A steam boiler, 3 m in diameter, is made of 25 mm thick mild steel plates. The efficiency of longitudinal riveted joint is 88% and that of circumferential riveted joint is 70%. Calculate the permissible steam pressure if the maximum tensile stress in the plate section through the rivets is not to exceed 120N/mm2. Also Determine (a) Circumferential stress in the solid plate section, and (b) longitudinal stress in the plate section through the rivets.