ASME Requirements for External Piping


On January 1, 1999 ASME, Section I Power Boiler Code (high-pressure steam or high temperature water) began requiring documentation and hydrostatic testing of all external piping. ASME requires this procedure on all new boilers after December 31,1998. Some changes have been incorporated in Section I, which clearly differentiates between what is considered boiler external piping and their respective testing requirements.
This external piping must be documented on the Manufacturer’s Data Report and a hydrostatic test of piping at 1.5 times the design pressure must be conducted. An Authorized Inspector must witness it. For piping supplied and installed in the field by someone other than the boiler manufacturer, the piping is to be documented on the manufacturer, the piping may be documented on the boiler data report or on a supplemental form P-6.
This change affects piping to all external valves, including bottom blowdown, surface blowdown, feedwater chemical feed, vent and any piping between boiler and steam valves or hot water supply/return valves. When two or more boilers with manholes are connected to a common steam header, steam piping must include the full assembly to the second (downstream) valve. Installations with two or more boilers fed from a common feedwater pump must include certification and testing of piping up to and including the by-pass valves on the regulating feedwater valve. If a 3-valve by-pass is not included, piping must be included to the regulating valve.
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