What types of joint are used in a boiler along its length and circumference and why? A boiler shell 1 m in diameter is subjected to steam pressure of 2.7 MPa gauge. It is proposed to have a longitudinal double riveted double cover butt joint with number of rivets twice in the inner row. Assume following ultimate strength values. Ultimate tensile strength ou = 352 MPa Ultimate shearing strength t= 256 MPa Ultimate crushing strength ouc= 512 MPa For plate and rivet materials. With machine riveting assume a factor of safety of 4. Sketch the joint and show dimensions. Calculate the efficiency of the joint.