Do non-sparking tools really prevent ignition in hazardous areas?
Abstract
Not completely. Copper-beryllium or aluminium-bronze tools make incendive impact sparks less likely, but they can still heat up by friction, sparks can come from rusty steel or grit, and they are not reliable against hydrogen or acetylene. Gas-free working is the safer basis.
They reduce the risk but do not remove it. Tools made of copper-beryllium or aluminium-bronze produce far fewer and cooler impact sparks than steel, which is why they are used where a dropped spanner could ignite a gas. But a hard blow can still cause ignition, especially with hydrogen, acetylene, carbon disulphide and some other sensitive gases; the tool can strike sparks from rusty steel, grit or the workpiece; and friction can make hot spots. The reliable protection is to keep the explosive atmosphere away from the work, with gas testing and a permit.
Short answer
- What they do: soft, non-ferrous alloys do not shed the burning iron particles that make steel sparks so incendive.
- What they do not do: they do not stop hot surfaces from friction, sparks from the other surface (rusty steel, concrete, sand), or ignition of the most sensitive gases.
- German technical rule TRGS 723: a single spark from simple hand tools only rarely ignites an explosive atmosphere, but for IIC gases (acetylene, carbon disulphide, hydrogen) and also hydrogen sulphide, carbon monoxide and ethylene oxide, ignition must always be assumed possible.
- Where they are a recognised measure: TRGS 723 accepts low-spark tools of non-hardened non-ferrous metal (it names copper-beryllium and a Brinell hardness of at most HBW 32) in Zone 0 and in Zone 1 with IIC-type gases only if the impact energy stays below 60 J and the absence of incendive sparks is shown for the actual material pairing.
- Spark showers (grinding, cutting, chiselling) are hot work, whatever the tool material.
- Special cautions: high-copper alloys can form explosive acetylides with acetylene; dust or fume from copper-beryllium is a health hazard.
Why soft alloys help, and where the protection ends
When steel strikes steel or rock, small particles are torn off and heated. Iron and unalloyed steel particles then keep oxidising in air and get hotter, which is why they are much more likely to ignite gases, vapours and dusts than particles that do not oxidise. TRGS 723, the German technical rule on avoiding ignition of explosive mixtures, describes this in its section on mechanical ignition sources (5.4) and adds that light metals such as aluminium in contact with rust, or titanium, behave in the same way. Copper-beryllium and aluminium-bronze tools avoid that mechanism, so a light accidental knock is far less dangerous.
Three effects remain:
- The other surface. The tool may be soft, but the flange, grating or floor it hits may be rusty steel or concrete, or there may be sand or grit in between. Particles can then come from the other material, which is why TRGS 723 asks for the absence of incendive sparks to be shown for the actual material pairing, including workpiece, supports and floor.
- Friction and hot surfaces. Rubbing, drilling or prolonged hammering heats both surfaces, whatever the alloy. TRGS 723 treats partially hot surfaces from friction and impact as ignition sources in their own right.
- Very sensitive gases. Hydrogen, acetylene and carbon disulphide ignite with very little energy. For these, and for hydrogen sulphide, carbon monoxide and ethylene oxide, TRGS 723 tells the user to assume that ignition by mechanical sparks is always possible.
What the rules say about tools by zone
The ATEX product directive does not cover hand tools: the European Commission's ATEX Guidelines list hammers, spanners, saws and ladders as having no own source of ignition, so tools cannot carry ATEX equipment marking. Tool use is a workplace matter under Directive 1999/92/EC, decided in the employer's risk assessment. EN 1127-1 contains an informative annex on the use of tools in potentially explosive atmospheres, and TRGS 723 gives one national interpretation:
| Area | Tool guidance in TRGS 723 (Germany) |
|---|---|
| Zone 0 and Zone 20 | No equipment that may produce even single sparks; low-spark tools of non-hardened non-ferrous metal are acceptable only below 60 J impact energy and with a demonstrated material pairing |
| Zone 1 and Zone 2 | High-grade steel tools allowed if they produce neither spark showers nor hot surfaces (for example by drilling) |
| Zone 1 with IIC gases, H2S, CO or ethylene oxide | No metallic tools of any kind unless special measures are taken, such as low-spark non-ferrous tools under the same 60 J and pairing conditions |
| Zones 21 and 22 | High-grade steel tools allowed without spark showers or hot surfaces; otherwise shield the work area and remove or wet down dust |
Other countries and company standards set their own rules, so check the site's Explosion Protection Document and permit system before relying on this table. The question Are hand tools required to be ATEX-marked or non-sparking in Zone 1? looks at tool selection in more detail.
The safer basis: make the area gas-free
Directive 1999/92/EC requires a permit-to-work system for hazardous activities where the Explosion Protection Document calls for one, and it sets prevention of the explosive atmosphere ahead of avoiding ignition. In practice, mechanical work on a line or vessel that has held flammable material is planned so that the work area is isolated, drained, purged or ventilated and tested with a gas detector before and during the job. Non-sparking tools are then an extra layer, not the main barrier. Grinding, cutting and welding need a hot work permit whatever tools are used.
Example: A maintenance team must open a flange on a hydrogen line in Zone 1. Bronze spanners alone are not an adequate safeguard: hydrogen is IIC, and TRGS 723 assumes mechanical sparks can ignite it. The permit requires isolation, nitrogen purging, a gas test showing no flammable gas at the flange and continuous monitoring during the work. The bronze spanners are still used, as an additional precaution.
Common mistakes
- Treating "non-sparking" as "cannot ignite". The term describes reduced impact spark energy, not a guarantee.
- Using copper-alloy tools on acetylene systems without checking the alloy. Because of the risk of explosive copper acetylides, ISO 9539 limits the copper content of materials that contact acetylene in gas welding equipment to 70 %; most copper-beryllium and many bronze tools contain far more copper, so keep them out of contact with acetylene.
- Dressing copper-beryllium tools on a grinder without controls. Copper-beryllium is a beryllium alloy; OSHA warns that inhaled beryllium dust or fume can cause sensitisation, chronic beryllium disease and lung cancer. Use dust extraction and follow the tool's handling instructions.
- Forgetting worn or contaminated tools. Embedded steel chips or grit on a soft tool face defeat its purpose; inspect and clean tools.
Related on excodex
- Ignition sources in hazardous areas: the 13 ignition sources and how to control them
- Hot work permits in hazardous areas
- Are hand tools required to be ATEX-marked or non-sparking in Zone 1?
- Which ignition sources are most often overlooked in hazardous areas?
- Gas cards: hydrogen, hydrogen sulphide
Standards and further reading
- TRGS 723, German technical rule for hazardous substances on avoiding ignition of hazardous explosive mixtures, sections 5.4 and 5.15 (public text, in German): bgn-branchenwissen.de
- EN 1127-1:2019, explosive atmospheres: explosion prevention and protection, basic concepts and methodology, informative annex on tools (public preview of the contents): standards.iteh.ai
- European Commission, ATEX 2014/34/EU Guidelines, 6th edition (January 2026), simple products and borderline list: single-market-economy.ec.europa.eu
- Directive 1999/92/EC, Article 3 and Annex II (permits to work): legislation.gov.uk
- ISO 9539:2010, gas welding equipment: materials for equipment used in gas welding, cutting and allied processes (copper limit for acetylene; public preview): standards.iteh.ai
- OSHA, beryllium: health effects and exposure: osha.gov
This article is general technical information prepared by the excodex editorial team. It does not replace the applicable standards, the equipment certificates and instructions, national regulations or the assessment of a competent person.