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CAN CSA W202-18 (2019): Classification of Covered Electrodes for Shielded Metal Arc Welding
A comprehensive guide to the Canadian national standard for welding consumables for carbon and carbon-manganese steels
Scope and Applicability
CAN CSA W202-18 (2019) is the Canadian national standard that specifies requirements for the classification of covered electrodes for manual metal arc (shielded metal arc) welding of carbon and carbon-manganese steels. It covers electrodes with all-weld metal tensile strengths in the range of 430 MPa to 550 MPa, intended for welding in all positions or restricted positions, and suitable for use with direct current (DC) or alternating current (AC). The standard is an adoption of ISO 2560:2009 with Canadian modifications, ensuring alignment with international practice while addressing specific domestic requirements.
The standard applies to electrodes manufactured for commercial use and provides a comprehensive classification system that allows users to select the correct electrode for the intended base metal thickness, joint design, service conditions, and welding procedure. It also includes supplementary designations for impact toughness, covering type, and diffusible hydrogen content.
Technical Requirements and Classification System
Classification Structure
The electrode designation follows a systematic code that begins with the letter E, followed by digits and letters conveying specific properties. The general format is:
E 43 1 B 1 1 H10
The meaning of each element is shown in the table below.
| Position | Symbol / Example | Description |
|---|---|---|
| 1 | E | Indicates a covered electrode for manual metal arc welding |
| 2 (two digits) | 43, 49, 55 | Minimum tensile strength of all-weld metal (430 MPa, 490 MPa, 550 MPa) |
| 3 (digit) | 1, 2, 3, 4 | Welding position: 1 = all positions; 2 = flat and horizontal-vertical; 3 = flat only; 4 = vertical-down |
| 4 (letter) | A, B, C, R, etc. | Type of covering: A (acid), B (basic), C (cellulosic), R (rutile), S (special) |
| 5 (digit) | 0, 1, 2, 3, 4, 5 | Impact test temperature code: 0 = no requirement; 1 = +20 °C; 2 = 0 °C; 3 = −20 °C; 4 = −30 °C; 5 = −40 °C |
| 6 (digit) | 1, 2, 3, 4, 5, 6 | All-weld metal composition group (e.g., 1 = C-Mn, 2 = low‑alloy) |
| Suffix | H5, H10, H15 | Maximum diffusible hydrogen content: H5 ≤ 5 mL/100g; H10 ≤ 10 mL/100g; H15 ≤ 15 mL/100g |
Mechanical Property Requirements
The all-weld metal test assembly must meet the minimum mechanical properties given in Table 2.
| Class (Tensile Strength) | Tensile Strength Rm (MPa) | Yield Strength Rp0.2 (MPa) | Elongation A5 (%) | Impact Test Temperature (°C) | Minimum Impact Energy KV (J) |
|---|---|---|---|---|---|
| E43 | 430–510 | ≥ 330 | ≥ 22 | 0 | ≥ 47 |
| E49 | 490–570 | ≥ 390 | ≥ 20 | −20 | ≥ 47 |
| E55 | 550–640 | ≥ 440 | ≥ 18 | −30 | ≥ 47 |
Note: The impact temperature shown is a typical requirement for general structural use; different impact codes will specify alternative temperatures.
Hydrogen Content
For electrodes classified with a hydrogen suffix, the diffusible hydrogen content measured on a standard test coupon must not exceed the stated value. Low‑hydrogen electrodes (H10 or H5) are essential for welding high‑strength steels and thick sections where hydrogen‑assisted cold cracking is a concern.
Implementation Considerations
Electrode Selection
When selecting a covered electrode, the designer and welder must consider:
- The tensile strength of the base metal (typically matching or slightly exceeding).
- The welding positions required by the joint geometry.
- Service temperature and toughness demands (impact code).
- The level of restraint and risk of cracking (hydrogen content choice).
- The type of current and polarity available (covering type influences this).
Tip: CSA W202‑18 does not mandate a specific electrode for a given application; rather, it provides a classification that allows the welding engineer to make an informed choice. Always qualify the welding procedure using the actual electrode class intended for production.
Storage, Handling, and Baking
Basic (B) covered electrodes absorb moisture rapidly and must be stored in sealed containers or heated cabinets. Re‑drying conditions should follow the manufacturer’s recommendations; typical temperatures range from 300 °C to 400 °C for basic electrodes. Rutile (R) and cellulosic (C) electrodes have different moisture tolerances and should not be overheated.
Caution: Welding with electrodes that have exceeded their allowable moisture content increases the risk of hydrogen cracking and poor weld metal properties. Always verify the electrode condition, especially in humid environments.
Compliance and Quality Assurance
Testing and Verification
Manufacturers claiming compliance with CAN CSA W202‑18 must conduct type tests on each electrode class. These include preparation of a multi‑run butt weld on a standardized test piece, followed by mechanical testing (tensile, transverse bend, impact), chemical analysis of the all‑weld metal, and measurement of diffusible hydrogen when a hydrogen suffix is claimed. The test laboratory should be accredited to ISO/IEC 17025.
Marking
Each electrode shall be marked with the full classification designation (e.g., E491 B 1 1 H10) and the manufacturer’s name or trademark. The standard also requires that the packaging includes a warning about storage conditions and the recommended welding currents.
Compliance benefit: Using electrodes classified to CSA W202‑18 provides a traceable, reproducible quality level that is recognized across Canada, simplifies welding procedure qualification under CSA W47.1 and W59, and demonstrates due diligence in meeting Canadian regulatory requirements.
Regulatory Context
In Canada, adherence to CSA welding standards is often mandatory for work governed by federal or provincial safety codes (e.g., pressure equipment, structural steel, cranes). CAN CSA W202‑18 is referenced by welding procedure and performance qualification standards such as CSA W47.1 and CSA W59, making it a foundation document for quality‑assured welding.
Important: The use of an electrode that does not meet the classification requirements of W202‑18 may invalidate a welding procedure qualification (WPQ) and expose the fabricator to non‑conformance during audits. Always verify that the electrode’s certification is current and matches the WPQ parameters.
Frequently Asked Questions
Q: Is CAN CSA W202‑18 equivalent to ISO 2560?
A: Yes, it is the Canadian adoption of ISO 2560:2009. The classification structure and property requirements are aligned; however, CSA W202‑18 may include additional notes and modifications to reflect Canadian welding practices and regulatory needs.
A: Yes, it is the Canadian adoption of ISO 2560:2009. The classification structure and property requirements are aligned; however, CSA W202‑18 may include additional notes and modifications to reflect Canadian welding practices and regulatory needs.
Q: What is the main difference between E49 and E55 electrodes?
A: The principal difference is the minimum all‑weld metal tensile strength: E49 requires ≥ 490 MPa, while E55 requires ≥ 550 MPa. E55 electrodes also have higher minimum yield strength and often require lower temperatures for impact testing, making them suitable for higher‑strength base materials and more demanding service conditions.
A: The principal difference is the minimum all‑weld metal tensile strength: E49 requires ≥ 490 MPa, while E55 requires ≥ 550 MPa. E55 electrodes also have higher minimum yield strength and often require lower temperatures for impact testing, making them suitable for higher‑strength base materials and more demanding service conditions.
Q: Can I use an electrode with position code 2 in a vertical weld?
A: No. Position code 2 limits the electrode to flat (downhand) and horizontal‑vertical (fillet) welding. For vertical‑up or overhead welding, an electrode classified with code 1 (all positions) or code 4 (vertical‑down) must be used.
A: No. Position code 2 limits the electrode to flat (downhand) and horizontal‑vertical (fillet) welding. For vertical‑up or overhead welding, an electrode classified with code 1 (all positions) or code 4 (vertical‑down) must be used.
Q: What does the hydrogen suffix (H5, H10, H15) mean for my welding procedure?
A: The suffix indicates the maximum diffusible hydrogen in mL/100 g of deposited weld metal. Choosing a low‑hydrogen class (H10 or H5) is critical for reducing the risk of hydrogen‑induced cold cracking, especially in thick sections, high‑restraint joints, or when welding high‑strength steels. The electrode must be stored and baked appropriately to maintain the claimed hydrogen level.
A: The suffix indicates the maximum diffusible hydrogen in mL/100 g of deposited weld metal. Choosing a low‑hydrogen class (H10 or H5) is critical for reducing the risk of hydrogen‑induced cold cracking, especially in thick sections, high‑restraint joints, or when welding high‑strength steels. The electrode must be stored and baked appropriately to maintain the claimed hydrogen level.
© 2026 Technical Article. This content is for informational purposes only and does not replace the official CAN CSA W202‑18 (2019) standard. Always refer to the latest edition of the standard for definitive requirements.