Ground joints, also known as "Boss" fittings, provide a convenient NPT threaded fitting for higher pressures.
The spud portion of the fitting is usually fixed permanently to the equipment, and the stem and nut attached to the hose are the other half. Rotate the wing nut on the spud to easily achieve the seal on a tapered seat.
Normally provided in iron, but steel is also available.
Recommended for steam service up to 450F.