210Pb content in natural gas pipeline residues ("black-powder") and its correlation with the chemical composition

The present work was carried out to assess the Pb-210 content in "black-powder" found in pigging operations on gas pipelines in Brazil, in particular, on the Campos Basin gas pipeline. Additionally, the chemical composition of such deposits was determined and an eventual correlation with Pb-210 concentration evaluated. Typical "black-powder" generated in the natural gas pipeline from Campos Basin oilfield contains mainly iron oxide (similar to 81%) and residual organic matter (similar to 9%). The Pb-210 content ranges from 4.9 to 0.04 kBq kg(-1) and seems to be inversely correlated with the distance to the platforms. On the other hand, Ra-226 concentration is higher on the pipeline branch between the platform and the onshore installations. Ra-228 was only observed in few samples, in particular, in the samples with the highest Ra-226 content. (c) 2005 Elsevier Ltd. All rights reserved.