MAWP
MAWP
(OP)
I'm trying to find out what formula is used to calculate the MAWP for presssure vessels.
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RE: MAWP
That is a pretty simplistic answer as for circumferential stress in a cylinder or in a head. It can get more complicated than that once other Code criteria is considered for cone-cylinder junction reinforcing, nozzle reinforcing, etc.
For a complete vessel you would calculate the MAWP for each component. The smallest value of MAWP would govern for the vessel.
For example, in ASME Section VIII Division the required thickness for a cylinder (based on circumferential stress) is given:
t = P*IR/(S*E-0.60*P)
But if 't' is known then the maximum pressure is found as:
P = S*E*t/(IR+0.60*t)
You have to subtract the static liquid pressure from this maximum pressure to get the MAWP.
RE: MAWP
TomBarsh gave you really good advice for vessels (since this is the "boiler and pressure vessel forum", that was probably a good way to go), but since your handle shows up as "petroleum" I'd like to add that for piping outside of a facility the calculation is dominated by location factors (e.g., population density) that are described very well in ASME B31.8.
David
RE: MAWP
RE: MAWP
RE: MAWP
Personally I hate MAWP. Its easy to ask for but can be hard to live with.
RE: MAWP
RE: MAWP
But as mentioned above there is no Code requirement (ASME, at least) to calculate the MAWP. In ASME Code the design pressure may be used in lieu of the MAWP for purposes of calculations, name plate, etc. Doing so simplifies a lot of issues but at the expense of greater flexibility for process design.
RE: MAWP
I mention the corrosion allowance since in general the corrosion allowance is an extra thickness that the designer defines depending on a relative criteria. So, it can be said that the easiest way to increase a MAWP is changing your mind about the CA value. (Of course, it is suposed that the CA should be defined on a correct basis).
Also, emphazising what Tombarsh said if there is a weaker component in the vessel, for example, a lower class flange, a thin neck, certain type of weld, etc., the MAWP would be the pressure that this component would resist.
RE: MAWP
RE: MAWP