Concerning boiler design (scotch marine) ASME Section IV HG.340 deals with "staying" flat plates. There is no mention of radial (as opposed to horizontal/vertical) staying. HG.345 makes no mention as well, but depicts radial staying for tube sheets in figure HG-345.1(a). Is radial staying allowed for flat plates in boiler design? Also, can radial staying be combined with horizontal/vertical staying on the same plate (i.e. .. a few rows of stays positioned horizontal and vertical, then begin a radially positioned set of stays) ?