Many factors can cause a leaky tank such as; heat, sudden temperature or altitude (pressure) changes, or filling a tank without repressurising (taking a few puffs). Other factors include; cracked, ripped, or swollen seals (damaged seals are most often the cause), cracked or chipped glass, worn out threads, pins and hinges, or any other factors that will not let the tank pressurize and let air in. An old or worn out coil will also cause a tank to leak as the wick degrades over time and loses its structure.