The process of refurbishment

Disassembly

  • Radiators are normally drained on site, removed from their transformer and sent to the Powerstrip plant in Auckland for processing.

  • We have a network of experienced carriers available for cartage New Zealand -wide.

  • Radiators are always inspected on receipt so that suitable arrangements can be made for any additional damage or faults identified.

Radiators being disassembled from a substation tranformer.

Pressure Testing

  • Pressure testing takes place immediately after the radiators have been inspected upon arrival at the Powerstrip plant.

  • Debate about the correct pressure to be used for testing means that we adjust it for each individual unit, depending on its condition.

  • The testing is performed with calibrated pressure equipment and dry air.

  • Any signs of weakness are noted by our staff and minor problems can be repaired by welds or the application of a stainless steel epoxy. More serious problems will be reported to the owner/contractor for further instruction.

  • Powerstrip Industries has used this method for a number of years, with a 100% success rate.

 

Stripping

  • Radiators are immersed in a stripping bath containing a purpose formulated and heated chemical mixture.

  • This effectively removes all paint, oil and dirt build up from the external surfaces without affecting galvanized substrates.

  • The stripping solution also contains a corrosion inhibitor.

  • Once removed from the bath, radiators are hot pressure blasted by water, removing any remaining traces of the old coating and stripping solution

 

Flushing
  • Flushing is crucial in any refurbishment as it cleans out the radiator internals.

  • The stripping process, including high temperatures and vibrations, often loosens carbon and sludge inside the radiators, which is removed during this stage.

  • A gear pump driven 48-element filter press and heat exchange unit removes particulate matter down to a sub-micron size.

  • In our experience, hot flushing at 65°C removes virtually all built-up sludge and carbon.

Powerstrip's radiator flushing unit


Corrosion Removal

  • Whether galvanized or not, when stripped of paint, most radiators will show signs of rust.

  • This must be treated by chemical conversion or removed entirely, before it can be repainted over.

  • An inhibited acid treatment is used to remove all traces of rust without affecting the metal substrate.

  • Non-galvanized radiators are then immersed in a phosphate solution, depositing a phosphate layer on the surface.

  • This seals the base metal, and provides a bond to the metal substrate for subsequent primers and paint coatings.
 Corroded radiators received for refurbishment  Powerstrip's phosphating tank

 

Recoating

  • Power Strip’s standard painting system involves 3 steps.

  • This process can of course be adjusted to suit the customer and their own approved specifications.

   Step 1: Primer

  • The priming coat is applied in an immersion bath.

  • A zinc phosphate dipping primer is used.

  • This is suitable for both mild steel and galvanized surfaces.

  • A full dip emersion ensures that every part of the radiator is evenly covered with paint.

Powerstrip's dip priming tank

   Step 2: Intermediate Coat

  • A two-pack epoxy, applied to 75 um DFT, serves as an intermediate coat.

  • This coating is sprayed on in our spray booth facility.

  • It forms a hard, abrasion resistant barrier to mechanical damage and corrosion.

Intermediate coat application in Powerstrip's spray booth

   Step 3: Top coat

  • The top coat is a re-coatable high gloss urethane.

  • This provides an UV and abrasion-resistant finish with excellent colour retention.

  • The coat is applied and allowed to dry thoroughly for a period of up to three days.

  • Over this period of time, the paint work is left to harden effectively.

  • This assists with minimisation of damage to the coatings during transport.

 

  • The application of these coatings is done in strict accordance with the paint manufacturer’s technical specifications and in controlled circumstances:
    • The ambient temperature must be more than 2.5ºC above the dew point
    • The surface temperature of the steel must be above 5ºC
    • The relative humidity is not in excess of 85%
    • There is no moisture or ice visible on the surface steel

  • By adhering to these guidelines, the recoating process offers the highest level of protection available against corrosion, ensuring the longevity of the transformer radiators.

  • Recoating is critical, whether the steel is galvanized or not…

 

Top coat application in Powerstrip's spray booth

Galvanizing and re-galvanizing radiators >