Dear colleague fcu45,
First, please clarify for me, what do you intend to do;- are you trying to harm the pipe with grease? It would be easier to blow it to bits, very quick and complete harm. Are you trying to prevent internal corrosion with harmful grease? That's a bit harder, you might need to remove the harmful bits from the grease (or don't add it to the grease). Are you trying to protect internally the pipe to prevent corrosion and you used the word harmful by mistake? There are many different type of treatment you may use for the corrosion protection of structural pipe, inetrnal and external, depending on size, application, etc. One way could be hot dip galvanized (no grease required), if it would fit in the zinc bath. The grease might provide some short term protection, but I wouldn't recommend it for long term.
Please come back with clarifications on what you try to achieve.