Section nine
WEL D ING
Polyflor strongly recommends vinyl sheet and
608mm vinyl tile floorings are welded, this includes
the internal and external joints when the vinyl
sheet is site cove formed.
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W E L DI N G Secti on n i n e
9.1 CORRECT TOOLS
Having the correct tools in good condition is a prerequisite of good heat
welding. The tools required are dependent upon preferred methods but
Polyflor recommend the following:
2 3 4
6 7 9
10 11 12 13
1. 2 metre straight edge 8. Seam cutter
2. Tape measure 9. Mozart trimming tool
3. Sharp pencil 10. Welding equipment
(manual or automatic)
4. Hand roller
11. Exacto trimming tools
5. Suitable bladed knives
12. Spatula trimming knife
6. Recess scriber
13. Hand grooving tool
7. Grooving tools
(manual or mechanical)
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WE L D IN G Se ction nine
9.2 WELDING IS MANDATORY ON MOST SPECIFICATIONS
Most specifications make welding mandatory, since it prevents ingress
of dirt and bacteria into seams and provides a floor surface which
is impermeable to water. Although seam welding is a recognised
installation technique – instructions can vary by manufacturer.
When installing Polyflor sheet products only Polyflor seam welding
instructions should be followed.
Welding will aid maintenance of high standards of hygiene. By carefully
following these guidelines; and executing correctly welding will
eliminate seam failures. In Healthcare establishments especially this is
a prerequisite and high standards of heat welding are demanded under
the guidance from NHS Infection Control Teams (NHS Health Building
Note 00–10 Part A Flooring March 2013).
9. 3 HEAT WELDING
Heat welding of vinyl floor coverings has been used successfully for
many years and employs the technique of heating both the vinyl flooring
and the vinyl welding rod to a sufficient temperature to melt and fuse
them together. The procedure is the same for both sheet and tile
installation with the exception that the edge of the tiles do not require
cutting in prior to grooving.
9.4 CUTTING IN THE S EAMS
Factory edges should never be butted together but should be
overlapped and cut by one of the following methods:
9.4.1 Using Seam Cutters
>>Polyflor recommends that the sheet is overlapped at the seams by a
P L E AS E NOT E minimum of 25mm.
Complaints arising from >>Set the first cutter to the thickness of vinyl sheet. Using the factory
the failure of welds due to edge as a guide, trim off 6mm along the length. Where it is not
not trimming off factory possible to use the seam cutter against the wall, or in other areas of
edges will not be accepted restricted access, use a straight edge and straight bladed knife held
by Polyflor Ltd. squarely to the floor.
>>Set the second cutter to the thickness of vinyl sheet. Using the edge
previously cut on the top sheet as a guide, cut through the bottom
sheet. Remove the scrap piece of material.
9.4.2 Using a Recess Scriber
>>Prior to overlapping the vinyl sheet, trim off the factory edge on the
bottom sheet. This is best done by striking a chalk line, then – using a
utility knife and straight edge – cut through to remove the scrap piece.
>>Overlap the top sheet and then trace the bottom edge onto the top
sheet with a correctly set recess scriber.
>>To highlight the scribed line, rub some chalk dust into the surface. Trim
the top sheet to the scribed line.
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W E L DI N G Secti on n i n e
9.4.3 Double Cut
>>Using a straight edge and keeping the utility knife upright, cut through
both layers to ensure there is a tight seam.
>>Once the seam is cut, discard the waste material and check the final
appearance.
9.5 GROOVING THE SEAMS
Prior to welding, some of the material must be removed from the seam,
creating a groove profile that will accept the vinyl welding rod.
Two shapes of groove profiles can be cut:
9.5.1. A ‘U’ shape profile
This leaves a semi-circular groove in the vinyl and should extend into the
vinyl for 2/3 of its thickness.
9.5.2. A ‘V’ shape profile
This leaves a 60º triangular groove in the vinyl and should extend into
the vinyl for 7/8 of its thickness.
NOTE The ‘V’ shaped groove profile has proven particularly suitable
for embossed versions of Polysafe vinyl sheet floor covering.
9.6 MANUAL GROOVING
>>Place the centre of the grooving tool over the centre of the seam.
>>Bring up the straight edge to touch the side of the grooving blade and
align the straight edge, maintaining an even distance from the seam.
FOAM BAC K E D
The groove on foam
backed ranges such as
Acoustic and Sports
flooring should only be
cut in the vinyl wear layer;
NOT cut through to the
PVC foam backing.
Figure 1 Grooving the seam
>>Pulling the tool towards you, groove to the required depth. Move the
straight edge as required and repeat until the whole seam is grooved.
>>Sweep well to remove any dust and trimmings from the groove.
9.7 POWERED GROOVING
>>Set the blade to the correct depth of cut.
>>Align the guides with the cut seam. Press the cutter in to the full depth
of cut and then move forward following the cut seam.
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WE L D IN G Se ction nine
>>Use hand tools to complete grooves next to walls, skirtings etc.
>>Sweep well to remove any dust and trimmings from the groove.
