Transcript The PerfectSeal Gasket: A Revolutionary Approach To Flange

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PerfectSeal
Constant Seating Stress Gaskets
A Revolutionary Approach To Improved Flange Sealing
TECHNICAL TUTORIAL FOR ENGINEERS
JJENCO, Inc.
University Research Park
10130 Mallard Creek Road | Suite 300 | Charlotte | North Carolina | 28262 | USA
[email protected] | +1.704.944.5568
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Introduction
 The PerfectSealEOS constant seating stress gasket:
• Does not rely upon (i) highly-trained assembly technicians, (ii) properly
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calibrated tooling, (iii) complex flange tightening patterns, (iv) timeconsuming multiple flange tightening passes, or (v) correct piping
alignment in order to achieve a ‘perfect seal’ every time
Cannot be ‘misinstalled’, regardless of flange orientation
Is at least 7X faster to install than conventional gaskets, even on small 8bolt flanges
Is a direct replacement for all semi-metallic gaskets, including spiralwound gaskets (SWG) and kammprofile gaskets
Is immune to (i) radially-inward buckling (RIB), (ii) foreign material castoff into the process fluid, (iii) flow-induced gasket degradation, (iv)
system vibration and (v) thermal transients
Is the least expensive semi-metallic gasket solution when gasket
installation costs are included
Can be inexpensively refurbished and reused
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Sealing Issues
Conventional Gasket Products
Unknown or imprecise gasket factors
Compression Variability (SWG)
Wrong Gasket for Application
Spent After Single Use
 Calculation Errors
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Required Seating Stress
Required Fastener Preload
Friction Estimate (Nut or ‘K’ Factor)
Required Torque Value
 Tooling Issues
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Torque Wrench Accuracy
Calibration Errors
Off-Axial End Effectors
Incorrect Torque Wrench Setting
SWG = Spiral Wound Gasket
CR = Creep Relaxation > Loss of Bolt Stress
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 Assembly Issues
 Product Issues
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Incorrect Wrench Reading (Dial/Beam)
Improper Torquing Technique
Insufficient Fastener Lubricant
Improper Lubrication Placement
Poor Fastener Thread or Bearing Surface
Improper Tightening Sequence
Piping Misalignment
Uneven Gasket Loading
Insufficient ‘Finishing’ Passes
 In-Service Issues
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‘Soft Joint’ Assembly >>CR
Plant Thermal Cycles >>CR
High System Vibration >>CR
Radially-Inward Buckling (SWG only)
Foreign Material Intrusion [to System]
External Blowout
Environmental Degradation (eg. Fire)
Process Degradation (eg. Oxidation)
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Sealing Solutions
PerfectSealEOS Gaskets
 Assembly Issues
 Product Issues
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Unknown or imprecise gasket factors
Compression Variability (SWG)
Wrong Gasket for Application
Spent After Single Use
 Calculation Errors
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
Required Seating Stress
Required Fastener Preload
Friction Estimate (Nut or ‘K’ Factor)
Required Torque Value
 Tooling Issues
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Torque Wrench Accuracy
Calibration Errors
Off-Axial End Effectors
Incorrect Torque Wrench Setting
SWG = Spiral Wound Gasket
CR = Creep Relaxation > Loss of Bolt Stress
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Incorrect Wrench Reading (Dial/Beam)
Improper Torquing Technique
Insufficient Fastener Lubricant
Improper Lubrication Placement
Poor Fastener Thread or Bearing Surface
Improper Tightening Sequence
Piping Misalignment
Uneven Gasket Loading
Insufficient ‘Finishing’ Passes
 In-Service Issues
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‘Soft Joint’ Assembly >>CR
Plant Thermal Cycles >>CR
High System Vibration >>CR
Radially-Inward Buckling (SWG only)
Foreign Material Intrusion [to System]
External Blowout
Environmental Degradation (eg. Fire)
Process Degradation (eg. Oxidation)
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Presentation Overview
 This self-paced technical tutorial is intended to:
• Explain the revolutionary ‘constant seating stress gasket concept’
• Illustrate the application of that concept to flange joint assembly
• Showcase different styles of the PerfectSeal gasket for specific
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applications
Present test data and field demonstration experience
Compare performance vs. conventional semi-metallic gaskets
Highlight the benefits of constant seating stress gaskets over
traditional gasket technologies in real-world applications
Demonstrate the cost-benefit of using PerfectSeal gaskets compared
to conventional gaskets
 This tutorial should take approximately 25 minutes to
complete
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SECTION I
UNDERSTANDING THE CONSTANT
SEATING STRESS GASKET CONCEPT
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What is a ‘Constant Seating Stress’ Gasket?
