Chlorine Production
and Uses
1

Objectives
This web seminar will enable the participant to
• identify the hazards of chlorine (Cl2)
• describe chlorine transfer and water
disinfection processes and other equipment
common in chlorine service
• recognize common causes and signs of
failures in chlorine systems, along with
current compliance policy
2

References
Many key safety related publications are
available for download free of charge from
The Chlorine Institute (Ci), a major
industry trade group, at http://www.cl2.org
The Ci also produces valuable RAGAGEP
on chlorine system design and operation
($$)
OSHA’s chlorine guidelines are at
http://www.osha.gov/SLTC/healthguidelines/
chlorine/recognition.html
3

Chlorine Production
• Most Cl2 is produced at large facilities by
electrolysis of salt brine:
2 NaCl + 2 H2O  Cl2↑ + 2 NaOH + H2↑
• 1.1 tons of caustic are co-produced with
every ton of chlorine
• The hydrogen may be vented, or captured
and purified for sale
• 15 million tons produced in the US in
2005, using 1.2% of total US electricity
supply
4

Chlorine Production
Hydro
Power
Major
Adapted from Kirk-Othmer, Encyclopedia of
petrochemical
Chemical Technology, 5th ed, Vol. 6, p. 191
users
5

Chlorine Production
• Much chlorine consumed close to
production sites to make chlorinated
intermediates, e.g., vinyl chloride for
plastics. These are shipped world-wide
• Chlorine shipped nationally by rail as
liquefied gas under pressure at ambient
temperature
• Repackaged into trucks, ton containers,
cylinders for local delivery to small users
6

Chlorine Consumption
Chlorinated
Organics, 27%
Inter., 8%
Pulp & Paper,
3%
Water
Treatment, 4% Vinyls, 39%
Others, 19%
• By volume, most consumed producing other chemicals
and intermediates and in pulp & paper (bleaching)
• Smaller quantities used very widely as biocide for
municipal, industrial, and waste water treatment
7

Chlorine Helps Make…
• Vinyl chloride  PVC plastic
• Phosgene  Polycarbonates,
pharmaceuticals
• Chlorine Dioxide / Hypochlorite  Bleaching
• Chlorinated intermediates  polysulfone, nylon,
polyurethanes (foams), coatings, pesticides
• Germ-free (disinfected) drinking water
8

Chlorine Properties
9

Physical / Chemical
• Yellowish-green gas at room temperature
• Boiling Point -29 F
• Gas specific gravity 2.4 (at room
temperature), ~2.9 at boiling point
• Pungent, irritating smell
• Sparingly soluble in water: 6.9 pounds /
100 gallons at 60oF
• Not flammable
10

Physical / Chemical
• Stable
• A powerful oxidizer – supports combustion
of many materials
• “Dry” chlorine has no free water present -
< 100 ppm at 41oF, <300 ppm at 86oF
• Generally stored and shipped as a liquid
under pressure
11

Physical / Chemical
• Reactive with many materials
●
Steel preferred as material of construction for
dry Cl2 below 250oF
●
However, steel ignites above 480oF
● Many metals react violently with dry Cl2 (e.g.,
titanium at ordinary temperatures)
●
Wet chlorine is highly corrosive; FRP, PTFE,
titanium (must be wet) are resistant
●
Many organics react, some violently
● Special cleaning required for steel in Cl2
service
12

Release Properties
• Liquid releases boil (auto-refrigerate)
releasing flash vapor
• Vapor heavier than air – releases tend to
stay near the ground, fill low lying areas,
and to disperse slowly
• Applying water to liquid Cl2 adds heat,
increases vaporization
• Cl2 and water form corrosive HCl
(hydrochloric) and HOCl (hypochlorous)
acids - water spray on release points can
worsen releases 13

Properties of Chlorine –
Vapor Pressure
550
500
450
Gage Pressure, psig
400
350
300
250
200
150
100
50
0
-50 0 50 100 150 200 250
Temperature, F
14

Properties of Chlorine –
Liquid Density
100
95
Liquid Density, lb/ft^3
90
85
80
75
70
65
60
-50 0 50 100 150 200 250
Temperature, F
15

Health Effects of Chlorine
• Chlorine is extremely
irritating and can burn the 0
skin and eyes
• If inhaled, chlorine causes
3 0
OXY
respiratory distress, and can be fatal
• Liquid chlorine releases will form an immediate
cloud (flash vapor) and will cool to -29 F.
• Exposure to liquid can cause frostbite, as well
as chemical burns.
16

Health Effects of Chlorine Exposure
Concentration
Health Effects
(ppm in air)
1-3 ppm Mild mucous membrane irritation
5-15 ppm Upper respiratory tract irritation
Immediate chest pain, vomiting, shortness of breath
30 ppm (dyspnea) and cough
Inflammation of lung tissues (toxic pneumonitis) and
40-60 ppm fluid accumulation (pulmonary edema)
430 ppm Death within 30 minutes
1,000 ppm Death within a few minutes
17

