TPi April 2008

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April 2008 Tube Products International 61
Resistance to slow crack growth (SCG)
We have seen before that SCG is a key parameter
when in comes to lifetime of the pipes; it is now
possible to demonstrate that this new material has
taken yet another step of at least one decade in
the resistance to slow crack growth in the notched
pipe test, and also an unprecedented resistance
to SCG in all of the tests to which the material has
been subjected.
Rauprotect II Rausisto
The increasing demand for heavy-duty gas, potable
water and sewer pipes suitable for the modern
and cost-effective trenchless technologies forced
pipe manufacturer Rehau to develop a new system
solution based on the latest state-of-the-art raw
material, Borsafe™ HE3490-LS-H: the Rauprotect II
Rausisto generation was born.
The design of the Rauprotect II Rausisto system
solution is based on the known stress concentration
at the opposite inner surface of the pipe, while external
point loads and internal pressure are combined for the
whole lifetime of the pipe system.
To archive an outstanding crack resistance to meet new
market expectations and needs, Rehau used the best
available PE100 VRC-Quality Borsafe™ HE3490-LS-H for
the co-extrusion of a thick inside layer of a smooth wall
pressure pipe, with overall measures of the established
European standards EN 12201 / EN 1555 / EN 13244.
This material combination of best PE100+ association-
grades for the outside layer
with Borsafe™ HE3490-LS-H on
the inside layer brings a cost-
effective, technical superior pipe
system quality to the market that
fulfils market expectations and
can be installed with all standard
pipe laying techniques, eg butt-
fusion welding or jointing with
standard-fittings. No expensive
special tooling for the removing
of outside protection layers is
necessary.
The testing institute Dr Hessel
Ingenieurtechnik in Roetgen,
Germany, approved that the
Rauprotect II Rausisto system
solution based on Borsafe™
HE3490-LS-H showed best
results against point loads, and can be used without risk
for trenchless technologies and in trenches without sand
embedding.
To improve the traceability of the heavy-duty pipe system,
Rehau marks all Rauprotect II Rausisto pipes with durable,
laser-marked traceability barcode, according ISO 12176-4
(Code 128, type C) and ISO 13950.
Every produced metre of Rauprotect II Rausisto can be
easily tracked and welded with modern welding equipment
to make pipe laying in the trench easier and safer.
▼ Bimodal Borealis BorStar polymerisation process
▲ Rehau Rauprotect II Rausisto pipes for gas, water and sewage