[PSUBS-MAILIST] Prestressed concrete pipe

[Marc de Piolenc <piolenc@archivale.com>]

I was recently reminded of my obsession with Eugène Freyssinet's 
advocacy of prestressed concrete for ship and submarine hulls by coming 
into possession of a copy of Nayyar's _Piping Handbook_. That book 
includes a chapter on prestressed concrete pipe which includes some 
information on its manufacture.

I compared the information in Nayyar's book to the prestress levels 
mentioned in the Smith paper on concrete hulls. There are significant 
differences.

For one, the commercial prestressed pipe uses only circumferential 
preload provided by high-tensile wire wrapped around the pipe and 
mortared in place. It makes sense: the pipe is designed to resist 
internal pressure. Longitudinal strength is provided only by a thin 
steel shell whose main purpose is to prevent leaks. Clearly, the product 
cannot be used as is for a submarine. It does not, however, appear 
impossible, or even especially difficult, to incorporate longitudinal 
prestress into the manufacturing process - more specifically into the 
manufacture of the (currently unreinforced) concrete core.

What really bugged out my eyes is the sizes of pipe that are 
commercially available; one type is made in internal diameters up to 
3600 mm - 12 feet!

Marc de Piolenc
Iligan City, Philippines




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