NCCER Millwright Practice Exam

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What type of packing consists of layers of packing material between layers of rubber?

Spiral packing
Laminated packing
Compressed packing
Threaded packing

The correct answer is: Laminated packing

Laminated packing is designed with layers of packing material placed between layers of rubber, which provides enhanced flexibility, durability, and compressibility. This design technique allows for better sealing capabilities because the rubber layers work in tandem with the packing material to adapt to surface irregularities and maintain a tight seal under pressure. The laminated structure also helps to distribute the load evenly across the surface, reducing wear and prolonging the life of the packing. In contrast, the other types of packing do not utilize this specific layered design. For example, spiral packing involves a continuous strip that is wound around a shaft or object, while compressed packing typically refers to packing material that is compacted into a space to create a seal. Threaded packing consists of a packing material with a specific thread design, favoring applications that require tight screw-like fitting. Each type of packing has its own unique applications and functionalities, but laminated packing stands out due to its layered construction, making it particularly effective in scenarios where sealing and adaptability to movement are critical.