Pipes and tubular conduits – Flexible – Distinct layers
Reexamination Certificate
2003-01-06
2004-02-03
Brinson, Patrick (Department: 3752)
Pipes and tubular conduits
Flexible
Distinct layers
C138S140000, C138S141000, C138S142000, C428S036910
Reexamination Certificate
active
06684910
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to a pipe of coaxial layers of thermoplastic olefins, which jointly form the wall of the pipe.
For a known pipe of this type (DE 299 06 998.2 U1), the pipe consists of an outer and an inner layer, the inner layer of which has the FNCT (full notched creep test) or NPT (notched pipe test) value of a single-layer pressure pipe and the outer layer of which has an FNCT or NPT value, which is higher by a factor of at least 3.
SUMMARY OF THE INVENTION
Starting out from this, the invention is concerned with the problem of increasing the load-carrying capability of the pipe while it is being and after it has been laid.
All of the layers of the inventive pipe consist of a material, which has not been cross-linked, so that the ends of the pipes can be joined together reliably, without problems, with all normal connecting techniques, such as electric sleeve or butt welding. The pipe, moreover, can be recycled without problems, since interfering, cross-linked regions are not present. Moreover, the pipe is exceptionally durable, since the crack growth in the outer layer, notch-stressed during laying, especially when laying without a trench, is a very low. This is the case particularly also at the low temperatures, which are encountered by pipelines, laid end-to-end for water, gas, etc. In particular, however, the pipe also withstands high point loads, such as those, caused, for example, by stones, since the innermost third layer, because of its increased FNCT or NPT value, can absorb, without a damage, the significantly higher tensile stresses in the inner layer, which occur during point loads.
The first and third layers may have an FNCT value, which is higher by a factor of at least 5, and an NPT value, which is greater by a factor of 2.5 than the corresponding values of the second layer, if this is desirable for overcoming special loads.
All layers of the pipe are combined by melting or welding into a pipe unit, which behaves like a single-layer pipe, the pipe with its three layers having a standard external diameter and a standard ratio of external diameter to total wall thickness (SDR) which is generally 11 or 17.
REFERENCES:
patent: 4211595 (1980-07-01), Samour
patent: 4892442 (1990-01-01), Schoffner
patent: 5472754 (1995-12-01), Douchet et al.
patent: 6287657 (2001-09-01), Gebizlioglu
patent: 6433095 (2002-08-01), Laurent
patent: 6569948 (2003-05-01), Laurent
patent: 6579922 (2003-06-01), Laurent
patent: 2002/0156214 (2002-10-01), Laurent
patent: 2002/0161157 (2002-10-01), Laurent
patent: 29706045 (1997-06-01), None
patent: 29906998 (1999-07-01), None
patent: 0358178 (1990-03-01), None
patent: 1046849 (2000-10-01), None
patent: 1008960 (1999-10-01), None
Guettouche Ali
Koestring Volker
Schroeder Helmut
Stoffelsma Jan Uilke
Brinson Patrick
Jordan and Hamburg LLP
Wavin B.V.
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