Hi Joey, mnpt stands for Male National Pipe Thread Taper (MNPT), sometimes called NPT or MPT. It means the threads are on the outside of the connector. As others have said, it means Male National Pipe Thread, which is a Standard.

FIP means Female Iron Pipe. MIP is Male Iron Pipe. As the Pure Water Gazette points out, sometimes FIP is called FPT or Female Pipe Thread. And MIP is called MPT or Male Pipe Thread. You can also find a brass compression to MIP elbow on the end of water hoses used in dishwasher kits.

The compression fitting with cap connects a tube to the fitting. MIP stands for Male Iron Pipe, or some would say Male International Pipe. The same pipe size can also be called MPT, for Male Pipe Thread. FIP means Female Iron (or International) Pipe and can also be called FPT for Female Pipe Thread.

Pipe Fittings Dimensions Tolerance as per ASME B16. 9

Yes, NPT (national pipe thread) has the same thread dimensions as an MIP (male iron pipe) and FIP (female iron pipe).

Male Iron Pipe
M.I.P.: Male Iron Pipe. Describes an external pipe thread end connection, typically threaded into a F.I.P. end connection.

The long radius elbow refers to the outer diameter of the tube whose radius of curvature is equal to 1.5 times, that is, R = 1.5D. A short radius elbow means that its radius of curvature is equal to the outer diameter of the tube, ie R = D.

If your elbow is a short radius it is 1 times your nominal pipe diameter. If it is a long radius it is 1 1/2 times your nominal pipe diameter.