Almost all plastic pipes are extruded in the same way as pvc pipe and
abs pipe. The outside diameter of the pipe is the controlled
measurement as this is what is used to fit into pipe sockets. The
internal diameter of all such pipe types will vary a little
depending on the pressure rating and size of the pipe but enough to
warrant the internal diameter of the pipe to not be stated. We can
advise on the likely internal diameter of a pipe, but we cannot
guarantee it. Also different pressure ratings require different wall
thicknesses of pipe and as the external diameter is the controlled
diameter of the pipe, the internal bore varies with the wall
thickness.
The
inside of a pvc pipe and abs pipe is nearly as smooth as the outside
note above internal diameter information there is sometimes a
slight, almost indiscernible change in the pipe wall thickness this
goes for ALL manufacturers of PVC pipe.
The
recommended temperature ratings of pvc pipe and abs pipe are as per
the tables below. The pressure rating of the pipe will reduce as
temperature increases and all pressure ratings quoted for pvc pipe and
abs pipe in literature are those at 20 degrees centigrade. PVC pipe
has a recommended operating range of 0-60oC, whereas ABS
wil operate as low as -40oC and up to 80oC. The
table below (Table 1) gives pressure de-rating values for pvc pipe and
abs pipe at different temperatures.
Table 1 Affects of temperature on working pressure of pvc pipe
Temperature deg C
Pressure de-rating factor
20
1.00
30
0.80
40
0.58
50
0.39
60
0.22
Example If using 7 bar rated pvc pipe at 30 degrees centigrade the
working pressure = 7 x 0.8 = 5.6 bar
Table 2 Affects of temperature on working pressure of abs pipe
Temperature deg C
Pressure de-rating factor
20
1.00
30
0.85
40
0.72
50
0.58
60
0.45
70
0.28
80
0.05
Example If using 7 bar rated pvc pipe at 30 degrees centigrade the
working pressure = 7 x 0.85 = 5.95 bar
This is a common mistake made when installing pvc pipe and abs pipe.
Insufficient support will cause the pipe to sag and may reduce the
working pressure or, under extreme circumstances, cause excess strain
on joints and affect the integrity of the pipe system. The table below
gives pipe support distances for different sizes of pipe.
Table 3 Recommended pipe support distances for pvc pipe and abs pipe
PVC
pipe and abs pipe are joined by a solvent weld process. After cutting
the pipe a chamfer is put on the end. This is ideally between 20 and
40 degrees and is done not to enable the pipe to go in the socket
better, but to act as a route for the cement to be squeezed in between
the pipe and socket. Failure to do this can result in all the cement
being pushed along the pvc pipe and abs pipe when assembling and a
consequent weak or leaking joint. First the pvc pipe and socket are
cleaned using a solvent cleaner this also acts as a keying / etching
process. Secondly the pipe and socket are lightly roughed up using a
piece of emery cloth. Solvent pvc cement is applied to the socket
first (this is important as if applied to the pipe first, the glue
will get dirty when the pipe is laid down to glue the socket) and
after ensuring no cement has run down into other parts of the socket,
the socket is laid down in a position where the glue cannot run into
unwanted parts. Then, solvent cement is added to the pvc pipe in a
motion towards the end of the pipe rather than being brushed around
it, ensuring the chamfered end of the pvc pipe, has sufficient cement
on it and that the cement is as far along the pipe as the depth of the
socket. The two parts are pushed quickly together do not twist the
pvc pipe at this stage as it can cause leaks. The joint should be held
in place for 30 seconds (1 minute for larger pipe sizes) and left
still for 5-10 minutes before handling.
The
solvent cement jointing process is fast curing and irreversible. PVC
pipe is slightly slower to cure than ABS pipe You have seconds to pull
the pipe and socket apart if you make a mistake. For this reason all
joints should be marked for position etc. before cleaning and gluing.
If the parts are to be pushed together dry first, ensure that they
have not been cleaned as they my weld together - this is particularly
the case with abs pipe. If you are able to pull them apart,
immediately clean both parts with solvent cleaner and remove all
traces of cement.
The
standard colour for pvc pipe is mid to dark grey, however it is also
available, in some pressure ratings in white and clear. The clear pvc
pipe has a much more limited range of fittings. ABS pipe is usually
only available in mid to light grey.
The
different classes refer to different pressure ratings There are
several groups of pvc pipe and abs pipe classification, the most
typical being the American ASTM D 1785Schedule
and BS 3505/6 Class systems (such as class C or class E) and the
Metric DIN 8062 or KIWA 49 / UNE 53.112 PN systems (such as PN10 or
PN16) . The tables below give information for such systems. Note that
with the Class system, the pressure rating of every pipe size is the
same within that class, but with the Schedule system the pressure
ratings change. This gets even more confusing for the metric pipe as
both the DN and KIWA pipe are rated at the same pressure (i.e. 10 bar
for PN10), but the DN rating has a greater wall thickness. The most
common classifications used are Schedule 40, Class C and PN10. We are
also able to supply other classifications such as ASTM D 2241 SDR.
The
number of pvc pipe and abs pipe joints you can make per litre of
solvent cement are set out below in table 3. You will need
approximately half as much cleaner.
Table 7 Joints per litre of cement for pvc pipe and abs pipe
PVC
pipe is a good, general purpose pressure pipe. It has the following
properties:
·Non-toxic and taint free
·Good resistance to abrasion
·Can be used above or below ground
·Is resistant to many inorganic chemicals and most acids,
alkalis and salts note however that it is not resistant to aromatic
and chlorinated hydrocarbons.
·Comes with the widest range of fittings of any plastic pipe
type
·Requires no special tools for installation
Applications include Industrial (liquids, air and gasses), aquatics,
swimming pool, aquaculture, agriculture
