United States valve standards have a long history, dating back to the first quarter of the 20th century. The first standard to make reference to valves was the Boiler and Pressure Vessel Code, published by ASME in 1915. Although it did not go into detail on design, this boiler document referenced safety relief Valves. The creation of MSS in 1924 opened the door for a number of additional valve-related standards, beginning with the organization