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Benefits of Integral Process Seals and Factory Seals
Reducing risks and costs of instrumentation electrical installation in hazardous
areas
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Slide 1
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Topics covered

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
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Some definitions of electrical system seals to start
The “real situation” concerning process seals in practice
Typical process seal practices used today
Definition of ANSI/ISA 12.27.01 process seal standard/requirements
The risk reduction and cost reduction available to engineers and
operations using certified integral process seal instrumentation
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Slide 2
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Some typical instrument related hazardous area seals
Conduit Seals
A seal installed in a conduit to minimize the passage of gas or vapor at atmospheric
pressure and to prevent the passage of flames from one portion of an electrical system to
another. Conduit seals are not designed to eliminate the passage of gas or vapor
under pressure.
Cable Seals
A seal installed in a cable to minimize the passage of gas or vapor at atmospheric
pressure and ,to prevent the passage of flames from one portion of an electrical system to
another. Cable seals' are not designed to eliminate the passage of gas or vapor under
pressure.
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Slide 3
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Some typical instrument related hazardous area seals
Process Seals
Primary Process Seal
A seal which isolates process fluids (gas or vapor) from an electrical system. One
side of the seal is in contact with the process fluids under conditions of normal
operation
Secondary Process Seal
A seal which is installed between a device which incorporates a primary seal and
conduit (s) or cable(s) systems. The design of the secondary seal must prevent
process fluids from entering the conduit or cable systems in the event of failure of
the primary seal
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Slide 4
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
The “real situation” process seal practices in industry
Source: ELECTRICAL PROCESS SEAL
REQUIREMENTS IN NORTH AMERICAN
ELECTRICAL CODES, IEEE Paper No. PCIC 2008-34
presented at the 2008 Petroleum and Chemical Industry
Committee Technical Conference Cincinnati, OH
September 23, 2008
• ”Experience has shown that conduit or cable seals do not provide the
necessary protection to prevent the migration of process fluids under pressure
through the wiring system. Despite this, the CEC and NEC “process seal”
requirements have been largely ignored.”
• “As a result, availability of certified (listed) and marked products is limited
and the NEC and CEC requirements are not being broadly applied”.
• “Mitigation of this hazard: Recognize product standard ANSI/ISA 12.27.01
for device certifications (listings), both single and dual sealed devices.”
”Device manufacturers need to get products certified (listed), as it is time
consuming, costly and subject to quality concerns if secondary seals or
engineered solutions are applied in the field.”
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Slide 5
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Typical process seal practices used today
Process

None

Double block and bleed (1)

Venting junction boxes/enclosures

Mineral insulated (MI) cable (2)
(1)
Explosion proof
Seal #1
Vent
Explosion proof
Seal#2
Wiring
(2)
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Slide 6
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
ANSI/ISA 12.27.01-2011 Standard recognition/requirements

Per current NEC* and CEC guidelines,
process connected equipment certified as
conforming to ANSI/ISA 12.27.01 and
marked either “Single Seal” or “Dual Seal”
do not need added process seals.

Integral Process Seal
•
ANSI/ISA 12.27.01 requirements designed
and built within the instrument without
externals
•
Generally these are provided within the
instrument certification and without cost
adders
•
Reduce requirements for electrical system
field engineering
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Slide 7
September 2014
* as of NEC 2010
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
ANSI/ISA 12.27.01-2011 standard recognition/requirements

Manufacturer/third party assessor has to conduct (or prove via modeling)
device meets rigorous fatigue cycling, leakage testing and burst pressure
testing
 Process temperature range Maximum Working Pressure (MWP)
 Process temperature range Maximum and Minimum extremes
 Manufacturer has to supply
 Information necessary for the determination of chemical compatibility of process
wetted materials that form part of a primary seal
 Instructions for installation and use of primary seal failure annunciation (if
applicable)
 Instructions necessary for proper maintenance of seals, vents, drains, and
annunciators
 Although it might seem counter intuitive, under ANSI/ISA 12.27.01-2011,
testing for “Single seal” is more rigorous than “dual seal” testing
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Slide 8
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Example certified integral process seal label
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Slide 9
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Example certified integral process seal label
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Slide 10
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Some ANSI/ISA 12.27.01 “add-on” process seal practices
External certified ANSI/ISA 12.27.01 “add-on” devices might be added to
conduit installations at additional cost when integral process seal instruments
are not available or be considered when there are requirements that the
integral process seal solution may not fit.
(1)
 Wiring/cable set feed-through (1)
 Housing assembly (2)
Secondary process
seal housing
assembly
hazardous area
(2)
Conduit wiring system
draw vent
indication
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Slide 11
September 2014
Craig McIntyre
unclassified area
Benefits of Integral Process Seals and Factory Seals
ANSI/ISA 12.27.01-2011 Standard
How to Annunciate or Not to Annunciate, That is the Question
Electrical Conduit
Annunciation
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Slide 12
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Factory sealing (XP Installation only)
Listed factory sealed equipment does not require use of additional associated
conduit seal fittings.
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Slide 13
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Sealing concepts
External conduit seal and external process seal
NEC 501.15: Conduit Seals are provided in conduit or cable systems to minimize the passage of gases and
vapors and prevent the passage of flames from one portion of the electrical installation to another through
the conduit.
pressurized
process tank
Flammable or
combustible
product
NEC 501.17: Process Seals are devices to prevent the migration of pressurized process fluids from the
designed containment into the external electrical system and the control room
NRTL certified
< 18 inches
Conduit seal (flame proof)
Class I, Div. 1
Process seal (gas tight)
vent, annunciation
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Slide 14
September 2014
Craig McIntyre
Control room or
unclassified area
Benefits of Integral Process Seals and Factory Seals
Sealing concepts
Integral factory seal and external process seal
NEC 501.15: Factory Sealed devices contain only non-incendive components in the connection
chamber, which is flame proof sealed against incendive components. “conduit seal not required”
pressurized
process tank
Flammable or
combustible
product
NEC 501.17: Process Seals are devices to prevent the migration of process fluids from the designed
containment into the external electrical system and the control room
NRTL certified including
FACTORY SEALED
< 18 inches
Conduit seal (flame proof)
Class I, Div. 1
Process seal* (gas tight)
Control room or
unclassified area
(*frequent practice: installation with vented junction box)
vent, annunciation
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Slide 15
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Sealing concepts
External conduit seal and Integral process seal
NEC 501.15: Conduit Seals are provided in conduit or cable systems to minimize the passage of gases
and vapors and prevent the passage of flames from one portion of the electrical installation to another
through the conduit.
pressurized
process tank
Flammable or
combustible
product
NEC 501.17: Single Sealed/ dual Sealed devices contain integral seals per ANSI/ISA 12.27.01 and do not
require a secondary process seal in the conduit
NRTL certified including
Integral SINGLE or DUAL SEAL (per ANSI/ISA 12.27.01)
< 18 inches
Conduit seal (flame proof)
Class I, Div. 1
Process seal (gas tight)
vent, annunciation
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Slide 16
September 2014
Craig McIntyre
Control room or
unclassified area
Benefits of Integral Process Seals and Factory Seals
Sealing concepts
Integral factory seal and Integral process seal
NEC 501.15: Factory Sealed devices contain only non-incendive components in the connection
chamber, which is flame proof sealed against incendive components. “conduit seal not required”
NEC 501.17: Single/dual integral sealed devices containing integral process seals per ANSI/ISA
12.27.01 do not require a secondary process seal in the conduit
pressurized
process tank
Flammable or
combustible
product
NRTL certified including
Integral SINGLE SEAL or DUAL SEAL (per ANSI/ISA 12.27.01)
and FACTORY SEAL
Class I, Div. 1
Control room or
unclassified area
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Slide 17
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Benefit by using certified integral process seals:
Safer installation, flexible wiring and repair, lower installation cost
• Flame proof conduit seal
• Installation ½ hour (fiber filler, mounting..)
$30
• Conduit seal package
$50
• Junction box
$20
• Fittings
$10
Use of a factory sealed device may save $110
• Secondary process seal with annunciation
• Installation ½ hour
$30
• Secondary process seal package
$140
• Fittings
$10
• Junction box
$20
Use of a single/dual sealed device may save $200
Use of a single/dual sealed and factory sealed device may save $310
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Slide 18
September 2014
Craig McIntyre
Benefits of Integral Process Seals and Factory Seals
Endress+Hauser - Safety by Design
http://www.us.endress.com/process-safety
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Slide 19
September 2014
Craig McIntyre