Technical Article on sealing of Drinking Water and Portable Water Seals in India based on correct certification. The importance of strengthening the weakest link in the pipeline to avoid contamination.

1. 44 • September 2016 Chemical Engineering World
CEW Features
Gasket: Strengthening Your Weakest Link
W
ater is one of the precious
resources in India and the Ministry
of Water Resources’ focus on
efficiency and conservation is one of the
hallmarks of the change being brought into
the country as it readies itself for future
growth. Unfortunately, the change required
is intermittent and needs a broader view
by enforcing strict compliance with zero
tolerance by understanding all the moving
parts in the Network from Water extraction
to Water utilization.
In a study conducted by The Delhi
ASSCHAM (2010) approx. 40% of water
is wasted through leaks and incorrect
fittings. While, The Observer Research
Foundation (ORF, 2012) reports that due
to leaking pipes, Mumbai alone loses 650
million litres of Water every single day.
Water has to pass through multiple
stages, systems, factories, pipelines and
mechanical devices before it reaches our
drinking glass. These can range from
pumps, meters, valves, pipe joints all
of which require Gaskets and Seals that
are in direct contact with the water and
can be extremely prone to leakages and
contamination. In fact, Gaskets are usually
the weakest link and your network is only
as strong as your weakest link.
The Indian Standard for Pipe Fittings (IS
SP 57 (QASM)) formulated during the
Rajiv Gandhi National Drinking Water
Mission offers some recommendation on
Pipe Fittings and Mechanical Devices;
but it is extremely vague on Gaskets and
Seals Specifications. The only Material
recommended is either Compressed Fiber
Board (it doesn’t specify the widely used
Compressed Asbestos Fiber) or using
Synthetic / Natural Rubber (as per IS 638).
Certification
Unlike India, the importance of the
Gasket is taken extremely seriously on an
International scale due to Seals being in
direct contact with the water and increasing
chances of contamination. The major
specifications international followed are
the NSF/ANSI 61 Certification (for Drinking
Water), the FDA Guidelines (Food and
Drug Safety, USA), the WRAS (UK) and
ISO 4633 (Only for Cold Water) along with
DIN (Germany) and EN (Europe) standard.
FDA
Gaskets deemed to comply with Food and
Drug Administration (FDA) regulation is a
broad and complex area and frequently
extends beyond food processing plants
to those involved in the making of
pharmaceutical products. Hence while it
may be acceptable it doesn’t necessary
adhere to the strict guidelines of the NSF /
ANSI 61 & WRAS regulations.
A gasket is considered FDA compliant
through three methods:
• GRAS—Materials that are generally
regarded as safe (GRAS). Many materials
have been used without problems in FDA
applications and are listed as GRAS. The
use of a food substance gasket may be
GRAS either through scientific procedures
or, for a substance used in food before
1958, through experience based on
common use in food.
• Existing FDA Regulations—some
materials are already covered by
existing regulations. For example,
perfluorocarbon resins and PTFE are
found in 21 CFR 177.1550.
• FDA FCN—New materials not covered
by either of the above can be submitted
to the FDA under a food control
notification (FCN).
FDA Regulations also have separate
specifications required for the Adhesive
Water is one of the valuable resources in India and the Ministry of Water Resources’ focus on efficiency and conservation
is one of the hallmarks of the revolution being brought into the country as it prepares itself for future growth. The
change required is alternating and needs a wider interpretation by implementing strict obedience with zero tolerance by
understanding all the moving parts in the network from water extraction to water utilization. Water has to pass through
several stages, systems, factories, pipelines and mechanical devices before it reaches our drinking glass. These can
range from pumps, meters, valves, pipe joints all of which necessitate Gaskets and Seals that are in direct contact with
the water and can be exceptionally prone to leakages and contamination. In fact, Gaskets are generally the weakest link
and the network is only as strong as your weakest link.
Technical Article
The Indian Standard for Pipe Fittings (IS SP 57 (QASM)) formulated
during the Rajiv Gandhi National Drinking Water Mission offers
some recommendation on Pipe Fittings and Mechanical Devices;
but it is extremely vague on Gaskets and Seals Specifications. The
only Material recommended is either Compressed Fiber Board (it
doesn’t specify the widely used Compressed Asbestos Fiber) or
using Synthetic / Natural Rubber (as per IS 638).

2. September 2016 • 45Chemical Engineering World
CEWFeatures
Drinking Water Pipelines Asbestos Cement Water Leak
Old Rusty Pipes
used (if there is) and there is additional
CFR Guidelines on the contents of the
Marking Ink used on the Gasket Sheet.
NSF/ANSI 61
The NSF / ANSI 61 Specification and its
similar equivalent across the Atlantic WRAS
(UK); verifies the entire Gasket manufacturing
process to ensure stringent quality control
throughout. Each aspect of the Gasket is
taken under strict formulation to ensure it is
contamination free and safe to be in contact
with drinking water. The certification process
is extremely rigid and throughout and takes
into account the following factors:
• Application: The raw material of the
Gasket used is specified and each
chemical component is independently
tested. This requires the Manufacturer
to disclose not only the chemical
nomenclature, chemical abstract
service (CAS) number, but also
their percentage of the composition,
formulation and toxicology.
• NSF formulation review: NSF
toxicologists further conduct their own
formulation review of each Gasket raw
material to determine if there are any
ingredients, contaminants, or reaction
by-products that could potentially leach
from the material into drinking water.
• Plant audit and sample collection:
NSF then inspects the production
facility to verify the formulation and
production process and to ensure that
adequate quality control procedures
are in place to prevent the use of
unauthorized materials.
• Laboratory testing: The Gasket
is then evaluated for three weeks
according to the exposure and analysis
methods of the standard.
• Toxicology evaluation: Contaminant
concentrations are then evaluated by
a toxicologist to pass/fail criteria as
per standard.
• Follow-up program: Once products
are certified and listed by NSF, they are
inspected and reviewed on an annual
basis. Any deviation from any of the
specifications at any stage results in
non-compliance and resubmission of
the Gasket again for certification.
Material used in India:
Rubber
Elastomers and Rubber compounds
account for majority of the preferred
Gaskets and Seals because of their
resilient properties. Compounds of
Natural, Styrene Butadiene, Acrylonitrile
and Neoprene are preferred for pipe seals,
gate valves, flange gaskets and O-rings.
The recommended Indian Standard (IS
638) for Rubber Gaskets is unfortunately
extremely insufficient as it neither specifies
the Rubber or Elastomer compound
or performance or taste or odour or
microbiogical growth support.
The actual recommended and certified
Elastomer for Drinking Water should
ideally be Ethylene Propylene Diene
(EPDM) Rubber with its superior hydrolytic
stability and resistance to chloramines
compared to the other homogenous
elastomers. Fluoroelastomers are also
increasingly being used in gaskets
for CPVC piping, where leaching of
plasticizers from other elastomers can
compromise the piping.

3. 46 • September 2016 Chemical Engineering World
CEW Features
Rubber Gaskets and Seals generally suffer
from the same drawbacks based on the
selected Elastomer but as a rule, majority
of Rubber Elastomers are extremely poor
in any equipment where the Operating
Temperature is above 100 Deg C and
Operating Pressure is more than 2 bar.
Asbestos
The Usage of Carcinogenic Asbestos
Fiber (CAF) in Gaskets is still extremely
relevant across India especially in
cases where there is a higher operating
Pressure and Elastomers is not an
option. India continues to be the largest
importer and consumer of Asbestos in
the world imperious to the future health
hazard at its doorstep. While, ingesting
Asbestos Fiber is not as dangerous as
inhalation, new studies have shown a link
between Asbestos and Gastrointestinal
Tract problems. The obvious solution is
nonAsbestos Gaskets. These Rubber-
bound fiber sheets find application in a
variety of flange gaskets where, because
limitations on size or gasket stress
or pressure homogenous elastomers
cannot be used.
100% AsbestosFREE Gaskets are a
combination of Elastomers, Fibers and
Binders in different proportions and
for different Operating Temperature
and Pressure ranges. While there is an
increase in using Asbestos Free Gaskets,
there is still no Indian Standard or a
Quality standard to use as a benchmark.
For nonAsbestos Gaskets used in
Drinking Water systems, recommend
using certified Seals with NSF/ANSI 61
Certification (USA) or WRAS Certification
(UK, Europe) to ensure material is safe
and free from all contamination.
PTFE/Teflon
Polytetrafluoroethylene and Teflon
(Dupont) are again material that is
chemically inert and offers excellent
application where high level of purity is
required. The problem with using PTFE
in its Virgin form is the inherent Creep
and Cold Flow properties that shorten the
life expectancy of the actual seal. The
recommended material is usage of Filled-
PTFE or Expanded PTFE which offers a
more suitable sealing solution, high level
of purity and with the life expectancy
similar to Elastomers.
Author’s Details
Darshan A. Parekh
Managing Director
Pilot Gaskets And Engineers
Email Id: darshan.parekh@pilotgaskets.com
Assorted Rubber Gaskets
Gasket Fitted into Pipe Hose
Conclusion
Gaskets are generally dismissed as the
most inconsequential part of the Pipeline
chain and rarely get the importance it
deserves. It is extremely important to
not only understand the compliance
requirements, but to also ensure that they
are being regularly met. As evidenced by
issues with other products that come into
human contact either directly or indirectly,
use of sealing materials that are either
unsafe or not recognized as being safe can
have significant adverse consequences.
While the price economics of the Gasket
is negligible the risk of using non-certified
Gaskets in the overall specification can
cost a lot more than initially anticipated.
Strengthening the Weakest Link in the
pipeline will go in a long way into ensuring
the overall integrity of the Network.