Exposure Limits for Chlorine
Standard Permissible
Setting Exposure Description
Body ppm
NIOSH 0.5 Recommended Exposure Limit (REL)
OSHA 1 Permissible Exposure Limit (PEL)
NIOSH 1 Short Term Exposure Limit (STEL)
Emergency Response Planning Guideline
AIHA 3 Level 2
Immediately Dangerous to Life or Health
NIOSH 10 (IDLH)
Emergency Response Planning
20
AIHA Guideline Level 3
18

Chlorine Transfer
Operations
19

Chlorine Transfer Operations
• Major users may take delivery directly from
Cl2 producers via railcar
• Cylinders and containers for smaller users
are usually filled locally/regionally by
chlorine “repackagers”
• All transfer operations share common
aspects
• Refer to Ci Pamphlet 17, Packaging
Plant Safety & Operational Guidelines
20

Chlorine Transfer Operations
21

Chlorine Re-packagers
xx
x x
x x x
x x
x x
x
x x x x x
x
x x x x x
xx x x
x x
x x
x x xx
x x x
x xx x
x
x x
x xx x
x x
xx x
xx x x
xx
xx
Data from Chlorine Institute
Pamphlet 10 - 2005 x
22

Chlorine Transfer Operations
Container being
filled (on scale)
Dry air or N2
Scrubbing solution
Chocked rail car
(usually caustic)
From CSB DPC-Glendale Report

Chlorine Transfer Operations
• Liquid Cl2 is displaced from the railcar using
dry gas (air or nitrogen)
• Liquid Cl2 flows into receiving container
• Cl2 vapor plus air/N2 present is vented
through a throttling valve to keep the
container pressure high to suppress flash
vapor formation
• Hose connections should have emergency
isolation valves on both ends
24

Chlorine Transfer Operations
• Cl2 vapor flows to a scrubber, typically filled
with NaOH solution
• The reaction produces bleach – sodium
hypochlorite – plus salt and heat
Cl2 + 2 NaOH  NaOCl + NaCl + H2O
• The scrubbing solution is usually circulated
through an eductor (aka, a venturi)
– High liquid velocity ensures good contacting
– Maintains a slight vacuum on the Cl2 line
25

Chlorine Transfer Operations
• Scrubbing is normally ~100% efficient
• The scrubbing solution is monitored using
redundant oxidation-reduction potential
(ORP) meters
– These alarm and/or shut off chlorine flow if the
scrubbing fluid becomes depleted
• A heat exchanger removes the heat of
reaction using air or cold water
26

Chlorine Transfer Operations
• The bleach produced may be sold as a
product
• Some (~0.5 – 1.0%) residual caustic must
remain in solution to maintain scrubbing
effectiveness and prevent decomposition
of the bleach
• Depletion of the caustic can cause the
scrubber to fail & the bleach to
decompose, emitting toxic gases
27

Chlorine Transfer Operations
When isolation
valves fail –
Festus, MO,
August 2002
• Ci Pamphlet 57
has details on
emergency shut-
off systems for
bulk Cl2 transfer

Water Disinfection
with Chlorine
29

Chlorine in Water
Treatment
• Excellent sanitizing agent
• Forms hypochlorous acid in
solution – active biocidal material
Cl2 + H2O  HOCl + HCl
• Good residual action –
bacteriostatic at 1-5 ppm Cl2 in water
• Can form undesirable chlorinated organic
materials, e.g., chloromethanes
• Ci Pamphlet 155 – Water &
Wastewater Operators Chlorine Handbook
30

Chlorine in Water Treatment
• Facilities tend to be lightly staffed
• May be located in populated areas
• Key components:
– Chlorine cylinders / containers
– Piping
– Chlorinator
– Water eductor
31

Chlorine in Water Treatment
To
injection
point
Chlorine Ton Containers in
Water Treatment System
(usually in separate building / Vacuum Chlorinator
room, with independent
Cabinet
ventilation. May exhaust to
scrubber)
32

Chlorine in Water Treatment
Ventilation In
Storage Shed Loss of Vacuum
Clean Water
Shut-off
Source
Vapor PSL
1-Ton Cl2
PY
Container PE Eductor
Spare To Water
Container(s) Chlorinator System
Drain
Trap
AAH
Heater HTR
Chlorine Sensor / Ventilation Out (may
Alarm go to scrubber)
33

Chlorine Incident
History
34

IMIS* Chlorine Incidents
• ~ 175 total incidents
– All SICs
– Since 1984
* Based on review of IMIS data only (i.e. no further analysis). Incident =
Cl2 release and acute exposure where injury or fatality is noted.
35

