A new testing facility for a high-velocity, three-phase fl ow consisting of a gas fl ow loop and a jet impingement rig is described. Flow velocities between the nozzle and specimen have been determined through computational fl uid dynamics (CFD) simulations and by particle image velocimetry. Tests were conducted on typical carbon steels (J55 and C95) that are used in tubings for the gas and oil industry. Flow conditions of a sweet gas condensate well have been applied. Mass-loss rates have been determined after testing times of between 4 h and 168 h using optical profi lometry. Damaged surfaces were investigated using optical and scanning electron microscopy. The effects of material and fl ow velocity on the mass-loss rate have been investigated. Mass loss of specimens under given conditions is determined by siderite formation and increasing degradation of siderite layer by impacts of sand and fl uid droplets. Degradation happens by erosionenhanced corrosion. Normalized steel J55 behaves like a ductile material resulting in a maximumdegradation rate under small impact angles outside the focal spot. Compared to J55 the quenched and tempered material C95 shows a generally lower depth of attack with its maximum degradation under large impact angles, indicating a brittle behavior. Cementite of pearlite may act additionally as a cathode and accelerate corrosive attack. KEY WORDS: carbon dioxide corrosion, carbon steel, erosioncorrosion, erosion-enhanced corrosion, fl ow-induced localized corrosion, fl ow loop, jet impingement, multiphase fl ow 0010-9312/08/000035/$5.00+$0.50/0

The erosion-corrosion behavior of two corrosion-resistant alloys (UNS S42000 and UNS N08028) has been assessed under gaseous-liquid-solid impingement conditions. Erosioncorrosion impingement tests were conducted at three different impact angles and at three different impact velocities up to 60 m/s, and furthermore, pure erosion and pure corrosion impingement tests were run for UNS S42000, and carbon dioxide (CO 2 ) at a pressure of 1,500 kPa was used as the gas phase. The sand content, with grain size below 150 µm, was 2.7 g/L brine. Artificial brine with a sodium chloride (NaCl) content of 2.7% was used as liquid phase. The damaged surfaces of samples exposed to the high-velocity multiphase flow were investigated using scanning electron microscopy (SEM) and an optical device for 3D surface measurements to assess the depth of attack. Electrochemical investigations according to ASTM G61 were performed to determine electrochemical behavior of tested materials including critical pitting potentials (E pit ) and repassivation potentials (E repass ). Furthermore, the surfaces near regions of the samples tested were investigated using applying atomic force microscopy (AFM), magnetic force microscopy (MFM), and nano-indentation measurements. From the analysis, variation of velocity shows the greatest effect on the degradation rate of both materials. In this paper the erosion-corrosion behavior and rates of two stainless steels are presented. The effects of their chemical composition and mechanical properties are discussed.

The ability to measure polished and strongly reflective surfaces with steep flanks in true color information has been mandatory for the Christian Doppler Laboratory for Localized Corrosion when it came to purchasing a new measurement device to perform meaningful corrosive investigations. Today, the institute uses high resolution 3D measurement device for the evaluation of individual corrosive mechanics, leading to the development of new measures to avoid corrosive attacks.