A thread protector is used to protect the threads of a pipe during transportation and storage, can be used on Casing Pipe, Tubing, Drilling Pipe. 

They are generally manufactured from plastic or steel and can be applied to the pipe manually or automatically (by machine), and they are used frequently in the oil and gas industry to protect pipes during transportation to the oil and gas fields. 

And there are mainly 2 categories: HDPE Plastic Thread Protector, Metal Thread Protector. 

Commonly the price for plastic thread protector is lower than that of metal plastic composite protector. Because there is steel material attached on second type. For Tubing, plastic thread protector is always the choice. Most popular sizes are : 2-3/8, 2-7/8, 3-1/2, 4, 4-1/2, 5, 5-1/2, 6-5/8.