The intent of TAPPI TIP 0420-14 is to provide a guide that may be used to increase the maximum allowable working pressure of American Society of Mechanical Engineers certified cast iron paper machine dryers. This process, in which no physical change is made to the dryer, is defined as an ?alteration? by the National Board Inspection Code. Machine capacity may be increased by increasing the dryer steam pressure. This benefit may be accompanied by an increase in machine speed. Any increase in machine speed will also need to be considered as dryer rotational velocity additive to the internal pressure stress. This guideline does not address determination of additional stress due to increased machine speed. This guide also provides insight on jurisdictional and insurance provider acceptance, which may be required before any pressure increase is implemented.

This guide does not address a paper machine dryer that was not originally certified to the ASME Boiler & Pressure Vessel Code. A dryer manufactured for use in a jurisdiction or country that does not recognize the ASME Code or follows an alternate set of design and manufacturing standards is not addressed in this guide. Seek guidance elsewhere for dryers that were not certified to ASME Code.