Alteration (Pressure Vessel)
An alteration is any change to the item described on the manufacturer’s data report which affects the pressure containing capacity or the pressure vessel. Nonphysical (re-rating) such as an increase in the maximum allowable working pressure (internal or external) or design temperature or the addition at loading not considered in the original design, shall be considered an alteration. A reduction in the (minimum) design metal temperature such that additional mechanical tests are required shall also be considered an alteration.
Source: Petroleum Safety Orders–Drilling and Production, Definitions, California Code of Regulations, 8 CCR § 6505, December 2012. Regulations