Do you need a hot work permit to descale in a Zone 1 area?
What an ATEX Category 2 tool takes out of the permit question, what stays with the site operator, and where the certificate stops answering it.
Usually not for the tool, if it is ATEX Category 2 certified and the site's risk assessment agrees. A certified pneumatic scaler involves no flame, arc or incendive spark, so the work is generally not hot work. But the permit decision belongs to the site operator under Directive 1999/92/EC, not to the certificate. And where acetylene is present, the beryllium copper consumables on most certified scalers are the wrong choice, whatever the tool is rated for.
Four ways to get rust off steel in a live hazardous area
Each is a real answer. Which fits depends on the zone, the substrate and how much of the plant you can shut down.
Shut down, gas-free, conventional tools
- Equipment
- Lowest
- Ignition source
- None once gas-free
- Permit overhead
- None
Cost: production downtime. Right for a full tank refurbishment, wrong for a spot repair on a live line.
Conventional tools under a hot work permit
- Equipment
- Low
- Ignition source
- Yes, by procedure
- Permit overhead
- Gas watch, fire watch, standby
Cost: every hour of work carries people who are not working, on a permit that expires. The overhead exceeds the tool cost within weeks.
ATEX Category 2 mechanical tools
- Equipment
- 10-50% premium
- Ignition source
- Removed by design
- Permit overhead
- Site risk assessment
Cost: the certification has limits, below. Otherwise the overhead disappears. The ATEX range →
High-pressure water blasting
- Equipment
- High
- Ignition source
- None
- Permit overhead
- None
Cost: flash rust on cleaned steel before coating, and water to contain and dispose of.
On rates, Trelawny report up to 30 m²/h for a walk-behind deck scaler against roughly 13 m²/h for 500-bar water blasting: their own figure, not an independent test. Water blasting or mechanical scaling.
What "II 2 G Ex h IIC T4 Gb" actually buys you
Trelawny's Ex tools carry two markings, II 2 G Ex h IIC T4 Gb for gas and II 2 D Ex h IIIC T135°C Db for dust, certified through Element Materials Technology, a European Notified Body, under Directive 2014/34/EU. Select each part to decode it.
Category 2 is Gas Zone 1 and Dust Zone 21, where an explosive atmosphere is likely in normal operation, roughly 10 to 1000 hours a year. Category 2 equipment also covers the less demanding Zones 2 and 22.
- Directive 2014/34/EU
- The equipmentThe manufacturer: marking, Notified Body assessment, EU Declaration of Conformity.
- Directive 1999/92/EC
- The workplaceThe employer: explosion risk assessment, zone classification, the Explosion Protection Document. Permits sit here.
- Old literature still shows
EX II 2 G c IIA T4under Directive 94/9/EC. IIA covers propane and methane; IIC adds hydrogen and acetylene. For a hydrogen site, ask for the current EU Type Examination certificate rather than working from a web page. - The certificate covers the tool. It does not cover the consumables bolted to the front of it.
IIC does not mean acetylene-safe
This is a chemical problem, not an ignition-energy problem, and it is the failure mode nobody writes down.
Acetylene reacts with copper alloys above roughly 65 to 70% copper to form copper acetylide, a shock-sensitive explosive. Beryllium copper runs above 80% copper, and so does aluminium bronze. The needles on a certified needle scaler and the heads on a certified scaling hammer are beryllium copper, because that is what makes them non-sparking.
So a tool certified IIC, a group that formally includes acetylene, arrives fitted with consumables that should not be used where acetylene is present. The certificate is not wrong: it addresses whether the tool can ignite the atmosphere, and it cannot. It does not address whether the tool's material will react with it.
Affected: acetylene cylinder filling plants, acetylene storage, and process areas that handle acetylene directly. Specify a low-copper alloy below 65% copper and take the certification question separately.
Not affected: refineries, LNG carriers, tankers, gas installations and the great majority of offshore work.
Non-sparking depends on housekeeping
EN 1127-1 identifies impacts involving rust together with light metals as capable of starting a thermite reaction. The research goes back to a 1968 Institution of Chemical Engineers paper by Gibson, Lloyd and Perry: glancing impacts of many metals, copper-beryllium and bronze among them, onto aluminium smears on rusty mild steel could ignite a flammable gas-air atmosphere.
The tool alloy was not the variable. The smear on the steel was. A correctly specified beryllium copper tool on contaminated steel can still produce an ignition source.
What that means on site: unglamorous and cheap
- Inspect consumables before use.
- Replace needles that have picked up embedded steel.
- Keep tools clean and dry between shifts.
- Know whether aluminium tooling has been used on the steel you are about to work.
How long can one operator run each Ex tool?
