# NORSOK M-501

Source: https://coatmentor.com/standards/norsok-m-501/ · Updated 2026-10-14

Surface preparation and protective coating of offshore and coastal installations.

**Publisher**: Standards Norway

**Area**: Systems, environments and degradation

NORSOK M-501 is the Norwegian offshore coating standard. Edition 7 came out in November 2022 and replaced the 2012 edition. It covers surface preparation, application and inspection of paints, metallic coatings and sprayed passive fire protection on offshore and coastal facilities. Pipelines and pipeline risers are outside its scope.

## How it is organised

Each coating system has its own data sheet, the coating system data sheet (CSDS). A data sheet gives the service, the substrate, the surface preparation, the build-up of coats, the adhesion test and the prequalification the system needs. Systems are known by number and split into sub-systems, for example System 1 for non-insulated carbon steel in the atmosphere, System 2 for thermally sprayed aluminium or zinc, and System 7 for the splash zone and submerged steel.

## What the inspector checks

- Blast cleaning with grit, not shot, to Sa 2½ (ISO 8501-1); dust no worse than rating 2 of ISO 8502-3; soluble salts sampled and measured by ISO 8502-6 and 8502-9.
- Final blasting and coating stop at 85 % RH or higher, or whenever the steel sits within 3 °C of the dew point.
- Shop primer is temporary protection: it is removed before the coating system is applied.
- Systems are prequalified by the tests of ISO 12944-9, which replaced ISO 20340.

**6** practice items in the members area mention NORSOK M-501 (CIP 2: 1 · FROSIO written: 5).

## Related

- **Concepts:** [Corrosivity categories (ISO 12944-2)](https://coatmentor.com/learn/corrosivity-categories/) · [Surface cleanliness grades](https://coatmentor.com/learn/surface-cleanliness/)
- **Standards:** [ISO 12944-9](https://coatmentor.com/standards/iso-12944-9/) · [ISO 12944](https://coatmentor.com/standards/iso-12944/) · [ISO 8501](https://coatmentor.com/standards/iso-8501/) · [ISO 8503](https://coatmentor.com/standards/iso-8503/)

## About this page

This page describes the subject of NORSOK M-501 in our own words; it does not reproduce the standard. For the full text, buy the current edition from Standards Norway. Checked on 2026-10-14; errors go in the [corrections log](https://coatmentor.com/method/). CoatMentor is an independent study aid. It is not affiliated with ISO, AMPP, SSPC, NACE International, ASTM or FROSIO.