Trade press article
Georg Fischer Piping Systems Ltd.
8201 Schaffhausen
Switzerland
www.piping.georgfischer.com
Ralph Schreiber
Public & Media Relations Manager
Tel +41 (0) 52 631 3374
Fax +41 (0) 52 631 2830
Mobile +41 (0) 79 830 2803
ralph.schreiber@georgfischer.com
Schaffhausen, April 2008
Piping systems for conveying, measuring and controlling high
purity media
Even though the specifications for pure and ultra pure media diverge
considerably from one industry to another, they are similar in one respect:
Contamination of the medium from the materials, pipes, fittings and valves
through which it is conveyed is not tolerated. If this should occur, exorbitant
sums of up to several million euros might have to be paid for rejected goods or
product liability. High purity media are used today, for instance, in
microelectronics, in power plants for boiler feed, in the life science industry,
hospitals and research laboratories. They are used as a cleansing agent, an
additive or a process medium. The specifications for pure or ultra pure media
are of major importance, since these define specifically the degree of
permissible contamination as well as any additional conditions which need to
be fulfilled.
In the chemical industry and in the food and beverage industry, the formulation,
the pH value and most notably the particle count are often specified, while in
medicine, the pharmaceutical industry and in biotechnology, the conductance,
the TOC (Total Organic Carbon) and the number of microorganisms play a
decisive role. The semiconductor industry is furthermore interested in the
maximum permissible contamination for anions, cations and specific elements,
such as O2 (oxygen), SiO2 (silicon oxide), NH4+ (ammonium) and B (boron).
Varied requirements
The technical product features alone do not constitute the quality of a piping system
or the corresponding measurement and control systems for conveying high purity
media. More important is the interaction of the various parameters that are present:
basic structure and the purity of the raw material, production and production
environment, scientific procedures, installation and operating conditions. Only when
all these factors are in equilibrium can we speak of “quality“.
This very brief look at the different application areas suffices to illustrate the
complexity of selecting an ultra pure media system including valves. Comprehensive
know-how is an absolute must if errors in the evaluation, design and planning phases
are to be avoided.
High purity applications
High purity media have one thing in common: they are treated in a series of process
steps in order to remove all objectionable solid or solvent impurities, ions and organic
content. Depending on the application, a different treatment profile is modeled.
Water is the medium most frequently used for high purity applications. It is the ideal
process medium because of its “neutrality”. Different purity levels are derived from
drinking water (especially for life science applications) or treated surface water.
These are related directly to the legal or normative body of regulations and the
specifications derived thereof for process management and control for the operation
of such systems. The various levels of quality for treated water and their key
properties are illustrated in the water pyramid (Fig. 1). In order to better understand
how the term “high purity“ is quantified, we can look at the following comparison:
From a microbiological point of view, the maximum concentration of microbes is
equally precisely specified for water for injection (WFI) as for drinking water. Albeit,
the total microbial count differs, from a simplified perspective, by a factor of 3000. In
contrast, the concentration of ions in WFI and in ultra pure water for microelectronics
is another significant parameter. In simple terms the permissible concentration is a
factor 1000 lower in microelectronics than in the pharmaceutical industry.
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Pure or ultra pure water is used to clean containers (for example reaction vessels), to
feed boilers or steam generators, or alternatively to rinse wafers in chip
manufacturing. Influential quality parameters in conveying high purity fluids are, in
addition to the original purity of the water, consistency and upholding of the purity
values at the place of treatment and the point of use (POU). Traditionally, stainless
steel pipes have been used for this, plastic piping has, however, become an
established alternative in recent years.
The two polymers polypropylene (PP) and polyvinylidene fluoride High Purity (PVDF
HP) are primarily used for pure and ultra pure applications today. The choice of
material depends first and foremost on the required degree of purity for the medium.
Other decisive criteria are temperature and pressure range, selected method of
disinfection, the available know-how and the budget.