>>Never use a powered grooving machine with a standard blade on
Polysafe safety vinyl sheet ranges. The silicon carbide and aluminium
oxide particles will destroy the blade. A diamond blade is commonly
used on Polysafe floor coverings.
9.8 PRIOR TO WELDING THE SEAMS
Before commencing heat welding Polyflor recommends leaving the
adhesive to set for a minimum of 24 hours. This should ensure the
adhesive does not bubble up when heat is applied; bubbling will
adversely affect seam strength.
If in any doubt contact Polyflor Customer Technical Services
Department (CTSD) on +44 (0) 161 767 1912.
9.9 WELDING THE SEAMS
>>Ensure nozzle attachment is free of debris — clean with a wire brush.
>>Pre-heat the welding gun to a setting appropriate to both the material
and the site conditions ensuring that the nozzle is pointing upwards
during this pre-heat period.
KEY P O I NT
>>Try out the welding rod on a scrap of material to ensure the
Ensure a constant rate of
temperature is correct and that fusion is taking place. Adjust
welding. Moving slowly
accordingly. When you are satisfied that the temperature is correct,
will ‘burn’ the vinyl and
you can proceed to weld the joint.
moving quickly will not
>>Place the welding rod into the nozzle aperture. Starting as close as
fuse the welding rod. The
possible to the end of the room, press the welding rod down into the
finished width of the weld
groove with the nozzle attachment, the toe of which should be parallel
may also vary and detract
to the vinyl surface. Pull the gun towards you whilst maintaining the
from the appearance.
downward pressure (fig. 2). Ensure the gun is kept square to the floor.
With your spare hand, alternately check the weld security and that the
welding rod is feeding freely.
>>Typically, you would start welding from the edge of the room towards
Figure 2 Applying the weld
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W E L DI N G Secti on n i n e
the centre. At this stage, pull the gun away from the groove and cut off
the welding rod. Using a trimming tool and guide trim off the excess
welding rod. Commence welding as before, from the opposite end of
the room. Run out the weld into the pre-cut ‘V’ (fig. 3) and cut off the
excess welding rod.
Pre-cut ‘V’
Figure 3 Weld joins
>>Where Ejecta set-in skirtings are used, the horizontal seam between
the skirting and the Polyflor sheet should be hot welded as described
previously however the vertical joints and mitres should not be hot
welded; simply neatly abutted/scribed.
9.10 TRIMMING THE WELD – Spatula or Mozart Tool
Prior to commencing, it is advisable to ensure that your preferred
trimming tool has a sufficiently sharp and properly defined blade profile.
This keen edge will make trimming easier and minimise the risk of
damaging the product. Trimming of the weld must be carried out in two
stages. Failure to follow this procedure will result in welds which are prone
to dirt pickup.
>>Place the trimming guide and blade over the welding rod and push the
knife forward and trim off the top layer of welding rod (fig. 4a or 4b).
This can be done whilst the weld is still warm. Trimming the weld speeds
up the cooling time.
Welding
Techniques are
covered on the 4 day
Polyflor Sheet
Vinyl Course
Figure 4a Trimming off the weld top layer (Spatula Trimming Knife)
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WE L D IN G Se ction nine
>>
KEY P O I NT
Polyflor foam backed
vinyl sheet flooring is
liable to compression
and sometimes, even
after the final trim, the
weld is proud of the
floor. In this case using a
Mozart trimming tool in
preference to a traditional Figure 4b Trimming off the weld top layer (Mozart Trimming Tool)
spatula is advisable.
>>Wait at least 10 minutes for the remaining weld to cool to room
temperature, the excess weld should be trimmed using the trimming
blade with the guide removed. Keep as shallow an angle as possible
between blade and floor to avoid the risk of damaging the product (fig.
5a or 5b).
Figure 5a Final trim after the weld has cooled (Spatula Trimming Knife)
Figure 5b Final trim after the weld has cooled (Mozart Trimming Tool)
9.11 GLAZING THE WELD
Should a glazed finish be required this can be achieved with the nozzle
attachment removed but still on the same heat setting; play the standard
gun nozzle over the trimmed weld. Repeat over the whole length of the
weld, keeping the gun moving constantly to prevent burning.
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W E L DI N G Secti on n i n e
Figure 6 Final weld
9.12 COLD/CHEMICAL WELDING
>>Once the seam has been accurately cut as described previously in 9.4
and remembering that this type of welding should not be considered
as gap filling, the seam can be welded.
>>Cover the seam with the correct grade and width of masking tape;
(min. 25mm wide) to prevent any excess welding liquid coming into
contact with the vinyl surface.
>>Cut through the tape at the seam, using a trapezoid or rolling knife with
a sharp blade. Apply the welding liquid (fig. 7), as per the Werner Muller
instructions, ensuring both hands are controlling the tube.
Figure 7 Cold welding
>>Keep fingers away from the needle applicator.
>>After approximately 10 minutes and once the welding liquid has cured,
the masking tape should be carefully removed.
9.13 WELDING OF RUBBER SHEET
Welding of rubber sheet is not a prerequisite in most installations.
However, where there is heavy wet cleaning or where due to hygiene
requirements a continuous smooth surface is demanded, the joints
should be heat welded using the recommended weld rod.
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