Steel and welding standards for resource road bridges
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CSA standard Unless otherwise specified by the Ministry, structural steel for permanent applications shall comply to CSA Standard G40.20 / G40.21 General Requirements for Rolled or Welded Structural Quality Steel / Structural Quality Steel.
Steel girder flange and web plates
Grade 350AT category 3
Other steel plates, diaphragms and plan bracing
Mill certificates The supplier of steel components shall provide steel mill certificates to the Ministry for all steel components.
Steel plate rolling direction Steel plates for main members, splice plates for flanges, and main tension members shall be cut and fabricated so the direction of rolling is parallel to the direction of the primary stresses.
Fracture-critical members For fracture-critical members, Charpy V-notch tests shall be specified on a per heat frequency (contrary to the CHBDC requirement for per plate testing) as defined in CSA G40.20/G40.21. The steel shall meet the impact energy requirements specified in Table 10.12.
Shop trial fit of girder splices Shop trial fit shall be undertaken for all girder bolted splices unless CNC equipment is used.
Bolts for structural steel connections All bolts for structural steel work shall meet the specifications of ASTM F3125 Grade A325 unless otherwise specified by the Ministry.
Bolts incorporated into steel girder connections (e.g.; splices, diaphragms, bracing, etc.) shall be A325 Type 3 installed in accordance with CHBDC, unless otherwise specified by a Ministry engineer.
Studs Shear studs shall meet the requirements of CSA W59 Appendix H for Type A and B studs (ASTM A108 Grade 1015, 1018 or 1020).
Welding See Ministry welding standards.
Unless specified by the Ministry, all structural steel (except piles and pipe columns) shall be uncoated atmospheric corrosion resistant (weathering) steel.
Uncoated weathering steel shall not be used in marine coastal areas, in areas where there is potential for road de-icing salts to come in contact with the bridge (either directly or by being tracked on from nearby roads) or in unusually corrosive environments (e.g. near waterfalls, in other very moist/damp environments). Concrete or galvanized or painted structural steel must be specified in these areas.
Steel guardrail component paint standard The Steel Guardrail Component Paint Standard (PDF, 261KB) provides detailed specifications to be used when HSS bridge guardrail systems, or portions of those systems, are to be painted rather than galvanized. Various pre-approved paint systems are described, including a powder-coated option. Also included are surface preparation requirements and directions for approval of alternate paint systems.
- All galvanizing shall be done in accordance with ASTM A123;
- All steel to be galvanized shall meet chemical composition recommendation as specified by the American Galvanizers Association (available at www.galvanizeit.org) to ensure against embrittlement.
Quality of welding is critical to the long term performance and integrity of Ministry bridges.
Typically Ministry bridge construction involves two types of welding:
a. Shop fabrication, including but not limited to: primary steel load bearing members, bracing, inserts for embedment into concrete; bearing components, and guardrails; and
b. Field welding required for erection, assembly, and installation of bridge components, including but not limited to: bearing components, steel substructure components, and welded connections for precast members.
Other than typical examples such as those in b) above, field welding of steel girders is not permitted except as specifically pre-approved by the Ministry.
All welding, and inspection of welding, must conform to CSA W59 Welded Steel Construction (Metal Arc Welding).
Welder qualifications All welders, welding operators and welding procedures shall be qualified under the requirements of the CSA standards.
Other requirements Other requirements related to welding and steel fabrication for Ministry bridges are specified on the Ministry standard drawings, in CHBDC and elsewhere. See Ministry in-plant QA inspection scheduling for steel bridge components.
Companies responsible for shop welded construction must:
- be certified, at the time of project tender and for the duration of fabrication, to Division 1 or Division 2 of CSA W47.1 Certification of Companies for Fusion Welding of Steel Structures; and
- have the equipment and capability to make web to flange welds continuously by machine or automatic welding using the submerged arc process.
