In Canada, a company that welds steel structures and parts is generally certified by the Canadian Welding Bureau (CWB Group) to CSA W47.1. The fabrication of welded assemblies follows CSA W59. These two standards set precise rules, and a CWB audit verifies that they are applied. Here are the essentials, in plain language.

Important: this summary does not replace the standards. On a job site, the CWB-approved welding procedure (WPS and WPDS) and the project engineer always have the final say.

1. What CSA W47.1 certification requires of the company

The standard classifies companies into three divisions, according to the role of the welding engineer.

• Welding procedures: each process used must have a written procedure (WPS) and data sheets (WPDS) accepted by the CWB.
• Qualified welders: each welder, operator and tack welder takes a test for the processes and positions they use in production.
• Requalification: most welder qualifications are valid for two years. The welder retakes a practical test within 90 days before or after the expiry date; past that window, they must redo the full test.
• Welding supervisor: at least five years of welding experience, written examinations and a short oral examination.
• Audits: a CWB representative visits the company periodically to verify all of this.

At Alliance Maintenance Industrielle, our welders are CWB-qualified in SMAW (stick electrode) and FCAW (flux-cored wire).

2. Statically or cyclically loaded structure: what difference does it make?

CSA W59 has a common part (Clauses 1 to 10), followed by two separate parts: Clause 11 for statically loaded structures and Clause 12 for cyclically loaded structures, that is, structures subjected to repeated loads that can cause fatigue. The project engineer determines the type of structure.

Simply put: on a part that vibrates or undergoes load cycles, every small defect can become the starting point of a fatigue crack. That is why Clause 12 is more demanding.

3. Low-hydrogen electrodes (E4918, the "7018"): why keep them heated

The coating of low-hydrogen electrodes absorbs moisture from the air. This moisture brings hydrogen into the weld, which can cause cold cracking (hydrogen cracking): a crack that sometimes appears several hours after welding, often invisible to the naked eye. The risk increases with thickness, steel strength and cold. Keeping electrodes dry and warm is the first line of protection.

Note: in Canada, the E7018 electrode is called E4918 (metric designation under CSA W48).

Storage and time out of the oven

How long and at what temperature to re-bake

• Follow first and foremost the temperature specified by the manufacturer on the box and in the procedure (WPDS).
• Hotter is not better: never exceed the manufacturer's maximum temperature, as it damages the coating.
• Several hours at a lower temperature do not replace baking at the correct temperature.
• After baking, the electrodes go back into the holding oven at a minimum of 120 °C.

4. Preheat: from what thickness, and at what temperature

Preheat slows the cooling of the weld and helps hydrogen escape. The table below gives the minimum temperatures for common structural steels (for example 300W, 350W, A36, A572 grade 50). The thickness to consider is that of the thickest part in the joint.

* Never weld on steel below 0 °C: first warm it to at least 20 °C. Also remove all traces of moisture or frost.

• Heat on each side of the joint and ahead of the arc, over a distance equal to the thickness of the part, but at least 75 mm.
• Maintain this temperature throughout welding, between passes. If work stops, preheat again before resuming.
• Check with a temperature-indicating crayon or a contact thermometer, not by eye.
• Let the part cool in air; never quench it with water.
• High-strength steels, quenched and tempered steels and highly restrained joints may require more: the approved procedure specifies it.

These values come from the minimum preheat table of AWS D1.1 (categories A and B). The Canadian standard CSA W59 has its own table (Table 5.3); for example, it also calls for 10 °C for a 25 mm joint in 350W steel welded with a low-hydrogen electrode. For CWB-certified work, the W59 table and the approved procedure apply.

In summary

• A CWB-certified company has approved procedures, welders requalified every two years, a welding supervisor and regular audits.
• Static or cyclic: the engineer determines it, and cyclic is more demanding.
• E4918 (7018) electrodes stay in the oven at 120 °C and are used within 4 hours; they are re-baked only once, and wet electrodes are discarded.
• Preheat starts above 20 mm of thickness with a low-hydrogen electrode, and always if the steel is below 0 °C.

Do you have a structural welding project or a repair that must meet the standards? Call us at 438-357-8800.

Sources

1. CWB Group — CSA W47.1, certification of companies for fusion welding of steel (divisions, engineer, supervisor, procedures, welders, audits)
2. CWB Group — Welder qualification (two-year validity, requalification)
3. CSA W59 — Welded steel construction: Clauses 5 (electrodes, preheat, Table 5.3), 11 (statically loaded structures) and 12 (cyclically loaded structures)
4. AWS D1.1 — Structural Welding Code, Steel: prequalified minimum preheat (categories A and B) and storage of low-hydrogen electrodes
5. CSA W48 — Filler metals and allied materials for metal arc welding (E49XX designations)
6. Lincoln Electric — Storing and Redrying Electrodes (holding and baking temperatures)
7. WeldCanada — Example SMAW procedure applying CSA W59 (oven at 120 °C, 4 hours, single re-bake)

Photo: Unsplash. This article provides general information; it does not replace the manufacturer's requirements or your facility's risk assessment.