2 replies to this topic

[Manoj.Selvaraj]

Hi All,

Are there any standards available (SHELL DEPs in particular) for level settings (HH,LL etc) for atmospheric storage tanks. The fluid handled is produced water however even if its crude oil or any other fluid will also do.

 

Regards,

Manoj

[fseipel]

API 2350, overfill protection may be worth reviewing though it is not intended for water storage tanks.  API 650 may also merit review.  In general it depends on fill rate, how robust level sensing devices are, thermal expansion, sloshing/seismic considerations, and response time which of course depends on fill rate and tank volume.  PEI RP 600 may also be worth acquiring.  In past work, in the specialty chemical industry, I prefer fitting tanks with both level transmitters and high level switches, and also a pressure transmitter (to detect vacuum or overpressure/plugged vent).  One advantage of two level transmitters is they can alarm on deviation between their readings.  Automated Overfill Protection Systems (AOPS, typically pump shutoff) are preferred for hazardous materials.  Whether containment is provided and how much may also impact setpoint.  Typical freeboard is 15% for tanks under 500 gal and 10% for tanks over 500 gal (general rule of thumb only).  API 2350 spells out standard terminology/response time between the various 'levels of concerns': HH High High, AOPS Activiation and critical high being the most important.  Critical high is the highest level material can reach without overfill or tank damage.  The standard then establishes that a response time of no less than 5 min or 75 mm, whichever is greater, between the levels of concern (LOC's).  Thus critical high, sets the other LOC values.

[ankur2061]

Manoj,

 

API STD 650 provides a general filling pattern of tanks designed as per this standard in Appendix L6. You may use this to determine your levels such as: LALL, LAL, NLL, LAH & LAHH. The Appendix L6 filling pattern is attached herewith. Please note that API STD 650  is frequently used as a design standard for produced water tanks

 

Regards,

Ankur.

 

PS: The sketch attached used to be present in the 10th edition of API 650 and also mentions that for overfill protection requirements refer API 2350. However, this sketch does not appear in the 11th edition of the same standard for reasons not known.

Attached Files

•  Appendix_L6_API_STD_650.JPG   24.3KB   166 downloads

Edited by ankur2061, 29 September 2013 - 01:36 AM.