ASME BPVC 2023 Section VI

8.2 PRESSURE GAUGE
8.2.1 General
Each steam boiler shall have a steam gauge or a
compound steam gauge connected to its steam space,
water column, or steam connection. Each hot water
heating or hot water supply boiler should have a pressure
gauge connected to it or to its flow connection in such a
manner that the point of connection cannot be shut off
from the boiler.
8.2.2 Mounting
On a steam boiler, a siphon tube pigtail is required to
protect the gauge from steam. A cock should be provided,
placed on the pipe near the gauge, to facilitate servicing of
the gauge. Piping or tubing for pressure gauge connections
shall be of nonferrous metal when smaller than NPS 1
DN 25. The handle of the cock shall be parallel to the
pipe in which it is located when the cock is open.
8.2.3 Types of Pressure Gauges
Pressure gauges may be either mechanical or electronic.
a Mechanical Gauges Analog. The scale on a water
boiler pressure gauge should be graduated to not less than
112 times nor more than 312 times the pressure at which
the safety relief valve is set. The scale on the dial of a steam
boiler pressure gauge should be graduated to not less than
30 psi 200 kPa nor more than 60 psi 414 kPa.
b Electronic Gauges. Electronic gauges should
1 be powered from the boiler power supply, have a
backup power supply, and have a display that remains on
at all times
2 have a full-scale range of 112 times the safety
relief valve pressure setting
3 be accurate to within ±2 of full scale
4 have a transducer compatible with both liquids
and gases and be temperature compensated
5 have an operating temperature range of 32°F to
250°F 0°C to 120°C unless otherwise required by the
application
8.2.4 Calibration
The gauge used on a boiler should be calibrated at least
once per year. This can be accomplished by comparing it to
a master-calibrated gauge or using a deadweight tester. If
the gauge is damaged or cannot be calibrated to provide
consistent readings, it should be discarded and replaced
with a new gauge.
8.3 CONTROLS
8.3.1 General
Automatically fired boilers may be equipped with operating,
limit, safety, and programming controls that may be
electrically or pneumatically operated. The functions of
these controls are described in 8.3.4 through 8.3.7.