SCOPE OF WORK
All welding for steel
construction shall conform to the requirements of this section and shall be
applicable to Contractor's work included in Book II, Subsection "Summary
of Work" and Book IIIA refers to
"General Civil and Architectural Design Requirements"
Welding covered in this
Specification shall include shop and field welding of the following, as
indicated in various technical specifications included with the bid of offer
document or as required for Contractor's work:
Structural steel,
galleries, embedded steel, auxiliary steel and miscellaneous steel, including
pile splices.
Welding studs.
All other work as
indicated.
The Contractor shall
comply with the requirements of Book II, Subsection "Codes and
Standards".
The codes and standards
of the following organizations extracted from Book II, Subsection "Codes
and Standards" are specifically applicable to the design, manufacture and
testing of the work included in this Specification:
ASTM American Society for Testing and
Materials.
AWS American Welding Society.
MATERIALS
GENERAL PROVISIONS
Ali materials shall conform to the requirements
of this Clause 3 unless otherwise indicated in the Bid of offer Document.
STUD WELDING MATERIAL
Materials for stud welding shall conform to the
requirements of AWS D1.1.
ELECTRODES
Except as otherwise
specified, all welding electrodes shall conform to the applicable provisions of
the AWS Structural Welding Code AWS D1.1 For steels with special properties,
such as resistance to brittle fracture, corrosion‑resistant steels, stainless
lad steels and stainless steels, the recommendations of both the steel and
electrode manufacturers shall be secured for each specified steel and each
specific use.
DETAILED
REQUIREMENTS
Complete penetration
welds shall be used for all groove welding unless otherwise specifically
indicated. All double welded joints shall be back gouged to sound metal before
welding the second side.
Fillet welds across
flanges of any steel member will not be permitted unless specifically flange area
will indicated on Contractor's design drawings; any undercutting or damage that
will reduce the not be permitted.
Preheat and interpass
temperatures shall conform to the requirements of AWS D1.1 and shall be as required for the
thickest part of the base metal being welded.
The maximum preheat and interpass
temperature for austenitic stainless steel shall be 175 OC.
Except for stainless
clad steel joints or stainless to carbon steel joints, the austenitic stainless
steel filler metal used shall contain a minimum of 5% ferrite.
The use of wide welds to
overcome poor fit‑up will not be permitted.
Surfaces and edges to be
welded shall be properly‑ prepared according to AWS 1.1, prior to welding. Unless specifically
reviewed by the Owner, the only coating which
does not have to be removed before welding is deoxaluminite.
In welding stainless
clad steel, the carbon steel side shall be welded first.
The following materials
shall not be welded unless otherwise indicated:
‑
Steel reinforcing bars (rebar’s).
‑ Nuts and bolts.
‑ Any carbon or alloy
steels containing more than 0.35% carbon.
The filling in by
welding of unused boltholes is riot permitted.
All welding including
stud welding shall conform to the requirements of AWS D1.1 unless otherwise
indicated. Welding shall be performed using Shielded Metal Arc or Submerged Arc
Welding Process.
The following welding
processes are specifically prohibited:
‑ Fuel Gas
- Electro slag
‑ Electro gas
- Gas Metal‑Arc (short
circuiting transfer)
- Flux Cored‑Arc
(without external gas shielding),
INSPECTION AND EXAMINATION
GENERAL PROVISIONS
All welding shall be
inspected and examined by Contractor's AWS certified welding inspector in
accordance with this Clause 6 and AWS D1.1 unless otherwise indicated in the bid of offer
document. Inspection and examination reports shall be submitted to Owner.
Have each welding
operator stamp his identifying mark or number on all work done by him (except
on handrails) as requested by inspector.
When inspector believes
a welding operator's work is not up to require standards
he may prohibit welding operator from continuing work pending results of
requalification tests.
Owners may, during the
course of the work, review the various phases of the work performed by Contractor, at
Contractor's plant and at the site, for compliance
with all requirements of this specification. Owner reserves the right to
approve facilities used for inspection and examination.
Radiographic inspection
shall be performed by inspecting laboratory retained by Contractor. Such
inspection will conform to the applicable requirements of AWS D1.1.
EXTENT AND METHODS OF
EXAMINATION
The extent and methods
of nondestructive examination for welding required for all work shall conform
to the requirements of Table 4.4.2.20-1, and all welds shall be 100 % visually
inspected.
