JEC COMPOSITES MAGAZINE - Issue #119 - March 2018 - 66

SOLUTlONS civil engineering

Repair and replacement of concrete
pipes with carbon composites

FraNcesc robles,
Technical Director
saturNiNo oJeda
Director
Navec Group Applied
Engineering

M

any plants in the
industrial sector, not
only nuclear power
plants, but also petrochemical,
chemical, electric generation,
fluid transport, and other
installations, are faced with a
major challenge regarding the
conservation and repair of the
refrigeration systems used for
the facilities or equipment, or
even water treatment.
All these facilities are of similar
age and, due to their long time
in service, they suffer from the
common corrosion and degradation problems of conventional
materials such as carbon steel
and reinforced concrete. Most
of them are buried systems with
great intervention and access
difficulties, in addition to high
operation costs.
Scope and description
Navec, Saertex and Henkel
shared their knowledge and
know-how in their respective
disciplines to develop a safe,
reliable, durable and innovative

66

This paper describes the in-situ manufacturing of a carbon fibre pipeline by
means of an epoxy resin infusion process followed by vacuum consolidation.
The process uses as a lost mould the existing reinforced concrete pipe with
steel core in poor condition, which serves for the cooling process of a nuclear
power plant reactor. The carbon fibre pipeline, which is buried at a depth of 4
to 9 metres, is designed to provide by itself the required structural resistance
and tightness, without considering the contribution of the existing pipeline.

solution for in-situ manufacturing of a carbon fibre pipe
using epoxy resin infusion
and vacuum consolidation
technology, a solution offering
the most economical, fast and
viable alternative. This innovative system was already used
successfully in the rehabilitation
of the tertiary cooling system of
a nuclear power plant reactor in
Spain, as well as in other facilities, using the existing pipe in
poor condition as a lost mould.
The new carbon fibre pipe - 800
mm diameter and 1,525 metres
in length - is buried at a depth
of 4 to 9 metres. It includes
horizontal, vertical and inclined
sections, and different elements
such as elbows, tees, flanges and
manholes.
Design, calculations and
characterization tests
A finite element modelling of
the complete system was carried
out to define the carbon fibre
laminate according to the design
requirements, considering that the
residual resistance of the existing
pipe is zero, so all the loads are
supported by the new carbon
fibre pipe (permanent loads,

jec composites magazine / N°119 March 2018

own weight, fluid weight, internal
pressure, terrain actions, traffic
actions, thermal actions and seismic loads). Likewise, calculations
were carried according to the
ASME CASE N-589-1, ASME
PCC-2 and ISO 24817 standards
without considering the substrate
contribution.
For each fitting or installation
element (sections, elbows, tees,

flanges and manholes), the
configuration of each carbon
fibre layer was designed, as well
as the overlap and dimensions.
Self-adhesive SAERfix carbon
non-crimp fabrics from Saertex
were used in this case. These
tacky fabrics helped the workers
for the lay-up, especially in the
vertical sections of the existing
pipe.

Fig. 1: Calculations and finite element modelling
Table of Contents for the Digital Edition of JEC COMPOSITES MAGAZINE - Issue #119 - March 2018