Exception to the foregoing - fabrication of bridge railings, shear connectors for concrete slab bridges, and miscellaneous steelwork for all-timber portable superstructures may be undertaken by companies certified for Division 3 of CSA W47.1.
Companies responsible for field welded construction must be certified, at the time of project tender and for the duration of fabrication, to Division 3 of CSA W47.1 Certification of Companies for Fusion Welding of Steel Structures.
The Canadian Welding Bureau (CWB) is accredited by the Standards Council of Canada as a Certification Body for the administration of CSA standards, including W47.1, for:
- Certification of companies involved in welding;
- Certification of welding inspection companies;
- Certification of welding inspectors; and
- Certification of welding electrodes.
All CWB certified companies are required to have certified welders and written welding procedures for each specific type of weld produced (Welding Procedure Data Sheets).
A list of CWB certified companies is found on the Canadian Welding Bureau (CWB) website.
Before welding, in addition to any other requirements specified by CSA requirements, the fabricator shall ensure that:
- Only documented materials are used for the project;
- All materials intended for incorporation into bridges or bridge components are examined after cutting for size, shape and quality;
- Before assembling any plate girders or complex parts, the surfaces of all materials are examined for imperfections and the joint edge preparation for all groove welds is verified as conforming with the Canadian Welding Bureau’s approved welding standards acceptable tolerances;
- After assembling any plate girders or complex parts, and before starting the strength welding, the assembly is checked for dimensional conformance;
- Any non-conformance is resolved; and
- Welding procedures (and accompanying proof that the welds are Canadian Welding Bureau pre-qualified) are available for review by an inspector.
During the welding process, in addition to any other requirements specified by CSA requirements, the fabricator shall ensure that:
- All shop welding on is done by a company certified to CSA W47.1, Division 2 or better; field welding done by Division 3 or better; and all done in accordance with the Canadian Welding Bureau’s approved welding standards;
- The edge preparations for all groove welds conform to the dimensions established in those standards;
- The strength level and chemical composition of all filler materials used in structural assemblies conform to the approved shop drawing details;
- All welding consumables conform to the standards and are received, stored and conditioned to the standards;
- Any preheating required before welding is done according to the standards; and
- The welding procedure, including the use of treatment in welding any joint in a structural component, conforms to the standards.
The following detailed welding specifications apply for FSR bridges:
- All welding shall be done under suitable cover;
- All welding, and inspection of welding, must conform to CSA W59 Welded Steel Construction (Metal Arc Welding);
- Fabricate girders as fracture critical members in accordance with CHBDC except that Charpy V-notch testing results are only required on a per heat frequency;
- Weld metal of primary tension members and fracture critical members shall meet the CVN toughness requirements specified in CHBDC table 10.14;
- Fillet weld leg size shall be a minimum of 6 mm unless otherwise noted;
- All welds shall be visually inspected;
- All tension butt welds shall be radiographically or ultrasonically tested;
- The desired objective for flange to web welds, for both I-girders and all-steel portable girders, is that they be made as continuous, uninterrupted and uniform welds free of abnormalities that could result in stress concentrations;
- Generally, web to flange welds shall be made continuously by machine or automatic welding using submerged arc welding, flux-cored arc welding or metal-cored arc welding;
- There may be instances where the Ministry may accept girder web to flange welds with stops and starts in the deposition of weld material (e.g., at plate diaphragm locations on box girders, at certain end of girder locations with limited access, or upon occasions of unexpected power outages). However, continuous welds made by automatic or machine methods are required wherever it is reasonably physically possible (e.g., welds made on the outside of all steel portable box girders, and interior welds on all steel portable box girders except as previously noted);
- Where welds require repair, they may be repaired using a semi-automatic or manual process, but the repaired weld shall blend smoothly with the adjacent welds. Weld repairs shall be undertaken in accordance with CSA W59;
- I-girder flange to web welds shall be made using submerged arc welding; and
- The welding procedure data sheets, as per CSA W47.1, shall be available for Ministry review prior to fabrication.