 A constant seating stress gasket is defined by two
common characteristics:
• The initial seating stress of the sealing material achieved
•
on assembly does not change appreciably over time
The seating stress of the sealing material is relatively
uniform radially across the entire sealing area
 JJENCO holds the patent on constant seating stress
gasket technology
 Constant seating stress gaskets are only available
directly from JJENCO
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Why is Constant Seating Stress Important?

Gasket leakage occurs primarily due to one of the following 6
reasons:
• Flange sealing surfaces too defective to achieve a seal
• Initial gasket seating stress too high
• Initial gasket seating stress too low
• Initial gasket seating stress sufficient to achieve a seal, but gasket creep
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relaxation leads to loss of seating stress over time
System conditions (thermal cycles, high vibration, etc) cause transient or
permanent reduction in gasket stress enabling leakage to occur
Gasket sealing material not compatible with environmental or process
conditions
 Assuming the sealing surfaces are acceptable and the sealing
elements are compatible with the process fluid, PerfectSeal
constant seating stress gaskets can mitigate all remaining factors
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Simple Design Premise
 The design premise for the PerfectSealEOS gasket
recognizes that:
• A specific amount of gasket seating stress is needed in order to
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create an effective seal between two flange faces
Gasket stress tends to change over time, primarily due to the
gasket sealing material’s continued response [creep relaxation]
to the external force used to create the initial seal, or due to
other forces resulting from thermal cycling, vibration, etc
If you can achieve the initial seating stress necessary to achieve
a seal, and control other factors that can change that seating
stress over time, then in-service leakage can be averted in most
cases
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Achieving Correct Gasket Stress
 Flange deflection – also known as ‘flange rotation’ – occurs at
the outer flange circumference in response to increasing
preload of the fasteners during flange assembly
 Finite element analysis (FEA) can accurately predict the degree
of flange deflection that occurs at various radial distances from
the flange axis at a given bolt preload for a specified flange
size, material and pressure class.
 Therefore, flange deflection can be used in lieu of applied bolt
torque to accurately determine required gasket tightness
 The PerfectSealEOS gasket profile models flange deflection
predicted for a desired preload, making ALL assembly factors
associated with achieving the target bolt preload unimportant
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Maintaining the Correct Gasket Stress
 Creep relaxation of the gasket sealing material is the main
cause of loss of gasket seating stress in service
 Gasket ‘creep’ occurs as the sealing material seeks to move
from a region of higher stress to a region of lower stress,
thereby causing an overall reduction in peak gasket stress
 A leak may result if the peak gasket stress drops below the
threshold necessary to maintain the seal between the flanges
 By fully containing the sealing material within opposing
channels on either side of the gasket carrier ring, creep
cannot occur in service, thereby self-mitigating the
opportunity for a leak to occur
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SECTION II
GENERAL APPLICATION TO
FLANGED JOINTS
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PerfectSealEOS General Description
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The PerfectSeal gasket is comprised of
a carrier ring (20) and a sealing
material elements (22)
The carrier ring has three important
features:
• Inner pivot point (30)
• Inner compression stop (32)
• Visual Compression Indicator (40)

The sealing elements can be any
compressible material (e.g., expanded
graphite, vermiculite, expanded
polytetraflouroethylene, etc.) as
appropriate to the application
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On Assembly
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As the fasteners (16) are tightened,
the flange faces (10A, 10B) begin to
compress the sealing elements (22)
into their respective channels (24) of
the carrier ring and ultimately contact
the inner pivot point (38) of the
carrier ring
Continued tightening of the flange
fasteners causes normal flange
rotation to occur, thereby further
compressing the sealing elements into
their respective channels
A proprietary process controls the
compression of the sealing elements
into their respective channels
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At Full Compression
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As the flange faces rotate* about the
inner pivot point, they finally engage
the inner compression stop (32)
The sealing elements are fully
compressed, resulting in
achievement of the desired gasket
seating stress
The sealing elements are fully
contained, therefore no change in
gasket stress can occur in service
The sealing elements are also
completely protected from both the
internal process flow and external
environmental factors
*flange rotation exaggerated for illustration
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Achieving Uniform Stress
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Due to flange rotation, gasket seating
stress generally increases with the
distance from the axial centerline of
the flange
This results in the achievement of the
target seating stress only at the outer
edge of the sealing area – the actual
gasket stress over the majority of the
sealing area is less
By matching the angle of the gasket
profile with the calculated degree of
flange rotation for a given flange size,
pressure class, and material, the
desired seating stress can be
achieved over the entire sealing area
– not just at the gasket’s outer edge
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The Visual Compression Indicator

By calculating the degree of flange
rotation occurring at two points,
• the outer compression stop (40)
• and the inner compression stop (32),
• the outer compression stop thickness can
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be sized to provide a positive visual
indication for the assembly technician that
the flange faces have positively engaged
the inner compression stop
thus fully compressing and capturing the
sealing elements in their grooves
