What must be verified before applying pressure on the dies?

Before applying pressure on the dies in a pipe fitting or similar application, it is essential to ensure that there is a presence of oil running to help start the segments on the pipe. This is crucial because the lubrication provided by oil reduces friction, aids in the smooth operation of the dies, and ensures that the segments can properly engage with the pipe material during the pressing process. Without adequate lubrication, the dies may not function effectively, which can lead to premature wear, damaging the dies, or even causing improper fittings, which can compromise the integrity of the pipe system.

The other factors listed, while important in their own right, are not as immediately critical as verifying oil presence. Correct alignment of the pipes is vital to ensure proper joint formation, but it does not directly influence the initial operation of the dies. The temperature of the dies can affect performance, especially in certain materials; however, it is not as essential as lubrication for preventing damage during the pressing. Knowing the type of fitting used is important for compatibility, yet it does not directly impact the operation of the dies at the initiation of the pressure application. Therefore, focusing on the presence of oil helps ensure that the process can begin safely and effectively.