2. For many years, stainless steel remains a piping material selected for industrial process systems
e.g. in pharmaceutical industry. High mechanical strength and low coefficient of thermal
expansion allow stainless steel components to be sterilized or sanitized in a variety of ways
while withstanding high temperatures.
Chemical passivation for stainless steel is frequently required to remove free ions from the
surface and restore the oxide film that gives stainless steel its corrosion resistance. But orbital
welding techniques used with stainless steel piping systems can cause rough surfaces. Roughing
surfaces (induced bacterial proliferation), metallic ion contamination and post‐installation
maintenance of inner surface finishes are the reason of many industries are seeking ways to
leave behind the currently‐used troublesome materials.
Due to its metallic ion contamination, most steel was removed from microelectronics UPW
(Ultra Purity Water) systems in the 1980s and replaced with high performance polymers PVDF,
ECTFE and PP high purity.
Properties and system performance of plastics may vary. When selecting the proper plastics
piping, the engineer optimizes performance by matching particular system requirements with
cost efficiencies. Non‐contamination, surface‐finish smoothness (reducing the possibility for
micro‐organic deposits and growth), sanitation and sterilization adaptability, as well as welding
and system capabilities, are among the chief criteria.
Thermoplastics piping is frequently used for commercial and industrial applications such as
for conveying chilled and process waters, aqueous solutions of corrosive chemicals, slurries,
foods, and substances that must remain uncontaminated by metallic ions.
3. Advantages of thermoplastics piping is virtual freedom from attack by ambient water
and moisture. Thermoplastics piping is not subject to surface attacks in any way comparable
to the rusting or environtmental corrosion of metals. Thermoplastics, being nonconductors,
are immune to the electrochemical based corrosion process induced by electrolytes such as
acids, bases and salts. In addition, plastics pipe materials are not vulnerable to biological
attack. In sum, thermoplastics are not subject to corrosion in most environtment in both
aboveground and underground service. This has resulted in negligible costs for maintenance
and external protection such as painting, plastic coating, galvanizing, electroplating,
wrapping, and cathodic protection.
Another principal advantage offered by thermoplastics is their lower specific gravity, which
results in ease of handling, storage, and installation, as well as in lower transportation cost.
The smooth pipe surfaces yield low friction factors and very low tendency to fouling. They
also offer very good abrasion resistance, even when conveying slurries that can rapidly abrade
harder materials. The smooth surface finish combined with the upgraded welding technology
give polymer pipe some significant advantages over current steel technology. Polymer’s less
frequent sanitization and cleaning cycles translate into fewer interruptions in plant operations
and lower overall production costs.
Many joining methods are available for plastic pipe. It can be threaded, flanged, cemented,
heat‐fused, and compression fitted. The many joining methods make plastic pipe adaptable to
most filed applications.
4. The principal limitations of thermoplastics arise from their relatively low strength and
stiffness and greater sensitivity of mechanical propertise to temperature. As a result, their
primary use is for gravity and lower pressure applications at near ambient temperatures.
Some plastics qualify for hot water service, and there are some specialty materials that can
be used to close to 150 °C. Not withstanding these restrictions, thermoplastics piping satisfies
the performance requirements for a very broad range of applications.
Additives are essential components of most thermoplastics piping compositions. They
facilitate processing, enhance certain properties, and provide required protection during
fabrication and service. There are only few thermoplastics (e.g. certain fluorinated polymers
such as polyvinyldene fluoride (PVDF) that do not require the incorporation of some type
of additive because they already have sufficient natural thermal stability and aging and
weathering resistance.
The precise nature and quantities of additives that can be used for piping compositions are
delimited by their effect on engineering properties, such as rigidity, impact strength, chemical
resistance, creep resistance, rupture strength under longterm loading, and fatigue endurance.
For example, the use of an inorganic filler can compromised the natural resistance of
polymers to very strong acids or bases. Also too much filler, or use of a filler of a coarse grade,
or its inadequate dispersion can introduce physical discontinuities, or internal faults, that can
compromise long term strength, ductility, toughness, and fatigue endurance. Another
example is the excessive use of liquid stabilizers or lubricants, which tends to plasticize the
plastic and thereby make it less creep‐resistant and more sensitive to temperature.
5. Additionally, the properties of the base polymer used in a plastics piping composition are not
only determined by the chemical elements, or atoms, from which the polymer is made, but are
also profoundly influenced by the specific geometrical arrangement by which the polymer’s
atoms are combined to form a macromolecule. A most important molecular structural
parameter is the length of the molecular chain. The longer the chain, the larger and heavier the
molecule. Polymers used for engineering applications consist of relatively long molecules in
order to yield satisfactory levels of longer‐term strength, ductility, and toughness.
