Temperature measurements shall be performed by Pt 100 elements (RTD – Resistance Temperature
Device) in accordance with EN 60751.
For temperature measurements above 600 degrees C, thermocouple material Chromel Alumel, type
K, in accordance with EN 60584-1/2 should be used.
Temperature transmitters shall be included within the sensor head except for motor winding
temperature measurement and similar.
Temperature sensors not accessible during operation shall for the selected critical equipment be
installed with backup.
Surface mounted temperature elements may be used if accuracy and response requirements are met.
Thermowells shall be of the flanged type, size 1.5″. For tanks, vessels and piping with pressure class
2500 lb and above, the size shall be 2″.
For non-critical utility service, thermowells of threaded type, NPT, can be accepted.
Thermowells shall not be longer than strictly necessary to obtain required accuracy and to avoid
Thermowell strength calculations shall be performed for process hydrocarbon systems according to
ANSI/ASME Performance Test Codes 19.3.-1974, chapter 1, section 8-19 thermowells.
Thermowell inner diameter suitable for TE/TI elements of 6 mm should be used.
Bi-metallic temperature gauges with 100 mm nominal head diameter should be used for local
Temperature gauges with capillary tubing should not be used.