Overview - ISO 23159:2020 (Gamma ray scanning on process columns)
ISO 23159:2020 specifies a non-destructive testing (NDT) method using gamma ray scanning to inspect and troubleshoot process columns and pipes in chemical and petrochemical industries. The standard covers transmission-based gamma scanning for in-service diagnosis of separation columns, including tray columns and packed-bed columns, enabling operators to assess internal conditions (tray damage, liquid levels, fouling, maldistribution) without process shutdown. The introduction highlights safety, environmental and economic benefits from timely problem detection.
Key technical topics and requirements
- Scope and applicability: All kinds of separation process columns and relevant piping; suitable for tray configurations and packed beds.
- Personnel qualification: Operators must have additional specialized training in gamma scanning; Annex A provides recommendations. Levels and responsibilities (e.g., Level 2/Level 3) are referenced for planning and approval.
- Radiation protection: Strong emphasis on legal/regulatory compliance and safety measures for ionizing radiation (controlled areas, monitoring, barriers, permits). The standard warns of health risks and references IAEA safety documents.
- Equipment requirements:
- Sealed radiation source (selection guidance in Annex B).
- Source holder with collimated beam (Annex C/D guidance).
- Radiation detector and data acquisition system (example: sodium iodide detector ~5 cm × 5 cm).
- Calibrated radiation monitor, handling tools, transportation in approved containers.
- Execution of scanning:
- Pre-work: obtain column dimensions, wall thickness, drawings and permits; ensure safe access.
- Scanning: align source and detector at elevations, record counts at defined intervals (example interval: 5 cm or per tray spacing), log observations and obstacles.
- Data processing & reporting:
- Produce graphical scan profiles (counts or density vs elevation).
- Interpret signatures for flooding, foaming, high liquid level, missing trays/packing, fouling, maldistribution (Annex F).
- Minimum report contents specified (equipment, source and activity, detector settings, geometry, tables/plots).
Practical applications and who uses it
- Primary users: NDT service providers, plant inspection teams, process engineers, maintenance and reliability engineers, radiological safety officers, and third‑party inspectors.
- Typical applications: troubleshooting underperforming distillation or absorption columns, diagnosing tray/packing problems, locating internal damage or debris, optimizing liquid/vapor distribution - all while columns remain online.
Related standards and references
- ISO 5576 (NDT radiology vocabulary) - referenced for terminology.
- IAEA General Safety Requirements - referenced for radiation protection guidance.
- Annexes in ISO 23159 provide practical guidance on personnel, source selection, equipment, preparation, detector orientation and data interpretation.
Keywords: ISO 23159:2020, gamma ray scanning, non-destructive testing, process columns, tray columns, packed beds, radiographic testing, radiation safety, NDT inspection.
