TPi March 2016

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68 TUBE PRODUCTS INTERNATIONAL March 2016
4-8 April 2016
Composite tubes with powerful bonding
Hoesch Schwerter Profile GmbH
develops its products in collaboration
with specific fields of industry and
customers. Modern power stations
and industrial plants are just two areas
where special steel solutions are used
that are required to withstand the most
extreme loads.
The classic seamless steel tube for
pressure vessels is a key construction
element in the building of thermal plants.
The requirements for boiler construction
steels become significantly more
exacting if – instead of conventional
boiler fuels such as coal, oil or gas –
other sources of energy are used that
result in strongly corrosive combustion
products. For instance, boiler tubes in
a waste incineration plant are not only
exposed to thermal loads, but are also
subject to corrosive attack, triggered by
the chemical element chlorine.
For this specific application, the
conventional boiler tube used in plant
construction with its proven component
strength was equipped with a ‘coating’
using a corrosion-resistant austenitic
material. The intention behind this
combination of materials is to allow
the carbon steel to handle the thermal-
mechanical load on the tube, while
the austenite provides protection
against corrosion from the prevailing
environment.
‘Combined materials’ tubing of this kind
is often referred to as composite. If
produced using the extrusion process,
the term used to describe this is
co-extruded tubing.
The high temperature structure
steel and high alloy layer are formed
simultaneously during the hot extrusion
process at temperatures from 1,150°C
to 1,250°C.
The development of composite tubing
pursued by Hoesch Schwerter Profile
was undertaken with the aim of
overcoming the known disadvantages
of clad pipes.
The carbon steel component and
austenitic layer of the extrusion billet
are manufactured in a common hot
forming process at around 1,150°C to
1,250°C. The metallurgical connection
between the two materials is achieved
in the solid state using pressure-
accelerated solid state diffusion. A
diffusion zone approximately 10µm thick
forms between the materials, which is
responsible for a high-strength, oxide-
free metallurgical bond of materials.
The fine microstructure configuration
of the layer and base material is
preserved, with no variation in the
alloy concentration. Smooth surface
structures avoid deposition of corrosion-
promoting ash and salt particles from
the flue gas.
Hoesch Schwerter Profile GmbH –
Germany
Preventing pipe damage during logistics
Dhatec specialises in developing and
manufacturing products that protect
pipes from damage during all logistics.
The organisation shows pipe companies
how they can guarantee safe, efficient
and damage-free delivery of pipes
through the entire supply chain.
The company claims its products and
technical support improve the quality,
efficiency and safety of the processes,
assisting project managers in organising
the logistics of pipeline projects.
Existing products are continuously
customised to comply with the latest
demands and specifications, including
special sizes and extreme conditions.
Dhatec also offers rental and recycling
possibilities of its products to stimulate
sustainability.
Dhatec offers more than 3,000 solutions
in the following categories:
• Pipe coating products for closure of
pipes during blasting and temporary
coupling during coating
• Pipe preservation – pipe closure in
combination with bevel protection,
anti-corrosion products and stack
covers to protect pipes against
damage and contamination
• Pipe handling – easy and efficient
pipe handling and movement can be
achieved with a range of pipe hooks
and pipe rollers
• Products for safe pipe transport, to
transport a range of pipe diameters
at the same time, on truck or train
• Pipe storage – safe storage of line
pipes can be facilitated by using
Dhatec storage systems
• Pipe construction – for construction
onshore, offshore and spool bases
Dhatec offers products such as
stalk joining clamps and masking
rings
Dhatec – The Netherlands
Extruded tubing with internal and external layer
St and no.
3B22
Sta nd no.
4G18