Answered by a different directive, 2002/44/EC: an action value of 2.5 m/s² A(8) and a limit value of 5.0 m/s² A(8). The heavy-duty VL303Ex is the highest of the three needle scalers at the worse grip, and the triple-head SF3-EX is a 17-minute tool.
| Tool | Declared vibration, worse grip (m/s²) | Trigger time to action value | Trigger time to limit value |
|---|---|---|---|
| VL223Ex needle scaler | 2.95 † | Not reached in an 8-hour shift | |
| VL203Ex needle scaler | 3.26 † | Not reached in an 8-hour shift | |
| VL303Ex needle scaler | 3.70 † | Not reached in an 8-hour shift | |
| VL203Ex chisel scaler | 4.14 † | Not reached in an 8-hour shift | |
| VL303Ex chisel scaler | 4.30 † | Not reached in an 8-hour shift | |
| SF11-Ex deck hammer | 5.76 | 6 h 02 min | |
| VLSF1-EX single head hammer, front hand | 9.90 | 2 h 02 min | |
| SF3-EX triple head hammer | 13.40 | 1 h 07 min |
The "under 2.8 m/s²" figure in the range literature holds only for the needle models, and only at the primary grip. For a real risk assessment use the HSE exposure calculator; our HAVS guide has a workforce calculator.
The extraction needs its own certificate
Certification covers ignition, not what the operator breathes. Scaling raises dust from the coating, which on older plant can include lead, and from wear on the beryllium copper consumables. The alloys are about 2% beryllium, alloyed rather than free, and no cases are recorded from non-sparking hand tools; the documented risk sits in foundry and machining work. It is still a reason to extract at source.
A general-purpose vacuum reintroduces the ignition source you just paid to remove, and a standard air hose on a certified tool gives static a path back in. Dust control and lead paint guide.
Deciding
- HydrocarbonsZone 1 or Zone 21ATEX Category 2 mechanical scaling removes the permit overhead and pays back the premium quickly. ATEX range →
- Acetylene in the classificationFilling plants, storage, process areasThe certificate is not the deciding factor. Copper-alloy consumables are the wrong specification.
- Whatever you chooseAny classified spaceThe site's risk assessment under 1999/92/EC decides the permit. The tool's certificate is evidence for it, not a substitute.
Hazardous-area descaling: common questions
Do ATEX tools eliminate the need for a hot work permit?
Not automatically. Trelawny state that their Ex range is certified for use without hot work permits, and the reasoning is sound: a certified tool is not a recognised ignition source, so the work is generally not hot work. But Directive 2014/34/EU governs the equipment while Directive 1999/92/EC governs the employer, and the permit decision sits with the site operator's risk assessment and Explosion Protection Document. Many operators still require a cold work or confined space permit.
What is the difference between "non-sparking" and "ATEX certified"?
Non-sparking describes the consumable material, usually beryllium copper or aluminium bronze, chosen because it does not throw incendive sparks on impact. ATEX certified describes the whole tool, independently assessed by a Notified Body against Directive 2014/34/EU for a specific zone, gas group and temperature class. Fitting beryllium copper needles to an uncertified scaler does not make it a Zone 1 tool.
Can you use beryllium copper tools around acetylene?
No. Acetylene reacts with alloys above roughly 65 to 70% copper to form copper acetylide, which is shock-sensitive and explosive. Beryllium copper and aluminium bronze are both above 80% copper. This holds even for tools certified to gas group IIC, because the hazard is a chemical reaction rather than an ignition-energy question. Acetylene facilities need a low-copper alloy below 65% copper.
What is the difference between Zone 1 and Zone 2?
Zone 1 is an area where an explosive gas atmosphere is likely to occur in normal operation, roughly 10 to 1000 hours a year. Zone 2 is an area where it is not likely in normal operation and only for short periods. Zone 1 requires Category 2 equipment; Zone 2 requires Category 3. Category 2 equipment is acceptable in Zone 2, but not the reverse. The dust equivalents are Zone 21 and Zone 22.
Does an ATEX vacuum need to be certified separately from the tool?
Yes. Dust extraction is separate equipment and needs its own certification for the zone it works in. Trelawny's KAV30 ATEX vacuum is certified II 2 G Ex h IIC T6 Gb and II 2 D Ex h IIIC T50°C Db, and each unit ships with an earth path continuity certificate. An anti-static air hose is also a separate item, because a standard hose on a certified tool restores a static path.
Keep planning
The Trelawny ATEX range
VL-Ex scalers, SF-Ex hammers and the KAV30 vacuum, for Gas Zone 1 and Dust Zone 21.
View the range → DustDust control for lead paint
Why the collector must be H class, and the ATEX airflow trade-off.
Read the guide → VibrationNeedle scaler trigger times
Every Trelawny needle scaler, at the grip that decides it.
Read the guide →Tell us what the classification says
We name the exact model and part number, with IMPA codes, and say what we ruled out and why. If your atmosphere rules out copper-alloy consumables, we will tell you that too. Quoted in EUR.
- Zone
- Gas group
- Substrate and coating
- Area
- Delivery port
Quote Request Sent!
Thank you. Your enquiry is on its way to the SepcoTech team. We'll respond within one business day.