When LPG is distributed or transported, it falls in the realm of the CGA (Compressed Gas Association) and its recommended practices. I believe if contact them through the Internet, you'll get all the information you need.
By Installations, I presume you mean storage facilities. The CGA might help you out on this and cite some local regulations and laws that affect your installation or proposal.
The NFPA has a few codes, NFPA 54 National Fuel Gas Code, NFPA 58-LP-Gas Code,
The Texas Railroad Commission has online downloadable stuff on Liquefied Petroleum Gas Safety Rules. Also search for the Texas Natural Resources Code.
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