vem case studies - premix system

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VEM CASE STUDIES – PREMIX SYSTEM

VEM CASE STUDIES:

PREMIX SYSTEM

Vem presents its new state-of-the-art system for

raw material consumption optimization.

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FOREWORDFOREWORDFOREWORDFOREWORD

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

have the same design as that of a standard

pipe: there is no chop in the core and there

are three different resin dosing systems: 1st

skin, premix mortar core and finally the 2nd

skin.

The mortar core is made of a polypropylene

veil that contains the resin mixed with the

sand; afterwards the premix “sausage” is

wound onto the mandrel.

The premixing machine has two different

extruders, depending on the wall thickness.

The second one is useful when the core

thickness is > 25 mm, for example:

- ND 2000 NP 10 SN 10.000 (25,87mm)

- ND 2300 NP 10 SN 7.500 (25,46mm)

- ND 3000 NP 10 SN 5.000 (26,50mm)

The old release had the static mixer fixed on

the premix structure. As you can see from the

picture, the device was designed to guarantee

the minimum gap from extruder output and

the pipe on production.

Photo 1: China premix in production, first release.

OUR TESTSOUR TESTSOUR TESTSOUR TESTS

The first test was performed in a plant in China

in 2009 with the first version of premix

machine, visible in photo no. 1 above.

The pipe produced was ND800 NP6 ST10000

and the laboratory test results were aligned to

the pipe design program. The composition was

in accordance with the pipe design expected

data, as indicated in the following table:

RAW MATERIALS STANDARD SAND

SYSTEM(%)

PREMIX

SYSTEM(%)

Sand 54 66

Hoop 7.9 7.4

Chop 6.8 2.9

Resin 30.4 23.6

Total resin

Kg/m 27.13 22.14

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The variation from design was:

L.O.I DEV (%)

Resin 1.1

Sand 0.5

Chop -0.8

Hoop -2,85

The second test was performed in Turkey

where a ND1300 NP6 SN2500 was produced.

The system was stable enough to produce a

very well compacted pipe core, thanks to a

second compaction roller together with

controlled vibration. Stiffness respected the

design values, namely 3365,58Pa at 5% of

deflection. The following tables and pictures

explain the above:

Photo 2: Turkey release premix

L.O.I. DEV (%)

Resin 0,43

Sand 1,96

Chop 0,02

Hoop -2,85

Photo set 3: see the optimum compaction thanks to

the second compaction roller and vibration

RAW

MATERIALS

STANDARD SAND

SYSTEM(%)

PREMIX

SYSTEM(%)

Sand 40 47

Hoop 20 20.2

Chop 9.3 6.5

Resin 30.3 25.4

Total resin

Kg/m

40 35

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A third test was done in Turkey on DN2000

NP6 SN2500 and the L.O.I. result showed good

values from a composition point of view and

variation from design:

L.O.I. DEV (%)

Resin 1,55

Sand -1,66

Chop -2,22

Hoop 2,23

VEM decided to further develop the

technology to obtain a more user friendly

system:

1) Use of a different veil: larger and

stronger.

2) Use of a forming mouth piece to close

the sausage and an auto-tensioning

device to make the process stable.

3) Changing of premix position: easier to

put it into operation.

4) Chopper plate conveyors.

5) Use of a larger core area and a second

compaction roller.

6) Changing of static mixer position from

premix structure to the chopper

bridge.

The last test was performed in Syria, where a

ND1200 NP6 SN10.000 pipe was made. The

production was very smooth and the

laboratory results showed successful values.

Photo 4: Syrian version, premix on trolley and premix guide

The 2010 release is more user friendly from an

installation point of view: installation and

removal can be performed in less than 1 hour

thanks to the fast connections and mechanical

facilities.

From a production point of view, the ND1200

NP6 SN10.000 pipe was designed as shown

below, where we have also indicated the

expected and actual values:

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PIPE

DESIGN

EXPECTED

ACTUAL

LOI Resin

(%) 23 23,72

Sand (%) 64,7 64,71

Hoop

(%) 9,3 9,94

Chop (%) 2,9 3,56

Thickness Mm 23,84 23,23

Stiffness 5%

deflection Pa 10000 10605

Axial tensile N/mm 280 354

Hoop tensile N/mm 1448 1669

Circumference

elongation on

Hydrotest

mm at

1xNP 6,4 2,5

mm at

2xNP 14 5,7

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 5: well compacted core

CONCLUSIONSCONCLUSIONSCONCLUSIONSCONCLUSIONS

The premixing system allows the production of

an extremely competitive pipe thanks to a

reduced consumption of resin, approximately

between 15 and 20% in the core, depending

on the pipe recipe, with good mechanical test

results.

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:

Photo set 6: Premix last release, 2011 version

vem case studies - premix system

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