Dehalogenation (removal) of PCBs in oil

Friday March 17th, 2017

For transformers (and other equipment) with insulating oils contaminated by PCBs, Sea Marconi has developed the CDP Process® (patent EEC No.0675 748 – USA No.5,663,479), an integrated solution that uses:

  • treatment systems created by Sea Marconi called DMU (Decontamination Modular Unit),
  • patented reactants (S/CDP®) without which the treatment would not be as effective
  • an unparalleled operational method because it is carried out on-site and in a closed circuit, meaning that the transformer is not emptied, not even partially
  • highly qualified operation staff

The CDP Process is able to reclassify “NO PCB” oil and transformers at the same time as restoring the optimal conditions in accordance with IEC 60422 Ed.4-2013 Art. 12.4.4; CENELEC PR 50503 – 2010 Art.; CIGRE 413 – 2010 Art. 10.1.4.

Sea Marconi is an industry pioneer since the first version of the CDP Process® , was developed in 1982, aimed at decontaminating transformers and dehalogenating/detoxification of PCB/POPs in the transformers’ insulating oils.

The CDP Process® is more effective and cheaper than changing the oil.. The latter in fact involves numerous problems: handling oil, PCB waste disposal and putting the transformer out of service whilst changing the oil, contamination of the new oil (despite the oil change, 10/15% of the old contaminated oil remains impregnated in papers and quickly mixes with the new oil gradually contaminating it).

The CDP Process® has a number of unique features, and ensures that PCB concentrations comply with the limits set by local laws or internal specifications: PCB < 50; < 25; < 10; <2; (<0,5 Japan) mg/Kg(on site, continuously and in a closed circuit, without emptying the transformer even partially with the possibility of treatment when filled (On-Load).
The CDP Process® operates in safety, at low temperatures (80-100 °C) and does not present risks of explosion and/or fire.

The CDP Process® is classified as the Best Available TechniqueBAT for PCB decontamination of transformers in service and those at the end of their life cycle (Italian Ministry of the Environment, Min. Decree 29/01/2007 – OJ No. 133 of 07/06/2007 Art. D. and Art. E.3).

Thanks to references from customers around the world, Sea Marconi has won several contracts from international organisations in developing countries.


  1. The CDP Process® enhances the functional operational resources without disposing the PCBs;
  2. It is the best solution in terms of equivalent CO2 (5 Kg of CO2 spared per Kg of oil contenting PCBs not being incinerated),
  3. The CDP Process® meets the requirements of the European directives on proximity, self-sufficiency and functional recovery.

Operating modes

Sea Marconi’s extraordinary results are based upon its experience in the industry since 1968, the use of Decontamination Modular Units (DMU), designed and manufactured internally, and the formulation of specific reactants (S/CDP®) used depending on the operating scenario.

The DMUs are connected to the transformer via flexible hoses, after which the decontamination process is started: the insulating fluid circulates through the DMUs where it is heated, degassed, dehumidified, filtered, decontaminated/dehalogenated (thanks to special patented reagents) then returned to the transformer.

The continuous circulation of the liquid creates a constant flow of fluid in the transformer that favors the elimination of deposits (sludge) on papers and in the case.
The task is done safety thanks to a control system software able to check moment by moment that the process is taking place in safety and with quality assurance; 24 hours a day even without the presence of an operator.

The treatment is performed with the On-Load option, keeping the transformer in service, under tension and filled, i.e. without any loss of production (with international experience also in nuclear power stations and transformers up to 760 MVA and 500 KV).

Sea Marconi’s closed loop treatments offer the advantage of avoiding critical operational problems related to fluid replacement, which involves putting the machine out of service and functional risks (e.g. electrical discharges) due to air bubbles and humidity.

Click here to see the detail of the activities:

  • Transport before/after of specialized technicians, treatment units (DMU), equipment, reactants and disposable objects from the Sea Marconi office to the sites of the transformers;
  • The hydraulic and electrical installation and set up of the decontamination modular units (DMU);
  • Sampling, analysis and diagnosis (Deosvision®) before treatment (if any);
  • Treatment of PCB dehalogenation (CDP Process®);
  • Treatment quality control with on site measurement kit SM-TCPs;
  • Physical treatment (degassing and dehydration in a vacuum) of the oil;
  • Monitoring the treatment parameters;
  • Changing of the oil of the OLTC (if necessary);
  • Level and vent controls;
  • Replacement of desiccant salts in silica gel;
  • Sampling, analysis and diagnosis (Deosvision®) at the end of the process;

Do you need more information? Do you need a quotation?


The CDP Process® is the unique and safe technology used for decontamination of transformers, dehalogenation and detoxification of PCBs in insulating oils with full functional recovery and “NO PCBs” reclassification of the machine and the oil.
With the following features:

The Best Available Technique (BAT)

for PCB treatment whilst in service and at the end of the life cycle as per Ministerial Decree 29 January 2007 published in the O.G No. 133

A unique and effective method

On site, in a closed circuit, without emptying the transformer, circulating hot oil (also on-load) able to meet the legal limits imposed by the various, and most strict, international authorities (eg.:Japan has a PCB limit of 0.5 mg/Kg)

Operational safety

  • using a solid patented reactant,
  • low process temperature (80-100 ° C),
  • the lack of emptying the transformer,
  • the use of a modular decontamination unit (DMU) created by Sea Marconi and equipped with an advanced monitoring system, providing 24 hour a day automatic safety

Environmental safety

as the CDP Process® avoids the replacement and the incineration of huge amounts of oil, that can still be used, as well as avoiding the risks associated with handling contaminated oil.Moreover it does not produce waste

Reference and regulatory compliance

IEC 60422 Ed.4 2012 and CENELEC CLC/TR 50503 (02/2010).

Highly efficient with other

chlorinated organic compounds (PCT, PCBT, PCDD, PCDF)

Logistic easy

The treatment units’ small dimensions mean they are operational even under extreme logistical constraints (e.g . in bunkers, and mines). The same process can be done with stationary plants in order to decontaminate in a place where large quantities of oil can be collected coming from small transformers

Strong case studies

with 80 pieces of equipment decontaminated from PCBs and approx. 684 tons of total oil decontaminated with PCB only in 2017

Following the decision matrix (E.3) according to the Guidelines of the Ministry of Environment for the definition of BAT (“Best Available Tecnique”) between the different PCB decontamination technology – D.M.29/01/2007

Techniques Functional safety Environmental Safety Employee safety Eco-balance and emissions Overall cost/benefit ratio
Refilling *** ** *** * **
Sodium, lithium and derivatives * * * ** *
KPEG ** *** *** ** **
CDP Process® by Sea Marconi *** *** *** **** ****

**** = EXCELLENT | *** = GOOD | ** = MEDIUM | * = CRITICAL


PCB* < 50; < 25; < 10; <2; (<0,5 Japan)  mg/Kg
*Measured by the IEC 61619 method

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