13. Fabrication Of Steelwork
[This section requires effective proof reading and altered as deemed necessary. It also requires a critical review in the light of more current practice, codes and specifications.
13.1 Standards
Read this specification in conjunction with the following standards and codes as referred to in the text or shown on the Drawings. The latest editions, including amendments, revisions and any superseding metric versions current on the date of closing tenders, shall be deemed to apply in each case.
Comply with the requirements of the following standards:
AS 1100 Drawing Practice
AS 1101.3 Symbols for welding
AS 1110 I.S.O. Metric hexagon precision bolts and screws
AS 1111 I.S.O. Metric hexagon commercial bolts and screws
AS 1112 Metric hexagon nuts
AS 1131 Dimensions of hot rolled structural steel sections
AS 1163 Structural steel hollow sections
AS 1167 Welding and brazing
AS 1171 Non-destructive testing
AS 1214 Hot-dip galvanised coatings on threaded fasteners
AS 1237 Plain washers for metric bolts, screws, and nuts for general purpose
AS 1252 High strength steel bolts with associated nuts and washers for structural engineering
AS 1365 Tolerances for flat-rolled steel products
AS 1448 Carbon steel and carbon manganese steel - Forgings
AS 1544 Methods for impact test on metals
AS 1554 Structures steel welding (Set)
AS 1594 Hot rolled steel flat products
AS 1796 Certification of welders and welding supervisors
AS 1816 Metallic materials - Brinell hardness Test
AS 1858 Electrodes and fluxes for submerged arc welding of carbon and low alloy steels
AS 2177 Non-destructive testing - Radiography of welded butt joints in metal
AS 2203.1 Cored electrodes for arc-welding – Ferritic steel electirodes
AS 2205 Methods for destructive testing of welds in metal
AS 2207 Non-destructive testing - Ultrasonic testing of fusion welded joints in carbon and low alloy steel
AS 2214 Certification of welding supervisor
AS 3678 Structural steel hot-rolled plates, floorplates and slabs
AS 3679 Structural steel - Hot-rolled bars and sections
AS 4100 Steel structures
AS/NZS 4680 Hot-dip galvanized (zinc) coatings on fabricated ferrous articles
AUSTROADS AGBT Austroads Guide to Bridge Technology
Comply with the additional requirements of this Specification.
Comply with the requirements of this Specification if they contradict clauses in the above Standards.
13.2 MATERIALS
13.2.1 General
[These designations should now be rechecked to ensure they are still adequate and that the codes still apply.]
Prequalify welding consumables if required by the standards. [(ie. use prequalified consumables)]
Use grade 250 steel unless otherwise specified.
Use grade C350 steel square and rectangular hollow sections unless otherwise specified.
Use grade 4.6 bolts to AS 1111 unless otherwise specified.
Comply with AS 1252 for all higher bolt grades unless otherwise specified.
13.2.2 Testing of Materials – Hold Point
Hold Point - Supply Certificates of Compliance proving compliance with the relevant Standards, and giving the results of mechanical tests and chemical analysis (where applicable) of the material or parts used in the work.
No material or part shall be used in the work unless it is identified with the conforming Certificates, and is approved by the Superintendent.
13.2.3 Storage and Handling of Materials
Store all materials above the ground on platforms, skids, or other supports, and adequately protect against corrosion.
13.2.4 Defective Materials
Bear the cost, expenses, and delays due to repair or replacement of defective material.
13.3 FABRICATION
13.3.1 Shop Drawings – Hold Point
Hold Point - Submit three copies of all shop drawings to the Superintendent for information and comment a minimum of 14 days prior to commencing fabrication.
[ Adjust the time for submission and the number of copies required to suit the particular project.]
13.3.2 Special Requirements for Fabrication of Articles for Galvanizing
Do not use fabrication techniques which could cause distortion or embrittlement during galvanizing.
Provide holes and/or lifting lugs to facilitate handling, venting, and draining during the galvanizing process. Obtain approval of the Superintendent for every such modification prior to enacting it.
Do not use marking paints that are incompatible with the galvanizing process.
13.3.3 Welding – Hold Point
Hold Point - Provide to the Superintendent 14 days prior weld procedure specification sheets.
Use GP category welding unless otherwise specified or approved.
Provide proof of welder prequalification and experience.
Provide proof of weld procedure and weld consumable prequalification.
Do not carry out any welding without the Superintendent's approval.
Remove and redo all welds carried out without the Superintendent's approval.
Do not use welders that are not prequalified for each welding operation they are to perform.
Remove all welding slag and burrs.
General
Standard: To AS/NZS1554.1.
Other parts of AS/NZS1554 may also need to be referenced e.g. AS1554.2 (studs), AS/NZS1554.5 (elements subjected to fatigue loading) or AS/NZS1554.6 (stainless steel).
Do not carry out any welding without the Superintendent's approval. Remove and redo all welds carried out without the Superintendent's approval.
Weld Category
Weld categories not shown on the drawings: Category GP.
Weld Type
Weld type not shown on the drawings: 6mm continuous fillet weld made using E48XX electrodes or equivalent.
It is preferable to show all the weld types and categories on the drawings. If they are, delete ‘category’ and ‘type’ clauses.
For elements subjected to fatigue loading, refer to AS4100 Section 11. Welding details to AS/NZS1554.5 should be shown on the drawings.
Certification of Welders and Welding Supervisors
Standard: To AS 1796
Standard: To AS 2214
The Superintendent may at any time request to see the “Certificate of Competency” of any welder involved in the works and/or witness the welding of a test piece. Do not use welders that are not prequalified for each welding operation they are to perform.
All welding shall be carried out under supervision of personnel who have had suitable training and experience in the fabrication of welded structures and who are certified in accordance with AS 2214.
Preparation
Provide proof of weld procedure and weld consumable prequalification.
Inspect all SP weld preparations to ensure correct setup of root gap and weld preparation size. All weld preparations are to be inspected by suitably qualified personnel in accordance with AS1554.
Non Destructive Weld Examination
Standard: To AS/NZS1554.1.
Where possible, place steelwork in a suitable position and orientation to enable testing to be carried out safely.
Other parts of AS/NZS1554 may also need to be referenced e.g. AS/NZS1554.5 (elements subjected to fatigue loading) or AS/NZS1554.6 (stainless steel).
Methods: Inspect welds in conformance with the Non-destructive weld examination (NDE) table.
Radiographic and ultrasonic inspection: Have the examination performed by an independent NATA registered testing authority.
Repairs: Repair welds revealed as faulty by non-destructive examination and repeat the examination.
Non-destructive weld examination (NDE) table
Type of weld and category / Examination method / Extent (% of total length of weld type) /GP Shop fillet welds / Visual means / 100 /
GP Welds / Visual means / 100 /
SP Welds / Radiographic or ultrasonic inspection / 20 Minimum /
Use the table unless the methods and extent of non-destructive examination are shown on the drawings. Vary the requirements as required/
For structures subject to high levels of fatigue, see AS/NZS1554.5. For stainless steel, see AS/NZS1554.6. Examination method: Depending on the application it may be necessary or desirable to show the test method designation number from AS2177 Table3.1 for radiographic methods, or AS2207 Section3 for ultrasonic methods. In this case separate schedule entries may be required for differing butt weld types, material thicknesses or locations
[Faulty welding should be picked up when tolerances are checked, and issuing defective notices should encourage the removal of poor quality, yet qualified welders.]
13.3.4 Bolting
Provide commercial bolts grade 4.6 tightened to snug tight condition unless otherwise specified or approved.
Ensure diameter of holes for commercial bolts do not exceed the nominal diameter of the bolt by more than 2 mm.
13.3.5 Cutting and Splicing
All corners on exposed edges shall be rounded to a radius of approximately 2mm.
Do not put splices other than at points shown on the Drawings.
13.3.6 Hot Bending
Do not bend unless specified or directed.
Do not heat the work above 820 degrees Celsius.
Bend within the temperature range 760 to 820 degrees Celsius.
Cool the heated members slowly in air to ambient temperature.
Protect the cooling work from draughts or other rapid movement of air.
13.3.7 Cambering
Do not heat the tension flange above 150 degrees Celsius.
Measured camber with the member laying on its side.
13.3.8 Dimensional Tolerances
Conform to the dimensional tolerances of the appropriate Australian Standard except as noted on the drawings.
Measurements stated on the drawings apply when the material is 27° Celsius.
13.4 TRANSPORT AND DELIVERY
13.4.1 Inspection
Allow the Superintendent free access for inspection at all stages of fabrication.
Provide written notice of intent to begin fabrication.
Do not carry out any fabrication work before receiving approval.
Do not begin any fabrication work, or critical phase of fabrication, earlier than seven after the Superintendent's receipt of such notice.
Lay out and arrange all fabrications to be inspected such that:
- they are accessible for inspection, and,
- erection marks are readily visible.
Turn the members for the Superintendent to permit examination on all sides.
Provide all labour, tools, scaffolding etc. required for the inspection.
Do not despatch any work from the fabrication shop without inspection and written approval.
Do not coat or paint any fabrication without inspection and written approval.
13.4.2 Rejection
Bear the cost, expenses, and delays due to repair or replacement of rejected or defective items.
The acceptance of any material or finished members by the Superintendent shall not prevent their subsequent rejection if found defective.
13.5 ASSEMBLY AND ERECTION
Submit to the Superintendent for his information before erection commences, details of the proposed method of erection of the steelwork, including falsework, together with the type and size of the erection equipment to be used. Where required by the Superintendent, detailed drawings and calculations shall accompany the proposal.
Erect the structure plumb and true to line and level.
Provide temporary supports where necessary, to ensure that the structure is not overstressed during erection.
Leave temporary bracing in position until the structure is sufficiently stable in itself.
Do not make permanent connections between the various parts of the structure until the alignment of all parts which will be affected has been checked and approved by the Superintendent.
Report to the Superintendent any errors in the shop fabrication, or deformation resulting from handling and transportation, which prevents the proper assembly and fitting up of the parts.
13.6 HANDLING AND STORAGE
Handle and store all structural steelwork so that the material and parts are kept clean and free from damage.
Place steelwork to be stored supports above the ground and all joists and beams upright and shored. Support long members at points sufficiently close together to prevent damage from deflection.
Pack loose angles or gusset plates in convenient bundles and temporarily bolt together or bind with heavy gauge wire.
Pack small articles such as bolts in secure containers adequately labelled, and clearly state the details and quantity of the contents.
13.7 INSTALLATION OF BOLTS
Use bolted connections only where specified or otherwise approved by the Superintendent or his representative.
Use tapered washers to compensate for the lack of parallelism where bearings faces of bolted parts are not parallel.
Ensure the angle between the axis of the bolt and the surface under the bolt head or nut is 90 + 3 degrees.
Place the tapered washer under the non-rotating component where possible.
Assemble and firmly clamp (with temporary bolts and erection pins) the parts of a member before reaming or permanent bolting is commenced.
Provide steel packing where necessary to ensure that the surfaces are in effective contact which has a surface condition similar to that of the adjacent material.
Ensure drifting during assembly does not enlarge the holes or distort the metal.
Ream or drill, and if required by the Superintendent, provide bolts of larger diameter if any holes do not match.
<DoI Bridgeworks Master – Dec 2012
FABRICATION OF STEELWORK