Machined components for explosive atmospheres: what compliance actually requires

A mechanical part is not "ATEX certified"

ATEX does not certify a part: it governs equipment and assemblies intended for use in an explosive atmosphere. A machined bracket, a flange, a shaft, a housing — taken in isolation — carry no ATEX marking. They are designed, manufactured and documented so that, once integrated, they introduce no ignition source into the zone where they operate.

The distinction is not abstract legal trivia: it decides who carries the liability. The manufacturer of the complete equipment marks and declares. The part supplier must deliver a part whose characteristics allow the assembly owner to sustain that declaration. A serious quotation describes that chain.

In Canada, "ATEX" is not the right word

ATEX is the European framework — the equipment directive and the workplace directive. In Canada, hazardous locations fall under the Canadian Electrical Code (CSA C22.1), using the class-and-division system and, increasingly, the IEC-aligned zone system. The international references IEC 60079 and ISO 80079-36 (non-electrical equipment) are the common language between both worlds.

In practice, on a Quebec or Ontario site, the request almost always arrives worded "ATEX" because the original equipment is European or the owner works to a group standard. That shorthand is acceptable, but the specification must state which reference governs acceptance — that is what sets the criteria, not habit of speech.

What the zone imposes on the designer

Zone classification sets the severity. In gas atmospheres, zones 0, 1 and 2 describe a presence that is continuous, occasional or unlikely; in dust atmospheres, zones 20, 21 and 22. The more likely the presence, the more ignition sources must be excluded — including those that appear only under foreseeable malfunction.

For a mechanical part, three families of constraints follow.

Materials: what gets used, and why

There is no such thing as an "ATEX material". There are defensible choices depending on the ignition mechanism of concern:

• Austenitic stainless steels (304L, 316L) — the default for process parts: conductive, non-magnetic, corrosion resistant, free of the problematic light metals. Most custom piping and structural parts in classified areas are stainless.
• Aluminium bronze and beryllium copper — used for tooling and rubbing parts, commonly called "non-sparking". A caution: non-sparking reduces risk, it does not remove it, and these alloys carry their own mechanical limits.
• Aluminium alloys — handle with care. They are not banned, but their use on surfaces liable to rub or be struck is constrained, and the ignition risk assessment decides.
• Engineering polymers — useful for wear and weight, but they reopen the static question: a dissipative grade and a documented earthing path become necessary.

The documentation: the part suppliers forget

A compliant part without a documentation package is not compliant — it is simply unverifiable. What the inspector or assembly owner expects:

• Material certificates (chemical composition and mechanical tests) tied to the heat actually delivered, not to the generic grade.
• Ignition hazard assessment, or its equivalent under the chosen reference: which sources were considered, which are excluded, and by what means.
• Welding qualifications per ASME Section IX (WPS/PQR) for welded fabrications, with the matching NDT reports.
• Dimensional records and, for fit-critical parts, a CMM inspection report.
• Installation instructions carrying the conditions of validity: tightening torque, earthing continuity, minimum clearances between fixed and moving parts.

The three mistakes that cost a shutdown

Confusing the part with the assembly. A supplier promising an "ATEX certified" part is selling a certification that does not exist at that level. The correct commitment is: a part designed and documented for the declared zone, under the customer's integration responsibility.

Forgetting friction under malfunction. A surface temperature calculation for normal running is not enough in the more severe zones. A seized bearing, a misalignment, a rotor-to-stator contact are foreseeable malfunctions.

Substituting a grade without redoing the assessment. Swapping stainless for aluminium to save weight or lead time potentially invalidates the original reasoning. Every substitution is handled as a modification, with its record.

FAQ

Can a machined part carry an ATEX marking? Marking applies to equipment and assemblies covered by the directive, not to an isolated mechanical component. A part is delivered with the characteristics and documentation that let the assembly owner establish their own declaration.

Should we say ATEX or CEC zones in Canada? Canadian hazardous locations fall under the Canadian Electrical Code. "ATEX" remains understood as shorthand when the equipment or the owner's standard is European. The specification must explicitly name the reference governing acceptance.

Is stainless always the right choice in a classified area? It is the default for process parts, but not a universal rule. The ignition mechanism of concern — friction, temperature, static charge — and the service constraints drive the selection.

Can a part destined for a classified area be welded? Yes, with procedures and welders qualified per ASME Section IX and appropriate NDT. The sensitive point lies elsewhere: welding on site, inside a classified area, falls under hot work permitting and assumes the area has been made safe — or that a repair method without hot work is used instead.

What lead time should we plan? It depends far more on certified material availability and documentation depth than on the machining itself. A simple stainless part from stock takes weeks; a part requiring a specific heat and a full ignition hazard assessment takes longer.

Having custom parts made for classified areas

Induscoat designs and fabricates custom industrial parts — stainless, machined, welded assemblies or other configurations — with the material certificates, welding qualifications and dimensional records your assembly owner will demand. We systematically ask for the zone classification and the governing reference before quoting: that is what prevents a part rejected at acceptance. Describe your requirement through our custom parts fabrication page or our quote request: reply within 24 business hours. Technical data sheets for the Induscoat range are published on the brand site, induscoat.com.