This document summarizes Vem's premix system for optimizing resin consumption in pipe production. [1] The premix system extrudes a mortar core made of resin-mixed sand contained in a polypropylene veil, reducing resin use by 15-20% compared to standard systems. [2] Case studies show the premix system produces pipes meeting design specifications with stable production and good mechanical properties. [3] Further developments have made the premix system more user-friendly and efficient.

1. VEM CASE STUDIES:
PREMIX SYSTEM
Vem presents its new state-of-the-art system for
1 VEM CASE STUDIES – raw material consumption optimization.
PREMIX SYSTEM

2. FOREWORD
This technology was developed to reduce resin
consumption in the core, as well as improving
the mixing of resin and sand, especially when
the sand granulometry is not exactly to VEM’s
specifications.
The premix system is convenient for the
production of pipe with a minimum wall
thickness of 10mm. The premix pipe does not Photo 1: China premix in production, first release.
have the same design as that of a standard
pipe: there is no chop in the core and there OUR TESTS
st
are three different resin dosing systems: 1
The first test was performed in a plant in China
skin, premix mortar core and finally the 2nd
in 2009 with the first version of premix
skin.
machine, visible in photo no. 1 above.
The mortar core is made of a polypropylene
The pipe produced was ND800 NP6 ST10000
veil that contains the resin mixed with the
and the laboratory test results were aligned to
sand; afterwards the premix “sausage” is
the pipe design program. The composition was
wound onto the mandrel.
in accordance with the pipe design expected
The premixing machine has two different data, as indicated in the following table:
extruders, depending on the wall thickness.
The second one is useful when the core
thickness is > 25 mm, for example:
STANDARD SAND PREMIX
RAW MATERIALS
SYSTEM(%) SYSTEM(%)
- ND 2000 NP 10 SN 10.000 (25,87mm)
- ND 2300 NP 10 SN 7.500 (25,46mm) Sand 54 66
- ND 3000 NP 10 SN 5.000 (26,50mm) Hoop 7.9 7.4
The old release had the static mixer fixed on Chop 6.8 2.9
the premix structure. As you can see from the Resin 30.4 23.6
picture, the device was designed to guarantee
Total resin
27.13 22.14
the minimum gap from extruder output and Kg/m
the pipe on production.
2 VEM CASE STUDIES – PREMIX SYSTEM

3. The variation from design was:
L.O.I DEV (%)
Resin 1.1
Sand 0.5
Chop -0.8
Hoop -2,85
Photo 2: Turkey release premix
The second test was performed in Turkey L.O.I. DEV (%)
where a ND1300 NP6 SN2500 was produced. Resin 0,43
The system was stable enough to produce a Sand 1,96
very well compacted pipe core, thanks to a
Chop 0,02
second compaction roller together with
Hoop -2,85
controlled vibration. Stiffness respected the
design values, namely 3365,58Pa at 5% of
deflection. The following tables and pictures
explain the above:
RAW STANDARD SAND PREMIX
SYSTEM(%) SYSTEM(%)
MATERIALS
Sand 40 47
Hoop 20 20.2
Chop 9.3 6.5
Resin 30.3 25.4
Total resin 40 35
Kg/m Photo set 3: see the optimum compaction thanks to
the second compaction roller and vibration
3 VEM CASE STUDIES – PREMIX SYSTEM

4. A third test was done in Turkey on DN2000 The last test was performed in Syria, where a
NP6 SN2500 and the L.O.I. result showed good ND1200 NP6 SN10.000 pipe was made. The
values from a composition point of view and production was very smooth and the
variation from design: laboratory results showed successful values.
L.O.I. DEV (%)
Resin 1,55
Sand -1,66
Chop -2,22
Hoop 2,23
VEM decided to further develop the Photo 4: Syrian version, premix on trolley and premix guide
technology to obtain a more user friendly
system:
The 2010 release is more user friendly from an
1) Use of a different veil: larger and
installation point of view: installation and
stronger.
removal can be performed in less than 1 hour
2) Use of a forming mouth piece to close
thanks to the fast connections and mechanical
the sausage and an auto-tensioning
facilities.
device to make the process stable.
3) Changing of premix position: easier to
put it into operation.
From a production point of view, the ND1200
4) Chopper plate conveyors.
NP6 SN10.000 pipe was designed as shown
5) Use of a larger core area and a second
below, where we have also indicated the
compaction roller.
expected and actual values:
6) Changing of static mixer position from
premix structure to the chopper
bridge.
4 VEM CASE STUDIES – PREMIX SYSTEM

5. PIPE
DESIGN ACTUAL
EXPECTED
Resin
LOI 23 23,72
(%)
Sand (%) 64,7 64,71
Hoop
9,3 9,94
(%)
Photo 5: well compacted core
Chop (%) 2,9 3,56
Thickness Mm 23,84 23,23 CONCLUSIONS
Stiffness 5%
Pa 10000 10605
deflection
The premixing system allows the production of
Axial tensile N/mm 280 354 an extremely competitive pipe thanks to a
Hoop tensile N/mm 1448 1669 reduced consumption of resin, approximately
between 15 and 20% in the core, depending
Circumference
mm at
elongation on 6,4 2,5 on the pipe recipe, with good mechanical test
1xNP
Hydrotest
results.
mm at
14 5,7
2xNP Since the case studies carried out in Turkey
and Syria, VEM continued to develop the
premixing system and we are proud to now
show you a photo of the latest version:
The good compaction of the mortar core is
shown in the photo number 5. A combination
of pressure compaction roller, gravity roller
and vibration in different points contributed to
this excellent result.
Photo set 6: Premix last release, 2011 version
5 VEM CASE STUDIES – PREMIX SYSTEM