Think for a moment about that question.....

"Is there also a clause in the master agreement that will prevent TPL to buy PTSC outright and turn it private?"

The Master Agreement is between TPL and PTSC, correct? So it doesn't matter if there are words in this regard or not. What you suggest would be an arrangement between the parties of that agreement. If the parties to an agreement agree to change the agreement, there is nothing stopping them from doing so (i.e., it's kind of a goofy question). Contracts, such as the Agreement, are always subject to change through bilateral/mutual agreement of the affected parties.

Thus, what you suggest (if not with PTSC's consent) could only be done through a hostile take-over. This led to my first post on this. My apologies, but it appeared the only obvious thought process.

SGE