This outer compression stop also
makes the use of calibrated assembly
tooling, complex bolt tightening
patterns, and sequential finishing
passes completely unnecessary, as
overcompression of the gasket
cannot occurr
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Installation Benefits
 Sealing element channel
prevents ‘crushing’ or
overcompression when
inserting gasket, aligning
flanges, or tightening
fasteners
 The outer compression
stop enables one-pass at
100% tightness,
rotationally-sequential,
tightening of fasteners
Single Pass Tightening in Sequential Rotation
Regardless of Flange Size
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1
2
7
6
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SECTION III
APPLICATION CONSIDERATIONS
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PerfectSealEOS Style
 Ideal for all raised and flat face
flanges
 Carrier ring extends outward of
the bolt circle
 Provides real-time proper
compression indicator to the
assembly technician
 Prevents misinstallation or gasket
misalignment from occurring,
regardless of flange orientation
 Unique bolt hole configuration
improves ability to insert
fasteners without perfect flange
alignment
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PerfectSealCRG Style
 Ideal for specific flanges
• Male-female
• Tongue and groove
 Eliminates flange fit and
tolerance concerns
 Sealing element
protected from process
flow degradation
 Can be manufactured
with or without exterior
alignment ring
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In-Service Performance
 Impossible to:
• Cast-off foreign material into plant systems or components
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(e.g., no radially-inward buckling (RIB) as with spiralwound gaskets)
Inadvertently ‘crush’ the gasket due to overcompression
Leak due to plant thermal cycles or high system vibration
Degrade sealing elements due to process flow impingment
Impact sealing element performance by direct external
contact
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Application Specifications
 Carrier ring normally made from 304/316 stainless steel, but can be
manufactured from any appropriate material according to client
requirements
 Standard bolt preload emulation is 45ksi, but can be manufactured to
emulate bolt preloads from 10-100ksi, according to client
requirements
 JJENCO has FEA design data available for ASME B16.5 carbon and
stainless steel flanges:
• RFWN flanges in all pressure classes and sizes from 0.5”-24”
• RFSW flanges in all pressure classes and sizes from 0.5”-2”
• Other flange types or configurations available (additional design fee applies)
 Sealing elements are normally expanded graphite, expanded PTFE, or
vermiculite, but can be made from any compressible sheet material
according to client requirements
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SECTION IV
PERFORMANCE DATA
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Creep Relaxation Comparison
 PerfectSealEOS gasket (red)
vs. all other semi-metallic
gaskets, including:
• Spiral-wound gaskets (SWG)
• Kammprofile gaskets
• Semi-metallic sheet gaskets
 Demonstrated less than half
the creep (>24hrs) of the
best gasket on the market
 Less creep = less chance of
leakage in service
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Comparison to ‘CG’ Style SWG
 Industry testing proves that
torque required to compress
spiral-wound gaskets (SWG) can
vary widely between gaskets
 CG-style* SWG without inner ring
can creep in-service, resulting in
leakage
 CG-style SWG are prone to
radially-inward buckling (RIB) of
their windings that can introduce
foreign material into system
causing damage to components
and system operability concerns
 Most concerning, not all RIBdegraded SWG in service result in
an identifiable leak
*The ‘CG’ designation is used here as a generic
identifier for a SWG possessing an outer
compression stop ring, but no inner stop ring, and
should not be construed to represent any particular
manufacturer
Multiple catastrophic
buckles with filler
material completely
washed out and
winding material
extending well into
the flow path
One of several pieces
of SWG metal
winding material
removed from tube
bundle of steam
generator during
routine inspection
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Comparison to ‘CGI’ Style SWG
 ‘CGI’-style* SWG can reduce
creep relaxation
 However, due to the inability
of ‘CGI’-style gaskets to relieve
stress by moving radially
inward:
• The same torque levels used
•
for ‘CG’-style SWG can cause
extreme radial loads in the
gasket sufficient to seriously
deform the gasket
Or, cause general deformation
and buckling of the inner ring
itself
*The ‘CGI’ designation is used here as a generic
identifier for a SWG possessing both an outer and
inner compression stop ring and should not be
construed to represent any particular manufacturer
Illustration of severe
‘CGI’-style gasket
deformation
Evidence proving
generalized inner ring
buckling can occur
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Comparison to Kammprofiles
 Kammprofile gaskets represent
‘the best of the best’ among
semi-metallic gaskets, with
respect to creep resistance
 However, as with SWG, all
kammprofiles perform differently
 Using identical test equipment
and procedures, the
PerfectSealEOS gasket (red) is
proven to creep 60% less than the
best available kammprofile gasket
 In addition, research shows that
kammprofile gaskets also vary in
their ability to seal minor surface
defects in flange face finish –
making excellent sealing surfaces
a prerequisite for success
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Field Test Example
 Demonstrated in 4”-Class
150 service water system
flange at Duke Energy
‘Riverbend’ fossil station
 Installed under blind
flange by one technician in
under 45-seconds using
standard combination
wrench
 Inspected after 1-hour at
system T/P with no leaks
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SECTION V
COST BENEFIT CASE
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Cost Benefit Considerations
 ‘Unit Cost’ basis is NOT a smart procurement
strategy for parts performing a critical function
 ‘Cost of Ownership’ procurement strategy for critical
parts takes into account:
• Installation costs
• Cost benefits of increased service reliability and availability
• Future maintenance costs
 ‘Total Cost of Ownership’ also takes into account
future avoided costs
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Initial Cost-of-Ownership*
COST COMPARISON ($USD)
Unit Cost (estimates)
Conventional
Gasket
10
PerfectSeal
Gasket
75
Installation Labor (20 min avg.)
40
2
12
0
20
0
Fastener Lubricant (8oz.)
10
0
Hardened Steel Washers (8)
4
0
2 mechanics @ $60/hr each
Calibrated Tooling
5% of $250 torque wrench life before req'd rebuild
Tooling Calibration Labor
1/3 labor-hour
TOTAL
$
Radiation Dose (Nuclear Only)
96.00 $
30
77.00
1.50
Estimate 0.1mR dose received x 2 persons @ $15K/man-rem
TOTAL w/ Dose Factor
*4-in Class 150 gasket
$
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126.00 $
78.50
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Subsequent Reinstallation Cost*
Conventional
Gasket
10
PerfectSeal
Gasket
10
40
2
12
0
20
0
Fastener Lubricant (8oz.)
10
0
Hardened Steel Washers (8)
4
0
COST COMPARISON ($USD)
Unit Cost (estimates)
(PerfectSeal sealing elements replaced only)
Installation Labor (20 min avg.)
2 mechanics @ $60/hr each
Calibrated Tooling
5% of $250 torque wrench life before req'd rebuild
Tooling Calibration Labor
1/3 labor-hour
TOTAL
$
Radiation Dose (Nuclear Only)
96.00 $
30
12.00
1.50
Estimate 0.1mR dose received x 2 persons @ $15K/man-rem
TOTAL w/ Dose Factor
*4-in Class 150 gasket
$
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126.00 $
13.50
33
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Potential Avoided Costs
 Production Penalties
• Forced plant outage, outage extension, production reduction
 Replacement Production
• e.g., replacement power
 Maintenance Effort Radiation Exposure (nuclear only)
 Third-Party Services
• Leak sealant injections, environmental cleanup, flange remachining,
etc.
 Consequential System or Component Damage
 Regulatory Fines
 Response to Regulatory Scrutiny
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SECTION VI
CONCLUSION
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Direct Benefits
 Simpler Tooling – No need to rely upon torque wrenches, stud
tensioners, or other calibrated tooling
 Simplicity of Installation– No complicated assembly patterns,
multiple tightening passes
 Speed of Assembly – Proven at least 7X faster to install on
even small 8-bolt flanges
 Reduced Training – Technicians require limited training to
assemble flanged joints successfully
 Increased protection from environmental- (e.g., fire, etc.) and
process-induced degradation
 No Possible Foreign Material introduction to system
 Reusable Carrier Ring dramatically reduces future
replacement costs
 Increased Personnel Safety during installation and in-service
 Potential to Reduce Personnel Radiation Exposure (nuclear)
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Indirect Benefits
 Simplified job planning
 Reduced risk of
• Future maintenance requirements
• Collateral or consequential equipment damage
• Production losses attributable to leakage events
• Replacement power acquisition (power industry)
 Potential for reduction in insurance costs
 Reduced gasket inventory
 Reduced maintenance administrative burden
 Increased availability of plant staff
 Reduced potential for regulatory scrutiny due to leaks
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Conclusion
 The constant seating stress gasket design:
• Uses commonly accepted materials
• Is based upon simple, proven principles aggregated in a novel manner
 It should be easy to install and require no follow-on
maintenance
 It is the least expensive gasket solution when gasket
installation costs are included
 It provides both immediate and future benefits in terms of
• Personnel safety
• Plant availability and reliability
• Total cost of ownership
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Maintenance Self-Assessment
 Do you have gasket leaks at your site?
 If so, is your Maintenance department using
PerfectSeal constant seating stress gaskets?
 If not, Why Not?
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For More Information…
 To obtain:
• Information on purchasing
•
PerfectSeal constant
seating stress gaskets, or
Subject-matter expertise
for fluid sealing issues…
John M. Jenco
President
Research, Technology & Consulting
University Research Park | Prosperity Place on Mallard Creek
10130 Mallard Creek Road | Suite 300 | Charlotte | 28262 | USA
(T) +1.704.944.5568 | (F) +1.704.944.3101 | [email protected]
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