What is Weightless or As-built when considering gapped supports?
Gaps may be specified to be set either As- built (weighted) or weightless. If a gap is As- built, it is assumed to be open (i.e. no support) for the gravity load case, then it is set to the specified gap AFTER the gravity load is applied. The stop will then engage only if the pipe displacement due to thermal expansion or any other loads exceeds the gap. In effect, a support with an As- built gap moves with the pipe for gravity load, then remains stationary for thermal and other loads. On the other hand, if the gap is specified in the weightless condition, the gap can change when the gravity load is applied, and the stop may engage. There is one important exception. If a value of zero is specified for any gap, it is always assumed that this zero gap is of the weightless type (i.e., the corresponding stop may engage under gravity load). This is done because we have found that users will generally assume that a zero-gap support acts in this way. If a gap is required to be zero and to be s
