1. (a) On horizontal-return tubular boilers—on the front head, above the central rows of tubes.
2. (b) On horizontal flue boilers—on the front head, above the flues.
3. (c) On traction, portable or stationary boilers of the locomotive type or Star water-tube boilers—on the furnace end above the handhole. Or on traction boilers of the locomotive type—on the left wrapper sheet forward of the driving wheel.
4. (d) On vertical fire-tube and vertical submerged-tube boilers—on the shell above the fire door and handhole opening.
5. (e) On water-tube boilers—on a head of the steam outlet drum near and above the manhole opening.
6. (f) On Scotch marine boilers—on the front head, above the center or right-hand furnace:
7. (g) On economic boilers—on the front head, above the central row tubes:
8. (h) On any of the above types where there is not sufficient space in the place designated, and for other types and new designs—in a conspicuous place:

The location of the American Society of Mechanical Engineers stamps shall be as follows and same shall not be covered by insulating or other material: