Burrs.
It is called the intake manifold.
Some cars don't require that metal pipe but if you think you need it, you may be able to find one at a junk yard if not, try the auto parts store.
A pipe bending machine is used in a factory to shape large pieces of metal for use in constructing things. This is a good way to get parts made for large projects.
Pipe is threaded outside making it a male end, or inside making it a female end. The pipe in this picture is bizarrely called a " short male nipple"
This is hard to answer with out knowing what type of metal. what the pipe is being used for, the amount of pressure that may be not the pipe.
A frozen pipe is a physical change, as it is just water changing state from liquid to solid (ice). However, a rusted metal bike is a chemical reaction as it is caused by the metal reacting with the oxygen in the air, in what is called an oxidation reaction.
If it is a copper or metal pipe, tap the pipe gentle with a some thing metal (screw driver/small wrench ect...) If the pipe makes a echo sound it is empty, if the pipe has water in it, It will not echo. this also works with pro pain bottles and other metal objects
Corrugated Metal Pipe. CMP
By the color
Non-metal
If the pipe is metal try a metal detector. If plastic, get out your shovel.
The base metal is iron - the active metal is zinc (galvanized)