| Over
the last few years, inspection and quality control on fabricated
structures of all types has become increasingly important
but for most companies it does not make economic sense to
tie up capital with specialised equipment for personnel.
We are able to
offer a Non-Destructive Testing Service which includes a
full report of the work carried out and the results obtained
by our inspectors. When on site we always work in close
liaison with our customer to minimise the problems caused
by interruptions to production and work flow and our qualified
personnel are always willing to answer queries regarding
the various inspection techniques summarised below.
Radiography
This technique relies on the ability of certain wavelengths
of radiation to pass through materials such as steel. In
passing through these materials some of the radiation is
absorbed or stopped. The amount of radiation absorbed is
proportional to the thickness penetrated, i.e., thinner
sections pass more radiation than thicker sections. If we
allow this radiation to fall on a sensitised film, it is
exposed according to the amount of radiation it received,
so film below the thin section is exposed to more than that
below the thick section. It is this phenomenon which enable
us to use radiography as a tool of inspection.
Our X-ray units
can be used at our own premises or, if necessary, on-site.
They cover a range of up to 300kv i.e., a working range
of up to 70mm of steel. This service includes interpretation
of radiographs to appropriate standards and issue of reports
as required. All our staff are, of course, fully conversant
with the safety requirements for operating this equipment
in on site conditions.
Results of radiographic
inspection are normally available within 24 hours, but if
quicker results are required, we are able to supply a site
dark-room. This enables us to process films on site so that
we are able to view the results almost immediately.
Ultrasonic
This method involves transmitting a very high frequency
sound pulse into the material to be tested and measuring
the time taken for it to return to its point of origin.
The technique
can be used for testing welds of various configurations
but is also very useful for measuring material thickness,
especially on vessels, etc., where access is only possible
from one surface. This ability can prove very useful for
charting the effects of corrosion on tanks, vessels, ships
hulls, etc. The Ultrasonic Set is an extremely portable,
battery operated piece of equipment and is therefore ideal
for site work.
Magnetic Particle
Inspection
This technique involves passing a magnetic field or flux
through the item to be tested and then applying a magnetic
ink between the poles of the magnet producing the flux.
Any irregularities are then highlighted by the ink.
Advantages of
this technique are that it gives an immediate result and
can be used where radiography or ultrasonics would not be
suitable. Disadvantages are that it is limited to locating
surface or slightly sub-surface defects, whereas radiography
and ultrasonics can be used to locate defects in the body
of a weld or component. The use of magnetic particle inspection
is also limited to ferro-magnetic materials.
Dye Penetrant
This is a simple but effective form of testing and involves
the application of a penetrating dye to the surfaces to
be tested. After a minimum period of twenty minutes this
is removed and developer is applied. If defects are present
the dye will seep out and stain the developing agent. The
main drawback with this method is that it will only locate
surface breaking defects.
Mechanical
Testing
Mechanical Testing can be carried out for welder or welding
procedure approved to various standards. This service includes
the cutting and preparation of test specimens when required. |