Table 4.4.2.20 - 1
Extent and Methods of
Nondestructive Examination for
Welding in Steel Construction
for All Work
|
Item
|
Extent
of
Examination
|
Method
of
Examination
|
Remarks
|
|
1. Structural Steel
1.1 Built‑up Girders and Columns:
a. All complete penetration groove welds.
|
100%
|
Radiograph
|
Welds
impractical to be radio graphed shall be examined 100% by both Ultrasonic and
either Magnetic Particle or Liquid Penetrate methods.
|
|
b. All other weld joining flanges, webs,
plates, stiffeners, connections, base plate details etc.
|
100%
|
Visual
|
|
|
1.2 Rolled Beams and columns:
a. All complete penetration groove welds.
|
100%
|
Radiograph
|
Same
as 1.1a
|
|
b. All other welds joining cover plates
stiffeners, connections, base plate details etc.
|
100%
|
Visual
|
|
|
2. Tank, Duct
Work etc.
2.1 All complete penetration groove welds
|
a.
100% for the first 3 m. of welds, in horizontal and vertical welds
respectively, for each welder or welding operator. (Any weld that fails to
meet the acceptance standard shall be replaced and reexamined 100%)
|
Radiograph
|
a. Welds impractical to be radio graphed shall
be examined by both Ultrasonic and either Magnetic Particle or Liquid
Penetrate Methods
|
|
|
b.
Thereafter, 1%: 1spot examination 30 cm long for each additional 33 m of
welds (If any spot fails to meet the acceptance standard, 2 additional spots
shall be examined at locations at least 30 cm on each side from failure spot.
If either of the 2 additional sports examined fails to meet the acceptance
standard the entire unit of the 33 m welds shall be completely examined).
|
Spot
Radiograph
|
b. The 1% spot radio graphed shall include 25%
of junctions of vertical and horizontal welds.
|
|
2.2 Fillet welds between plates and
stiffeners
|
100%
|
Visual
|
|
|
2.3 Welds for supporting Structural Steel
|
Same
as Item 1
|
Same
as Item 1
|
Same
as Item 1
|
|
3.1 Composite Beam Shear Connectors
|
a.
The first two studs welded on each beam, through metal deck where applicable,
after being allowed to cool, shall be bent to an angle of 30 from their
original axes by being struck with a hammer. (If failure occurs in either
stud, the procedure shall be Corrected and
|
Bend
Test
|
Additional
acceptance standard indicated in AWS D1.1.
|
|
|
two more shall be welded to the beam and
tested.
If either of the second pair of studs
fails, additional welding shall be continued on separate plates until two
consecutive studs are tested and found to be satisfactory.)
|
|
|
|
|
b. 100% of all studs
|
Visual
|
Any
stud which does not show a 3600 weld under visual examination is
subject to the bend test
|
|
3.2 All other studs
|
a.
Before the start of welding operations on each day for each welding gun and
associated power source two studs shall be welded to separate material in the
same general position (flat, vertical, overhead sloping) and of similar
thickness and material. After being allowed to cool, each stud shall be bent
to an angle of 300 from its original axis with a hammer. (If
failure occurs in either stud, the procedure shall be corrected and repeated
until two consecutive studs have been successfully welded and tested before
any studs are welded to the member).
|
Bend Test
|
AdditionaAdditonal acceptance
standars
indicated in AWS D1.1
|
|
|
|
|
|
|
|
b. 100 % of all studs
|
Visual
|
Any stud which does
not show a 3600 weld under visual examination is subject to the
bend or torque test.
|
|
|
|
|
|
|
|
|
|
|
|
|
c. At least one stud
in every 100 shall be bent to an angle of 150 from its original
axis by being struck with a hammer. If threaded, the stud shall be torque
tested with a calibrated torque wrench. (If the stud fails, the procedure
shall be checked in accordance with (a) above, and two more existing studs
shall be bend or torque tested. If either of these two studs fails, all the
studs represented the tests shall be tested).
|
Bend Test (Torque Test
for Threaded Studs)
|
Additional acceptance
standard indicated in AWS D1.1
|
Notes: 1. Extent
of examination (1%, etc.) shall be applied equally to shop welding and field
welding.
2. Magnetic Particle method is for ferrite materials, and liquid
Penetrate method is for austenitic materials.
