Influence of tapered thermowell length on temperature measurement

Book · Sun Dec 01 04:00:00 EST 1996

OSTI ID:404310

Zhou, Z J; Motriuk, R W ^[1]

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1. Nova Gas Transmission Ltd., Calgary, Alberta (Canada)

Temperature probe assemblies are frequently subjected to vibrations at their natural frequencies. Centrifugal compressor generated acoustic energy is large enough to excite piping and the temperature probe assemblies attached to it. Vibration of the assemblies leads to their component failures. The thermowell is a main mechanical component of such an assembly and it often fails due to fatigue phenomena. Incidents of thermowell failures at Nova Gas Transmission Limited (NGTL) piping system triggered a complete review of the company standard defining design of a temperature probe assembly. The proposed new standard recommends a reduction of the thermowell insertion length from six to three inches. Implementation of this recommendation changes the mechanical natural frequencies (MNFs) of the temperature probe assembly. To ensure that the modified temperature probe assembly has an adequate temperature measurement accuracy and acceptable response time, a number of heat transfer analyses have been performed. This paper summarizes the analytical results taking into account the following factors: (i) the effects of gas pressure, velocity, and material properties on the accuracy of measurement, (ii) the time required to obtain a reasonable measurement accuracy, and (iii) implications of design changes on the measurement procedure.

• OSTI ID: 404310
• Report Number(s): CONF-960706--; ISBN 0-7918-1780-6
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
MECHANICAL VIBRATIONS
NATURAL GAS DISTRIBUTION SYSTEMS
ON-LINE MEASUREMENT SYSTEMS
SYSTEM FAILURE ANALYSIS
TEMPERATURE MEASUREMENT
THEORETICAL DATA
THERMAL ANALYSIS