A stud or stud-bolt is a round metal bar screwed at both ends or fully screwed. Engineered stud bolts can also have flanges at a set distance from one screwed end, which provides a positive collar against which the stud is tightened. Studs are used with anchor fixings in civil and architectural engineering and when fastening machinery to concrete flooring. It has many advantages such as improved stress concentration factors are possible, uniform section reduces local material variations, less clearance required on holes allowing more accurate assemble and studs with two nuts can be tightened from either side of joint. There are also engineering applications when stud bolts (with two nuts) are used in place of bolts. These are generally highly loaded, large diameter, long bolted items for which the material control and heat treatment is more economically completed on a stud as opposed to a bolt. For high load-high duty applications, high strength stud-bolts can provide significant advantages if properly engineered.
Studded Tubes are used to assist ignition and to promote complete combustion for sections of the furnace where maximum temperatures are desired. Studded tubes are used in reheaters in refineries and in the fluidized bed of an FBC boiler. The tubes are securely welded with studs to increase the surface area for better heat-transfer.