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4.Fabrication Procedure.rev 2
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QUALITY PROCEDURE Doc No. POS-QP-01
Rev No. 2
Fabrication Page 1/13
Page 1/13
PROJECT NAME: AIN ARNAT - AIR COOLED CONDENSER
Controlled Copy
Uncontrolled Copy
POSCO E&C-VIET NAM Co., Ltd.
Address: Nhon Trach Industrial Zone
Dong Nai Province, Viet Nam
Tel No.: +84 (0) 613 560 869
Fax No.: +84 (0) 613 560 871
Website : http://www.poscoencvietnam.com
Prepared by Reviewed by Approved by
Name Ho Trong Phap Nguyen Anh Tuan
Signature
Date 17-Apr-2014 17-Apr-2014
QUALITY PROCEDURE Doc No. POS-QP-01
Rev No. 2
Fabrication Page 2/13
Page 2/13
Contents 1.0 Revision History.
1.1 General
1.2 Application
1.3 Applicable code and standards
2.0 Material control
2.1 Material for fabrication
2.2 Receiving and ensuring of material
2.3 Mill certificates
3.0 Fabrications
3.1 Fabrication flow chart
3.2 Shop drawing
3.3 Steel measuring tape
3.4 Marking
3.5 Cutting and machining
3.6 Grooving
3.7 Drilling
3.8 Treatment of friction surfaces
3.9 Bending .
3.10 Straightening of distortion
3.11 Welding
3.12 Assembly
4.0 Painting and galvanizing
5.0 Packing
6.0 Attachment
QUALITY PROCEDURE Doc No. POS-QP-01
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1.0 Revision History.
Rev. No Description of change Effective Date
0 Initial release Aug. 17, 2009
1 Change name of company July.18,2010
2 Revise to follow clients comment Apr.17,2014
QUALITY PROCEDURE Doc No. POS-QP-01
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1.1 General
1.2 Application
This procedure covers fabrication for steel structure.
1.3 Applicable Code and Standards
AISC: American institute of steel construction
ASTM: American Society for Testing and material
ASME : Americal Society mechanical
AWS: American Welding Society
2.0 Material Control
2.1 Material for Fabrication
Plate: ASTM (A36),
Pipe: ASTM (A105, A106-B,A53-B)
2.2 Receiving and ensuring of material
Materials shall be stored on the sleeper or an adequate place not to be tied
to deformation, and shall be protected from corrosions, dusts, oils or other
foreign materials ingress.
Before commencement of manufacture, following shall be carried out:
- Appearance: Free any defects, such as scratching, strain or corrosion on
the surface of raw materials.
- Identification marking: Ensuring of material with stencil or stamp on raw
materials that the sort, size and quantity of these materials are
strictly in accordance with those on drawings and mill
certificates.
2.3 Mill certificates
All mill certificates furnished by supplier of material shall be submitted.
3.0 Fabrication
3.1 Fabrication Flow Chart
Refer. to the figure 3.1 attached herewith
3.2 Shop drawing
(1) Shop drawings shall be made accurately based on basic (design)
QUALITY PROCEDURE Doc No. POS-QP-01
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drawing and specifications and shall be issued by client.
(2) Shop drawings shall serve as instructions for fabrication instead of the
design documents and the following details shall be contained as much
as possible in principle
j ) Steel framing plan, framing elevation, structural members schedule,
etc
ii ) Detailed shape, dimension, quantity, mark and materials
iii) Shape, dimension, joint detail, material specification, etc.
3.3 Steel measuring tape
(1) Steel measuring tape for fabrication shall be no.1 class of JIS B 7512
(steel measuring tape).
(2) Steel measuring tapes to be used in each process of shop fabrication
shall be checked for error against a standard steel measuring tape in the
custody.
(3) Tensile force at the time of above mentioned checking shall be 7-8kgf.
3.4 Marking
(1) Marking shall be made accurately and clearly on items to be required in
subsequent processes referring to ruler and template.
(2) Punch or drill marks shall not remain on the external surface of high
strength steel or mild steel to be bent as long as they are not removed by
cutting, punching or welding.
(3) Marking shall be made taking into consideration shrinkage, deformation
and finish allowance.
3.5 Cutting and machining
(1) Cutting of steel products shall be done by the most appropriate method
such as machine cutting, gas cutting or plasma cutting, taking into
account the shape and size of the steel product.
(2) In cutting steel products by gas, automatic gas cutting equipment shall be
used in principle.
(3) The precision of gas cutting plane at free edge of structural members
shall comply with the special notes. If not specified, the standards
indicated in table3.1 shall be applied.
Table3.1Roughness and notch depth
(4) Gas cut surfaces which do not meet the above requirements shall be
finished by grinding.
Roughness Below Rz200m
Notch depth Below 2mm
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(5) Cutting of weld bevel and the accuracy of machined surface shall comply
with the requirements in 3.6 "grooving"
(6) Thickness of steel plate to be sheared shall be not more than 13mm.
When slag or burr is generated on the cut surface, they shall be removed
by grinding.
