Techcoat Insitu Electroless Nickel Coating

Electroless nickel plating was developed in the late 40’s early 50’s.It is used today in areas requiring uniform plating, high corrosion resistance and high abrasion resistance.

Electroless nickel plating is an auto-catalytic reaction used to deposit a coating of nickel on a substrate. Unlike electroplating, it is not necessary to pass an electric current through the solution to form a deposit. This plating technique used is to prevent corrosion and wear rather than aesthetics.

Electroless nickel plating has several advantages versus electroplating. Free from flux-density and power supply issues, it provides an even deposit regardless of work piece geometry as demonstrated in the diagram below:

Conventional Electroless nickel plating involves numerous heated pre-treatment and activation baths, followed by one or more plating bath and then rinsing baths. The items for plating are progressively immersed in each bath. This process severely limits the size and types of items that can be plated and as such only smaller components are generally plated with EN.

Techcoat Services can Electroless Nickel Plate tanks and reaction vessels with Hi-Phos Electroless Nickel offering outstanding corrosion resistance and overall durability. This plating can offer a far more cost effective lining to that of inconel cladding. Each plating job is individually designed and completed. Electroless Nickel Plating is vastly superior to electroplating and is used extensively throughout the Oil & Gas and Resources industries in the most aggressive exposures (down hole oil pipeline fittings). Until now works have been limited to smaller workshop applied items.

Techcoat Services has developed processes to plate Road Tankers, Reaction Vessels and Storage Tanks.

This process is completed insitu, without the need for Nitric acid surface activation, pre-treatment or post-treatment baths. The entire process is completed within the vessel being plated.

Property
 Techcoat
Insitu EN		 Conventional
Workshop EN		 Electroplated
Nickel		 Inconel
Cladding		 Epoxy
Tank
Lining		 Polyurethane
Lining		 Stainless Steel
Tank Fabrication
High heat resistance Yes Yes Yes Yes No No Yes
High abrasion resistance Yes Yes Limited Limited Limited Yes Yes
Low Coefficient of Friction Yes Yes Yes Yes No No Inferiorto EN
High corrosion resistance Yes Yes Limited Yes Limited Limited Yes
High heat transfer Yes Yes Yes Yes No No Yes
Can treat large vessels insitu Yes No No Yes Yes Yes Yes
Very high adhesion Yes Yes No Limited Limited Limited n/a
Highly resistant to thermal shock Yes Yes Limited Yes No No Yes
Ability to protect hiden areas Yes Yes No No No No n/a
Inherently antiscaling Yes Yes Lower thanInsitu EN Lower than Insitu EN No No Lower thanInsitu EN
Internally non-stressed and chemically bonded to the substrate Yes Yes No No No No n/a
Speed of application Base
Comnparision
Rate		 Same Same Much Longer Much Longer Much Longer Much longer to fabricate new vessels
Cost comparison Base
Comparision
Rate		 Lower cost than Insitu EN Lower cost
than Insitu EN		 Higher than Insitu EN Lower cost than Insitu EN Lower cost than Insitu EN Much more expensive than EN

Case Study A 12 meter long by 1.5 meter diameter high temperature, high pressure, caustic reaction vessel fabricated from carbon steel was corroding at around 3,000um per annum and was being replaced regularly every 3 years. After 2 ½ years use (and with only 2,000um corrosion allowance remaining) Techcoat Services Insitu Electroless Nickel Plated the vessel, the vessel was subsequently checked every 3 months for wall internal corrosion and resultant wall thickness and the EN has effectively halted the corrosion of the carbon steel. After an additional 2 ½ years of use the vessel still retains the corrosion allowance that was evident pre plating. Essentially this vessel has been given a new lease of life and continues to perform in service well beyond its normal replacement date.

Insitu Electroless Nickel Plating

Electroless Nickel Plating (EN) offers many benefits to the Resources Industry,
EN has the following properties:

  • Outstanding corrosion and abrasion resistance
  • Inherently antiscale surface
  • Low coefficient of friction
  • High surface hardness, further improved with post heat treatment
  • Outstanding resistance to thermal shock
  • Internally non stressed and chemically bonded to the surface
  • Very high temperature resistance
  • Very good heat transfer

Insitu Electroless Nickel Plating of Heat Exchangers for the Alumina Industry

Electroless Nickel Plating (EN) of heat exchangers would offer comparable heat transfer to that of normal tubing, reduced rates of scaling and resistance to periodic acid descaling. This combination of properties potentially results in Heat Exchangers that once plated do not need retubing (as a result of corrosion/loss of wall thickness from acid descaling). The EN is highly resistant to corrosion and any loss of metal due to acid washing would be the nickel and not the underlying steel and at a far reduced rate to that of steel. The EN can be reapplied to reinstate its original thickness and thus eliminate the need for retubing.

EN on Heat Exchangers

  • Comparable heat transfer to that of unplated steel
  • Improved flow and production (due to reduced rates of scaling)
  • Reduced cleaning costs (both in frequency and duration)
  • Elimination of retubing costs (both in terms of lost production and maintenance costs)
  • Retubing replaced by less frequent and more cost effective EN replating