Pipes and tubular conduits – Plural duct – With spacer and encircling element
Reexamination Certificate
1999-09-16
2001-03-13
Brinson, Patrick (Department: 3752)
Pipes and tubular conduits
Plural duct
With spacer and encircling element
C138S114000, C138S113000, C264S045700
Reexamination Certificate
active
06199593
ABSTRACT:
DESCRIPTION
The invention relates to a process and apparatus for producing insulated pipes by introducing a mixture for the preparation of polyisocyanate polyaddition products between a carrier pipe and an outer pipe running parallel to the carrier pipe and reacting the mixture to give foams containing polyisocyanate polyaddition products, and to the pipes which are insulated with foams and which can be produced by this process.
The invention also relates to a double-pipe system made from an inner carrier pipe and an outer pipe arranged parallel to this, where a holder which can be moved axially is arranged between the two pipes and positions the carrier pipe in the outer pipe and is provided with at least one aperture for the introduction of mixtures for the preparation of polyisocyanate polyaddition products.
The invention also relates to a holder which is designed so that it can be displaced in an axial direction between a carrier pipe and an outer pipe running parallel to the carrier pipe and positions the carrier pipe in the outer pipe and includes at least one aperture through which mixtures for the preparation of isocyanate polyaddition products can be distributed.
The continuous and discontinuous production of insulated pipes, which are used, inter alia, in the heat-transmission industry, is well known and is described, for example, in the Huiting GmbH company publication (5/96 issue, pp. 30-33, Huting GmbH, Heidelberg, Germany).
In the discontinuous processes, mixtures for the preparation of rigid polyurethane foams are usually introduced with high pressure and high delivery rate into the space which is to be filled between an inner pipe to be insulated, also called a carrier pipe below, and an outer pipe which serves to protect and to stabilize the insulated inner pipe. In these processes, a disadvantage is the exacting requirements placed on the mixtures, which must be sufficiently free-flowing.
In known continuous processes, the mixtures for the preparation of the rigid foams may be applied onto the carrier pipe, and a film, for example, is then used during the foaming process as outer pipe, also termed jacket pipe below. It is also known that the carrier pipe may be laid into mixtures for the preparation of the rigid foams, these mixtures being applied onto the film. A disadvantage in these processes is the high equipment cost, since the pipes must run through a pressure belt during the foaming process in order that the films can withstand the pressure which the foaming process creates. The processing in particular of signaling wires which run within the foam is moreover complicated.
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EPO Search Report.
BASF - Aktiengesellschaft
Borrego Fernando A.
Brinson Patrick
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