When a thermic lance does not ignite, the cause is almost always one of four factors: an unstable oxygen supply, insufficient preheating of the lance tip, gas leaks in the holder assembly, or a contaminated or defective lance pipe. A thermic lance is ignited by heating its tip with an oxyacetylene torch until the steel glows red hot, then gradually opening the oxygen valve to start the exothermic reaction. If any step in this sequence is compromised, the lance fails to light or loses its flame shortly after ignition.
For steel mills, foundries, and smelting plants, repeated ignition failures disrupt production schedules and increase operating costs. This guide breaks down the technical causes behind thermic lance ignition problems and provides systematic field fixes.
Most ignition failures originate from a disruption in the conditions required to start the exothermic reaction between high-purity oxygen and the steel core wires inside the lance pipe. Once ignited, this reaction reaches approximately 3,000–3,600°C, which is what allows the lance to melt through steel, slag, and refractory.
The correct ignition sequence is straightforward: the operator preheats the tip of the lance pipe with an oxyacetylene torch until it glows red hot, then opens the oxygen valve slowly. Ignition problems appear when the oxygen supply, the preheating step, or the condition of the pipe itself deviates from this standard procedure.
A continuous, correctly regulated oxygen flow is the most critical factor in starting and sustaining the reaction. Oxygen flow issues typically appear when supply lines are bottlenecked, regulators are set incorrectly, or cylinder pressure falls below the operating threshold.
A sudden oxygen pressure drop prevents the preheated core wires from transitioning into self-sustained combustion. The tip may glow briefly and then die out, leaving the pipe dark and unignited. Low oxygen purity has a similar effect, so always use high-purity industrial oxygen that meets the specification recommended for oxygen lancing work.
The tip of the lance must be genuinely red hot before oxygen is introduced. If the oxyacetylene torch is removed too early, or the flame is not held on the tip long enough, the core wires never reach ignition temperature and the lance fails to light.
Attempting to ignite the lance against cold, heavy slag left over from a previous cut is another common error. The slag absorbs the preheating energy, so the tip stays below ignition temperature despite repeated attempts. Clean the tip, or trim it back to fresh steel, before preheating again.
Before questioning the consumable pipe itself, audit the hardware configuration. A poorly maintained preheating torch or a minor gas leak anywhere along the holder assembly can prevent ignition even when the lance pipe itself is sound.
A stable, intense preheating flame is required for a successful light. Standard practice is to ignite a thermic lance only with an oxyacetylene torch; improvised heat sources do not deliver enough concentrated energy to bring the tip to red heat.
Check that the torch nozzle is clean, the flame is correctly adjusted, and the operator holds the flame on the lance tip until the steel visibly glows red hot. A rushed or uneven preheat is one of the most frequent, and most easily corrected, causes of a thermic lance not igniting.
A leaking handle or holder is both a safety hazard and an ignition problem. If oxygen escapes through worn rubber seals or loose connections inside the lance holder, the gas volume reaching the tip becomes insufficient to sustain combustion.
Leaks also enrich the operator’s immediate breathing zone with oxygen, which sharply increases fire risk. Replace worn seals immediately and pressure-test all connections before every shift.
The structural integrity and manufacturing consistency of the consumable pipe determine how reliably it ignites and burns. Inconsistent manufacturing leads to field defects that disrupt normal operation.
Moisture is a direct enemy of the exothermic cutting process. Moisture contamination occurs when lance pipes are stored in uncovered, damp environments before use.
When a damp pipe is preheated, the trapped water vaporizes and absorbs the thermal energy the steel needs to reach ignition temperature. The result is a pipe that is difficult to light and prone to sputtering or popping. Store lance pipes in a dry, covered area and keep bundles off wet ground.
The internal configuration of the lance pipe controls the flame characteristics. If the core wire packing density is inconsistent, operators will experience burning defects.
A critical failure occurs when the inner wires melt back inside the tube faster than the outer casing burns. This structural imbalance destabilizes the oxygen channel and can extinguish the flame shortly after ignition. Consistent wire packing during manufacturing is the only reliable prevention.
When dealing with a thermic lance not igniting on the shop floor, follow a structured sequence to identify and resolve the issue without compromising plant safety:
Before attempting another light, shut down the oxygen supply and inspect the mechanical connections. Set the regulator precisely to the pressure recommended for the specific pipe diameter, and verify that the pipe tip is free from rust, grease, and slag. Only then repeat the standard preheating procedure with the oxyacetylene torch.
During intensive cutting operations, slag or debris can back up into the tube mouth after a failed ignition. Check the front opening of the pipe: if slag has solidified over the tip, trim the contaminated end with a mechanical saw to expose fresh, clean core wires before re-igniting.
Maintaining a steady burn after the initial light requires stable gas dynamics. If the flame goes out immediately after ignition, the system is experiencing a combustion collapse.
A complete combustion failure happens when the balance between iron consumption and oxygen velocity is broken. If the oxygen valve is opened too quickly or too wide immediately after the tip catches, the excessive gas volume can blow out the young flame.
Train operators to crack the valve gently at ignition and scale up the pressure gradually as the burn stabilizes.
If the gas velocity drops below the burning speed of the steel, the flame can begin to retreat toward the operator. Flame instability requires immediate pressure adjustment.
If a popping sound is heard, stop and follow backfire protocols. A flashback arrestor must be installed on the oxygen line to prevent the flame from traveling back into the hoses if a pressure drop causes reverse gas flow.
In heavy industrial settings, safety is the first measure of operational success. Because a thermic lance not igniting can tempt operators to bypass standard protocols to save time, the consumables themselves must meet strict quality criteria before they ever reach the shop floor:
Minimizing operational failures such as a thermic lance not igniting begins with sourcing consistently manufactured consumables.
Manufactured at Daiwa Lance International’s factory in Vietnam, Daiwa Thermic Lance combines Japanese technology and high-quality materials with ISO 9001, ISO 14001, and JIS standards.
Controlled core wire packing density and strict surface cleanliness address the structural causes of ignition failure described in this guide.
Daiwa Lance exports to more than 52 countries with full export documentation support, including certificates of origin and fumigation certificates, and uses packaging designed to keep pipes dry in transit. The minimum order quantity starts at 50 pipes, and free samples are available for field evaluation.
The most common cause is insufficient preheating. The lance tip must be heated to red hot with an oxyacetylene torch before the oxygen valve is opened. If the tip is not hot enough, the exothermic reaction cannot start. Check oxygen pressure and supply next, then inspect the pipe for moisture or blockages.
No. A thermic lance is ignited only by preheating the tip to red hot with an oxyacetylene torch and then opening the oxygen valve. Other ignition methods are not part of the correct operating procedure for Daiwa Thermic Lance.
Once the exothermic reaction starts, a thermic lance can burn up to 3,000~3,600°C. This is why correct ignition, stable oxygen supply, and full personal protective equipment are required before starting work.
Check the oxygen system first: cylinder pressure, regulator setting, and hose or valve leaks. Then confirm the pipes are dry and straight, with clean surfaces and sound welds. Pipes stored in damp conditions or bent during handling are a frequent cause of ignition and combustion problems.
Here is a quick summary of the core technical factors behind a thermic lance not igniting and how to resolve them on the shop floor:
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Established since 1997, Daiwa Lance has positioned ourselves as a pioneer in thermic cutting and oxygen lancing technology. Based in Ho Chi Minh City, Vietnam, we have been providing quality customer service and products with advanced Japanese technology.
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