The allowable working pressure of expansion joints may vary greatly and depends on several factors. Generally, it varies with the material of a bellow. The bellow is a flexible element in the expansion joint. Factors such as the size and working temperature of the expansion joint or the type of medium flowing through it, are also very important. The lowest allowable working pressure is that of fabric expansion joints. Because of the material used in their construction, the pressure cannot normally exceed 0.5 bar overpressure. Both rubber and PTFE expansion joints can withstand much higher working pressure, which can reach a maximum of 25 bar and 16 bar respectively. Steel expansion joints are manufactured to handle the highest allowable working pressures, which can reach 100 bar and depends on the size and type of the expansion joint.