Q & A > Storage Tanks and Terminals
Date  Replies
12/12/2018 Q: What is best practice for design of dewatering systems on pressurised LPG storage spheres and how is this affected (if at all) if the installation is located in an extreme cold climate? Is manual or automatic draining recommended? Automatic drain systems are likely to be a more complex design.
For example, a new-build design might be fully automated and comprise a 2" nozzle with a remote-operated, accessible fire safe primary isolation valve at minimum distance followed by a dewatering pot with an interface level sensor. The interface level sensor would throttle a control valve with bypass on the dewatering pot drain line and an independent lo lo interface level sensor would trip closed the primary isolation valve and de-energise the solenoid on the downstream interface level control valve to force it closed. The trip system would also impose an output high limit of 0% on the interface level controller forcing its output to zero to avoid the valve bumping open when the trip is reset. The dewatering pot would have a hard-piped connection to flare and a hard-piped connection to a closed drain. The interface level sensor would have a local repeater indicator visible from the bypass valve. The drain line would reduce to 3/4" diameter downstream of the control valve (this serves as a restriction orifice on the drain system). It would be designed to be self-draining with no pockets and would be well-braced to minimise vibration while in operation. The number of flanges in the system would be minimised and the majority of joints would be socket-welded (screwed fittings not allowed except perhaps for instruments). Cold climate considerations (also mitigating Joule-Thomson expansion effects) might include electrical tracing on the dewatering pot drain line with a common alarm to DCS on tracing circuit failure and provision for methanol (anti-freeze) injection into the dewatering pot flare connection.
 
26/10/2018 Q: Kindly advise that if a leakage arises from LPG tank lorry during filling operation, how should the leakage be handled? Are there any code and standards that outline what exact steps we need to take in case of a leakage?  
25/09/2018 Q: Our naphtha sample from crude distillation unit went off on chloride content with result showing 1.3 ppm.So we checked organic chloride in our crude tank. The result showed presence of organic chloride in that particular crude tank. So that tank is kept blocked and we resumed to our normal operation.
We did many brain-stroming and looked for solution.
Can the experts in this forum please suggest how to process this crude having high organic chloride. Is there any chemical treatment available. How can this problem be solved?
(6)
08/09/2018 Q: Naphtha vapours are observed at manway lid of roof top when its opened . Mild naphtha vapours are also observed at roof drain of the storage tank when its opened. Generally roof drain of the storage tank is kept in open condition only . The storage tank is of Internal Floating Roof type . Tank safe height is 10.75m . Generally tank height is maintained at 9 m or lower. Tank outlet Temperature is between 36 to 42deg. Let me know why naphtha vapours are emanating from roof tanks and roof drains. I dont think there is swivel joint leak .
(2)
07/08/2018 Q: What are the safety precautions that must always be taken before entering the Confined Space Work in order to install the floating suction inside the tank? (1)
27/06/2018 Q: High content of solid particles in crude oil or Delayed Coker feed can cause accelerated fouling in the furnace.
Has anyone experience on how to measure solid particles concentration and particle size distribution in crude and/or vacuum residue? I have seen the use of laser difraction or particle counter for other products (kerosene, lubricants, etc) to measure both total content and particle size, but I am not sure if this could be succesfully applied to vacuum residue.
What is the maximum solid concentration recommended to avoid fouling issues?
What is the maximum solid particle size recommended?
(4)
26/02/2018 Q: I have been entrusted with the task of assigning line numbers to refinery circuits, not something of which I have any experience or training. Are there any industry standard numbering conventions?  
12/10/2017 Q: How do we calculate the bblpd to mmtpa if we have one month shutdown once in a year? (2)
31/08/2017 Q: How do you estimate the approx. quantity of sludge in a crude tank before handing over for Tank Cleaning? (1)
29/08/2017 Q: What is the best way to re-process Fuel Oil Blend Stock (FOBS) or waste that contains 20-30% water and sediments?
Any recommended third party company doing this job?
Any way to sell such material?

(3)
29/08/2017 Q: In our plant we have three floating roof tanks, it's receiving crude oil from the field and the same pump out the oil to the terminal for export. The production still the same no change, but when we stopped the shipping pumps to the terminal next day the production decrease. What accounts for this?  
24/07/2017 Q: Is a microbiological assay for storage tanks necessary? (3)