ASME STP-PT-034:2013 pdf free download.ALIGNMENT 0F SUSTAINEDLOAD STRESS INDICES INTHE ASME B31 CODE.
none of the ASME 1431 codes explicitly define “sustained loads.” But because they are often called out as “susiained loads such as pressure and weight,” sustained loads are understood to mean pressure (internal or external) and weight. In the case of buried pipe, the soil weight on the pipe would also be a sustained load.
In contrast, occasional loads arc loads “such as wind or earthquake” to which we may add pressure transients (watcrhamrncr. explosions, etc.). Finally, thcrmal expansion and contraction loads and loads due to hcrmal gradients constitute (he third cacgory of loads on piping syscins. Unlike ASME VIII or ASME Ill, ASME B3 I does not rcfcr to “primary” or “secondary” loads or stresses.
There arc in the current codes three areas among (he piping and pipeline codes design equations for stresses due sustained loads which descre attention, clarification and possibly improvement. These arc:
a. Consistency of design equations.
Since the stresses caused by pressure and weight in pipes and pipelines arc the same irrespective of application (power, process. pipelines), the ASME Ill and ASME 1331 codes should have the same design equations for sustained loads. This is not the case today.
b. Consistency in thc usc of stress indices and stress intensification factors.
While ASME III uses stress indiccs (Sis such as BC’ and K indices). ASME 1331.1 and 1331.3 usc stress intensification factors (I, and i1, or i). As stated in the request for proposal for this project “since they are defined by principles of engineering mechanics, there should be no differences in stress indices from book to book.” In fact, the SIFs and Sis relate to two different failure modes. and arc different.
ASME STP-PT-034:2013 pdf free download
