Recording of local flow disturbances behind obstacles where mesa attack have occurred
- SINTEF Energy, Trondheim (Norway). Multiphase Flow Lab.
- Norsh Hydro, Stabekk (Norway)
Laboratory investigations have demonstrated that flow induced limits for the application of C-steel exist. Flow limits have been found for all types of C-steels investigated. Obstacles in pipes constitute exposed areas for destruction of the carbonate film and determine the maximum allowable production rate rather than the smooth pipe sections. The purpose with the ongoing research project is to connect the strength of carbonate films with stress caused by fluid flow. Flow-induced wall shear stress fluctuations on smooth pipe sections and behind obstacles have been systematically mapped. Mean wall shear stress and shear stress amplitudes have been recorded downstream obstacles in a 69 mm diameter stainless steel pipe with single phase oil flow. The influence from obstacle location, its height and flow velocity on mean shear stress, shear stress amplitudes and dominant frequencies have been studied. The fast K-tubes allowed recording of the instantaneous shear also when the stress cycled to negative values. Relationships for the wall shear stress amplitudes, frequencies and mean values have been developed. The paper shows why weld like obstacles constitute exposed areas. A model has been developed which describes the time to failure of the corrosion product when delaminated from the base metal. This model connects the residual strength of the corrosion product with the fluctuating wall shear from the liquid, its dominant frequency and the mean shear. The model allows transformation of observed flow limits in the laboratory to completely different flow conditions. Simple limits to production rate in the form of wall shear have been found for smooth pipes and pipes with weld like obstacles.
- OSTI ID:
- 350206
- Report Number(s):
- CONF-980316-; TRN: IM9925%%554
- Resource Relation:
- Conference: Corrosion `98, San Diego, CA (United States), 22-27 Mar 1998; Other Information: PBD: 1998; Related Information: Is Part Of Corrosion `98: 53. annual conference and exposition, proceedings; PB: [6600] p.
- Country of Publication:
- United States
- Language:
- English
Similar Records
Acceptance criteria for corroded carbon steel piping containing weld defects
Acceptance criteria for corroded carbon steel piping containing weld defects