March 2021

Maintenance and Reliability

Down with downtime: Repair complex petrochemical components with selective electroplating

The volatile impact of the coronavirus pandemic hit at the same time the petrochemical industry was entering a downcycle.

Arana, T., SIFCO ASC

The volatile impact of the coronavirus pandemic hit at the same time the petrochemical industry was entering a downcycle. Demand has already started to slow, while a surplus in capacity is eroding margins and value. The global disruption that the pandemic has brought will only serve to further exacerbate these issues.

Several factors are at play, but the key one is the global clampdown in the use of plastics. The damage plastics cause to the environment and oceans is well documented, and more countries and businesses are cutting back on these petrochemically produced products. Indeed, 250 organizations—collectively responsible for 20% of the plastic packaging produced around the world—have committed to reduce waste and pollution under the New Plastics Economy Global Commitment.1

Meanwhile, billions of dollars’ worth of refineries and processing plants have come, or are about to come, online. Between 2014 and 2019, $120 B was spent on new facilities in Texas, much of it focused on producing high-density polyethylene.2 At least 108 petrochemical plants are scheduled to start operations in Asia and the Middle East by 2023. With the cutback in plastics production, this is causing a perfect storm of global overcapacity, and analysts predict the bust will happen in as little as five years.

However, not all petrochemicals will be affected. According to Deloitte’s The Future of Petrochemicals report, certain petrochemicals—such as ethylene and propylene—are still predicted for growth and have a high utilization rate. However, shutdowns and maintenance activities may inhibit current capacity required to sustain the production needed to keep up with demand, thereby introducing volatility in the price of base chemicals.

Minimizing downtime is imperative

Minimizing downtime is vital. Operators cannot afford for plants to be down longer than their scheduled maintenance periods—or worse, be plunged into unplanned downtime—as this would result in huge losses in productivity and profits.

Maintenance planners and turnaround managers must be able to control and plan maintenance work, and the ability to estimate time and resources is essential. Methods of repair must also be quality assured, reliable and cost effective.

A wide range of methods are available, each with varying benefits and challenges. When it comes to components with complex geometries that must be repaired fast and must be able to withstand the harsh, continuous operating conditions of petrochemical production, few solutions are as adept and as effective as selective electroplating.

Selective plating: Serving many functions, suitable for many applications

Selective electroplating, such as the author’s company’s proprietary selective electroplating processa is a proven, efficient and economical way of performing surface treatment repairs. The proprietary process is a portable plating method used to enhance, repair and refurbish localized areas on manufactured components.

Plating can serve a variety of purposes, such as a localized defect repair or bringing an inside diameter (ID) or outside diameter (OD) back to size. Plating can also enhance wear or corrosion resistance exactly where it is needed, even on new parts where it would be prohibitive to tank plate the entire part.

The process uses fundamental electrochemical principles. An electrolyte solution, which contains ions of the metal to be deposited, is introduced between the negatively charged part to be plated and the positively charged plating tool (i.e., anode). A portable powerpack provides the required direct current and allows precise control of amperage, voltage and plating time for high-quality and accurate plating results.

The circuit is completed when the anode touches the surface of the part to be plated. A suitable cover material around the tool provides a reservoir to evenly distribute the electrolyte. The current causes the metal ions in the electrolyte to bond with the surface of the part and build up the plating layer. The result is a highly adherent and dense metal deposit. The metal or alloy to be deposited can be chosen from more than 50 different solutions, which allows the application to be tailored to the desired characteristics of the plating material.

The following are a few examples of where selective electroplating can commonly be used effectively in the petrochemical industry:

  • Corrosion protection
  • Defect repairs
  • Dimensional restoration
  • Wear resistance
  • Improved hardness
  • Prebraze
  • Anti-galling and slip.

Quality of selective plating

One of the key criteria that maintenance and turnaround managers need to consider is quality. Here, selective plating gives the assurance needed due to the deep, strong molecular bonds it creates between the coating and the substrate. Along with this benefit, repairs conform to rigorous quality standards and are performed by trained, highly skilled technicians.

Judge by adhesion. When judging surface coatings, a telling sign of its quality is its adhesiveness (i.e., how strong the deposit’s bond is with the base metal). Typically, when comparing selective plating, there are two alternative surface coating choices: thermal spray coatings and metal-filled epoxy coatings. Against both, selective plating is superior in bond quality and performance.

Unlike selective plating, thermal spray coatings can only achieve a mechanical bond. This means the coating is not fused to the base metal, and adhesion comes from mechanical interlocking formed chiefly from the roughness of the substrate surface, making it comparatively weaker and much more susceptible to wear and corrosion.

Conversely, metal-filled epoxy coatings are coatings that stick to the substrate like an epoxy glue. Generally, these coatings can only achieve an adhesion between 1,500 psi and 5,000 psi. In an adhesion test against selective electroplated deposits, the epoxy coating fails long before the electroplated coating delaminates. This is an indication that the adhesion of selective electroplated coatings is in excess of 10,000 psi.

Such strength and quality are achieved because of the deep molecular bonds that selective plating creates between the deposit and substrate. The plating nucleates on the existing metal surface, extending the crystal structure of the base metal.

Quality standards. Another mark of quality and performance is the standards and specifications the repair method has achieved. Selective plating can be looked at from a host of different industry specifications, including military standards, aerospace material standards and federal standards.

The proprietary selective electroplating solution has been used for more than 50 yr in oil and gas, industrial and military industries and adheres to numerous standards and specifications, including the AMS 2451 and MIL-STD-865_D standards.

