standard of pressure gauge accuracy class for boiler hydrostatic test

[PJesus]

I have to witness the power boiler hydrostatic test but I have no detail about the pressure gauge conditions. I am finding the requirements from ASME Code B31.1 which accuracy class is not specified. where can I get this info? and what is the maximum typical error percentage of the pressure gauge used for boiler hydrostatic test?
thanks.

 

[weldstan]

Standard gages have + or - 1% accuracy. Look at the gages, it's written on them. Grater accuracy can be obtained with digital gages.

 

[danw2]

It's not just a given gauge by itself; it's the pressure gauge PLUS the calibration certificate and its uncertainties from which correction values are used to get a 'corrected' pressure value.

From the 2 page article on pages 6 & 7, entitled Calibration.

http://www.nationalboard.org/sitedocuments/bulletins/fa2013.pdf

^Link

"The National Board Inspection Code (NBIC) and Sections I, IV, VIII, X,and XII of the ASME Boiler and Pressure Vessel Code require the ASME certificate holder or R stamp holder to have a system for the calibration of all test and measuring equipment (see Table 1).

Although measurements are required, the accuracy of most measurements is not defined. The codes do not require the certificate holder to purchase the most accurate measuring equipment available, and accuracy of measuring and test equipment may degrade over time because of wear from use and handling. As a result of inherent and cumulative inaccuracies, the values from the test or measuring device (test device) may not be true values. Calibration is the means of correcting the inaccuracies of the test device."
<snip>
"During a hydrostatic test, pressure gage readings are corrected to true pressure via the calibration curve or table."