neutralise any charge differentials that may exist between the
tank contents and ground. The internal grounding conductor
should run the length of the tank, inside the tank, and be
anchored or somehow secured to the tank bottom. In addition,
all metal tank fittings, such as flanges, hatches, etc., must also be
bonded and grounded. Ironically, NFPA 77 goes on to state that
non-conductive tanks ‘are not permitted for storage of Class I,
Class II or Class IIIA liquids’.
Conclusion
Floating roof petroleum storage tanks and non-metal and lined
production tanks are vulnerable to the effects of lightning, for
unique but related reasons. Best practices indicate that several
mechanisms have been identified to reduce or eliminate these
lightning-related concerns. Several applicable industrial
standards, published both by NFPA and the API, address these
situations and offer practical, achievable techniques to lower
lightning-related risk. Some lightning protection equipment
manufacturers have also responded by designing and
manufacturing equipment to prevent lightning-related ignitions
on these types of tanks.
T&T
References
1. PERSSON, H., and LÖNNERMARK, A., Tank Fires, Review of Fire Incidents
1951 - 2003, Brandforsk Project 513 - 021.
2. Large Atmospheric Tank Fires (LASTFIRE), Project Analysis of Incident
Frequency Survey, June 1997.
3. The entire video can be viewed at
.
4. The entire video can be viewed at
.
5. BEERS, B., Exposure to Lightning Strikes at Injection Well Facilities,
Energy Pipeline Magazine, August 2015.
6. SAE ARP (Aerospace Recommended Practice) 5412, Aircraft Lightning
Environment and Related Test Waveforms, SAE Publications, USA, 2000.
Figure 5.
Lightning flash components (not to scale).
6
Figure 6.
Unequal electrical potentials from lightning
strike near non-conductive tank.
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