ASME standard PTC 19.3 for thermowells undergoes major revision

摘要

COMPANIES that source thermowells for oil, gas and petrochemicals applications will now need to consult the new, revised ASME PTC 19.3 (2010) standard, which has just undergone its first major revision in more than 35 years. This is likely to encourage engineers to seek out better, alternative, more innovative thermowell designs for process pipelines. The original standard worked on a frequency ratio of f s < 0.8 f c but now this has changed to a more complex process whereby the cyclic stress condition of the thermowell needs to be taken into account. If the thermowell passes the cyclic stress then the ratio of f s < 0.8 f c is still applicable. However, if it fails, then the ratio of f s < 0.4 f c is applicable. Also of concern to manufacturers and end users is that the standard only applies to thermowells with a service finish of 0.81ìm (32ìin.) Ra or better.