I've just been looking at API 521 (2007) and discovered that Sections 5.10.3 and 5.10.4 (on page 28) specifically state that for estimating the relieving flow through a failed inlet and outlet control valves "All flows should be calculated at relieving conditions", i.e. the set-pressure plus...
Thanks for your insights.
If the Flare KO Drum has no internals, isolation valves, or other potential causes of blockage then do upstream vessels that cannot be isolated from the Flare KO Drum need a PSV. JoeWong88 suggests a SAC of A.4.c.4 which says that you can avoid the need for a PSV if a...
API 14C SAC A.4.c.5 seems to indicate that a PSV is required on a pressure vessel (max pressure >5 psig) unless it is the final vessel on a flare header (i.e. Flare KO Drum). However, this implies that any other vessel venting into the flare header (e.g. Closed Drain Sump) needs a PSV to protect...
If you are not already locked into a HYSYS licence than I suggest you look at alternatives that may be better suited to your requirements. In particular, check out the simulator produced by the Virtual Materials Group (VMG).
http://www.virtualmaterials.com/
It has been created by the members of...
Just a follow-up to gr2vessels response.
If the high pressure fluid (tube-side) is a gas or a cold, light liquid that would be vapour at the (shell-side) LP conditions, then a PSV may not react fast enough to give protection against the pressure transients created by tube failure. A...
Reliance on the others to guarantee the performance implies that they are considered to have 'better' experience/methodologies/specialist engineers etc. Unfortunately, such companies are no less subject to the same economic constraints and given the competitive nature of the market may actually...
I would add that a HAZOP Review of the plant would highlight such problem areas and enable them to be documented in an open way acceptable to both client and contractor. The close-out of actions raised by the HAZOP team would require both the client and contractor to sign-off the solutions as...
I couldn't agree more.
Perhaps I have a jaundiced view of the capitalist market but too often the 'progressive' attitudes of management suffer when the company becomes publically-quoted on the stock market. A short-term approach becomes the norm, driven by the need to continue past profit...
Unfortunately, I'm currently working for an international engineering contractor company and we cannot justify the expense of updating the basis of our standard in-house engineering methodologies without the driver of working for a client who requires it.
Production clients (such as yourself)...
UmeshMathur,
Whilst I agree with your sentiments, the standard methodologies used within much of the contracting industry are aimed at reducing the need to apply 'judgement and caution'. Whilst corporate policy dictates the use of internal standard methods, these may not address the use of...
Thanks for the direction to the other thread. The discussion there is very detailed but focused on compression.
I'm concerned more about the impact on sizing relief valves. Using the 'real' ratio in the standard API 520/521 equations for sizing the orifice required for a defined flowrate can...
Since 2000 HYSYS (and possibly other simulators) has calculated a 'real' Cp/Cv Ratio as its default and this can create potential problems if used inappropriately.
As pressure increases the 'ideal' Cp/Cv Ratio typically reduces from 1.4 towards 1.2 but the 'real' ratio can increase from 1.4 to...
If the recycle valve fails open then there should not be any pressurisation of the compressor suction. If the compressor is considered as a black box then taking all the discharge to the suction stops the flow of gas into and out of the box but does not increase the contents (and therefore...
Hysys has been calculating the 'real' Cv value and the associated Cp/Cv since v2.1.3. Prior to that they used the (Cp/Cp-R)- 'semi-ideal' as the Cp value was calculated from the EoS. The result is a Cp/Cv value that appears to be closer to experimental data but can differ considerably from the...
Buchi,
Surely the height of liquid in the sphere to be used for calculating the wetted area for the API RP-521 calc should be the maximum of:
1 25ft minus the distance from the bottom of the sphere to grade (excluding the depth of the burning liquid pool in the bund?)
2 the sphere radius's...