System concept
Within the framework of the given conditions, quality can only be realized with an
integrated system. Each link in the chain of a pure/ultra pure water project must meet
the purity specifications and legal requirements and continue to meet them on a
sustained basis. So besides the physical properties of the product, all the other
parameters must be considered, the scope of their influence analyzed and assessed,
registered and evaluated as a basis for statistical process control. Furthermore, the
trend and long-term data are very important indicators for the above mentioned
consistency in quality. The complete chain, from raw material to the final approved
installation, is subject to the same logic.
Valves – indispensable elements in a piping system
In a complete piping system, valves play a major role since it is these which
ultimately enable checking the flow, distributing and controlling the transported media.
PW quality (pure water) or WFI is the most important raw material in the
pharmaceutical industry and in biotechnology for the production of active ingredients
and drugs. It is distributed through complex piping systems that can stretch over
several kilometers, depending on the plant size. The water is generally tapped at the
POU via diaphragm valves, in particular outlet valves, such as T-valves or zero static
(diaphragm) valves. The manufacture of such valves, as for all components in ultra
pure systems, should therefore correspond to the respective applications. For
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extremely stringent requirements, clean room segments, in which the production
conditions are clearly defined, have proven to be the best solution.
Pipes, fittings and especially valves, which have been manufactured in this manner,
exhibit consistently high quality and purity, which precludes a possible contamination
from the production process and at the same time offers optimal conditions for
installation.
Materials which have proven ideal for ultra pure media systems and the respective
valves, are the high-performance polymer PVDF in high purity quality and for
extremely demanding specifications PFA (perfluoroalkoxylalkane). These materials,
which belong to the group of fluorocarbon polymers, exhibit ideal properties for ultra
pure media distribution systems and have been used successfully in diverse
branches of industry for over 20 years.
Jointing technology
Besides the valve design, the integration of the valves in the actual piping system is
crucial in ultra pure applications and naturally in the pharmaceutical industry as well.
As jointing technique, the pharmaceutical industry tends to prefer permanent
connections, i.e. fusion jointing, instead of removable connections, such as unions,
clamps, etc.
Flange connections. Generally, the only connections which are permitted are those
free of gaps, undercuts and dead legs as these are the spots in which
microorganisms can grow.
Predestined for use in PW and WFI systems is the BCF fusion technology (bead and
crevice-free), which enables optimal joining of PVDF and PP pipes because, for
instance, the fusion technology satisfies the specified criteria and produces excellent
surface quality Ra _ 0.25 µm in relation to SYGEF PVDF HP.
The BCF fusion technology offers another major advantage over other fusion
methods for metal piping systems: BCF welds can be inspected with a light source
from the outside. Endoscopy, X-ray examination or the conventional passivation used
for stainless steel systems are not necessary, which represents a huge cost savings
in PW and WFI projects.
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From raw material to product
Using the example of high purity manufacturing of PVDF products, the entire
production process can be demonstrated from the viewpoint of contamination
minimization. During production, impurities in however minute quantities can have a
negative impact on the medium to be transported. These could potentially wash out
into the system and must be ruled out unconditionally. Starting with the raw material
and ending with components manufacturing, the purity-relevant parameters are the
subject of continual inspection and monitoring. The high purity chain comprises
diverse elements in the production of high purity piping components.
Raw material testing:
Stringent materials testing on the PVDF-HP granulate, prior to release for production
Production in the clean room segment:
Injection molding of valve bodies in class 10,000; machining, if necessary, in class
100
Cleaning the components:
UPW (Ultra Pure Water), specified resistance 18.2 M_/cm, TOC < 15 ppb, particles <
100 particles/l, size 0.2 µm
Packaging:
Double bagged, pipes also sealed with end caps
Transport:
In cardboard boxes with bubble plastic wrap
Installation:
Fusion technology corresponding to the HP piping components, such as BCF, IR
(infrared).
Production itself takes place in the clean room, where constantly monitored
conditions prevail. The process logic dictates various categories of clean room. The
closer the process is to the end product, the higher the category of clean room and
the more intensive the monitoring. In the final manufacturing phase, the products are
rinsed with ultra pure water.
