Hilti Product Technical Guide Vol 1 Direct Fastening - page 150

3.6.1 Self-Drilling Screw Fastener Selection and Design
Screw Fastening Systems
150
Hilti, Inc. (US) 1-800-879-8000 |
I en español 1-800-879-5000 I Hilti (Canada) Corp. 1-800-363-4458 I
I Direct Fastening Technical Guide 2013
L
MF
T
3.6.1.4 Sealing Criteria
Sealing washer screws offer weather resistant fastenings
where moisture or condensation is a factor. The washer helps
seal the hole to help prevent moisture from dripping into the
fastener threads from the fastened material side, reducing
corrosive build-up. As added protection against corrosion,
all sealing washer screws come standard with Kwik-Cote
coating. The torque control or depth gauge of the electric
screwdrivers help ensure that the optimal seal is applied
(Reference Section 3.6.1.7).
3.6.1.5 Length Selection
Length of the screw (L)
Depending on the screwhead, there are two different ways to
measure the overall length of a screw.
For HWH
/
HHWH, PPH, PTH, PFTH, SHWH and PPCH screws,
the overall length is measured from the bottom of the washer
under the head to the point of the screw.
For PWH, PFH, PBH and PFHUC screws, the overall length is
measured from the top of the head to the point of the screw.
Maximum Total Thickness (MT)
The maximum total thickness (MT) for all screws is the length
of the threads reduced by the first three threads (protruding
past the back-side of the base material). See drawings above
and below.
The maximum total thickness (MT) describes the maximum
thickness of all attachments to be fastened plus the
base material.
3.6.1.3 Head Style Selection
HWH (HHWH)
(High) Hex Washer
Head : Washer face
provides a bearing
surface for the driving
sockets.
PPH (PPFH)
Phillips Pan
(Framing) Head:
Conventional head for
general applications
and provides low
profile fastening.
PFH
Phillips Flat Head:
Used primarily in
wood to countersink
and seat flush without
splintering the wood.
PWH
Phillips Wafer Head:
Large head provides
the bearing surface
necessary to seat
flush in soft materials.
PBH
Phillips Bugle Head:
Used primarily for
fastening drywall,
plywood or insulation
board to steel studs.
PTH (MPTH)
(Modified) Phillips
Truss Head: Large
head and low profile
provides surface area
needed to attach wire
lath to metal stud.
PPCH
Phillips Pancake
Conventional Head:
Head for general
applications and
provides low and
flat profile.
PFTH
Phillips Flat Truss
Head: Lowest profile
head available for
attaching metal
to metal.
PFHUC
Pancake Framing
Head Undercut: Used
for countersinking
where a full head
taper would cause
stand-off of the screw.
SHWH
Slotted Hex Washer
Head: Hex washer
head with slot in
center to provide
additional drive
connection.
L
MF
MT
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