Flanged electric heaters in Atex-Ex EXECUTION

Reart produces flanged electric heaters in Exd execution for the heating of liquids and gases of all kinds, for the civil, and industrial applications in potentially explosive classified environments (Zone 1 & 2). Reart’s experience in the Atex (Explosive Atmosphere) sector on electric heaters and the product certification obtained at the Cesi in Milan, guarantees a design of Atex-Ex flange heaters designed to fix the electric heater to the process to be heated by means of a flange special connection that is defined according to the UNI or ANSI 16.5 standards. The process connection flanges can also be designed and built according to the customer’s specifications or requests.

This type of heater is used for heating fluids in:

  • storage tanks under pressure, in direct contact with the fluid to be heated
  • piping in line with the process fluid to increase its operating temperatures

Electric flange immersion heaters are suitable for heating all non-corrosive process fluids. They consist of one or more U-bent heating elements welded to the main connection flange by TIG welding, complete with electrical connections, safety devices and relative protection casing.

All the heating elements welded on the main flange of the heater are tested through hydraulic tests at well-defined pressures according to the design conditions indicated by the customer.

Thanks to the hydraulic test performed by Reart on the welded heater, it is possible to guarantee the tightness of the welding of the heating elements to the flange, declaring this test in the final test certificate issued together with the product issued by Reart.

Flanged electric heaters in Atex-Ex EXECUTION

Technical features

The flange Electric heating elements in Exd execution are essentially composed of:

  • Process heater connection flange.
  • Electric heating beam with dimensions and materials according to the process fluid
  • splitters for cooling and heat exchange between the electric bundle and the fluid
  • Explosion Proof execution electric protection group and head
  • Thermal sensors for regulation and safety of the system and heater.

The connection flange of the electric heater is defined and sized according to the customer already in the offer phase, so that the heater can be sized on the process data.

The design for this type of heater is carried out according to the functional data requested by the customer, and also considering and evaluating dimensional, physical, chemical and thermodynamic characteristics of the fluid to be heated, so as to guarantee a very precise and accurate choice of the sizing of the heater and building materials. The size of the flange depends on the electrical conditions imposed by the regulations for Atex execution.

The electrical power installed on Atex flanged electric heaters can vary up to thousands of kW with the aid of settings according to customer specifications, Reart engineering and reference standards for the sizing of heaters in Exd execution.

Usually, we can have the following reference design parameters for the sizing of the flange electric heaters:

  • Flanges up to 24”(DN600) in accordance with ANSI B 16.5 specifications in carbon steels, stainless steels and nickel alloys.
  • Diameter of the heating elements that form in the tube bundle 10 and 15 mm;
  • Material of the heating elements in carbon steel, stainless steel 304-321 316 (L), or much more noble alloys such as Incoloy 800 or 825, Titanium or Copper.
  • Protection rating of the electrical enclosures of the heaters IP55, IP65, IP66;
  • Installed electrical power up to 1.65MW per single heater.
  • Maximum immersion length of the electric beam about 3 meters.

All flanged electric heaters in Atex execution are equipped with thermal sensors such as thermostats and/or thermocouples or temperature probes (PT100) to protect the system and the heater itself in case of anomalous or unexpected situations on the system.

Atex flanged heaters can be equipped with the following accessories:

  • 4-20mA temperature transmitters in SIL execution according to IEC 61508
  • Process control and safety sensors and heater (thermostats, PT100 temperature probes, thermocouples).
  • Power and safety cable glands in Exd execution
  • Electric control panel and heater control in a safe and classified area
  • Local command and control panel in classified area (Atex).

Anti-condensation heater (prevention against humidity)

Certification and product description

Reart has the product certifications for the Atex execution for both liquid and gaseous fluids with the following classification in reference to the Atex directive 2014/34/EU:

II2G Exd IIB T1 ÷ T4 IP 65          

valid for classification area of use called zone 1 & for zone 2, with coverage for groups IIA and IIB according to the reference standards EN 60079-0 and EN 60079-1.

Summary table of certification conditions

Heater for surface installations with the presence of gas and vapours, category 2, suitable for zone 1 and (with redundancy) for zone 2 (2G)
Ex d
Explosion-proof heater with explosion-proof terminal box.
Group II B enclosure suitable for Group II A or II B substances (gases)
Housing temperature class (maximum surface temperature) suitable for the corresponding temperature class of the flammable substance (gas)

Flanged electric heaters in Atex-Ex EXECUTION

Marking of conformity with ATEX Directive 2014/34/EU and related technical standards.
Marking of conformity with applicable European directives
AB xx ATEX yyyx
AB : name of the laboratory that issued the EC certificate
xx : year of issue of the certificate
yyy : type certificate number
x : condizioni particolari d’impiego
  1. Group II B enclosures are also suitable for II A environments

  2. The explosion-proof enclosures are designed for service with ambient temperature and temperature class T1-T4.

Table of Temperature Classes according to Atex Standards and Reference Directives

Temperature classes Temperature °C
< 450
< 300
< 200
< 135
< 100
< 85

Table of Heater Temperature Classes on Flange in Atex – EX execution according to the system operating temperature

Flanged electric heaters in Atex-Ex EXECUTION
Flanged electric heaters in Atex-Ex EXECUTION
Flanged electric heaters in Atex-Ex EXECUTION

Together with the product certification, Reart has obtained the notification relating to the production of products in Ex execution, in its plant in Frossasco (TO).

Flanged electric heaters in Atex-Ex EXECUTION

All products supplied by Reart in Atex-ex execution are accompanied by the “Declaration of Conformity” with reference to the Atex Directive and applicable regulations.


electric flange heaters are typically used for heating systems for:

  • Fresh and treated water
  • Storage tank heating and frost protection
  • Synthetic oils, lubricants, minerals and fuels
  • Accumulation and steam boilers
  • Process gas and gaseous fluids in general (Nitrogen, Methane, Natural gas, etc.) – Refineries
  • Forced air heating (UREA -UTE treatment plants)

Liquid and gaseous hydrocarbons

The Flanged electric heaters in Atex-Ex execution are applied for the following reference sectors: