THPP Pre-filtration box for PETRO PLUG® cartridge


The SPI® THPP filtration box is an essential accessory that complements the mechanism of the PETRO-PLUG® cartridges to limit the risk of clogging and ensure they work properly.




The PETRO-PLUG-THPP is a pre-filtration cage that fits all cartridges in the SPI®  PETRO PLUG® range. Invented by SPI® in the 1990s, it completes the filtration system of PETRO-PLUG filters, which fit easily onto all types of retention tanks and pits. It helps to ensure continuous filtration of drainage water, while trapping harmful hydrocarbons. It prevents soil pollution in compliance with EN 858-1 and the Water Act, with a discharge rate of less than 5ppm. It also complies with paragraph 471 of NF C13-200 (“All precautions must be taken to ensure that the recovery tank does not fill with water or that water is evacuated“). Our filters and pre-filters are regularly tested in independent laboratories, when new, in half-life conditions and after their recommended period of use (see Additional Information tab).


Pre-filtration is essential to limit the risk of clogging the P-PLUG cartridges due to dust in the water.


Description of PETRO PLUG® THPP:

  • Aluminium cage design
  • Composed of several foams and geotextiles: a black reinforced filter sheet and a layer of white filter foam to block dust in the water.
  • Length: 45 cm / Width: 15 cm / Height: 15 cm / Weight: 2.4 kg
  • Service life of internal components: approx. 5 years 

(*) Depending on the conditions of use at each site, depending on the quantity of traces of hydrocarbons filtered by the cartridge, the regularity of maintenance of the tank/pit/prefilters, etc. Conditions of use for which SANERGRID® and SPI® cannot make any commitment.


For over 30 years, SPI filters have been recognized for their high reliability, extreme robustness and longevity, even under the most difficult conditions: resistance to hot transformer oils (>100°C), water emulsified with dielectric oil, high resistance to ultra-violet rays and thermal amplitudes, etc. SPI has ISO 9001 quality certification for its production process, and has integrated an eco-design approach aimed at reducing the amount of material and CO2 used during the manufacturing process.

Accessories and options

The PETRO-PLUG THPP pre-filter can be fitted to all filter cartridges in the PETRO-PLUG® range.


Contact us for more information.

Technical data

Additional information

Weight 2,4 kg
Dimensions 45 × 15 × 15 cm

Aluminium, Geotextile

Conditions of use

indoor, outside


Dielectric oils, Hydrocarbons, mineral oils, natural esters, synthetic esters

Use and maintenance

All industrial equipment or storage units containing hydrocarbons must be fitted with retention tanks.


Before installation:

  • Remove the drain cover and clean the inside of the drain hole to remove any dirt and rust that may be present. The surface must be clean to ensure good watertightness.
  • Make sure that the PETRO PLUG is well adapted to the site configuration. If it is too long, an elevating mounting ring (supplied) may be necessary.



  • The THPP pre-filtration cage is screwed to the floor above the filter. The PETRO PLUG THPP pre-filtration cage is always placed in the retention tank at the point where the water enters the filter.
  • The cage is delivered without nuts or screws for fixing to the ground. These accessories depend on the location of installation and the thickness of the concrete.



  • SPI filters are sensitive to sludge and impurities carried by the water, which can considerably reduce the flow rate or even block the filter. Good pre-filtration is therefore essential to protect the filter inlet, and should be checked regularly. The pre-filter should be washed with clean water as often as required by the place of use, the frequency of rinsing depending on the quantity of impurities carried to each drainage point.
  • To keep track of your filters and replacement schedules, SPI products have a batch serial number corresponding to the batch of active ingredient tested and approved by the manufacturer. So you too can track your filters and recommended replacement dates simply by visual inspection.
  • At the end of their life, the filter and pre-filter should be disposed of as conventional hydrocarbon waste under code [150202*].


For your specific needs in terms of traceability and automatic reminders of your maintenance dates, SANERGRID® can set up a unit tracking system for you in return for a maintenance contract with one of our national partners.

Additional information

Part of the SPI® filter technology, the PETRO-PLUG® range is the European benchmark for small-volume rainwater filter cartridges for hydrocarbon retention. It is the only filter on the market that has been validated for over 30 years by the largest French and European industrial companies (EDF, ENEDIS, SNCF, SCHNEIDER, RTE, ABB HITACHI, SIEMENS, IBERDROLA, NATURGY, REE, EDP, ENEL, IREN, TERNA, E-ON, RWE, VATTENFALL, ELIA, ESB, SCOTTISH POWER, NATIONAL GRID, NETWORK RAIL, UK PN, BRITISH PETROLEUM, TOTAL ENERGIE, BASF, BAYER, ELES, CERN, ITER, VOLVO, DEUTSCHE BAHN, ADIF, SNCB, REPSOL, etc. non-exhaustive list).

Rainwater drainage and hydrocarbon pollution: thanks to the SPI anti hydrocarbons filter system, the tank is empty of water most of the time and ready to receive hydrocarbons. In compliance with water legislation, the water discharged from the tanks is not contaminated with more than 5 ppm of hydrocarbons, in accordance with standard EN 858-1 (“light liquid separation installations”).

SPI® filters are regularly tested by independent laboratories: SANERGRID Bureau Veritas report COFRAC I.D. certified: 003606/2776443/1/1/1 in 2015 (France), SPI Phoenix I.D. laboratory reports: AR67044 from 2002, 2004, 2005, 2009, 2018, 2022 (USA), TÜV report Nr 2432974 in 2016 (Germany), NUA report -Z-11895-1/1-2016.


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