The quality of the clean room production is ultimately judged on the basis of the
product itself. The purity values per customer specifications or norms are determined
in comparative testing. The test points are metal leach-out values, organic elutriation
(TOC) and inner surface roughness. Leach-out measurements are additionally
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conducted in periodic and statistical form at EMPA (Swiss Federal Laboratories for
Materials Testing and Research) in Dubendorf (Switzerland). The tests conducted
over years enable continually optimizing the process and guarantee high process
stability.
Consistent product performance in life science sector
Traditionally, the pharmaceutical industry has used stainless steels in quality 1.4404
or 1.4435, but corrosion, rouging and the costs of components and system
qualification have led to the high-performance plastic PVDF in high-purity quality
often being preferred over stainless steel.
Water in PW or WFI quality is the most important raw material in the life science
industry for production of active ingredients and drugs. It is transported through
complex piping systems that can stretch over many kilometers.
Georg Fischer piping systems are tested in scientific analyses for their application
suitability and requirement congruency. Particularly in the life science sector, the
legislation for production or processing of pharmaceutical products is extremely
rigorous and is scrutinized closely. For example, in an effort to protect consumers
and patients, all the process steps in the complete production chain are subject to
testing for high and consistent microbiological purity. These parameters ensure that
the medicines produced in each batch are of the same high quality and possess the
same properties.
In addition to conventional hydraulic and mechanical testing, other internal purityrelated tests are standardized in the manufacturing plant. Decisive parameters of
quality for plastic piping, such as leach-out and inner surface roughness, when
studied over years, supply relevant basic data. Additionally, a scanning electron
microscope (SEM) is frequently used to collect data on the surface structure as well
as pore size and number. This becomes manifest when the inner surfaces of PVDFHP pipes are examined immediately after production and then compared with results
from pipes after two years of use in a pharmaceutical production facility with the
medium pure water at room temperature.
The respective tests at GF Piping Systems are periodically supplemented with
updated pharmaceutical-specific microbiological specifications and field data from
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plants in active use. The consistency of the collected data and the perceived process
mastery are the requisite basis from which concrete customer benefit can be drawn.
Specifications, requirements and customized solutions
A great deal of effort is put into supplying high purity, uncontaminated piping
components for a variety of industries – piping components which often contribute to
industrial advancements. A discussion on the subject of pure or ultra pure media
should always include explicit specifications, clearly defining the intrinsic values and
the tolerance range. Attention should be given to the corresponding guidelines of
authorities, such as the FDA (US Food and Drug Association) in the pharmaceutical
industry and the respective guidelines, regulations or the technical literature specific
to an industry, which reflect the current state of the art.
Furthermore, it is important to consider the general requirement profile for the entire
planned piping system including valves because today many sectors require a
system solution from one source instead of a component solution from various
suppliers. Regarding the valves in an ultra pure media system, attention should be
given not only to the design and flow characteristics, but also the connection options,
dimension range, surface quality, leach-out behavior, cleaning and automation
possibilities. Naturally, the varied ambient conditions, as well as the price for the
actual valve and maintenance and repair, should be taken into consideration in the
planning.
Author:
Christina Granacher, Head of Global Market Development & Innovation,
Georg Fischer Piping Systems, Schweiz
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Georg Fischer – Adding Quality to People`s Lives
GF Piping Systems is one of the three core businesses of the Georg Fischer Corporation and a leading supplier
of piping systems in plastic and metal with global market presence. Connecting technology, fittings, valves,
measuring devices and pipes are used for water conveyance and treatment as well as the transport of liquids and
gases for industrial purposes. GF Piping Systems provides innovative, engineered solutions for the segments
building technology, chemical process industry, cooling, life science, microelectronics, ship building, water and
gas utilities and water treatment. Sales companies in more than 25 countries and representatives in another 80
countries ensure customer support 24 hours a day. Production sites in Europe, Asia and the US are near the
customers and meet local requirements. The Georg Fischer headquarters is based since its foundation in 1802 in
Schaffhausen, Switzerland.
Key figures GF Piping Systems 2008
More than 4’700 employees worldwide (per 31 December 2008)
1224 MCHF sales
122 MCHF EBIT
Further information is available at www.piping.georgfischer.com
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