Propeller dye penetration test

From MarineWiki

A dye penetration test is used to detect surface damages only.

Contents 1 Preparation 1.1 Propeller cleaning 1.2 Propeller polishing 1.3 Grinding 1.4 Weld built up 1.5 Grinding 2 Test 2.1 Applying Cleaner 2.2 Applying Penetrant (Dye) 2.3 Wiping 2.4 Applying Developer 2.5 Interpret 3 To be noted

Preparation

Propeller cleaning

High pressure washing is done to remove the barnacles.

Propeller polishing

If there is suspect of damage, then a Non Destructive Test (NDT) like dye penetration test is done to verify. But, for such a test, the propeller must be polished by grinding.

Grinding

Careful process to avoid damage. It is also done before and if propeller has to be repaired by weld built up or apply belezona ceramic.

Weld built up

If the damage is severe, either by cavitation or crack, then welding has to be done. This is more long lasting than the belezona application.

Grinding

After welding, the surface has to made smooth by grinding.

Test

Applying Cleaner

The first chemical that is applied is the cleaner.

Applying Penetrant (Dye)

This reddish colored dye is applied on the surface that require testing.

Wiping

Applying Developer

This is a white colored spray and the cracks and pits are evident in the surface color of dark red.

Interpret

The surface damages like cracks and pits are visible.

To be noted

It is important to use the same brand of cleaner, penetrant (dye) and developer. For example, use Magnaflux brand of cleaner (SKC-S), penetrant (SKL-SP1) and developer (SKD-S2).