(7) Where metal touch is specified in the design documents, the surfaces
shall be finished by such machine tools as facing machine or rotary
planer so that they fit accurately. The accuracy of the finished plane shall
comply with fig. 3.1.
(8) If a machine cutter (cold saw, etc,) which can secure the same accuracy
as by using cutting forming machine is used, the edges may remain as
cut.
(9) For scallop formation, a machining tool or a manual gas cutting machine
equipped with attachment shall be used. Forming accuracy shall comply
with table 3.1 if the accuracy prescribed in table 3.1 cannot be secured,
finishing shall be made by grinding.
Figure 3.1 Accuracy of Finished Plane
3.6 Grooving
(1) Tolerance for roughness and notch depth of grooving shall comply with
table 3.2.
Table 3.2 tolerance for roughness and notch depth of groove
Roughness Not more than Rz200m
Notch depth Not more than 2mm
(2) If the roughness and notch depth exceed the prescribed tolerance, the
surface shall be corrected by appropriate such as weld reinforcing or
grinding
3.7 Drilling
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(1) Holes for high strength bolts shall be drilled. If the joint zones undergo
blasting, drilling shall be done prior to blasting.
(2) Drilling shall be done in principle for holes for bolts, anchor bolts and
reinforcing bars. Punching may be done. When slag or burr occurs in the
hole, they shall be corrected by grinding.
(3) Gas cutting may be done for holes, not less than 31mm in diameter. Gas
cutting holes shall be not more than Rz200m, and accuracy of hole
diameter shall be within 2mm.
(4) The hole diameters for the high strength bolts, ordinary bolts and anchor
bolts shall comply with diameter on the drawing.
(5) Hole surfaces shall be at right angle to the member surface, and in the
designated positions. Burrs, slag or chips around holes shall be
completely removed after drilling.
3.8 Treatment of friction surfaces
3.8.1 Treatment of friction surfaces
Methods of treating friction surfaces for high strength bolted connection to
secure a slip coefficient not less than 0.45 shall be either spontaneous rust
generation or blasting as specified hereunder special treatments of friction
surfaces other than the methods specified hereunder shall comply with the
special notes.
(1) Spontaneous rust generation
Friction surfaces shall be treated by removing mill scales with disc grinder
to an extent of more than twice the outside diameter of the washer, and be
kept to the open air in which red rust is spontaneously generated.
(2) Blasting
Friction surfaces shall be shot or grit blasted. Friction surface with
roughness of not less than 50s shall be secured and red rust generation is
not necessary.
3.8.2 Remarks for treatment of friction surfaces
(1) Floating rust, dust, oil, paint, varnish and welding spatter on friction
surfaces and parts of surfaces which are to be in contact with washers
shall be removed.
(2) There shall be no clamping flaws or irregularities on the friction surfaces
and parts of surfaces.
(3) Mill scales may remain on friction surface in cases where light gauge
steel of thickness less than 600mm is used and a design slip coefficient
of 0.45/2 (approximately = 0.23) is adopted. Floating mill scales shall be
removed.
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3.8.3 Slip test
(1) When test for confirmation of slip coefficient is made, the time and
method of the tests shall comply with the special notes.
3.9 Bending
(1) Bending shall be carried out at room temperature or by heating. Bending
by heating shall be done in red heated condition, and shall not be done in
the range of blue brittleness(200-400oC)
In this case, temperature shall comply with para. 3.10 Straightening of distortion."
(2) The inside radius of bending at room temperature shall be not less than
twice the plate thickness, as shown in figure 3.2
3.10 Straightening of distortion
(1) Distortion generated during fabrication shall be straightened at room
temperatures or by heating (Refer to Correction distortion Doc No :
POS-QP-001) to the extent that avoids impairing quality, if the specified
accuracy of the product is not secured.
Figure 3.2 Inside radius of bending
(2) In straightening distortion by heating, a press or a roller shall be used.
(3) The temperatures at which distortion is straightened by heating shall by
in accordance with the following standards:
Maximum temperature shall not exceeds:
600oC for quenched and tempered steel
650oC for other steel
3.11 Welding
3.11.1 General
Posco e&c Viet Nam shall submit the following documents to be used in welding of the works which are subject to clients approval.
Welding procedure specification (WPS)
List of qualified welders and welding operators
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3.11.2 Welding material
(1) All welding materials shall be stored and handled with care and in
accordance with the manufacture's recommendations.
(2) Covered electrodes shall be stored in the drying place and shall be dried
in the drying oven before use in accordance with the conditions shown
manufactures recommendations
3.11.3 Welding procedure qualification
The Design Team shall specify the requirements for weld joints.
The Production Team shall then establish Welding Procedure including
welding material control to meet such weld joints requirements.
Quality Team shall certify or authorize Welding Procedure Qualification Test
Records according to requirements of the applicable code.
Test records shall be reviewed by the Quality Assurance section and then
submitted to the client for reference.
Following information are to be included.
Procedure reference number
Specification or type of material to be joined
Range of materials thickness
Welding process
Size and brand name of consumables
Deposition sequence
3.11.4 Welder's qualification.
All welders and welding operators engaged in welding of the works shall be qualified in accordance with applicable standard. Qualified welders can be engaged in production welding of the works.
