Pressure vessel head

In combination with a pressure vessel component such as cylindrical shell, a head comprising:

• a circumferential base stiffener attached to the end of the pressure vessel component;
• a plurality of meridional stiffeners attached to and extended outwardly from the base stiffener and converging toward the center of the head, the stiffeners being generally tapered in cross-section, with their inwardly presented surfaces being wider than their outwardly presented surfaces, the stiffeners further being stepped in cross-section so as to have alternate shoulders and lands;
• a plurality of curved plates located between each pair of adjacent meridional stiffeners, with the plates overlying each other and adjacent plates being directly against each other, the plates between each pair of adjacent meridional stiffeners being progressively larger in surface area, with the plate of smallest surface area being presented inwardly and the plate of largest surface area being presented outwardly, all to accommodate the taper of the stiffeners, the plates between each pair of adjacent meridional stiffeners being positioned and configured such that the shoulders of the pair of stiffeners are located opposite to the side edges of the plates and the lands of the pair of stiffeners underlie the peripheral portions of the plates;
• and welds extended along the peripheral edges of the plates and along the base and meridional stiffeners to join the plates to those stiffeners, the welds for successive plates being offset by reason of the variance in the surface areas of the plates between pairs of meridional stiffeners.