ABSTRACT

Slurry pipes often are exposed to heavy wear at or around the 6 o’clock position. In oil sands hydrotransport and tailings, wear of steel pipes is much higher under erosion-corrosion conditions. Whilst a number of metallic wear protection solutions, e.g., alloys, hardened steels, or chromium- carbide overlays can significantly extend useful life of such pipes, their protective effect can be severely reduced if erosion-corrosion conditions prevail.

Internal coatings made from high-performance polyurethane elastomers often allow similar or somewhat longer life extension compared to such metallic solutions, at a much lower investment cost. Under erosion-corrosion conditions, however, these elastomer coatings last much longer than metallic solutions. Life extension factors of 2-10 have been observed in oil sands slurry lines.

A former disadvantage of polymeric internal coatings was the fact that non-destructive testing and monitoring methods used on steel pipes could not be applied. For almost three years now, “instrumentation spools” in oil sands tailings service have successfully been in operation. The internal coating contains sensors rendering it “intelligent” in that it measures its own wear, including information on actual wear location on the 360 degree circumference. No hole through the pipe wall is required for data transmission to the operator.

This presentation will describe high-performance polyurethane elastomer internal coatings, the intelligent coating system, and field experience with it.

INTRODUCTION

Elastomers Resistant to Wear and to Erosion-Corrosion

In mining, but also in numerous other industries, wear of metal surfaces and particularly the highly detrimental effect of erosion-corrosion, cause high maintenance and repair cost. These effects significantly contribute to limiting useful life of equipment exposed to them. Prominent examples are mining equipment like slurry pipelines, truck beds, slurry pumps, flotation equipment, chutes, and hydrocyclones, Examples from other industries are tracks of chain vehicles (e.g., street repair machines), heavy duty rollers, cutting table surfaces, or snow plough blades.

In the pipeline industry, inline inspection (“ILI”) tools (“pigs”) as well as cleaning pigs bear disks or cups that are exposed to strong erosive wear as well. These disks or cups need to be made from an elastic material since their purpose is to seal the tool against the inner pipe wall to create a pressure differential in the product stream which will propel the pig through the pipeline. Essentially, the disk or cup material needs to combine highest possible elasticity, wear resistance, and tear propagation resistance whilst at the same time having enough mechanical strength to keep its overall shape and not distort in a way that product stream can bypass the tool. Figure 1 shows a selection of ILI tools with cups and disks.

This content is only available via PDF.
You can access this article if you purchase or spend a download.