Practical examples from industrial stainless steel processing

Despite the use of stainless steel materials that comply with general industry standards and established as well as validated cleaning processes, corrosion and similar surface problems often occur in standard stainless steel systems. The causes rarely lie in a single factor, but rather in a combination of surface condition, manufacturing history, choice of type of alloy and cleaning procedures. The following practical examples from the food and pharmaceutical/biotech industry illustrate how NIROPLAN systematically analyses recurring corrosion phenomena, clearly identifies their causes and derives sustainable corrective measures. The focus is not on short-term effects, but on verifiable results, standards-compliant processes and economically viable solutions during ongoing operations.

Flash rust on production equipment (food industry)

Recurring rust-coloured stains on a stainless steel surface jeopardised cleaning validation and led to increasing maintenance costs. Despite intensive cleaning, the findings remained unchanged. The case study shows how a sustainable solution was achieved through structured root cause analysis, targeted on-site measures and adaptation of the cleaning processes – without replacing parts and with measurable success over 12 months.

Initial situation
Recurring rust-coloured stains on stainless steel production equipment despite intensive cleaning; following cleaning validation was at risk of failing

Investigations
On-site inspection, photo documentation, profilometric roughness measurements, sampling of corrosion products, recording of component history and detailed cleaning processes

Findings
Foreign ferrous-oxide particles (abrasive particles from former assembly work) + following localised damage to the passive layer; surface roughness values above the specified limit. Unacceptable high rate of singular areas because incorrect mechanical grinding steps.

Measures & results
Local mechanical grinding operations and chemical pickling on site followed by chemical passivation, adjustment of the cleaning protocol and instructions, monitoring → 12 months without findings; savings by future proper cleaning and avoiding part replacement.

Key figures
(Example) Complaints: decrease to 0 within 12 months.

Pitting corrosion in stainless steel tanks on the process side (pharmaceutical and biotech industry)

Complaints about cleaning validation led to repeated production interruptions and additional Cleaning in Place (CIP) cycles. Despite repeated cleaning, the local defects could not be removed and the causes remained unclear. The case study describes how localised passive layer damage and unsuitable surface conditions were identified, specifically addressed and safeguarded long-term through adapted processes – with robust validation and reduced cleaning requirements.

Initial situation
Recurring issues during cleaning validation led to production shutdowns and to the need for repeat CIP (Cleaning in Place) cleaning operations.

Investigations
On-site inspection, photo documentation, mobile microscopy, profilometric roughness measurements, sampling of corrosion products and analysing using SEM-EDX (Scanning Electron Microscopy combined with Energy-Dispersive X-ray Spectroscopy), investigation and documentation of component history concerning manufacturing and media contact during regular processing and recording of detailed applied cleaning processes.

Findings
Localised damage to the passive layer caused by improper surface treatment before installation on site and commissioning as well as following insufficient chloride resistance of the related stainless steel material. Additionally, incorrect localised manual cleaning increased surface roughness and reduced corrosion resistance level additionally.

Measures & results
Locally performed fully controlled mechanical grinding of the tank and proper electropolishing on site using fully controlled material removal layer followed by chemical passivation, adjustment of the cleaning process and CIP (Cleaning in Place) instructions with a regular re-passivation step, monitoring → 12 months without findings; cost savings through elimination of additional manual cleaning and CIP cycles.