3.11.5 Welding preparation
All welding edge shall be fully cleaned by wire brush of equal. The surfaces
for welding shall be dry and free any scale, rust, oil, or other foreign
materials.
All welding electrodes, wires and fluxes shall be stored in a clean
place and protected. All welding consumables shall be property
identified and shall retain their identification up to the time of use.
- Tack welds shall be subject to the same quality requirements as the
final welds except that;
(1) Preheat is not mandatory for signal pass tack welds which are remelted
and incorporated into continuous submerged arc welds.
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(2) Discontinuities such as undercut, unfilled craters and porosity need not
be removed before the final submerged arc welding.
Tack welds to be incorporated into the final weld shall be made with
electrodes meeting the requirements of the final welds and shall be
cleaned thoroughly. Multiple-Pass task welds shall have cascaded ends.
Tack welds not incorporated into final welds shall be removed, except that
for buildings they need not be removed unless by the engineer.
Pre-heating shall be carried out by electric resistance or induction
equipment or by specially shaped gas burners.
Temperature shall be checked by temperature indication crayons or
equal at a distance of about 50mm from the welding point to ensure the
homogeneity of specified temperature at whole part from weld line to
100mm apart.
- The standard edge preparation for the steel structure work shall be
made in accordance with shop drawing.
3.11.6 Welding
After welding, all slag, excess reinforcement and surface irregularities shall
be removed.
Cleaning may be carried out by hand or power tools. Flame gouging is
prohibited.
Harmful defects (cracks, undercuts, overlaps, arc strikes, etc.) in welds shall
not be accepted.
The welding materials shall give a satisfactory deposited metal which
has mechanical properties superior to that of the base metal.
Table 3.6 Drying of welding material
Division Drying condition
Temperature (oC) BakingTime (Hour)
Low hydrogen Type
Electrode, AWS A5.1 260 - 430 2
Other Type Electrode,
AWS A5.4 150-200 0.5-1
3.11.7 Tack welding
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(1) Tack welding shall be shielded arc welding or flux cored arc welding
process.
(2) Welders for tack welding shall be properly qualified.
(3) The selection and storage of welding materials for tack welding shall
comply with item 3.11.2 "welding materials. If Shielded metal arc Welding
is used for tack welding, welding material with low hydrogen content shall
be used.
(4) In tack welding, beads having required length and leg length shall be
deposited. at required intervals, in order to keep the shape during the
assembly, transportation and finish welding work, and furthermore in order
to avoid cracking of tack welding.
The minimum length of a bead for tack welding shall comply with table 3.5.
Table 3.5 Length of bead for tack welding (unit: mm)
Material (t) Minimum Length of Bead for Tack Welding Pitch
Manual, Semi Auto Auto
300-400 Mild steel 40 50
High strength Steel 50 70
(5) Tack welding quality shall be same as that of the final welding. Tack
welding shall not be done in grooves. If tack welding of the inside of
grooves is inevitable, it shall be done so as to secure the required quality
of finish welding
3.12 Assembly
3.12.1 General
(1) The method and order of assembly and the order of welding will greatly
affect on the accuracy and quality of products. Therefore, they shall be
fully examined at the stage of making the outline for fabrication or prior to
that stage
(2) First article shall be pre assembled at shop.
3.12.2 Preparation for assembly
(1) Structural members shall be checked beforehand for member codes,
material quality and quantity as well as for damages/stains, corrosion
and harmful directs. If there are any abnormalities, members shall be
replaced or repaired.
(2) Any distortions such as bending or warping of members, shall be
QUALITY PROCEDURE Doc No. POS-QP-01
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straightened before assembly to achieve the prescribed product
accuracy.
3.12.3 Assembling work
(1) Assembling shall be done using surface Plates or jigs suitable for the
work so as to keep accurately the positions and angles of structural
members to be assembled.
(2) Backing strips and end tabs shall be provided at the prescribed intervals,
so that the space between base metal and such members are
eliminated.
(3) Presence of surface gap between each members and groove shape in
butt weld joints shall be checked and repaired if any inadequacies are
found,
4.0 Painting and Galvanizing
Painting or galvanizing for steel components required on the shop drawings
shall be performed in accordance with the Painting procedure, or
Galvanizing procedure.
5.0 Packing
All materials and steel components shall be adequately anchored, braced
and packed in accordance with the Packing procedure.
6.0 Attachment
6.1 Fabrication flow chart
QUALITY PROCEDURE Doc No. POS-QP-01
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DRAWING; SPECIFICATION
PREPARING PROCEDURE SHOP DRAWING MATERIAL PROCUREMENT
REVIEW ANDAPPROVAL
REVIEW ANDAPPROVAL
INSPECTION
MARKING, CUTTING, DRILLING
INSPECTION
FIT-UP
INSPECTION
WELDING
INSPECTION
BLASTING AND PAINTING
INSPECTION
PACKING
INSPECTION
DELIVERY
No
Yes
No
No
No
No
No
No
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
OR GALVANIZING
Attachment 6.1 Fabrication flow chart
Recommended