Molecule size is denoted by molecular weight, which is the sum of the atomic masses of all the
elements in the molecule. Since all the molecules in a polymer are not of the same size, the
degree of polymerization is usually expressed by the polymer’s average molecular weight. The
nature of the distribution of molecular sizes also bears a significant influence on a number of
physical and mechanical properties. Thermoplastics used for piping applications tend to be of
relatively high molecular weight and of relatively narrow molecular weight distribution.
However, the molecular weight cannot be so large as to result in a melt viscosity so high as to
hinder proper fabrication of the end product.
Polypropylene (PP) piping
Polypropylene (PP) is an economical material that offers a combination of outstanding physical,
chemical, mechanical, thermal, electrical properties not found in other thermoplastics.
Compared to low or high density PE, PP has a lower impact strength, but superior working
temperature and tensile strength. PP is tough, heat resistant, semi rigid material that is ideal for
the transfer of hot liquids or gasses. Polypropyelen‐ based piping is also the lightest weight
plastic material.
9. PP‐R, natural
(Polypropylene –random‐copolymer, natural). PP‐R natural contains no colour additives,
it is applied mainly for high purity water piping system. However this material is not UV
resistant.
PP‐B, grey
PPB is a polypropylene block copolymer grey coloured , the product is characterized by
its excellent impact properties, as well as a high heat stability and extremely high
extraction stability.
PP‐R natural AGRU for purity piping
10. Polyvinyldenfluoride (PVDF) piping
Today, pure and ultra pure water has become an essential ingredient in a wide range
applications, such as :
1) Water for cleaning the surfaces of semiconductor wafers and liquid crystal panels, which
must have no minute foreign particles (use in semiconductor and electronics industries).
2) Water for steam generators for the power generating turbines needed for the stable
operation of power stations (use in electrical power industries).
3) Refined water and injection water for medical care and pharmaceutical industries where
safety is vital in any situation (pharmaceutical and hospital industry)
4) Blank water for microanalysis in analytical chemistry, directly linked with the analysis level
(laboratory, biotechnology, and chemical industry).
5) Water for food and beverage processing industry
Many industries are seeking ways to leave behind the currently‐used troublesome materials.
Stainless steel imposed constant and increasing problems: rouging, pitting, corrosion, metallic‐
poisoning, aggravated compliance issues, costly and environmentally adverse cleaning
protocols, and inadvertent fracture, plus costly biofilm issues. Stainless steel corrode over time
as the minor ingredients are lost and as electrochemical potentials arise which promote the
oxidation in even the “mildest” of chemical conditions, i.e. hot steam, and the resulting rust
(”rouging”) contaminates and compromises the quality of the products being produced in such
equipment.
11. PVDF piping system offering lower initial cost, less weight, complete resistance to corrosion,
good thermal insulation, elimination of the passivation process, extremely smooth interior
surface have increased their application, particularly in system such as purified water
distribution loops and other critical processes.
PVDF is extremely pure polymer and contains in comparison with a lot of other plastics no
stabilizers UV, thermo stabilizers, softener, lubricants or flame retardants additives. Its
particular suitable for ultra pure water constructions and for the transport of clear chemical
liquids in the semiconductor industry. Due to its chemical inertness, reaction against most
media is nearly impossible. PVDF offers with its properties an ideal compromise in connection
with a very easy processing and an advantageous to price performance ratio.
Advantages of Polyvinyldenfluoride PVDF Piping
• outstanding mechanical properties, even at high temperatures
PVDF has a high tensile strength and stiffness (Tensile strength at yield 50 Mpa compare to PP
30 Mpa), means it can take lots of abuse. That makes it an ideal choice in vibration‐or impact
prone applications. PVDF's advantages are particularly prevalent at higher temperatures. This
is due to the high fluorine content which causes strong interactions between the PVDF chains.
This, in turn, displaces the softening and the loss of properties to higher temperatures. This
also has an effect on the long‐term creep strength. PVDF shows its outstanding properties in a
temperature range from ‐20 °C to +140 ºC. This allows using the material in a wide range of
applications.
12. Especially at high temperatures, PVDF provides maximum security. Its high crystalline melting
point at around 173 °C speaks for itself. (*Please consult the pressure‐temperature diagrams
for your operational temperature).
The thermal expansion coefficient of PVDF of 0.12 to 0.18 mm/m K lies clearly above that of
metals. Because of this, its thermal expansion must be taken into account during the planning
of the piping system. As for all polymers.
• excellent chemical resistance
PVDF is resistant to most inorganic solvents and additionally to aliphatic and aromatic
hydrocarbons, organic acids, alcohol and halogenated solvents. PVDF is also not attacked by
dry and moist halogens with the exception of fluorine. PVDF is not resistant against strong
basic amines, alkalis, and alkaline metals. Strong polar solvents, such as ketones and esters and
organic acids can cause PVDF to swell somewhat. (*For detailed information, please refer to
the detailed list of chemical resistance) .
