The Power Pipe Ruins is a location in Xenoblade Chronicles. It is located south of Ulna Passage on the Fallen Arm, and is where Reyn and Sharla wake up after falling from Galahad Fortress. This is also where the Oath Sword is found, required for The Oath Sword. An Ice Ether Crystal Deposit containing Chill Plus IV and Auto-Atk Stealth IV gems can be found here.
After leaving this location, it cannot be reached again until the Mechonis Key is received for completing The Wilted Flower. The key is used to activate the Pressure Control Device west of Ulna Passage, revealing a wall which can be climbed to reach a passage leading to the Power Pipe Ruins.