In brief
Pressure vessel inspection for a silo trailer is mandatory every 3 or 6 years and is a prerequisite for legal operation of the vehicle for bulk material transport under pressure. It covers weld condition, wall thickness, armature, and a pressure test conducted by a TDT inspector. PHS Magnum in Chorula organises the inspection with a TDT inspector on-site at the workshop — no need to transport the vehicle to a TDT inspection point.
A silo trailer pressure vessel is an element that seemingly needs no attention — sealed, no visible damage, working for years. Until a TDT inspector finds pitting corrosion under the paint layer, a weld crack in a hard-to-reach spot, or measures wall thickness that has silently dropped below the permissible minimum.
What does the pressure vessel inspection cover?
External inspection (every 3 years)
- External vessel condition — corrosion, deformations, mechanical damage
- Weld inspection over the entire surface
- Armature check: safety valves, pressure gauges, ball valves, nozzles
- Pressure test (fill to test pressure and observe)
- Documentation and calibration certificate check
Internal inspection (every 6 years)
- Same as external inspection plus:
- Opening access hatches and entry into the vessel
- Internal surface condition (corrosion, coating damage)
- Welds from the inside
- Filter and material sieve check
Pre-inspection preparation — what we do beforehand
Tank cleaning: Emptying, pneumatic interior cleaning, residue removal. For internal inspection: hatch opening, thorough interior cleaning.
Wall thickness measurements: Ultrasonic measurements at critical points. Documented and provided to the inspector. Unacceptable corrosion → repair before inspector arrives.
Armature check and replacement: Safety valves (seals, calibration dates), pressure gauges (calibration), ball valves (leaks, seals), nozzles and connections. Expired calibration → replace or re-calibrate before inspection.
Weld repairs: If pre-inspection reveals weld cracks — we weld before the TDT inspection. Post-inspection repair requires a second inspector visit at extra cost.
When does a tank need overhauling?
The tank requires immediate repair or grounding when:
- Pitting corrosion >20% of nominal wall thickness — structural risk
- Weld cracks in stress zones — pressurisation failure risk
- Permanent vessel deformation — geometry loss
- Corrosion losses at nozzles — critical stress points
PHS Magnum has UDT-certified welders and equipment for pressure vessel repairs.
Contact: +48 602 716 551 | Roland Sobota (TDT): +48 504 788 385
Related: TDT inspections · Safety valve legalisation · Spitzer service · Feldbinder service · How to prepare for TDT