TPT May 2008

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May 2008 70
Technology Update
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Steel pipes and wheels producer Interpipe,
Ukraine, manufactures a wide variety
of seamless pipe products for special
applications. The company’s principal
products are boiler pipes, roller pipes, pipes
for submerged pump stations, precision
pipes and cold drawn pipes. These products
are primarily used in the power, oil and gas,
machinery, automotive and shipbuilding
industries.
Boiler tubes and pipes are the specific
products used in boiler plants (steam
generators), operating under high pressure
and high temperature, and are used in
industries where indirect heating and
steam are used. The major consumers are
heat power plants, petroleum processing
and chemical plants, as well as the food
industry.
In boiler plants the pipes are built up as
coils in units and welded by high frequency
welding. Inside the boiler, water circulates
in tubes externally by hot gas, which
can be generated inside the boiler itself
(conventional steam generator), or outside
the boiler (heat recovery steam generator).
The growth surge in the power industry
and the growth in demand for electrical
energy has directly challenged producers of
power generation equipment. As a result of
these circumstances, Interpipe launched a
new line for the production of boiler pipes
up to 24m in length and from 31.8mm to
114.3mm in diameter, according to ASTM,
DIN, EN standards. The new production line
is situated at one of the company’s mills –
Interpipe Niko Tube.
The first step was the test rolling of
boiler pipes from low-alloy steel grades
13CrMo4-4, 16Mo3, 13CrMo4-5,
10CrMo9-10 in the range from 32mm to
76mm. As a result of test rolling, many
of the issues associated with boiler pipe
production were identified and defined,
such as the high requirements of metal
cleanness, internal cleanness (descaling)
and external surface and precision of
geometric measurements. The advantages
of rolling at pipe-rolling mill 30-120 are:
high quality of internal surface (due to free
moving long mandrel); availability of large
squeezes at 24 stand stretch-reducing mill
that helps to avoid internal cutting; and
high total deformation providing high quality
metal structure. The company made the
decision to reduce the diameter of boiler
pipes from 57mm to 32mm.
The heat treatment of boiler pipes depends
on the grade of steel, class and category
based on standard and includes annealing
and tempering. Pipe quality is monitored
by testing such as stretching, flattening,
dispensing, chemical analysis, hydro and
eddy-current and ultrasonic (for avail-
ability of longitudinal, transversal defect,
exfoliations).
The process flow currently includes hot
rolling through the piercing mill, continuous
rolling mill and sizer. To exclude the
influence of limescale at surface (as a result
of heating), the line is equipped with a
capacity of descaling water (p=160atm). In
order to provide the highest quality of heat
treatment (normalising and tempering),
the tempering furnace of 111m has been
considerably upgraded.
The company has also installed a new
finishing line which includes equipment
for pipe straightening in oblique roll
straightening machines, pipe facing, and
finishing line control room. It also has a
geometry measuring and a non-destructive
testing machine (MAC), which provides
ultrasonic, electromagnetic testing and
grade verification. The line project facility
has a capacity of 30,000 tubes per year.
Production facilities include a continuous
mandrel mill for the production of seamless
pipes (32mm to 114.3mm); general finishing
floors (including testing equipment); and a
quench and tempering heat treatment line
for seamless OCTG and transport line pipes,
other equipment comprises upsetting lines
for seamless OCTG, non-destructive testing
(ultrasonic, electromagnetic, magnetic and
vortex-current), lines for pipe and coup-
ling threading, hydrotesting, coating and
bundling, and a finishing line and annealing
heat treatment line for boiler pipes.
Interpipe – Ukraine
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Website:
Seamless tube and pipe for boiler applications
 Hot mill in operation