Wear Locations in Stainless Steel Pipe Fittings From the Turbulent Flow of a Liquid-Solid Slurry

The United States Department of Energy (DOE) is building a Waste Treatment Plant (WTP) at the DOE Hanford Site in the state of Washington to process stored radioactive wastes for long-term storage and disposal. The Savannah River National Laboratory (SRNL) is helping resolve technical concerns with the WTP, which are related to piping erosion/corrosion (wear). SRNL is assisting in the design of a flow loop to obtain long term wear rates that will use prototypic simulant chemistry, operating conditions, and materials. The challenge is to accurately measure slurry wear to a pipe wall thickness tolerance of 47 microns/year anywhere in the test flow loop in a timely manner. A first step in such a test is to secure knowledge of high wear locations so that highly sensitive measurement techniques can be incorporated and properly located. Literature exists to help locate such wear locations in pipe and pipe fittings but most of the information deals with slurry flows that have significantly different velocities, different flows steams, e.g., steam, gas-liquid-solids, or made from different materials. To better estimate these high wear rate locations under the WTP conditions a separate pre-test flow loop was constructed and operated. This loop is referred to as the paint loop because it was internally coated with paint, which wears faster than the steel pipe, when a solids-laden slurry is circulated. The test flow conditions were a slurry velocity of 4 m/s in a 0.0762 -m (3-inch) Schedule 40 pipe system, resulting in Reynolds number just above 3 × 10⁵, i.e., turbulent flow at a temperature of 25°C. The slurry was a mixture of water and sand, d₅₀ ∼ 199 microns. This paper describes the test paint loop, its operation, and indicates the high slurry wear locations, as well as a comparison of those locations to existing literature sources.