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These darts are used for cleaning tubing before or after a job or for
inspection in the yard and are effective at sweeping through liquids
and residues. They are also used in cementing jobs as a top dart to
push cement down behind the cementing dart, keeping it coherent and
minimising mixing with the driving fluid; however, if circulation is
to be maintained, the top dart must be another cementing dart. In
some simpler cementing jobs these wiper darts have been used alone
to displace cement. They may of course be used to displace any fluid
within the tubing, not just cement. We also now make solid metal
cored darts as top darts.
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Material: These are standard in 75A
orange polyurethane. If required they can also be, and have been, made
in other materials. As a result, they are now also listed at 6.2.3.
in 65A blue.
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Sizes: They come in two
lengths. The normal standard is a 5-chevron length but some prefer
the 10-chevron; however, the latter have never been requested in the
larger sizes above 2.00". Other lengths or diameters on request.
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Note that darts may be required to suit different wall thicknesses
from those currently available. Where necessary, we will make a
variation; please ask. The size indicated in the list is that for
which a brushing fit has been designed. If a parallel string is
being used, this is ideal. For the commoner taper strings, choose
the dart for the wall of least thickness; thus a 109 will work with
a 156/125/109 string but will obviously require a squeeze to start
it in the 156 section. In the yard, reverse pigging may be
desirable where possible, so that the lips are at maximum
effectiveness in the wider bore. In the extreme case it is not
possible to have one pig of this type which will suit a taper from
190 to 109 without a loss of effectiveness in the wider bore or
undue squeeze in the narrower bore sections. We have developmental
possibilities if this is a problem; please ask.
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It is suggested that you specify the tubing wall thickness where there
is a choice of dart. If not otherwise specified, we will supply the
unmarked size as being generally more appropriate, regarding the * marked
size as on special request.
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NOTE: Wiper darts can also be, and have been, supplied for standard
tubing as well as coil tubing. Please ask. Sizes and tolerances may vary.
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