UNITRACC - Underground Infrastructure Training and Competence Center

Glass-fibre reinforces plastics - GRP

(Image: Installation of a GRP jacking pipe)

(Image: GRP jacking pipe)

Glass fibre reinforced plastics - GRP (UP) belong to the class of duroplastic synthetic materials that can no longer be melted under the influence of temperature. The starting materials for GRP jacking pipes are reaction resins (epoxide-, vinylestere or unsaturated polyester resin) as binders, glass as well as quartz sand and calcium carbonate flour as additives. The two latter components …

Oct 06, 2008

European standards for GRP pipes

(Table: European standards for GRP pipes (as at 10.2008))

Oct 06, 2008

Material properties

(Table: Material properties for GRP)

Oct 06, 2008

Manufacture of GRP pipes - centrifugal casting process

In centrifugal casting process, polyester resin (UP resin, at least type 1130 of the [DIN16946:1989], cut glass fibres of 2.5 - 5 cm length of almost boron-free and alkaline free silicate glass (E-glass) to [DIN61855:1987], as well as the fillers are added simultaneously or in any desired sequence to the rotating chill mould by a special additive arm, so that a special layer structure adapted to the requirements is achieved [Stein85c].

(Image: Manufacture …

Oct 06, 2008

Corrosion resistance

(Image: Attention!)

(Image: Checking the corrosion resistance as part of a long-term crown pressure test)

The corrosion resistance of the GRP multi-component material is directly connected with the resistance of the resins used.

If fibres project out of the resin layer or if this layer is not diffusion-proof or if cracks are present, then aggressive media from the sewage or the sewer atmosphere can migrate along the fibres due to the capillary effect …

Oct 06, 2008

Pipe joints

The design of the pipe joints depends on the nominal size. Use is made of non-restrained, flexible socket and spigot joints with GRP or single-sided fixed stainless steel guide rings in combination with elastomeric sealing profiles .

(Table: Overview of the different pipe joints of GRP jacking pipes)

(Image: Pipe joints for GRP jacking pipes manufactured with the centrifugal casting process of type HOBAS Rohre GmbH to DIN 19565 [FI-Hobasc] - …

Oct 06, 2008

Pressure transfer ring

(Image: Attention!)

With centrifugal casting GRP jacking pipes, the use of pressure transfer rings can generally be dispensed with as unevenesses and manufacturing tolerances under a compressive load are quickly equalized by the elasticity of the GRP. As a form of adhesion effect occurs between the pipe end faces with high thrust pressures, the steerability of the pipe string can be affected. For this reason for large planned steering movements, …

Oct 02, 2008

Glass fibre reinforced plastics - GRP (UP-GF)

Jun 12, 2006

Pipes made of polymer concrete (PRC)

PRC (polyester resin concrete, also called polymer concrete) jacking pipes according to DIN 54815 part 1 are made of a mixture of mineral and quartz additives in a reduced-pore grading curve to DIN 1045 and reaction resin based on unsaturated polyester resins (UP resins) with properties according to DIN 16946-2 [DIN54815:1998] [DIN1045:2001] [DIN16946-2:1989].

The polyester resin is very resistant to aggressive media (pH range 1.0 to 10) and the …

Oct 06, 2008

Standards for PRC pipes

(Table: European and other standards for PRC pipes (as at 10.2008))

Oct 06, 2008

Shape variants of cross-sections

Shape VTK:
Circular cross-section in the nominal size range 150 ≤ DN/ID ≤ 2600

(Image: Polycrete jacking pipe with circular cross section [FI-Meyera])

Shape VTE:
Cricular cross-section outside, egg-shaped cross-section inside in the nominal size range 300/450 ≤ DN/ID ≤ 1600/1800

(Image: Polycrete jacking pipe with external circular cross section and ovoid cross section inside [FI-Meyera])

Shape VTD:
Circular cross-section outside, kite cross-section …

Oct 06, 2008

Pipe joints

The design of the pipe joint depends on the nominal size. These are generally non-restrained, flexible socket and spigot joints in combination with a guide ring and elastomeric seals.

