1.1 This practice is intended as a summary of destructive and
nondestructive quality control test methods for determining the
integrity of factory fabricated seams used in the joining of flexible
sheet materials. This practice outlines the test procedures available
for determining the quality of bonded seams. Tests chosen to be
performed shall be selected from the nondestructive and destructive
tests for their specificity to the liner system and the design
application. These test methods are applicable to the seaming methods
commonly used on manufactured flexible sheet geomembranes that are
scrim-reinforced or nonreinforced.
1.2 The types of factory seams covered by this practice include the
1.2.1 Thermally Bonded Seams:
188.8.131.52 Dielectric--A dielectric seam is produced by clamping two
lapped sheets of polymeric membrane between two conductive bars and
applying an electric current to the bars, thus producing a field that
generates friction heat at the interface between the two sheets to
melt the surfaces. The pressure of the clamping bars creates a
homogeneous bond which is allowed to cool by cutting off the electric
current, while still under pressure.
184.108.40.206 Hot Air--A hot air seam is produced by applying high
temperature air or gas between two polymeric sheet surfaces, thus
melting the surfaces, at which time pressure is applied to form a
homogeneous bond between the two membrane surfaces.
220.127.116.11 Hot Wedge (or Knife)--A hot wedge seam is produced by melting
the two intimate surfaces by running a hot metal wedge between the
surfaces, followed immediately by pressure to form a homogeneous bond.
18.104.22.168 Extrusion--A bond seam is produced by extruding molten parent
material between or at the edge of two over-lapped polymer sheet
materials to effect a homogeneous melt between the two sheets to be
joined. Hot air is sometimes applied between the two sheets to bring
their temperature close to the melt point. The extrudate heat then
melts the two preheated surfaces to effect the homogeneous bond.
1.2.2 Solvent Bonded Seams--A solvent is used to soften the surfaces
to be bonded, followed by pressure to form a homogeneous bond.
1.2.3 Bodied Solvent Bonded Seams--The parent lining polymer material
is dissolved in a solvent that is then applied in the same manner as a
straight solvent, thus effecting a homogeneous bond.
1.2.4 Cured or Vulcanized Seams--These are thermally bonded seams that
are produced prior to vulcanization of a cured ribbon sheet. A
homogeneous bond is obtained by curing the seam along with the parent
1.2.5 Adhesive Bonded or Cemented Seams, Taped Seams, and Waterproofed
Sewn Seams--These seams are rarely made at the factory during the
fabrication process and are generally limited to field installation
seams. Adhesive bonded and taped seams provide a means, although
nonhomogeneous, of joining cured sheets. Waterproofed sewn seams are
used with geotextiles, which may be laminated to a geomembrane film.
1.3 The types of factory seams covered by this practice include the
following seam constructions:
1.3.1 Lap Seams--One sheet overlaps the other by a recommended minimum
amount, with the bonded area between or at the edge of the two sheets.
1.3.2 Cap-Stripped Seams--A separate strip of the parent sheet
material is bonded to both sheets covering the lap seam.
1.3.3 Butt Seams, Envelope Seams, and Standing Seams--These seams are
not commonly used in factory seam fabrication.
1.4 The values stated in SI units are to be regarded as the standard.
1.5 This standard does not purport to address all of the safety
concerns, if any, associated with its use. It is the responsibility of
the user of this standard to establish appropriate safety and health
practices and determine the applicability of regulatory limitations
prior to use.