REQUIREMENTS
FOR EXAMINATION
Nondestructive
examination for welding for all work shall conform to the following
requirements unless otherwise indicated:
Radiographic
Examination
Radiographic
examination shall conform to the requirements of this section and to all
applicable requirements to the following:
a. AWS : AWS D1.1.
b. ASME : E94 and E142
X-Ray
or Gamma Ray shall be used in radiography and the quality level shall be 2-2T
as specified in ASTM E142, unless otherwise indicated.
a. Radiographic Films
a.1 The double film technique shall be used
to obtain two films at each radiographic location. Single film viewing shall be
use interpretation.
a.2 Radiographic films shall be of fine
grain, high contrast, Type 1 or 2. Lead intensifying screens shall used. Films
density shall 2.0 minimums for single viewing or 2.6 minimums for composite
viewing of a double film exposure. Each film for composite viewing shall have a
minimum density of 1.3 as determined by either film density strips or
densitometry. The maximum density shall be 3.8 for either single or composite
viewing. The quality of film and the steps of processing shall be such as to
retain the best possible definition during storage.
a.3 Any films not acceptable to Owner will
be rejected; and Contractor shall repair and radiograph again these portions of
the work covered by these films until satisfactory results are obtained, at no
cost to the Owner.
Ultrasonic
Examination
Shall
conform to all applicable requirements or the following standard:
AWS : AWS D1.1
ASTM : E164
Magnetic
Particle Examination
Shall
conform to all applicable requirements or the following standards:
AWS : AWS D1.1
ASTM : E709
Liquid
Penetrate Examination
Shall
conform to all applicable requirements of the following standards:
AWS : AWS D1.1
ASTM : E165
Visual
Examination
Shall
conform to all applicable requirements of AWS D1.1.
ACCEPTANCE
Welds
meeting the acceptance standards indicated in AWS D1.1 will be accepted.
Any
welds failing to meet the indicated in AWS D1.1 Standard shall be repaired or
replaced and reexamined 100% until they meet the requirements. Contractor shall
perform additional examination in accordance with Table 4.4.2.20 – 1 and AWS
D1.1, with no additional cost to Owner.
Acceptance
of work by the Owner shall not relieve the Contractor from full responsibility
for the work.
QUALITY ASSURANCE PROGRAM
GENERAL
PROCEDURE
Contractor
shall submit, after award of contract, two copies of General Procedures that he
(and his subcontractors, if any) will follow for all welding for the work.
These
procedures shall include, but shall not be limited to, all of the following:
Selection
of welding methods, equipment and materials.
Control
of personnel proposed to be used for this work, and quality control of
workmanship.
Control
of Contractor's welding inspection and examination.
Types
of weld and welded joints.
Weld
profiles and weld sizes.
Size,
classification and material specification for all electrodes proposed for use.
Methods
of groove and edge preparation.
Lengths
and spacing of intermittent welds.
Methods
and/or sequence of welding to avoid distortion and to minimize residual shrinkage
stresses.
Number
and travel speed of passes for each weld.
Procedures
for preheating base metals, and minimum preheat and interpass temperatures
required.
Stud
welding, including welding shear connector studs to beams through metal deck.
QUALIFICATION
OF WELDERS AND VVELDING OPERATORS
All welders
and welding operators employed on any welding work shall be qualified by an approved
testing laboratory in accordance with AWS D1.1. Laboratories for testing welders and welding operators
shall be of recognized
standing. All costs in connection with this qualification shall be borne by
Contractor.
These
qualifications (including requalification, if any) test reports and certificates shall be
available before the start of
welding and shall be submitted for information to Owner if requested.
QUALITY
ASSURANCE/QUALITY CONTROL (QA/QC)
Quality
assurance/Quality control shall conform to the requirements of Part Book II refers to ‘Quality
Assurance/Quality Control’.
The
quality control procedures shall include but not be limited to the following:
- Material certificates
- Welding
- Nondestructive testing
- Shop test & inspection procedures
The
quality control documentation shall include but not be limited to the
following:
‑ Material certificates
‑ Welding
procedures
‑ Shop
test and inspection reports
WELDS IMPRACTICAL TO RADIOGRAPH
Welds
that are considered impractical to be radio graphed are those where the joint
detail does not permit radiographic examination or the radiography will not
yield meaningful results. The absence of suitable radiographic equipment shall
not be justification for the alternate examination. Examination by the
alternate methods shall require permission of the Owner.