Corrosion Passivation: Does it help steel wire ropes?

Corrosion Passivation: Does it help steel wire ropes?

Corrosion Passivation: Does it help steel wire ropes?

nC Nano Corrosion Passivation (NCP) means to stop the corrosion process. Material thickness will remain stationary. This without the need for sandblasting, coating or other expensive and time-consuming work and materials. If you are looking at material thickness that is sufficient now, but will be subject to regression as corrosion takes over because of longer periods of standstill, corrosion passivation can be a solution of choice to keep thickness as it is right now. That’s good. But does it help steel wire ropes?

As steel wire ropes do corrode, and have long periods of standstill, the principles of nC NCP were tested out in the field

As steel wire ropes do corrode, and have long periods of standstill, they provide ideal circumstances for testing the principles of nC NCP in the field. For instance steel wire ropes on tugboats (Kotug). Umbilical cables on geo-vessels (Fugro). Tension-wires on rigs, steel wire ropes on bridges in locks and ports (Provincie Groningen).

Chelation

Both nC NCP Marine and Archoil AR5600 Corrosion Passivator & Lubricant work through a process called chelation. In this process, large synthetic molecules form a bond with the iron behind the rust. Consequently this pulls the loose iron oxide from the surface. NCP Marine forms a flexible barrier inside the capillar and intermolecular structure of the metal surface. The formulation passivates the metal corrosion process. Archoils’s AR5600 takes it a step further and adds lubrication into the equation. Here VCI-particles (Volatile Corrosion Inhibitors) bond into the surface of the individual single wire strands, together with particles that have strong abrasion resistant properties together with a very low CoF (Coefficient-of-Friction).

Corrosion passivation on steel wire ropes

Pic (credits: nC Surface Technology BV, NL) left shows passivated (lowest four cables) and not-passivated (upper six cables) steel wire rope during the accelerated salt spray test at Proton Technology (accredited testing lab) alongVOLVO STD 423-0014 iss.5 standard, accredited method according to ISO/IEC 17025. Pic right shows nanopicture of nano boron nitride platelets which are reponsible for a longlasting and very low coefficient-of-friction.

 

Both approaches have two very big advantages over traditional treatments of steel wire rope:

1. Because of the bonding characteristics the corrosion passivation and lubricating properties will stay much longer in place than coatings and lubricants that mechanically stick.

2. The corrosion passivation and lubricating properties will reach also the inner surfaces of the single wire strands of already made steel wire ropes. This is what nanoparticles do. Because of the bonding characteristics and the nano-size particles in these formulas,

Again, pictures tell best:

Steel wire rope before passivation

Picture above shows steel wire rope #1 torn open after servicing for more than 2 years in and at sea. Pic shows steel wire rope before passivation bath (pics De Ruiter Staalkabel/Usha Martin NL).

 

Steel wire rope after corrosion passivation

Pic shows steel wire rope #1 torn open after servicing for more than 2 years in and at sea. Now the steel wire rope was bathed in corrosion passivator and opened after 4 hours working time.  This shows that the nano technique of corrsion passivation reaches every single wire strand completely. It shows it’s suitable to refurbish steel wire rope as well. (Pictures: De Ruiter Staalkabel/Usha Martin NL).

 

Steel wire rope not galvanized, but corrsion passivated.

Showing the results of exposing two steel wire ropes in full saturation salt water (39% salt) after 4350 hours. The untreated left rope is covered with rust, and shows pitting. The right and treated rope remains unaffected (although the bindings on bottom side start to corrode). Both steel wire ropes were not galvanized. (Picture taken at De Ruiter Staalkabel/Usha Martin NL,

 

Accelerated salt spray test on steel wire rope.

This picture shows nC NCP treated steel wire rope during accelerated salt spray test at Proton Technology (accredited testing lab) along VOLVO STD 423-0014 iss.5 standard, accredited method according to ISO/IEC 17025, after 6 weeks.

 

Accelerated salt spray test VOLVO STD 423-0014

Picture shows bitumen treated steel wire rope during accelerated salt spray test, after 6 weeks.  Proton Technology Lab performs along VOLVO STD 423-0014 iss.5 standard, accredited method according to ISO/IEC 17025.

Volvo Standard 423-0014 accelerated corrosion test

VOLVO states in their definition of Standard 423-0014: the corrosion rate in metal mass loss after this test is 130 – 210 µm after six weeks in these conditions. Comparing the results between a NCP treated and a bitumen treated steel wire rope after six weeks show the following results:

nC NCP treated steel wire rope: Rp8 – #5

AR5600 treated steel wire rope: Rp8 – #5

Bitumen treated steel wire rope: Rp4 – #3

Table: Corrosion resistance according to ISO 10289:1999

Table: Corrosion resistance according to ISO 10289:1999

 

For the solution only highly refined vacuum salt (NaCl) was used which was dissolved in de-ionized water. The test solution was mixed from a saturated salt solution and 0.01 M sulphuric acid. Data gathered in the process is gathered at Proton Technology AB.

The full Proton Technology VOLVO Std 423-0014 verification report of NCP on steel wire rope is available on request.

Pic shows single wire treatment with NCP, before building up the complete steel wire rope.

Pic shows treatment of steel wire rope.

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