• no electrochemical corrosion
Metallic and anionic contamination in UPW (Ultra Purity Water) systems can shut down
enzymatic processes in bioprocessing, corrode equipment in the electrical power generation
industry and result in either short or long‐term failure of electronic components in
semiconductor chip and photovoltaic cells.
13. • long service life, even under intensely corrosive conditions
PVDF offers excellent chemical resistance to weak acids, strong acids, oxidizing acids, mixed
acids, organic solvents and many aggresives gases. Such resistance makes it an ideal choice for
severe applications such as : chemical; pulp and paper production, accu battery, fertilizer (super
phospat), pesticide, biodiesel, bioethanol, pharmaceuticals, etc.
• outstanding resistance against UV and γ‐radiation
Outstanding resistance against UV light as well as gamma radiation permits, among other
applications, the use of PVDF piping outdoors. No loss of properties occurs.
• very pure material by implementing without additives
Due to the excellent stability of the PVDF molecule, it is one of the very few materials that can
be processed, welded and used under severe conditions without the use of additives (no
pigments, thermostabilisers, processing aids or fillers). This makes it the material of choice for
applications that demand a very high purity of the medium and have stringent requirements
stipulating that the materials which come in contact with the medium do not leach
contaminants.
• no support of microbial growth
Smooth walls – the extra smooth walls PVDF produces help assure turbulent‐free flow of liquids
and prevent the collection and breeding of fungi, bacteria and other biological impurities.
• physiologically harmless
PVDF is physiologically non‐toxic as long as it is used below the maximum temperature of 150 °C.
During welding, good ventilation is required or alternately the released gases must be extracted.
PVDF can be used in accordance with the relevant regulations of the Food and Drug
Administration (FDA) for items that come into contact with food.
14. • secure joining by high‐quality welding technology
Joining methods for PVDF pipe include both, welding methods (socket fusion, butt fusion,
beadless fusion, and infra red joining) and mechanical methods (threading, flanged).
• very low heat conductivity
As for all polymers, PVDF is a good thermal insulator because its heat conductivity of 0.19W/m
K is very low. (For comparison, the value for steel is 250 W/m K). Therefore in most cases, no
thermal insulation is required for hot flow media piping system.
• excellent flame retardant properties
PVDF is flame retardant and self extinguishing after removal of the ignition source, the amount
of smoke produced is minimal at 450 °C and only slight at 600 °C. The oxygen index is 78%
(ASTM D 2863). This index indicates the minimum oxygen level necessary for combustion.
PVDF is practically non inflammable in normal environments (comparison of the oxygen index
of other thermoplastics : PE HD 18 %; PMMA 18 %; PPs 28 %; PVC‐U 40 % in the case of
values below 20,8 %, ignition and continuous combustion is possible after removing the
ignition source.
15. PVDF Application range
PVDF homopolymer is the strongest of the pipe lining thermoplastics, strong enough that it
can be used as stand alone pipe.
Pharmaceutical industry
PVDF are very pure materials for handling water and chemicals that have special purity
requirement, PVDF can be repeatedly autoclaved and cleaned with steam without changing
physical properties
Food and beverage and dairies industry
requiring low extractable and FDA approved compounds
Ultra pure and pure water systems
Used for : semiconductor manufacturing; electrical power plant construction and for
different industries (e.g. petrochemical industry) ; pharmaceuticals
Chemical processing industry
General chemical processing for corrosive chemical and higher temperature application e.g.
pulp and paper industry : in handling halogens and acids
Metal preparation and Mining
In the metals industry, a variety of acids are used to clean, treat/prepare or separate the final
product. Strong acids like hydrofluoric, hydrochloric, sulfuric, nitric and chromic are all
common to this industry. The concentrations of these chemicals can vary throughout the
process, temperatures tend to be elevated, and mixture of acids are common.
Battery
PVDF are exceptionally pure and free of any additives or ionic impurities that can interfere
with electrochemical reactions.
17. Ethylen Chloro Tri FluoroEthylen (ECTFE) piping
Piping system for the transport of highly aggressive chemicals and ultra high purity media,
ECTFE provides excellent chemical resistance and high mechanical strength even at high
temperatures. These characteristics enable the use of ECTFE as a cost effective solution for
many applications with ultra pure media.
Advantages of the ECTFE system :
ECTFE shows a remarkable hardiness and excellent chemical resistance to most organic and in
organic chemicals ( pH value 0 to 14, max 140° C) as well as solvents ( max. 120° C).
Sulphuric acid H2SO4 98%
Hydrochloric acid HCL 37%
Hydrofluoric acid HF 90%
Sodium hydroxide NaOH 50%
Hydrogen peroxide H2O2 60%
Nitric acid HNO3 65%
Solvents
Chorine and chlorine compounds