May 18 (Reuters) - French steel pipe maker Vallourec said on Wednesday it was starting a process to close its German manufacturing sites as it had failed to find a "credible" buyer for the assets.

The firm, which in November announced plans to dispose of its German assets and relocate its oil & gas activities to Brazil, said the closure process would take place over the next two years and include the sale of land and buildings. (Reporting by Olivier Sorgho, editing by Kirsten Donovan)