Electric heat exchangers in atex-ex execution

For over 40 years Reart has been producing electric heat exchangers for heating liquids and gases of all kinds. Electric exchangers are the optimal solution for heating process fluids in forced convection with the heating elements in direct contact with the fluid to be heated.

Thanks to its experience and product certification in accordance with the Atex Directive obtained at the Cesi in Milan, Reart is able to produce heat exchangers for applications in the Ex classified area.

Thanks to the experience of the technical department, the electric exchangers in Ex execution can be designed for the following types of fluids:

  • diathermic oil and fuel
  • hydrocarbons
  • industrial, fresh and demineralized water
  • sea water
  • Natural gas, technical and process gases
  • air or nitrogen

The electrical power installed on the electric exchangers can reach up to 1750 kW for each individual exchanger, according to specific customer requests.

The electric exchanger consists of an electric heating bundle with several resistive elements connected to each other and welded on a flange for coupling to the tank and inserted inside a tube (exchanger shell) sized and designed according to the project data (temperature and pressure ) in compliance with regulations according to the country of destination: VSR, PED, ASME, U-STAMP, TEMA, ADMERKBLATTER, STOOMWEZEN.

The tank and the heater are sized (materials and dimensions) by the technical office based on the operating conditions indicated in the customer’s reference specifications and on the design conditions by means of thermodynamic and mechanical calculation software.

For this type of exchanger in Ex execution, the electrical dimensions certified for Ex approval of the electrical enclosures of the exchanger are considered:

  • electrical enclosure dimension (model DN – thickness and dimensions)
  • current on single element max 0.9 A.
  • type of electrical connection (star – delta)
  • maximum installed power
  • power subdivision (connection step)
  • power supply voltage and maximum installable current.

Different materials are applied to the part under pressure (tank and coupling flanges) and to the heater depending on the operating conditions:

  • carbon and/or low alloy steel for low temperature conditions and non-corrosive fluids
  • stainless steel for aggressive fluids and high temperatures (Aisi 304 – 316L).

For the heating elements (electric heating beam) the following can be used:

  • austenitic materials such as AISI 321 for corrosive fluids and high temperatures.
  • austenitic materials such as AISI 316L for corrosive fluids and low temperatures
  • noble alloys such as incoloy 800 for high temperature systems.

The electrical enclosure of the heater connections designed in Ex-d execution, based on the maximum operating temperature of the system, can be in direct contact with the heater flange or in the “cold head” transmission execution. The protection rating can be IP55, IP65 or IP66 with relative sealing gasket. The manufacture materials can be in carbon steel painted with aluminium zinc paint or in Aisi 304 stainless steel.

The electric heat exchangers in Ex execution are sized by the technical office with the aid of a software for thermodynamic sizing thanks to which it is possible to obtain the real operating conditions, based on the needs and specifications of the customer, to create flows at controlled temperature.

Thanks to the use of this software for the sizing of the electric exchangers, it is possible to define the main parameters including:

  • electrical power needed
  • process side pressure drops
  • surface load or specific power
  • maximum surface temperature of the heating element
  • fluid flow rate inside the tank
  • dimensions of the electric exchanger
  • building materials
  • conditions of the exchanger during normal foreseen operating conditions.

Together with the exchanger, Reco supplies the relative insulation supports in the most suitable material for the installation site, the exchanger lifting eyebolts, the tank support saddles for mechanical fixing of the exchanger and any couplings to the tank (vent and drain).  

Electric exchangers in Atex – Ex execution can be equipped with the following accessories:

1-4-20mA temperature transmitters in SIL execution according to IEC 61508

2-Process control and safety sensors and heater (thermostats, PT100 temperature probes, thermocouples).

3-Power and safety cable glands in Exd execution

4-Electric control panel and heater control in a safe and classified Ex area

5-Local command and control panel in classified area (Atex).

6- Anti-condensation heater (prevention against humidity)

The control and safety instrumentation installed (thermal sensors) on the electric exchanger, mandatory for Atex certification, complies with the regulatory requirements for product certification.

The experience Reart, in many years of presence on the market in various sectors, allows to give its customers the most suitable technical solutions for the type of application required.

Reart manufactures process skids and supplies the turnkey package by supplying, in addition to the electric exchanger, the relative electrical command and control panel of the exchanger for safe area and Ex classified area (see section relating to “Control Panel Heaters”).                         

Reart is able to provide the following services to support the products supplied:

  • assistance in commissioning & start-up at the client’s premises
  • commissioning at the customer
  • maintenance assistance for existing plants supplied.
  • spare parts on supplied products.

The following documentation is provided for the electric exchangers in the final certification file accompanying the product:

  • “CE” declaration of conformity
  • use and maintenance manual
  • safety instructions
  • heat exchanger assembly drawings
  • wiring diagram for connection
  • technical data sheets of the components used and relative declarations of conformity of the suppliers
  • internal test Report.
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.

Tabella riassuntiva delle condizioni certificative

Riscaldatore per impianti di superficie con presenza di gas e vapori, di categoria 2, idone per zona 1 e (con ridondanza) per zona 2 (2G)
Ex d
Riscaldatore a prova di esplosione con scatola morsetti a prova di esplosione.
Custodia del gruppo II B idonea per sostanze (gas) del gruppo II A o II B
Classe di temperatura della custodia (massima temperatura superficiale) idonea alla corrispondente classe di temperatura della sostanza infiammabile (gas)

Marcatura di conformità alla direttiva ATEX 2014/34/UE ed alle relative norme tecniche.
Marcatura di conformità alle direttive europee applicabili
AB xx ATEX yyyx
AB : nome del laboratorio che ha rilasciato il certificato CE
xx : anno di emissione del certificato
yyy : numero del certificato di tipo
x : condizioni particolari d’impiego
  1. The enclosures of group II B are also suitable for environments II A
  2. The explosion-proof enclosures are designed for service with ambient temperature and temperature class T1-T4.

Tabella classi di Temperatura secondo norme e Direttive di riferimento Atex

Classi di temperatura Temperatura °C
< 450
< 300
< 200
< 135
< 100
< 85

Tabella classi di Temperatura Riscaldatore su Flangia in esecuzione Atex – EX in funzione della temperatura esercizio impianto

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

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 heat exchangers in Atex-Ex execution are applied for the following reference sectors: