UNIVERSITY OF MINNESOTA
Dept. of Environmental
Health and Safety
www.dehs.umn.edu
Hazard Analysis Process for Adding
Amines to Steam System
C. Moody, A. Streifel, and M. Nagel
Southeast steam plant
Background
• Peak campus steam demand - 450,000 lb/hr
– Hospital demand – 20,000 lb/hr
• Corrosion of boilers, coils, pumps, traps and
piping
– Increased maintenance and energy costs – $1M
per year
Causes of corrosion
• Corrosion caused by formation of carbonic
acid
– CO2 + H2O

H+ + HCO3- (carbonic acid)
• Major sources of CO2
– Dissolved gas in make-up water
– Thermal breakdown of NaHCO3 and Na2CO3
• Oxygen enhances corrosion
Amine addition
• Add neutralizing amines to keep pH range
at 8.5 - 9.2
– Morpholine condenses soon after release to
protect close-in piping
– Cyclohexylamine protects far reaches of
condensate piping
Health Effects
• Eye irritation
• Irritation of upper respiratory tract
• Dermatitis and sensitization from skin
contact
Health standards
Amine
Type
OSHA
PEL
(ppm)
FDA limit
in steam
(ppm)
Odor
Threshold
(ppm)
Morpholine
20
10
0.14
Cyclohexylamine
10
10
0.90
NIOSH Health Hazard
Evaluations
• 1982 – Museum study
– Diethylaminoethanol (DEAE) produced eye irritation
and dermatitis
– Air samples - 0.01 ppm
• 1988 - Electrical components factory
– Nausea, dizziness, throat irritation
– DEAE and cyclohexylamine added at 4x normal
strength
• 1989- Nurses in humidified nursery & newborn
ICU
– Eye and upper respiratory irritation
– Cyclohexylamine and morpholine
NIOSH Evaluation -1993
VA Medical and Research Center
• Morpholine and cyclohexylamine
– Fatigue, allergy symptoms, eye and upper respiratory
irritation
• Air, surface and steam samples
– Air samples not exceeding minimum detectable
concentrations
– Detectable concentrations in surface samples
– Measured concentrations in condensed steam samples
• Recommended no amines for humidification
Potential campus exposures
• Humidification of sensitive patient areas
• Medical device sterilization
• Irritation for students and staff when added
in excessive amounts to steam
• Food preparation
Control Options for Hospital
• Clean steam generators
• Direct steam humidification with
monitoring and control
Team approach to evaluate
proposal
• Facilities Management Department
• Contract steam plant operator
• Department of Environmental Health and
Safety
Options for amine addition
• Inject amine based on:
– pH of condensate return
– Steam demand
• Grab samples versus real-time monitoring
• Metered injection
Proposal
• Inject amine based on steam demand
– Use computer to calculate injection rate
– Use chemical metering pump
• Install analyzer to continuously monitor
downstream concentration
• Use analyzer signal to prevent overfeed of
amine
Metering Pump
Analyzer
Monitor
Failure analysis
• Conduct “What If” analysis based on
description of monitoring/control system
– Review possible failures
– Evaluate control features
– Make additional recommendations for
monitoring and control
What If Analysis
What If
Consequences/Hazards
Safety Features
Recommendations
Vendor delivers wrong
concentration of
solution
Amine concentration in
steam may not be able to
be adjusted by metering
pump
Certification
provided by vendor
of amine type and
concentration
Analyzer detects
and adjusts injection
rate
Certification should
accompany the
shipment and should
be logged in by steam
plant staff
There is an
interruption in steam
flow
Steam flow interrupted,
amine injection continues
without interruption,
producing excessive
amine concentration
Control system
shuts down amine
injection within
several seconds
None
There is a sudden
drop in steam demand
As above
Analyzer
continuously
monitors the
concentration,
computes required
concentration and
makes adjustments
to injection pump
Target concentration is
1 ppm, but has
capacity to deliver up
to 10 ppm. Notice and
approval of University
necessary for increase
in dosage.
What If Analysis …
What If
Consequences/Hazards
Safety Features
Amine
concentration
exceeds upper
setpoint
Excess amine in steam
DCS system adjusts pump
rate down, or shuts down
the injection pump
depending on excursion;
generates operator alarm
Connect the alarm
point to central
monitoring system
Test the shut down
mode during
calibrations
Chemical pump
failure
Pump begins to operate
at excess rate
On-line analyzer indicates
an excursion and shuts
down pump
Not enough pressure to
inject amine
None
False high concentration
signal generated
Analyzer adjusts
concentration downward
only (fails closed)
Incorrect low
concentration signal
generated
Analyzer calibrated against
laboratory samples of amine
blend
Take independent
samples in critical
areas at peak and
non-peak steam
demand periods
Pump leaks
Analyzer failure
Recommendations
Recommendations
• Certify amine concentration
• Request written permission of the
University to change amine concentration
• Route alarm conditions to central
monitoring point
• Take independent steam samples
Results
• Real time analyzer
– Amine concentrations 1.0 - 2.5 ppm
• No complaints of irritation or odor
Benefits and Conclusions
• Safety and health assurance
– Patients, employees and students
• Cost effectiveness
– Alternative to clean steam generators
– Reduce maintenance and energy costs
• Process hazard analysis useful
Craig Moody, CIH
Department of Environmental
Health and Safety
University of Minnesota
moody002@umn.edu
612-626-4399