I realize this is not directly linked to railway preservation, but I have noticed a number of people on this board that have at least some knowledge of the ASME Code so I thought I would bring to the community something I recently discovered in the 1951 API-ASME Unfired Pressure Vessel Code that I feel is rather amusing. While working on a rerate for a vessel manufactured in 1952 to the 1951 Code, I noticed on the Data Report (today called an ASME Form U-1, Manufacturer's Data Report) that a portion of the vessel had been subjected to a "Proof Test" a process still available to manufacturer's as a way of proving the design of a vessel when the rules for design of a particular vessel is not clearly provided for within the Code. When I looked up the 1951 definition of a proof test I found the following in paragraph R-526(d):

"The component parts of the vessel in which stresses cannot be computed satisfactorily shall be coated with a lime wash or other brittle material...Not more than one coat shall be applied and the test shall not be conducted until the coating has become thoroughly dry and brittle...a test pressure shall be applied gradually until either a pressure of 1 1/2 times the assumed allowable working pressure is reached, or until strain lines or flaking off of the brittle coating indicating yielding of the material in that portion of the vessel."

In an era before the common use of strain gauges and before 3D modeling and FEA analysis this simple shade tree method was the order of the day. Pretty cool I think.

S.O.