Chemical and petrochemical

Chemical and petrochemical plants, solvents and flammable products

Chemical plants handle flammable gases, vapours and dusts, so ATEX equipment must match the gas group and temperature class. Maffioletti supplies it.

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Where the hazardous areas are

In chemical and petrochemical plants, hazardous areas surround reactors, columns and pumps and extend to tank farms, loading bays, solvent stores and drum filling. The inside of vessels holding flammable liquids is often Zone 0; Zones 1 and 2 depend on the grade of release and ventilation. Where combustible powders such as polymers are handled, Zones 20, 21 and 22 apply.

Many hydrocarbons and solvents, such as propane, toluene and acetone, are IIA; ethylene is IIB; hydrogen, acetylene and carbon disulphide are IIC, and carbon disulphide, with its very low ignition temperature, also requires T6.

Typical requirements

Chemical resistance: acid vapours, solvents and cleaning agents attack plastics, seals and metals, so check material compatibility.
Static electricity: tankers, drums and IBCs must be earthed during transfers, as must Type C FIBCs.
Temperature class: base it on the substance with the lowest ignition temperature.
Instruments in Zone 0: Category 1 equipment is needed, for example Ex ia.
Standards: Directives 2014/34/EU and 1999/92/EC; IEC/EN 60079-10-1 and IEC/EN 60079-10-2 for classification, IEC/EN 60079-14 and IEC/EN 60079-17 for installation and inspection.

Products for this sector

Enclosures, junction boxes and control stations: Ex e junction boxes and Ex d flameproof enclosures; for analysers and non-certified equipment, Ex p pressurisation systems.
Static grounding: Newson Gale systems for road tankers, drums, IBCs and FIBCs, including systems that verify the connection.
Gas detection: detectors for flammable and toxic gases and for oxygen deficiency where nitrogen inerting is used.
Intrinsic safety: Pepperl+Fuchs isolated and Zener barriers and remote I/O for instruments in Zones 0 and 1.
Tools: non-sparking beryllium copper and aluminium bronze tools to reduce the risk of mechanical sparks.

How we help

We design and assemble custom Ex enclosures, junction boxes, control stations and panels in-house, reviewing materials with you. Junction boxes and control stations are available with the 72-hour Express service, and the online configurator helps you prepare your request. As an authorised partner of Pepperl+Fuchs, we support you on intrinsic safety.

Through Atex Italia we offer consulting on area classification, training and inspections. Get in touch with the substances and zones involved.

FAQ

Frequently asked questions

How do I choose the temperature class in a chemical plant?

The maximum surface temperature of the equipment, expressed by classes from T1 (450 °C) to T6 (85 °C), must be below the ignition temperature of the substances in the area. Where several substances are present, the one with the lowest ignition temperature sets the requirement.

What ATEX zone is the inside of a solvent tank?

The inside of a tank holding a flammable liquid, where an explosive atmosphere is present continuously or for long periods, is usually Zone 0; the classification may differ if the tank is inerted. Instruments installed inside must be Category 1G (EPL Ga), for example intrinsically safe Ex ia.

Do drums need earthing when transferring solvents?

Yes: transferring flammable liquids can generate static charge, so metal drums, containers and transfer equipment should be bonded together and earthed before work starts. Clamps and systems that verify the connection reduce the risk of a poor contact going unnoticed.