Surface solutions

Derek Vanek discusses the application benefits and possibilities of selective plating for the oil and gas industry

Why take the surface to the tank when you can take the tank to the surface?’ is the idea on which the portable, selective brush plating process is based. Applying engineered surface coatings can provide a wealth of benefits including protection against corrosion and wear. However, with many surface finishing options available, including thermal spray processes, IVD, PVD, tank plating and selective brush plating, choosing the right one for a particular application can be a complex task. So when should you choose selective plating?

There are many benefits to choosing selective plating, including the ability to accurately focus the plating onto specific areas of a component, enabling parts to be plated in-situ, helping to minimise downtime and production delays. This is particularly beneficial in an industry which has very large components that can be difficult to transport and where every hour of downtime can cost the platform operator thousands of dollars in lost production. Selective plating is best suited for localised areas on simple shapes such as inside and outside diameters or flat surfaces. In contrast to tank plating, the SIFCO Process does not require extensive masking or special fixtures to plate the component. The length of time a plating operation will take is primarially determined by the amount of material that needs to be applied. SIFCO Process deposits can be plated at rates that are 30 to 60 times faster than conventional tank plating. The performance and cost differences that these factors can make to maintaining, enhancing or repairing critical components can be significant, hence why it is important to consider all of the variables involved before deciding which surface finishing process to specify.

Whilst damage from wear, corrosion or mis-machining can be repaired using selective, brush plating, the SIFCO Process should not just be considered for repair or salvage. The full range of pure metal and alloy deposits available with the SIFCO Process offer enhanced wear resistance, increased surface hardness, low electrical contact resistance or corrosion protection for OEM component applications.

Oil and gas is an industry that is highly demanding when it comes to surface finishing performance requirements. So how is the process used here?
The oil & gas industry is highly demanding of material performance, often operating in hostile, challenging environments, where the cost of downtime resulting from component failure can be extremely high. The SIFCO Process is well proven, and extensively utilised, within the oil & gas industry in a wide range of applications from OEM component manufacture, to provide enhanced wear or corrosion resistance, to repair, where the process portability is important in reducing expensive downtime. Let’s look at some specific application examples.

One common application is silver plating onto dynamic sealing and bearing surfaces in drill bit components for lubricity. Another common application is the use of selectively plated copper onto premium threaded connections, for drill pipes, risers, tubulars, and couplings in order to prevent galling during make-and-break operations. SIFCO ASC is approved by industry leadering licensors for oil thread design to apply these critical deposits as well as to train operators from approved companies, worldwide, to apply copper onto premium threaded connections because SIFCO’s Copper Select Technology and Training Program meet the highest standards in the industry.

For oil & gas producing operations, there is no escaping the challenge of corrosion due to the harsh marine and subsea environment. The properties of AeroNikl make it an extremely popular material to be selectively plated in highly corrosive applications such as high-chloride down-hole applications. Additionally surfaces that are mechanically damaged are often plated with a combination of copper and AeroNikl.

An example of such a repair carried out in-situ with the SIFCO Process was the repair of critical damage – caused by a lightning strike – to a crown-mounted compensator (CMC) on an oilrig in the Gulf of Mexico. The CMC is responsible for applying constant tension to the drill string and to compensate for any rig movement. The significant gouge on the cylinder caused by the lightning strike would cause severe leakage at the cylinder seals, threatening production and the loss of thousands of dollars for each hour of downtime.

Using SIFCO ASC’s AeroNikl 7280 for corrosion protection and Cobalt 2043 to cap the repair for hardness and to protect against surface wear, the CMC was back in full operation within 24 hours – saving potentially three months downtime to replace the shaft.

A typical operation using the SIFCO Process
The SIFCO Process was developed more than 50 years ago, and was initially used for industrial repair applications, with early acceptance by the US Navy. Over the years, the SIFCO Process was developed to service a wide range of industrial repair and manufacturing applications.

The range of metals used in selective plating is extensive. The SIFCO Process is used to apply any metals that are traditionally carried out by tank electroplating, the most common being; nickel, copper, cobalt, nickel-tungsten, cobalt chromium carbide, silver, gold and platinum.

There are several preparatory steps in which a work area is prepared to receive an adherant deposit. The appropriate preparatory procedure is determined by both the substrate of the component and the plating solution to be applied.

The process can be carried out manually, it can be mechanised, or it can be automated for high volume applications. The thickness of the plating is accurately controlled through use of an ampere-hour meter and once the required ampere hours are reached, plating is stopped and finished with a final water rinse and dry.

Automating the process for high volume
Selective plating is a precise and effective method for the enhancement of localised surfaces on OEM components and can be mechanised or fully automated to meet the demands of high volume plating applications.

We recently developed a semi-automated workstation for Powell Electrical Systems Inc., a division of Delta/ Unibus, which reduced the processing time to selectively plate non-cyanide silver onto each side of its copper bus bars by 90 per cent.

Its portability and versatility has allowed the SIFCO Process to be employed in some of most challenging locations and applications around the world including submarines, space stations, hydro-electric power stations, nuclear power plants, oil rigs in remote locations and on critical aircraft components.

Selective brush plating has dramatically evolved from its origins of repairing existing plating jobs, and is now considered an overarching term describing a highly technical process used for repairing or improving the surface properties in an array of circumstances. It is specified at initial engineering design stage as well as being called out for component repair.

The various advantages provided by the SIFCO Process, combined with the wide range of engineered deposits, make it an attractive choice for OEM and repair applications. Whatever the requirements or size of a job, selective plating should always be considered a viable alternative to other methods of metal deposition.

Derek Vanek works at SIFCO Applied Surface Concepts (ASC), part of Norman Hay plc. SIFCO Applied Surface Concepts provide practical, cost-effective selective brush plating solutions to improve part performance and reduce manufacturing costs through corrosion protection, increased wear resistance, increased hardness, improved conductivity, anti-galling or slip.

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Issue 125 October 2015