Option Explicit
Sub Essai()
If ActiveSheet.Name <> "BDD" Then Exit Sub
Const nature$ = "Petits outillages" '<--- ici : la Nature à chercher
Const local1$ = "USINE": Const local2$ = "BUREAU" 'USINE ==> BUREAU
Dim dlg&: dlg = Cells(Rows.Count, 1).End(3).Row: If dlg = 1 Then Exit Sub
Dim lig&: Application.ScreenUpdating = 0
For lig = 1 To dlg
If Cells(lig, 1).Value = nature Then
If Cells(lig, 6).Value = local1 Then Cells(lig, 6).Value = local2
End If
Next lig
End Sub