This document discusses nozzle sealing system failures that can occur in drier plants and the risks associated with such failures. It notes that leaking nozzles pose a fire risk and can impact safety, production and insurance costs. Current nozzle sealing designs are prone to damage and may not meet pressure standards. A new axial seal design is proposed that is more robust, easier to assemble and maintain, and complies with high pressure standards, reducing risks associated with nozzle failures.

1. MitigatingnozzlesealingsystemfailureandimpactsuponRiskmanagementandsafetyindrierplant | 1
TheRisk&Safety
Understanding the relationship between high
pressure nozzle sealing system failure and plant
safety is essential. One approach is to view this
issue within a Risk analysis framework with regard
to the normal drier risk management program
which would be maintained at the dairy plant.
In respect to such an approach, it should also be
considered the various stakeholders in regard
to such Risk, ie; plant and product insurance
loss underwriters, statutory authorities,
management, commercial, customers, etc, etc and
how they would view and potentially investigate a
failure.
One risk area we are aware of is the potential for
a Drier fire, and how this can impact other factors
such as lost production, plant safety etc. the dairy
plant would already be well aware of various risks
attached to the operation of Spray drier plant and
possible outcomes due to plant failure. Nozzle
hardware suitability, performance and condition
is a critical consideration in a Fire Risk analysis.
In one case we are aware of an insurance
investigation undertaken in respect to a drier
fire. This fire resulted in significant loss. It was
reported that the fire was due to a leaking
nozzle assembly.
When exposed to this level of scrutiny and
investigation post such an event, and being aware
that a leaking nozzle can directly precipitate a fire
loss, it is essential for responsible parties to see that
the nozzle systems are operated within certain
known and standard industry conventions of
high pressure operation, and that the equipment
has been designed and is maintained to an extent
which ensures conformance to these standards.
Mitigatingnozzlesealingsystemfailureand
theimpactsuponRiskmanagementand
safetyindrierplant
Leakage has occurred at the
rear of this nozzle
Scorched
product
Leakage due to seal damage despite inclusion
of back-up ring. Such an assembly is difficult
& complex to service correctly on a daily basis.
Gland surface damage may have pinched &
torn O-ring at assembly.
Back-up
ring
Seal damage
bySprayNozzleEngineeringLtd
Severe scorched product due to seal leakage.
The beginning of a potential drier fire.
FIG 1.
FIG 3.
FIG 2.

2. 2 | MitigatingnozzlesealingsystemfailureandimpactsuponRiskmanagementandsafetyindrierplant
Observingstandards&improved
designcanhelp
It is well known in many industries that standards
of sealing integrity are covered by widely adopted
standards such as AS4716A, along with pressure
integrity standards for plant such as ASME B31.3,
amongst other very similar international standards.
Nozzles can be designed to conform to the
required pressure & service duties in observance
of such standards and manufacturers can
provide design data to support their product
duty. Such information should be pursued in any
Risk management model for drier safety.
Management Systems must exist to ensure that
such spray nozzle hardware sealing standards
are not easily compromised. This can be
achieved through improved hardware design
and proper maintenance so as to reduce the
likely hood of such a failure in the first instance.
Multiple seal gland surface damage due to
mishandling. Unsuitable for service.
Multiple seal gland surface damage due to lance
handling impact on a NEW nozzle and lance.
Unsuitable for service.
Severe single point damage due to lance
handling impact on a NEW nozzle. Unsuitable
for service.
Damage seal gland
surface
Even without damage, sealing standards limit such
an arrangement to a max. pressure of only 103 barG.
FIG 4.
Radial seal gland damage with localised impact
damage. Note old imbedded seal. New seals
should be installed on each run. Unsuitable for
service.
FIG 5.
FIG 6.
FIG 7.
FIG 8.

3. MitigatingnozzlesealingsystemfailureandimpactsuponRiskmanagementandsafetyindrierplant | 3
Typicaldrierpressuresrequire
reliablesealingsystemsfitfor
purpose
We know that leaking nozzles can cause a drier fire,
and this is directly related to their ability to reliably
seal in their typical operating environment,
The following should be understood and
considered in respect to a related risk analysis:
Most Spray nozzle systems in driers are required
to function without failure at pressures typically
up to, or in some cases even exceeding,
350 barG.
This is a very high pressure by any industry
standard.
If the nozzle seal fails under these known pressure
conditions, what are the likely risks attached to such
a failure, and how would such potential risk impact
safety, product quality, lost production, etc.
In the interests of all concerned, it is important that
stakeholders can see that known industry standards
of practice have been adopted to help avoid seal
failure, material and design failure (amongst a
number of other potential failure conditions),
particularly in the event that a significant loss has
somehow occurred.
Damaged seal gland surface compromising
sealing integrity
Severe seal gland
surface damage
FIG 9.
Typical back up ring extrusion failure due to
gland wear. The back up ring is designed to
prevent O-ring extrusion. When the back up ring
extrudes itself, failure is inevitable. High risk
FIG 10.
Similarly nozzle carriers (caps) can also exhibit
damaged seal gland surfaces compromising
sealing integrity. These lance components must
also be risk managed.
FIG 11.
Nozzle carriers must be designed to function
safely at the maximum operating pressure of the
drier. These carriers have been over-pressured
and on the verge of significant stress yield
failure.
Note stress
bulge & crack
FIG 12.

4. 4 | MitigatingnozzlesealingsystemfailureandimpactsuponRiskmanagementandsafetyindrierplant
ReasonsforSealingSystemfailure:
______________________________________________
• PROBLEM: Poorly designed seal gland systems
that lend themselves to be easily damaged during
normal use and exposed sealing surface at the
lance end that is easily damaged by impact during
handling.
Most dairy plants currently operate spray lances
with readily exposed nozzle hardware seal
surfaces at their end which are regularly subject
to impact during handling, such impact can
compromise sealing efficiency and cause failure.
Click&Dry® has a Heavy duty female
threaded lance fitting with heavily
concealed sealing surface which is
highly resistant to normal impact
damage during lance handling
______________________________________________
• PROBLEM: Poorly maintained nozzle seal gland
systems in drier. Seal gland damage has been
observed and reported at many dairy sites.
In most cases the pressure integrity of such
hardware cannot be guaranteed. It is a standing
recommendation that the compromised hardware
is immediately replaced when such damage is
observed.
Regular damage inspection is an
absolute must.
Monitoring of seal gland
condition and checking for radial
dimensional conformance is
critical in any nozzle hardware risk
management program.
Click&Dry® system will
eliminate the need for radial
measurement monitoring.
______________________________________________
________________________________________
• PROBLEM: Seal gland systems that do not
comply with known sealing conventions
and standards in respect to the operating
pressures required. It is known that most
sealing glands operated by most dairy
plants are of a radial type and do not
comply with known sealing standard
recommendations and conventions for
high pressure operation, specifically, they
do not deal with gland gap inherent in
such radial seal designs and the resultant
potential for O-ring extrusion at pressures
exceeding 103.4 BarG, most dairy systems
require gland conformance to 350 BarG +.
It is also known that required minimal seal
gland gap cannot be easily and practically
maintained within normal dairy plant
operational processes using current designs,
even with the adoption of more stringent
maintenance programs.
Click & Dry® uses a non
radial AXIAL SEAL which
are a known & published
industry preference in
high pressure sealing
applications since THEY
HAVE NO GAPin a face to
face contact.
Old radial seals without
back up rings should only
operate at pressures well
below typical operating
pressures according to
typical O-ring standards.
Required assembly joint
gap of radial seals allows
seal extrusion at high
pressures. Click&Dry®
operates with NO GAP and
therefore no seal extrusion
can occur.
________________________________________
FIG 13.
FIG 15.
FIG 14.
OLD RADIAL SEAL GLAND
GAP
Requires assembly joint gap.
May allow seal extrusion & leaks
at normal operating pressures.
Should not exceed 103.4 barG
without backup rings
Axial compressive seal with NO
GAP for use well above typical
operating pressures of 350 barG
plus. Seal face protection skirts
for extra seal face protection
NO GAP
NEW AXIAL SEAL GLAND
SEAL FACE
PROTECTION SKIRTS
SOLUTION:
SOLUTION:
SOLUTION:

5. MitigatingnozzlesealingsystemfailureandimpactsuponRiskmanagementandsafetyindrierplant | 5
________________________________________
• PROBLEM: Seal gland systems require
allowable material stress due to pressure of
operation to comply with the requirement
standards such as ASME B31.3. It is not
shown that hardware arrangements
currently in use by dairy sites comply to
such pressure integrity requirements
Click&Dry® system is
shown to comply with
satisfactory operational
factors of safety in regard
to allowable stress in
service.
________________________________________
• PROBLEM: Difficulty in positive assembly
and use. Most current nozzle systems
in use by dairy sites require great
deal of assembly skill and the risk of
misalignment of components is high.
This can lead to leakage. In particular, if
radial seal backup rings are adopted as
required, these can be incorrectly installed
on the wrong side of the seal or can catch
on assembly, compromising the seal before
use. These backup rings are also very
expensive.
Click&Dry® axial seal does
not require troublesome
backup rings, it also
eliminates misalignment
of wear parts during
assembly (clasp model)
which can cause leakage
________________________________________
________________________________________
Conclusion
In conclusion, it can be seen that a significant
level of risk in respect to seal gland integrity
is currently being carried by dairy sites,
whereby if a drier Fire did occur, that this
might compromise safety, and that if such an
event could be linked to a leaking nozzle, then
it might be most difficult to disprove that it
was as a result of any of the above mentioned
weaknesses in the current nozzle systems.
________________________________________
Adopting the Click & Dry® system delivers dairy sites
a state of the art nozzle design, with Design features
which improve nozzle seal gland life, reduce the
likely hood of handling damage, reduce the likely
hood of misalignment during assembly (amongst
many other benefits not mentioned here), and most
importantly more readily conforms to known sealing
standards and conventions for high pressure use, in
particular the pressures operated by dairy sites. As
such this reduces significantly the risk of leakage,
and therefore fire, and the resultant potential
compromises to safety)
________________________________________
_________________________________________
• PROBLEM: Lack of vendor technical support
in respect to operator training and product
information including technical literature and
user guidelines along with product care and
management accessories.
Click&Dry® is a fully
supported product in
the field with on-site
operator training and a
comprehensive library of
technical support material
tailored for field use.Click&Dry®
NOZZLE ASSEMBLY GUIDE FOR MAXI FIRST GENERATION SYSTEM
O-RING GROOVE IN CAP - NON CLASP SCREW PIN
This guide relates to early First Generation O-ring groove in nozzle cap. To reduce bearding and/or increase operating
pressures please contact us regarding the new SEAL-IN-DISC SYSTEM now available.
WARNING!
1300 Nozzle
TECH TIP!
ASSEMBLY SHEET #1
Click&Dry 228.3
MPa
-48.9
0.0
FIG 16.
FIG 17.
FIG 18.
SOLUTION:
SOLUTION:
SOLUTION:

6. 6 | MitigatingnozzlesealingsystemfailureandimpactsuponRiskmanagementandsafetyindrierplant
Addenda
I have found in the“Dichtomatik O-Ring Handbook”the following
statement
Extrusionisaconcernforradialsealswherethereisagap
betweenthepistonandtheboreforamaleglandsealor
betweentherodandtheboreforafemaleglandseal.Extrusion
isnotaconcernforfacesealswherethemetalpartstobesealed
aretypicallyinline-to-linecontact
Ithinkweshouldagainemphasizethefollowingpoints:
• Thereisanincreaseinergonomicsandhandling
advantagesastheuserdoesnothavetohandlethefiddly
andbrittleback-upringswiththedesign.
• Ifback-upringsisnotusedoriscrackedinaradial
sealingarrangement,thesealmayfailinhighpressures
duetovariousstatementsinO-ringdesignhandbooks
worldwide,suchasfromDichtomatikandParker.Thiswill
thereforemaketheaxialsealingmethodsaferunderthese
conditions.
• Needtoemphasizethefeedbackwehavehadinregardsto
theuseofback-upringsandhowoftentheyhavecracked
orbroken.
• Lessconsumablestopurchase
ParkerO-ringHandbooksaysofmetalnogap:
Commentsfromourengineer,CharlesVuong: