Set Up and Operate Welding Equipment

Setting Up and Using Welding Equipment

Introduction to the Welding Station

Proper setup of welding equipment is the first critical step in producing welds that meet the requirements of the Canadian Electrical Code, Part I (CE Code) and applicable CSA standards. A Red Seal welder must not only know how to handle the torch but also understand the electrical parameters, gas flow rates, polarities, and mechanical adjustments that determine weld quality.

This chapter covers all the knowledge required for the Red Seal exam regarding the installation, adjustment, and safe use of arc and gas welding equipment.

1. Arc Welding Equipment

1.1 Welding Power Sources

Power sources are divided into three main categories based on their output characteristics:

Power Source Type	Characteristic	Typical Applications
Constant Current (CC)	Variable voltage, fixed amperage	SMAW (stick electrode), GTAW (TIG)
Constant Voltage (CV)	Variable amperage, fixed voltage	GMAW (MIG/MAG), FCAW (flux-cored)
Pulsed Power Source	Adjustable pulsed current	GMAW-P, GTAW-P, specialized processes

Open-circuit voltage (OCV) is the voltage measured at the terminals of the power source when the circuit is open (no arc). For arc welding, OCV typically ranges between 50 V and 100 V. This value is important for safety: any OCV above 80 V DC or 80 V AC requires additional protective devices according to CSA W117.2 (Safety in welding, cutting, and allied processes).

1.2 Duty Cycle

The duty cycle is the percentage of time a power source can operate at a given amperage over a 10-minute period without overheating. For example, a 60% duty cycle at 300 A means the machine can weld at 300 A for 6 minutes, followed by 4 minutes of cooling.

The formula for calculating the equivalent duty cycle at a different amperage is:

DC₂ = DC₁ × (I₁ / I₂)²

Where:

DC₁ = rated duty cycle (in %)

I₁ = rated current (in A)

I₂ = operating current (in A)

Example: A machine has a 60% duty cycle at 300 A. What is the duty cycle at 400 A?

DC₂ = 60 × (300 / 400)² = 60 × (0.75)² = 60 × 0.5625 = 33.75%

The duty cycle is approximately 34%.

1.3 Polarity and Connections

Polarity determines the direction of electron flow and influences penetration, deposition rate, and heat distribution.

Polarity	Electrode Connection	Workpiece Connection	Main Effects
DCEN (electrode negative)	Negative (−)	Positive (+)	Narrow penetration, high deposition rate, heat concentrated on the workpiece
DCEP (electrode positive)	Positive (+)	Negative (−)	Deep penetration, oxide cleaning, heat concentrated on the electrode
AC (alternating)	Alternating	Alternating	Balance between cleaning and penetration, used for aluminum in GTAW

Rule of thumb: In SMAW, E6010 and E6011 electrodes run on DCEP. E7018 electrodes run on DCEN or AC. In GMAW, the standard polarity is DCEP for most metals (electrode positive, workpiece negative).

2. GMAW and FCAW Equipment

2.1 Wire Feeder and Gun

The wire feeder must be configured according to the wire diameter and liner type. The main adjustments are:

Drive roll pressure: must be sufficient to feed the wire without crushing it. A crushed (deformed) wire causes feeding problems and unstable arcs.

Spool brake: must be adjusted to prevent excessive unwinding ("bird's nest" effect) while allowing free wire payout.

Liner: must match the wire diameter and metal type. Steel liners are for steel wires; Teflon or nylon liners are for aluminum.

Cable length affects voltage: a voltage drop of 1 V per 15 m of cable is typical. For lengths greater than 15 m, you must increase the output voltage accordingly.

2.2 GMAW Welding Parameters

The four main parameters are:

34.Voltage (V): controls arc length and bead width. Voltage too high produces a wide, flat bead with spatter; voltage too low produces a short arc, excessive spatter, and poor fusion.

35.Wire feed speed (m/min): controls amperage. The faster the wire is fed, the higher the current.

36.Travel speed: affects bead width and heat input.

37.Gas flow rate: typically 14 to 20 L/min (30 to 40 ft³/h) for CO₂ or Ar/CO₂ mixtures.

The relationship between wire feed speed and amperage is approximately linear for a given wire diameter. For a 1.2 mm wire, a feed speed of 5 m/min corresponds to approximately 150 A.

2.3 Metal Transfer Modes

Transfer Mode	Voltage	Current	Gas	Applications
Short-circuit	16–22 V	50–200 A	100% CO₂ or Ar/CO₂	Thin sheet, all positions
Globular	22–30 V	200–350 A	CO₂	Avoid if possible (spatter)
Spray	24–32 V	200–350 A	Ar ≥ 85%	Thick plate, flat position
Pulsed	22–35 V	50–400 A	Ar/CO₂ or Ar/O₂	All positions, aluminum

Exam trap: Spray transfer requires a gas containing at least 80% argon. With 100% CO₂, spray transfer is impossible.

3. GTAW (TIG) Equipment

3.1 TIG Station Components

The TIG station includes:

A constant current power source (DC or AC)

A TIG torch with tungsten electrode

A gas supply system (argon, helium, or mixtures)

A foot pedal or manual current control

A water cooler for high-amperage torches (≥ 200 A)

3.2 Tungsten Electrode Preparation

Electrode grinding is critical. The tip must be ground longitudinally (along the axis) to create parallel striations that stabilize the arc. Transverse grinding creates perpendicular striations that destabilize the arc.

Recommended tip angles:

Electrode Diameter	Tip Angle	Recommended Current
1.6 mm (1/16")	30°	50–100 A
2.4 mm (3/32")	30–45°	100–200 A
3.2 mm (1/8")	45–60°	200–350 A

For AC welding of aluminum, the electrode is often balled (rounded) rather than pointed.

3.3 AC Balance Adjustments

In AC welding of aluminum, the balance control adjusts the ratio between the cleaning half-cycle (electrode positive, DCEP) and the penetration half-cycle (electrode negative, DCEN).

50/50 balance: maximum cleaning, minimum penetration

70/30 balance (DCEN dominant): maximum penetration, minimum cleaning

65/35 balance: typical recommended setting

AC frequency (in Hz) affects bead width and arc concentration. A higher frequency (150–250 Hz) produces a narrower, more concentrated arc; a lower frequency (60 Hz) produces a wider arc.

4. Gas Welding Equipment (Oxyacetylene)

4.1 Oxyacetylene Station Setup

The station includes:

Oxygen cylinders (black or green) and acetylene cylinders (red or maroon)

Regulators with high- and low-pressure gauges

Hoses (green for oxygen, red for acetylene)

Torch with interchangeable tips

Lighter (friction striker)

Essential safety rule: Acetylene must never be used at a pressure greater than 15 psi (103 kPa) due to the risk of explosive decomposition. The acetylene regulator is calibrated accordingly.

4.2 Flame Adjustment

Flame Type	O₂/C₂H₂ Ratio	Characteristics	Use
Neutral	1:1	Sharp inner cone, no excess	Carbon steel, stainless steel
Carburizing	< 1:1	Elongated cone, excess acetylene	Aluminum, high-carbon alloys
Oxidizing	> 1:1	Short cone, excess oxygen	Brass, bronze, galvanized steel

The neutral flame is the most commonly used. To obtain it, first open the acetylene slightly, ignite it, then increase the oxygen until the inner cone becomes sharp and well-defined.

4.3 Calculating Working Pressures

Typical working pressures for a medium-sized tip (No. 3):

Oxygen: 15–25 psi (100–170 kPa)

Acetylene: 5–10 psi (35–70 kPa)

The 1/7 rule: for acetylene, never exceed 1/7 of the cylinder's hourly capacity in flow rate. A standard-size cylinder (300 ft³) must not exceed a flow rate of 42 ft³/h (300 ÷ 7).

5. Cutting and Gouging Equipment

5.1 Plasma Cutting

Plasma cutting uses an electric arc to ionize a gas (air, argon, nitrogen) which becomes conductive and melts the metal. The main parameters are:

Cutting current: determined by metal thickness (typically 20–40 A per 6 mm of thickness)

Torch height: 3–6 mm above the workpiece

Cutting speed: must be constant to avoid drag lines and dross

5.2 Air Carbon Arc Gouging

Air carbon arc gouging uses a carbon electrode and a jet of compressed air to remove molten metal. Typical settings:

Current: 300–500 A depending on carbon electrode diameter

Air pressure: 550–700 kPa (80–100 psi)

Electrode angle: 30–45° relative to the workpiece

Arc length: 3–6 mm

Exam trap: Air carbon arc gouging must never be used on austenitic stainless steels or high-carbon alloys without special precautions, as it can cause carburization of the metal.

6. Safety and Regulatory Compliance

6.1 CSA W117.2 Requirements

CSA W117.2 (Safety in welding, cutting, and allied processes) is the primary reference for welder safety in Canada. Key requirements include:

Ventilation: a minimum airflow of 28 m³/h per welder for arc welding in confined spaces

Eye protection: minimum shade No. 10 lenses for arc welding, No. 4 for gas welding

Personal protective equipment (PPE): insulating gloves, apron, sleeves, respiratory protection if necessary

Lockout: lockout/tagout procedures for equipment maintenance

6.2 Canadian Electrical Code, Part I

The Canadian Electrical Code, Part I applies to welding installations. Rule 8-200 requires that welding circuits be protected by fuses or circuit breakers conforming to code requirements. Rule 8-202 specifies requirements for grounding workpieces to be welded.

Key points of the CE Code:

Power sources must be installed in dry, well-ventilated locations

Welding cables must be of appropriate size for the maximum current

The workpiece must be grounded or connected to the ground terminal of the power source

Connections must be tight and free of corrosion

6.3 CSA B149.1 and Welding Gases

CSA B149.1 (Natural Gas and Propane Installation Code) applies to combustible gas installations, including acetylene and shielding gases. Requirements include:

Cylinders must be stored upright and secured

The minimum distance between oxygen and acetylene cylinders in storage is 6 m (20 ft) or separation by a one-hour fire-rated wall

Empty cylinders must be clearly identified and separated from full cylinders

Hoses must be checked for leaks with a soap solution (never with a flame)

7. Equipment Troubleshooting

7.1 Common GMAW Problems

Symptom	Probable Cause	Remedy
Unstable arc, excessive spatter	Voltage too low or too high	Adjust voltage by ± 2 V
Irregular wire feeding	Insufficient drive roll pressure	Increase pressure
"Bird's nest" (tangled wire)	Spool brake too loose	Tighten the brake
Porosity	Insufficient gas flow or leak	Check flow (14–20 L/min) and connections
Lack of fusion	Current too low or travel speed too fast	Increase current or slow down

7.2 Common GTAW Problems

Symptom	Probable Cause	Remedy
Unstable arc	Contaminated or improperly ground electrode	Re-grind the electrode
Tungsten inclusion	Electrode contact with the weld pool	Increase arc length
Porosity in aluminum	Insufficient cleaning or low gas flow	Clean the workpiece, increase flow
Erratic AC arc	Incorrect balance setting	Adjust balance to 65/35

8. Practical Calculations for the Exam

8.1 Heat Input Calculation

Heat input (in kJ/mm) is calculated by:

H = (V × I × 60) / (S × 1000)

Where:

V = voltage (V)

I = current (A)

S = travel speed (mm/min)

60 = conversion factor (seconds/minute)

1000 = conversion factor (J to kJ)

Example: V = 25 V, I = 200 A, S = 300 mm/min

H = (25 × 200 × 60) / (300 × 1000) = 300,000 / 300,000 = 1.0 kJ/mm

8.2 Gas Consumption Calculation

Gas volume consumed (in L) is:

V = Flow rate (L/min) × Time (min)

Example: Flow rate of 18 L/min for 45 minutes of actual welding time.

V = 18 × 45 = 810 L

8.3 Imperial/Metric Unit Conversions

Imperial	Metric	Factor
1 psi	6.895 kPa	× 6.895
1 ft³/h	0.472 L/min	× 0.472
1 in	25.4 mm	× 25.4
1 lb	0.454 kg	× 0.454

Summary

Polarity determines penetration and cleaning: DCEP for deep penetration, DCEN for high deposition rate.

Duty cycle is calculated using the formula DC₂ = DC₁ × (I₁/I₂)².

In GMAW, spray transfer requires ≥ 80% argon; short-circuit is used for thin sheet.

In GTAW, the tungsten electrode must be ground longitudinally with an angle suited to the current.

Acetylene must never exceed 15 psi (103 kPa) working pressure.

CSA W117.2 governs safety; the Canadian Electrical Code, Part I governs electrical installations; CSA B149.1 governs gases.

Heat input is calculated using H = (V × I × 60) / (S × 1000) in kJ/mm.

Systematic troubleshooting starts by checking voltage, gas flow, and drive roll pressure.

Traps to Avoid

145.Confusing DCEN and DCEP: In SMAW, E6010 requires DCEP. In GTAW, steel welding is done on DCEN (electrode negative). Don't reverse them.

146.Forgetting the duty cycle: The duty cycle is always based on a 10-minute period. A 60% cycle = 6 minutes of welding, 4 minutes of rest.

147.Using CO₂ for spray transfer: Impossible. You need at least 80% argon.

148.Neglecting the maximum acetylene pressure: 15 psi (103 kPa) maximum. Beyond that, there is a risk of explosive decomposition.

149.Grinding the tungsten electrode transversely: The striations must be longitudinal to stabilize the arc.

150.Ignoring voltage drop in cables: For cables longer than 15 m, increase output voltage by 1 V per 15 m.

151.Confusing gas hoses: The oxygen hose is green, the acetylene hose is red. Never interchange them.

152.Forgetting the ground connection: The workpiece must be connected to the ground terminal per the Canadian Electrical Code, Part I, Rule 8-202.

153.Calculating heat input with incorrect units: Speed must be in mm/min, not mm/s. Check units before calculating.

154.Using a flame to detect gas leaks: Always use a soap solution. A flame can cause an explosion.

This chapter covers all essential knowledge for the "Equipment Setup and Use" section of the Red Seal exam. Master the calculations, adjustments, and standards, and you'll be ready for the technical questions in this section.