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 210Pb 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 210Pb concentration evaluated. Typical “black-powder” generated in the natural gas pipeline from Campos Basin oilfield contains mainly iron oxide ( 81%) and residual organic matter ( 9%). The 210Pb 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, 226Ra concentration is higher on the pipeline branch between the platform and the onshore installations. 228Ra was only observed in few samples, in particular, in the samples with the highest 226Ra content.