site.
§
To unload precast elements and stock them in
the correct place or directly erect them to their final position.
§
Ensure that equipments are in good operating
conditions prior to the start of the site lifting and installation of precast
elements.
§
Make sure that the riggers, equipment
operators and erection crews are competent and know their job properly.
§
He must be present at all times during the
lifting and installation operation, and will leave the area only when replaced
by an equally competent person.
§
Qualified rigger is responsible for the
specific area of stocking, lifting or installation and exact equipments needs.
5.3
Site QC Engineer
Site QC Engineer have to ensure that
the QC section is provide by the necessary facilities and cooperation from all
supervisors, foremen and laborers to enable satisfactory inspection and
verification of activities performed.
5.4 Site Safety Officer
Site Safety Officer have to ensure
that all safety requirements will be enforced by manners to prevent injury to
personnel, damage to plants and equipments. He should provide written
instructions to established work methods; explain the sequence of the
operation, outline the potential hazards at each stage ad indicate precautions
to be adopted.
6. Safety
a.)
All personnel shall wear personal protective equipment (PPE) and should
be instructed how to use the PPE correctly.
b.) Signs and barriers have been provided when warranted to isolate
the job site from public and unauthorized personnel.
c.) Conduct tool box meeting related to work activities. Safety
officer shall conduct the activities all the time.
d.) All equipment shall be inspected/passed Saudi Aramco requirements.
e.) All requirement operators must have their valid
license/certificate.
f.) Housekeeping.
7. Attachments
7.1 Erection Process Flowchart
7.2 Checklist – site inspection
of element upon arrival
7.3 ITP
7.4 JSA (Job Safety Analysis)
WELDING FINISHING TABLE OF
CONTENTS
1.
PURPOSE.......................................................................................................... 3
2.
SCOPE................................................................................................................ 3
3.
REFERENCE.................................................................................................... 3
4.
PROCEDURE.................................................................................................... 3
5.
RESPONSIBLITIES.......................................................................................... 7
6.
ATTACHMENTS................................................................................................ 8
1. Purpose
·
The purpose of this method
statement is to set guidelines and methodology to be followed for welding
activities during precast concrete elements erection works at site.
2. Scope
·
The scope of this procedure is to
standardized method of the weldingo f connection for precast concrete elements during
erection. Hence, execution of the work shall be done be done as per the
acceptable standards and the relevant project specifications.
3. References
·
Project Specification
and Design Drawing
·
SAUDI ARAMCO Standards
· Sub Contractor Quality Management system
·
Erection Method Statement
·
Risk Assessment & Safety
Plan
·
Welding
Details as per Approved Shop Drawings
·
AWS D1.1 and D1.4.
·
ARA-WPS-01 Rev. 00
·
ARA-PQR-01
4. Procedure
4.1.
Planning of welding works
Hot work permit shall
be obtained 24 hrs prior to start of welding activity.
Raise RFI minimum 24
hours prior to start of work to inform client & main contractor.
Prior to start
welding activity explain to the crew the job description and requirements and
each individual scope of work.
Make sure that all
safety requirements are fulfilled.
4.2.
Materials
Welding Electrodes E7018 (see attached
datasheet)
4.3 Tools
1.
Welding Machine (either electrical or diesel
– to be specify later stage)
2.
Welding Cables
3.
Welding Rod Oven
4.
Welding Torch
5.
Welding Hammer
6.
Grinder
4.4 Personal
Protective Equipments (PPE)
1.
Welding Machine (either electrical or diesel
– to be specify later stage)
2.
Welding Jacket
3.
Welding Mask (Helmet Type)
4.
Welding Gloves
5.
Fire Extinguisher
6.
Fire Blanket
4.5 Welders
·
Only certified welders are allowed to do
welding on site. A welder can only do welding that is covered by his
certification.
·
Welder must hold his ID card all time with
him.
4.6 Safety
Precautions
·
No welding activity will
take place under boom radius during crane operation.
·
Hot
work permit shall be obtained prior to start any welding job.
·
Welders
must wear protective clothing and eye protection when welding or chipping slag
from welds.
·
A
fire extinguisher should be kept in close proximity to welding operations.
·
Any
combustible material should be removed from the vicinity of welding operations;
where removal is not possible the material should be protected.
·
The
area around the welding operation should be cordoned off to protect other
people from welding sparks or spatter.
·
Welders
should not interfere or tamper with welding equipment.
·
The
mains supply to the welding machine should be transformed down to a safe
working voltage (usually between 80 and 110 volts).
·
The
actual welding circuit should be isolated from the mains.
·
Trailing
leads should be as short as possible, armoured and visible to avoid trip
hazards or damage.
·
All
equipment should be properly earthed.
·
All
connections should be made with proper fittings or equipment.
·
Connections
to the work to be welded should be made with clamps or lugs.
·
When
not in use, all welding equipment should be disconnected from the main supply,
or isolated, and protected if left unattended for any length of time.
·
The
welding equipment must be well maintained and in good condition.
·
When
welding the welder must always use standard protection equipment for welders.
If welding is done on galvanized steel or steel with toxic paint then a mask
that protects against toxic fumes must be used.
