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Silo cleaning

Paraformaldehyde operation: silo inspection under inert gas

Our case studies present real operations carried out by NT Service GmbH – including specific requirements, challenging hazard situations and professional execution. Each case study demonstrates how we reliably and compliantly manage safety critical specialist operations.

The initial situation

A blocked paraformaldehyde silo, 25 metres high, filled with agglomerated hazardous material.

The client

Hüttenes-Albertus Chemische Werke GmbH in Hanover

The assignment

Blockage removal and complete inspection – under oxygen exclusion. An operation that can only be carried out by specialists with experience, safety discipline and the right equipment.

The hazard situation

Paraformaldehyde is highly reactive, harmful to health and potentially explosive. Even the smallest amounts of the resulting formaldehyde can cause severe irritation, while finely dispersed dusts combined with atmospheric oxygen are extremely flammable. For this reason, the entire silo was fully inerted with nitrogen before entry – with a target value of below 1 vol.% oxygen.

The procedure

Access was provided via a temporarily installed internal climbing system with redundant fall protection. The specialists deployed worked in positive pressure chemical protective suits, class 3. A permanent gas detection system monitored all relevant parameters, including O₂, formaldehyde, CO, LEL and temperature. In addition, safety attendants and a three stage rescue concept were in place.

Mechanical removal and complete inspection: the blockage in the cone area was manually loosened and the agglomerated material removed. Specially developed stainless steel tools were used. The material was extracted using ATEX protected vacuum suction technology. This was followed by a complete visual inspection of the silo, including walls, internal components and discharge area. All findings were documented.

The result

Der Einsatz verlief störungsfrei, innerhalb der vorgegebenen Zeit und ohne Zwischenfälle. Die Anlage konnte nach Abschluss der Arbeiten planmäßig wieder in Betrieb genommen werden.