To avoid plastic shavings turning into powder when cutting pipes, you can try using a sharp blade or cutting tool specifically designed for cutting plastic pipes. Make sure to cut the pipe slowly and steadily, applying even pressure to prevent the shavings from becoming too fine. Additionally, you can try using a cutting guide or a clamp to stabilize the pipe during cutting, which can help control the shavings. Finally, cleaning the cutting tool regularly and ensuring it is in good condition can also help prevent the plastic shavings from turning into powder. **

The valves on heating pipes are typically ball valves or gate valves. Ball valves have a spherical disc inside that controls the flow of water by rotating the handle, while gate valves have a gate or wedge that moves up and down to control the flow. Both types of valves are used to regulate the flow of hot water through the heating system and can be manually operated to adjust the temperature or shut off the flow completely. **

Longitudinal turning involves cutting along the length of the workpiece, while face turning involves cutting across the face of the workpiece. Longitudinal turning is used to create cylindrical shapes and grooves, while face turning is used to create flat surfaces and contours. Additionally, longitudinal turning is typically used for creating external features, while face turning is used for creating internal features. **

Turning off refers to the action of deactivating or shutting down a device, system, or appliance. This typically involves stopping the flow of power or energy to the device, causing it to cease functioning. On the other hand, turning on refers to the action of activating or starting a device, system, or appliance. This involves initiating the flow of power or energy to the device, allowing it to begin functioning. In essence, turning off stops the operation of something, while turning on initiates its operation. **

A turning point with a horizontal turning tangent occurs when the slope of the curve at that point is zero, meaning the tangent line is horizontal. This indicates that the function changes from increasing to decreasing or vice versa at that point. In other words, the function reaches a maximum or minimum value at that point. This type of turning point is also known as a stationary point. **

Face turning and longitudinal turning are two different types of machining operations used in metalworking. Face turning involves cutting material from the surface of a workpiece to create a flat surface, while longitudinal turning involves cutting material from the length of the workpiece to create a cylindrical shape. In face turning, the cutting tool moves perpendicular to the workpiece, while in longitudinal turning, the cutting tool moves parallel to the workpiece. Overall, the main difference between the two is the direction in which the cutting tool moves in relation to the workpiece. **

There could be several reasons why it's not turning. It could be a mechanical issue such as a broken or worn-out part, a lack of lubrication, or a problem with the power source. It could also be an electrical issue such as a faulty motor or a problem with the wiring. It's important to troubleshoot and diagnose the specific problem in order to determine the best course of action to fix it. **

It is unclear what "that" refers to in the question. If "that" refers to a specific object or device, please provide more context so that I can accurately answer the question. **