Feldbinder Tank Cleanliness Certificate – When Required

Summary

A Feldbinder tank cleanliness certificate is a set of documents confirming that the interior of a semi-trailer meets the requirements of the food, pharmaceutical, or chemical industry. Requirements include: Ra ≤ 0.8 µm (profilometer), passivation protocol, ATP test, and FDA / (EC) 1935/2004 seal certificates. PHS Magnum in Chorula carries out the full procedure and issues a complete documentation set – the protocol is essential for registration with food-grade hauliers and for TDT inspection.

What Is a Tank Cleanliness Certificate?

The term “cleanliness certificate” does not refer to a single, standardised document – it is a colloquial name for a set of protocols and certificates which, taken together, confirm that a tank semi-trailer is safe for contact with a specific product category. The scope of this documentation varies depending on the industry and the requirements of a particular client or haulier.

In the context of stainless steel Feldbinder EUT semi-trailers, there are three main scenarios in which such documentation is required:

1. Food industry – bulk transport of flour, sugar, starch, food-grade granulate
2. Pharmaceutical industry – transport of active pharmaceutical ingredients, excipients, GMP products
3. Chemical industry – transport of raw materials for packaging (PE/PP granulate in food contact) or specialist chemicals

Ra 0.8 µm Parameter – What It Means and How It Is Measured

Surface Roughness Ra

Ra (Average Roughness, ISO 4287) is the primary parameter describing the smoothness of a tank’s internal surface. It is measured as the arithmetic mean of profile deviations from the mean line over a defined sampling length (typically 0.8 mm or 2.5 mm).

Why Ra ≤ 0.8 µm?

On surfaces with Ra > 0.8 µm, micro-scratches and recesses form in which:

• Product particles and microorganisms accumulate
• Detergent cannot penetrate during CIP (Clean in Place) washing
• Bacterial biofilms develop (particularly hazardous in food product transport)

A Ra value of ≤ 0.8 µm provides sufficient smoothness to ensure washing and product run-off are complete and reproducible.

How Ra Is Measured at PHS Magnum

Measurement is carried out using a contact profilometer (with a diamond stylus) or an optical profilometer, calibrated with a current calibration certificate. Typical measurement points include:

• Tank floor (2–3 evenly distributed points)
• Lateral wall near the base (2 points, left and right)
• Weld zone (one point either side of the weld)
• Inlet and outlet of the discharge valve

Each measurement is recorded: point location, Ra result, date, and operator’s signature. The Ra protocol forms an integral part of the service documentation.

Cleaning and Passivation Protocol

Before a cleanliness certificate can be issued, the tank must undergo a strictly defined procedure:

Stage 1 – Alkaline Cleaning

Purpose: removal of product residues, grease, and dust.

• Alkaline detergent (pH 10–12) at the appropriate concentration
• Solution temperature: 40–60°C (more effective grease removal)
• Contact time 15–30 minutes; mechanical brushing if required
• Rinse with deionised water (VE) – pH and conductivity of rinse water recorded in the protocol

Stage 2 – Visual Inspection

Interior inspection using work lighting or an industrial endoscope. Checks include:

• Absence of visible contamination and product residues
• Absence of corrosion (rust spots, pitting)
• Condition of welds (no cracks, crevice corrosion, or excessive stress)

Stage 3 – Chemical Passivation (Where Required)

Passivation is mandatory after any weld repair and is recommended prophylactically every 3–5 years.

• Method 1: 30% nitric acid (HNO₃) at 20–50°C for 20–30 minutes. Used on flat surfaces and the tank floor.
• Method 2: Avesta 401 gel (passivation agent) applied with a brush to weld zones and hard-to-reach areas, contact time 30–60 minutes.

After passivation: rinse with deionised water to neutral pH (6–8); verify pH and conductivity of the rinse water.

Stage 4 – Ra Measurement

Surface roughness measurement with a profilometer after cleaning and passivation are complete. Ra results recorded in the protocol.

Stage 5 – ATP Test (If Commissioned)

ATP Testing – Rapid Microbiological Cleanliness Verification

The ATP (adenosine triphosphate) test allows the microbiological cleanliness level of tank surfaces to be assessed within 30 seconds. It is used as an additional verification of cleaning effectiveness before the semi-trailer returns to loading food products.

How the ATP test works:

1. A swab collects a sample from the selected area of the tank (typically the floor and area around the discharge valve)
2. The swab is placed in a luminometer – the reagent reacts with ATP molecules, emitting light
3. The luminometer measures emission intensity in RLU (Relative Light Units)
4. Result < 100 RLU (typical food-grade threshold) = microbiological cleanliness acceptable
5. Result > 100 RLU = repeat cleaning and retest

ATP test results are recorded in the cleanliness protocol along with the date, sample point locations, and operator’s signature.

Note: The ATP test detects the presence of biological matter (not only pathogens) – a high result may indicate food product residues rather than bacteria alone. The ATP test therefore serves as a cleaning verification, not a substitute for microbiological culture testing.

When Is a Cleanliness Certificate Required?

Registration with a Food-Grade Haulier

Food hauliers and producers (Südzucker, Nestlé, Tchibo, Cargill, and others) require a complete documentation set when registering a semi-trailer for food product transport. Without the Ra and passivation protocols, the trailer will not be approved for loading.

TDT Inspection of Pressure Tanks

TDT (Transport Technical Supervision) checks the internal condition of pressure tanks during periodic inspection (every 2 years). For food-grade tanks, the passivation protocol and Ra results are required as evidence of appropriate maintenance.

After Any Weld Repair

Any welding on a stainless steel tank destroys the passive Cr₂O₃ layer in the weld area. Without passivation and Ra verification following the repair, the tank loses its food-grade status. The protocol must be issued before the semi-trailer returns to food-grade service.

Following a Contamination Incident

If an unauthorised cargo was carried in the tank, chemical contamination occurred, or microbial growth was detected, a specialist cleaning protocol, passivation, and ATP test are required before the tank may resume food product transport.

Typical Documents for Food Industry Clients

The complete documentation package issued by PHS Magnum after servicing a Feldbinder food-grade semi-trailer:

Every document is issued on PHS Magnum letterhead, dated, and signed by the responsible technician.

PHS Magnum – Full Procedure and Documentation Under One Roof

PHS Magnum in Chorula near Opole (4 km from the A4 motorway, 180 km from the German border) provides comprehensive service for Feldbinder food-grade semi-trailers:

• Weld repairs on 304L/316L tanks – certified welders to ISO 9606-1
• Chemical passivation (HNO₃ 30%, Avesta 401 gel)
• Ra roughness measurement (calibrated profilometer, protocol issued)
• ATP test (luminometer) – rapid microbiological verification
• Replacement of food-grade fittings and seals (EPDM FDA, PTFE)
• Complete documentation: protocols, certificates, WPS

Contact: +48 602 716 551 · biuro@magnumchorula.pl

Related: Feldbinder Service · Stainless Steel Passivation · TDT Inspections · Feldbinder Spare Parts