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An operating load case describes a specific condition of a piping system with defined temperatures, pressures, contents and, where applicable, further loads.
An operating load case describes the piping as it actually is in a particular operating condition: with a temperature for each section, a pressure, a state of filling and the movements of the connected equipment. Unlike the design load case it is not an upper bound but a snapshot.
A stress analysis normally contains several of them. A single case “everything hot” describes only the simplest plant completely.
Which operating load cases have to be considered follows from the mode of operation – and needs to be clarified with process engineering and the owner.
The operating load cases yield the quantities that determine the everyday life of the line: displacements at every support, loads on supports and structure, connection loads on equipment in the hot condition, and the sizing of spring hangers with hot and cold load.
For the thermal expansion stress check it is not a single condition that counts but the difference between two. What governs is the largest stress range occurring between any two conditions – the cold installed condition included.
Two parallel pump trains, one hot and one cold, load the common header differently from two hot trains: the cold train holds where the hot one wants to push. Such mixed conditions frequently produce the highest connection loads but appear in no design table.
The reference temperature is part of the load case too. Thermal expansion is calculated against the temperature at which the line was installed; for cryogenic lines or installation in winter this is not a minor detail.
What Entracon offers here is on the matching page.
See what we offer| Load case | Train A | Train B |
|---|---|---|
| Installed condition | cold | cold |
| Normal operation A | operating temperature | cold, on standby |
| Normal operation B | cold, on standby | operating temperature |
| Changeover | operating temperature | operating temperature |
| Steam-out | steam-out temperature | steam-out temperature |
The design load case is the most severe condition, used to size wall thickness and rating. The operating load case is an actual condition; displacements, support loads and connection loads follow from it.
As many as the plant has distinguishable conditions. For a single line between two items of equipment one may suffice; branched systems with redundant machinery often need several.
The temperature of the respective operating load case, relative to the installation temperature. Some project specifications require the design temperature instead; this is permissible but gives higher forces than occur in operation.
One short conversation usually settles more than three quotations. Call or write — you will reach an engineer directly.
Start typing – for example “balancer”, “SAP” or “pipe stress”.
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