DNV DNV-CP-0106 PDF

This CP gives a description of the procedures and requirements related to documentation, design and type testing applicable for TA of fastening devices of sacrificial anodes.

This CP does not set the design requirements for the fastening devices of sacrificial anodes. TA is based on compliance with design requirements given in [1.1]. The CP describes how to document compliance with the requirements in order to obtain a TA certificate for the equipment. This includes, where relevant, technical requirements for how the type tests shall be performed.

The Society's type approval certificate will normally cover one main type of anode design (grade), with the possibility of including variants, e.g. series with different dimensions and mass. Other arrangement may be agreed upon.

For anode fastening devices this means:

— Grade: the anode and fastening device design

— Variants: different dimensions and mass.

This type approval programme concerns primarily the safety aspect of fixing of sacrificial anodes to steel structures. Anodes shall not fall down and cause incendive sparking in gas hazardous area. Of secondary concern is that the anode shall not be lost and cause reduced protective effect.

The Society's type approval certificate is limited to one manufacturer at one production site unless otherwise agreed.

Guidance note:

1) There may be an inherent conflict of interest between demands for cathodic protection efficiency and safe installation of anodes. The efficiency may be optimal with maximum stand-off distance (from the steel structure that it shall protect), while optimally safe installation is obtained with the anode close to the structure (flush mounted).

2) Ballast tanks of mobile offshore units and fixed offshore structures are usually not defined as gas hazardous areas. Loosening of anodes thus represents no explosion hazard, but should nevertheless be avoided. Established practice shall have minimum 2 fixing points per anode.

3) Type approval with respect to the efficiency of sacrificial anode alloy materials as regards protective current capacity (Ah/kg) is not comprised by this type approval programme but is offered as a separate service, based on long term (normally 12 months) testing submerged in sea water.

Type tests as specified in Sec.2 [3], shall be carried out and verified in one of the following ways:

— at one of the Society's laboratories

— at a recognised and independent laboratory or a laboratory accepted by the Society

— at the manufacturer’s premises in the presence of a surveyor.