Does a Feldbinder stainless steel trailer require passivation before a TDT inspection?

Passivation is mandatory after any weld repair to the tank. Before a standard TDT inspection where no repairs have been carried out, passivation is not compulsory, but it is recommended every 3–5 years as a preventive measure. The inspector may, however, request passivation if signs of corrosion or surface contamination are found.

What is a cleanliness certificate and when is it required?

A cleanliness certificate is a document confirming that the tank is free from contamination and meets the requirements for the specific product being carried. For food-grade trailers it is required by freight forwarders and food manufacturers. PHS Magnum issues a cleanliness certificate after every repair or service of a food-grade trailer.

Does the TDT inspector measure surface roughness (Ra) inside a food-grade tank?

Ra measurement is not normally a mandatory element of a standard TDT inspection. However, freight forwarders such as Nestlé, Tchibo, and Südzucker may require an Ra certificate from the trailer owner. PHS Magnum carries out Ra measurement and issues the corresponding certificate as part of its TDT preparation service.

18.07.2025

Feldbinder TDT Inspection – Requirements and Procedure

Name: PHS Magnum
Address: ul. Kościelna 9, Chorula, Opolskie, 47-316, PL
Telephone: +48 602 716 551
Price range: $$

DAF Magnum silo trailer fleet at PHS Magnum depot

In Brief

Feldbinder trailer TDT inspection – pressure vessel, mandatory every 2 years. Preparation involves: tank cleaning, PT weld assessment, UT wall-thickness measurement (where corrosion is suspected), Ra measurement (food-grade trailers), nitric acid passivation (after weld repairs), and full documentation compilation. Food-grade trailers additionally require a cleanliness certificate and EC 1935/2004-compliant seal/gasket certificates. PHS Magnum carries out a pre-inspection service visit and coordinates the TDT inspector. Book at least 4–6 weeks before the current TDT certificate expires.

TDT Inspection for Feldbinder Tank Trailers

Why TDT Compliance Matters for Feldbinder Trailers

Feldbinder trailers used for food products (sugar, flour, starch, powdered milk) operate under the most demanding hygiene conditions. A damaged or contaminated tank interior can compromise an entire product batch — losses that can run into hundreds of thousands of euros.

For that reason, owners of food-grade trailers should regard the TDT inspection not as a bureaucratic formality but as a mandatory check-up that safeguards their commercial viability. A comprehensive overview of TDT technical supervision for silo trailers is provided by Aleksy Pasternak.

Preparing a Feldbinder Trailer for TDT Inspection

Step 1: Tank Cleaning

The tank must be clean and dry before the inspector arrives. For food-grade trailers:

Dry cleaning (brushing, industrial vacuum)
Water rinse at 60–80 °C with detergent (if required by the freight forwarder)
Air-drying
No residues of product (sugar, flour), mould, or corrosion

Step 2: Tank Condition Assessment

PHS Magnum carries out:

Internal inspection through the manhole
PT (dye penetrant) weld testing where cracking is suspected
UT (ultrasonic) wall-thickness measurement where corrosion is suspected
Ra surface roughness measurement on the internal surface (food-grade trailers)

Step 3: Testing and Repairs

Where defects are identified — weld repair, grinding, nitric acid passivation or Avesta passivant treatment.

Step 4: Documentation

Compilation of:

Tank passport (Technical Operating Documentation)
Service records from the previous 2 years
Passivation certificate (if applicable)
Cleanliness certificate (food-grade trailers)

Step 5: TDT Inspection

The inspector conducts a pressure test at 1.25 × MOP and issues the inspection certificate. With a trailer in good condition and complete documentation, this typically takes 2–3 hours.

Call +48 602 716 551 to arrange a pre-inspection service visit — we recommend booking at least 4–6 weeks before your TDT certificate expires.

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