Please help me out with the detail regarding minuimum percentage of NDT to be done in construction of high pressure boilers with reference to relevant codes Standards (ASME).
The amount of non-destructive testing depends upon the design safety factor used for the boiler, which in turn determines the plate thicknesses used to fabricate it. The design safety factor is determined by the types of welds used and the amount of radiographic inspection performed on the welds. These are all as specified in the code. After completion of fabrication of the boiler and of all radiographic inspection, the boiler must then be hydrostatically pressure tested to 1 1/12 times the design pressure. Spot radiography of all the welded seams is usually performed as a minimum, but in many cases the shell will be 100% radiographed to save on material and fabrication costs. An increase in the amount of radiographic inspection allows them to use thinner plate materials.