(Image: Polycrete jacking pipe with circular cross section DN 150 - pipe joint [FI-Meyera])

(Image: Polycrete jacking pipe with circular cross section DN 200 to DN 1143 - pipe joint [FI-Meyera])

(Image: Polycrete jacking pipe with circular cross section DN 1000 …

Oct 02, 2008

PRC (polymer concrete)

Jun 08, 2006

Structure of plastics

Plastics are macro-molecular, organic connections which are created by chemical juxtaposition of low molecular weight basic components (so-called monomers) [Bos00]. Because of the large numbers of possible juxtapositions (linear, branched, cross-linked), plastics can be deliberately synthesized according to their desired properties into thermoplastics and thermosetting materials.

(Image: Schematic view of the structure of plastics according to [Bos00] […

Jun 09, 2006

Plastic pipes

Plastics originating from linear or branched molecule fibres result in thermoplastics that can be repeatedly melted and dissolved and which form the basis of the following:

Pipes of polyethylene (PE)
Pipes of polypropylene (PP)
Pipes of polyvinylchloride (PVC-U).

Oct 06, 2008

Polyethylene pipes (PE)

Polyethylene is a member of the semi-crystalline thermoplastic (polyolefin) group. It is distinguished by a high degree of flexibility and ductility also at low temperatures.

(Image: Attention!)

PE is resistant to non-oxidizing acids, alkalis and weak solvents. It is not resistant to oxidizing acids and halogens.

Usually in trenchless installation PE pipes are only installed by pulling-in.

Oct 06, 2008

Pipes of cross-linked polyethylene (PE-X)

In PE-X pipes the PE molecules are linked to a three-dimensional network by a chemical or physical connection improving the temperature resistance of the pipe.

Depending on the linking process it is distinguished between:

peroxide cross linking (PE-Xa) (physical)
silane cross linking (PE-Xb) (chemical)
electron beam cross linking (PE-Xc) (physical)
azo cross-linking (PE-Xd) (physical)

(Image: Attention!)

Pipes of peroxidic cross-linked polyethylene (…

Oct 06, 2008

Material properties

(Table: Material properties for PE- and PE-X pipes [Bos00])

Oct 06, 2008

European standards for PE and PE-X pipes

(Table: European standards for PE and PE-X pipes (as at 10.2008))

Oct 06, 2008

Pipe joints of PE pipes

The heating element butt welding (HS) method is available for joining PE pipes for trenchless installation and, with this welding, seam quality can be achieved that correspond to those of the pipe material.

Process steps in heated butt welding

(Image: Heating element butt welding - aligning the joining areas)	Step 1: Adjustment	(Image: Heating element butt welding ? adjusting the joining areas)	Step 2: Warming
(Image: Heating element butt welding - …

Oct 06, 2008

Polypropylene pipes (PP)

Polypropylene (PP) is a member of the semi-crystalline thermoplastic (polyolefin) group. It is manufactured by the polymerization of ethylene and has a comparable chemical resistance to PE, is also normally combustible and non-adhesive.

(Image: Attention!)

Mostly, PP-HM pipes are used in trenchless installation. PP-HM means polypropylene with a higher E modulus than is usual with PP pipes.

Oct 06, 2008

Polyvinylchloride (PVC-U) pipes

PVC-U (polyvinylchloride, free of plasticiser) belongs to the thermoplastic group. It is a polymer of vinylchloride, which is made of ethylene (natural oil or gas) and chlorine (of NaCl) and to which thermal stabilisers and lubricants are added for pipe production [Rosch00].

(Image: Attention!)

Besides the hardness and form stability, a characteristic property of PVC-U is the high degree of resistance to acids, alkalis, alcohols, oils, fats, aliphatic …

Oct 06, 2008

Material properties

(Table: Material properties for PP-HM)

(Table: Material properties for PVC-U)

Oct 06, 2008

European standards for PP-HM and PVC-U pipes

(Table: European standards for PP-HM and PVC-U pipes (as at 10.2008))

Oct 06, 2008