Let us see how high pressure water
jet pumps can be effectively used in the steel and iron industry. Hydro
desclaing Customers require delivery of hot rolled products not only
on-time, but also in a condition immediately suitable for further processing,
such as forming, painting, cutting, welding and so on. Steel properties
such as chemical composition, cleanliness and mechanical strength are
easily measured. However, surface quality is not necessarily easy to
measure. Conversely, poor surface quality will be immediately apparent
to the customer during further processing. Customers react immediately
to shortcomings regarding surface quality, and the results can be very
expensive in terms of defect claims and lost business. During hot rolling,
the steel plate is descaled to remove any surface imperfections and
the scale-oxide coating that forms as the steel cools. Thus, descaling
is of great economic importance for all rolling mills.
Mill scale formation is initiated in
the reheat furnace and continues after furnace discharge until the heated
steel product is at a temperature low enough to allow instantaneous
oxidisation by air. Scale formation obtained in the furnace under heating
is defined as primary scale formation; secondary scale formation occurs
in transit to the roll stand and during rolling and cooling of the heated
product. Satisfactory descaling requires adequate control to remove
primary and secondary scale. Primary and secondary scale ruin considerably
the surface quality of ingots, slabs, blooms, plate bars, sheet metals,
strips, profiles and pipes. Not only is the rolling stock surface affected
but scale also causes high wear to the rolls. Mill scales are complex
oxides of iron, silicon, manganese and other steel constituents. Mechanical
properties of mill scales are also complex. Some parts will consist
of brittle, loose layers of iron oxides; while other parts consist of
‘sticky’ semi liquid particle with high silicon content. Most
often, there is a gap separating the brittle and sticky scale layers.
Complete removal of the loose brittle layer and sticky layer is required
to produce the steel surface quality required by customers. If left
intact, the sticky layer may allow the once-removed brittle scale to
rebound and adhere to the surface, producing unacceptable surface quality.
To fight scale effectively, high pressure water jet pumps are required
to remove impurities from steel plate and billet in order to produce
high quality steel. Specially designed nozzles, which focuses water
to a razor sharp, extremely high jet impact stream guarantees optimal
descaling. Optimal descaling provides perfect surface quality, high
product quality, low maintenance costs and low roll wear.
Hydro test of pipes/tubes/boilers‘Hydrostatic
testing’ is a diagnostic technique to test pipes, pressure vessels
and boilers for leaks or defects. The equipment to be tested is filled
with an incompressible liquid, usually water or oil. With the help of
a positive displacement triplex plunger pump incorporating appropriate
safety reliefs and controls, the pressure of the test component is slowly
increased to a predetermined set point and held for a predetermined
time. Visual inspection is subsequently performed to determine whether
any leakage exists or the pressure reduces from set pressure point.
Acid cleaning after pickling After pickling, it is required to remove
the film of pickling acids and salts that cling to the surface. These
actually cause corrosion even under coatings if they are not removed.
The film can be difficult to remove if it dries so its cleaning must
be done immediately. To accomplish this acid cleaning task, high pressure
water jet is an advanced, fast, cost effective and environmental friendly
method.We have supplied several pumps for this application to various
clients including Chandan Steels Ltd from Umbergaon.
Other applications
These include internal pipe cleaning; coke oven cleaning; billet
mould cleaning; drain, sieve, filter and tank cleaning and so on. The
author, a mechanical engineer, is MD of PressureJet Systems, Ahmedabad.
He can be contacted at sales@pressurejet.com
....CONTD