·
Welding
on close containers, tanks and pipes are not allowed.
·
The
gas cylinders used by the flame cutting must be supplied with intact pressure
gauges.
·
The
fire hazard must be observed by welding and flame cutting. If the welding or
cutting take place near flammable materials then the welder must have a helper
looking for fire while the welding or cutting is ongoing.
4.7 Welding
Consumable Control Procedure
·
All
Electrodes shall be kept in welding rod oven.
·
Any
combustible material should be removed from the vicinity of welding operations;
where removal is not possible the material should be protected.
·
Particular
care must be exercised in damp weather to avoid contact with the welding
electrode or holder.
·
Electrode
stubs should be rejected into a metal container or other non-combustible
receptacle.
·
In
case of non-availability of Welding Rod Oven, vacuum packed electrodes shall be
used.
4.8
Basic Principles of Welding Process
The basic principles
are illustrated in below Figure. One pole of the power source is connected to
the clamped (chuck) end of the electrode via the welding lead and the electrode
holder, the other to the workpiece. With DC welding, it is the electrode which
is normally the minus pole. The plus pole is only on the electrode when high
alloy or basic electrodes are involved. Welding current can be also alternating
depending on the welding appliance. After ignition the arc burns between the
electrode and the workpiece. The welder draws the electrode in the direction of
the weld while at the same time constantly compensating for the gradual melting
of the electrode itself. The arc melts both the workpiece material and the
filler material, which then form a bead which is covered with slag from the
electrode coating. This slag is removed after the welding operating.
4.9
PREPARATION OF MATERIALS
Surfaces
and edges to be welded shall be smooth, uniform, clean and free from cracks or
other defects which may weaken the effective quality or strength of the weld.
Surfaces
of the parent-metal shall be free from scale, slag, rust, moisture, oil, grease
or other harmful materials that will prevent achievement of good welds. Before
welding every materials shall be checked and inspected in detail for any
defects.
4.10
TACK WELD
Prior
to performing main welds, tack welds shall be done by shielded metal arc
welding, under the same conditions as for actual welds.
All
parts shall be adequately supported to provide the best possible alignment and
minimize stresses on tack welds and root passes.
Every
defective tack weld shall be cut out before completion of finished welds.
Care
shall be taken while removing tack welds. Temporary fittings will be used for
assembly ensuring the base metal is not damaged.
4.11
CLEANING
All
slag and flux shall be ground or brush cleaned from each bead before depositing
the next successive layer. The edges of the parts to be welded shall be free of
rust, paint, sand, tar, oil and grease.
If they
are wet, they must be dried before proceeding with the weld.
4.12
REPAIR OF DEFECTS
- Blow holes,
irregularities of deposit, undercut sharp corners of other unacceptable defects
shall be removed by grinding or chipping before depositing the next successive
layer of welding.
- Cracks shall be
removed by grinding, chipping or arc grouging and rewelded in accordance with
this specification.
- Defects such as
porous slag including lack of penetration irregularities of deposit shall be
removed by chipping, grinding or arc grouging and rewelded in accordance with
this specification.
4.13
Finishing of Welded Connection
After all welding is
completed the total connection should be painted with an anti-corrosive paint.
4.14 Testing (BY OTHERS)
Non-Destructive
Test (by others)
-
Dye Penetration Test
or
-
Magnetic Particle Test
or
-
Ultrasonic Test
Testing
shall be done on random location at least 10% of total weld spots or If there
is doubt about certain location.
5. Responsibilities
5.1
Main Contractor Engineer
Site Engineer or his representative is the overall
in-charge of the site, and coordinates all activities related to welding works of
all pre-cast elements. His responsibilities are, but not limited to the
following:
§
Inform all persons involved in the welding
work of pre-cast elements, making sure of their presence during the operation.
§
Prepare the site for the welding, ensuring
that there are no objects or other activities going on in the site that will
disrupt the welding works of the pre-cast elements.
§
Coordinate equipments and manpower as
necessary for the safe and successful welding works.
5.2 Erection
Supervisor / Foreman (Sub Contractor )
The Erection Supervisor / Forman are directly responsible for the welding works of
the precast elements. They directly supervise all persons involved in the
operation. Their responsibilities are as:
§
Full coordination with client’s engineers.
§
Ensure that equipments are in good operating
conditions prior to the start of the welding works of precast elements.
§
Make sure that the welders, helpers are
competent and know their job properly.
§
He must be present at all times during the welding
operation, and will leave the area only when replaced by an equally competent
person.
5.3
Site QC Engineer
Site QC Engineer have to ensure that
the QC section is provide by the necessary facilities and cooperation from all
supervisors, foremen and laborers to enable satisfactory inspection and
verification of activities performed.
5.4 Site Safety Officer
Site Safety Officer have to ensure
that all safety requirements will be enforced by manners to prevent injury to
personnel, damage to plants and equipments. He should provide written
instructions to established work methods; explain the sequence of the
operation, outline the potential hazards at each stage ad indicate precautions
to be adopted.
6. Attachments
6.1 Sub Contractor-WPS-01
6.2 Sub Contractor-PQR-01
6.3 ITP
6.4 JSA (Job Safety Analysis)
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