User Guide

Installing PureFlow Systems
53
PG-PF 724998 0320 PureFlow System
Installing PEX Below Grade as
Service Line
Viega PureFlow PEX and FostaPEX
tubing may both be used underground
and for water service piping. When
running lines underground, it is important
to provide a stable, continuous trench
base to support the tubing.
Always allow su󶈷cient slack when
tubing is laid in trenches. Snake the
tubing slightly side to side to provide for
contraction due to temperature change.
Allow su󶈷cient
slack when tubing
is laid in trench
Do not use blocking to support tubing.
PEX tubing can be damaged by contact
with sharp objects. Ensure that the
trench bottom and 󶈵ll do not contain
sharp rocks or other items. In good
soil conditions, tubing may be placed
directly on trench bottom. In poor soil
conditions (rocky, loose, etc.) the trench
should be excavated at least six inches
below the tubing level and back󶈵lled with
appropriate material to provide a stable
base (coarse sand, pea gravel, or similar).
Back󶈵ll material must be free of large
rocks, glass, or other sharp objects.
Provide su󶈷cient coverage over tubing
so that expected tra󶈷c loads will not
deform tubing (consult local codes).
Compact this material to at least 6"
above the tube.
Installing PEX under the slab
PEX tubing must be sleeved at all expansion
joints and every point where it enters, exits, or
penetrates the slab. For expansion joints that
are to be cut, the tubing must be dipped below
the slab to prevent damage
Trench in poor soil
Installing PEX below grade
Trench in good soil
Do not install Viega
PureFlow PEX
tubing where soil
is or may become contaminated with
solvents, fuels, or similar chemicals. Do
not install tubing above or below septic
tanks, leach 󶈵elds, pits, or cesspools.
Always follow local codes when
installing Viega PureFlow PEX tubing.
Consult standards such as ASTM
D2774: Standard Recommended
Practice for Underground Installation of
Thermoplastic Pressure Piping for further
information.
Trace Wire
It is an acceptable practice to use trace
wire to assist with the detection of Viega
underground piping systems. Refer to
local code for minimum wire gauge and
material requirements.