It is also important to use trained technicians to perform the selective electroplating repairs. Technicians can control the plating process and, depending on the deposit solution, the process provides desired features such as hardness and corrosion, ensuring repairs are tailored to each unique situation.

Reliability repairs to run to the next scheduled downtime period

In tandem with quality and performance is reliability. With shutdowns scheduled 3 yr–6 yr in advance and in an industry that must run like clockwork, reliability is mission critical.

However, with petrochemical plants and machinery subject to steam and corrosion, along with wear and scoring, the question is how the components can be effectively protected to last from one downtime period to the next. Some common applications where repairs are often required include compressors, ball valves, gate valves, and casings and housings for pumps and turbines.

For scored, heavily worn or mis-machined components, copper can be electroplated onto the base metal to build the part back up to its original dimensions and tolerances. Meanwhile, a variety of nickel deposits can be used to provide corrosion protection, whether that is from chemicals or steam.

In many cases, restoring or enhancing components with complex geometries are not an issue, so long as the anode is able to touch the surface that is being plated. Repairs can be made to IDs, ODs, flat surfaces and more.

All repairs are evaluated on a case-by-case basis, considering disassembly, downtime and throughput, among others, to ensure the best possible outcome.

Protecting 1,500 valves per year from steam and acid corrosion

One such example of where reliability was increased due to selective electroplating was when the author’s company helped with the plating of 1,500 original equipment manufacturer (OEM) valves per year. This was to prevent various valve assemblies from steam and acidic water corrosion.

Steam control systems are an essential part of refineries and large petrochemical plants. Corrosion resistant coatings are vital to valves and valve assemblies as the steam and acidic water found in these applications corrode the IDs of the valves.

However, plating these components comes with its challenges. In this application, the bore sizes of the valves varied in diameter from 1 in.–10 in., and turnaround time needed to be fast. This meant the alternative surface coating option (electroless nickel) was unsuitable.

Selective plating was chosen for this application because it was able to control the parameters and the deposit. The corrosion protection on the valves’ IDs was much greater than what electroless nickel could achieve. The turnaround time was also much shorter due to less processing time, providing a better overall value.

Valves were prepared by first using general masking around the location of the ID to be plated. Using a proprietary coatingb specially formulated for high corrosion resistance, the deposit was applied using ID 13’s anodes and a special tool plating to a thickness of 0.001 in (FIGS. 1 and 2).

FIG. 1. A proprietary coatingb was applied to an OEM’s valve assemblies.
FIG. 2. The proprietary coatingb on the valve seat.

Lowering costs through selective plating

Selective electroplating is a cost-effective repair method for several reasons.

The first is that it is portable. Whether the job is in a shop or out in the field, selective plating can be conducted almost anywhere. It can also be mechanized or automated for minimal operator intervention. Repairs can be made in-situ for unplanned downtime situations, which mitigates the costs of disassembly, transportation and re-assembly.

Secondly, costs and downtime are also reduced due to the minimal amount of pre- and post-machining required. The specific area needing protection or repair must be masked off. By following the appropriate preparatory steps for the procedure, the deposit will adhere without issue. Due to the precision and accuracy of selective plating, there is often no need for post-machining, as the deposit can be plated to size.

Finally, repairs are fast. Once the repair case has been evaluated, and if machinery does not need disassembling, turnaround time can be as quick as a single working day.

Leaving your sustainability credentials intact

With increasing pressures across all industries to set and meet sustainability targets and reduce emissions, there is a growing focus on the environmental impact of unexpected shutdowns at petrochemical plants and refineries.

Plant interruptions can be highly damaging to the environment, and years’ worth of gases and emissions can be leaked into the atmosphere from just a few hours of unplanned downtime. For example, gas flaring is one of the common side effects of unplanned shutdowns. Data published by the World Bank’s Global Gas Flaring Reduction (GGFR) program shows that 145 Bm3y of gas is released into the atmosphere from gas flaring, equating to 270 MMtpy of CO2 emissions. Therefore, getting facilities back online as fast as possible is crucial to lessening the environmental impact, and selective electroplating helps make this possible.

The proprietary electroplating process is highly sustainable, as well. In comparison to other surface coating methods (e.g., tank plating), selective plating uses much less solution and chemicals and generates very little wastewater. For workers and the environment, it is also much safer, with fewer fumes emitted and less hazardous waste to dispose.

With the portable nature of selective plating, there often is no need to ship components off for repair, which incurs transportation costs, more emissions and a bigger carbon footprint. Instead, technicians can bring portable selective electroplating equipment—containing all the solutions and accessories required to make the repairs—directly onsite.

Managing maintenance in a new era

The turn of the decade has brought many unforeseen events; however, the petrochemical industry was looking at a precarious new era long before the coronavirus pandemic arrived.

With a shrinking value pool, margin erosion and the changing way society views plastics, plants and machinery must be managed more carefully. Maintenance schedules are just one factor that petrochemical executives will need to be mindful of, but they are possibly the most important. However, by considering selective plating, maintenance planners can approach these situations with confidence. Due to each selective plating application being unique, repairs will be thoroughly considered and performed by trained, knowledgeable technicians, ensuring quality and reliability for years to come. HP

NOTE

         a SIFCO Process®
         b SIFCO ASC’s AeroNikl® 250 coating

LITERATURE CITED

  1. Hughes, K., “Three ways we are making an impact on plastic pollution,” World Economic Forum, September 2019, online: https://www.weforum.org/agenda/2019/09/we-created-an-initiative-to-fight-plastic-waste-here-are-3-takeaways-from-our-first-year/
  2. Tomlinson, C., “Petrochemical industry has five years to prepare for bust,” Houston Chronicle, July 2019

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