IMIS* Fatal Chlorine Incidents
• 11 total fatal incidents related to chlorine
release and acute exposure
– 5 fatal incidents related to cleaning/disinfecting
• Inadvertent mixing of sodium hypochlorite and formic
acid resulting in reaction w/Cl2 gas generation
• Cleaning storage (e.g. CTMV and tank)
* Based on review of IMIS data only (i.e. no further analysis)
Incident = Cl2 release and acute exposure where injury or
fatality is noted.
36

IMIS* Fatal Chlorine Incidents
• 2 fatal incidents related to chemical processing
facilities (SIC 28)
– Bleed valve not closed resulting in trapped pressure
between valve and cap. When operator began
removing cap to bleed Cl2 line, Cl2 released. During
incident respirator pulled off and employee was
exposed and dies later.
– Purging Cl2 from cylinder to prepare it for pressure
test, used 3,000 psi nitrogen resulting in catastrophic
failure of the cylinder. There was no pressure
regulator or pressure relief device on the filling system
between the 3,000 psi nitrogen system and the 480
psi chlorine cylinder.
37

IMIS* Chlorine Incidents Related to
Chemical Manufacturing (SIC 28)
• 37 total incidents (fatalities + others)
– Chlorine was connected by manifolds to a bleach
manufacturing process as well as to a chlorine
repackaging process. The manifolds were equipped with
air and electric operated valves. The compressed air was
introducing debris into the system which caused the
actuators to stick and prevent the valves from closing.
• Result – Cl2 release, 5 employees hospitalized.
– A block valve under 300 psi chlorine failed
• Factors contributing to release included lack of maintenance and
inspection program for smaller valves.
• Result – Cl2 release, 10 employees hospitalized.
38

IMIS* Chlorine Incidents Related to
Chemical Manufacturing (SIC 28)
• Subcontract employees were working ~ 50 ft from a
tank, which held chlorine. The tank PSV opened and
released due to tank overpressure.
– RV discharge was designed to release into the work area.
– Result – Cl2 release, 2 employees hospitalized.
• Brine coolant got into the dry chlorine production
stream
– Resulted in accelerated corrosion and production piping
failure.
– Fire fighters, responded to the incident, and were exposed to
liquid chlorine hazards when they secured the incident
scene
– Result – Cl2 release: 60 tons of liquid chlorine were
released from a 150-ton production storage tank , 6
firefighters hospitalized & 42 others non-hospitalized injuries
39

Cl2 Release DPC Enterprises
•A hose used to transfer Cl2
from a railroad tank car
suddenly burst and released
thousands of pounds of Cl2
liquid and gas
•DPC is a Cl2 repackager
•Automatic and manual shutdown systems failed to
work, and the release continued for about three
hours.
●
Moisture into dry system resulting in corrosion
40

CSB Issues with DPC Cl2 Release
• Emergency training and drills were inadequate
• Facility Siting of the Cl2 protective gear
– gear stored in the chlorine packaging building too close to the
tank car unloading station
• Employees could not get to gear as it was engulfed in Cl2 cloud
• Develop MI QA program to ensure that chlorine hoses
are made of the correct materials of construction
– Positive Material Identification (PMI)
– chlorine transfer hose should have an inner Teflon lining
reinforced by an exterior metal braiding made
of Hastalloy C-276
• Need MI for ER systems and chlorine-
related corrosion
41

Chlorine Specific PSM
Issues
42

43

Process Safety Information
1910.119 (d): Piping
• Do materials for piping and components
comply with Ci recommendations – for
metallurgy, schedule, and welding?
– Ci 6 Sec 2
• Are materials for threaded connections
PTFE tape or non-reactive pipe dope?
- Ci 1 and 6 Sec. 3
44

Process Safety
Information (d)
(Piping) cont.
•Are gaskets
compatible with
liquid and gaseous
chlorine? – Ci 95 Sec 3
45

Process Safety Information (d)
(piping) cont.
• Is piping adequately
supported and braced?
– Ci 6 Sec 10
• Is piping system
protected from
vehicular traffic?
– Ci 6 Sec 10
• If piping is
underground, is it
continuously leak
monitored?
– Ci 60 Sec 3
46

Process Safety Information (d)
(Piping) cont.
• Are there expansion
pots where liquid Cl2
can be blocked in?
– Ci 5 Sec 5
• Is the expansion pot
isolated by rupture
disk and monitored?
– Ci 6 Sec 5
47

Process Safety Information (d)
(Piping) cont.
• Are liquid valves
designed to prevent
trapping Cl2 in the
body? – Ci 6 Sec 4
• When Cl2 pressure is lower than
process pressure, is there backflow
prevention? – Ci 9 Sec 4 and 5
48

Process Safety Information (d)
(Vaporizers)
• Is the vaporizer heating medium non-organic
and limited to 250 F? – Ci 9 Sec 3
• Is the heating medium pressure lower than the
chlorine supply pressure? – Ci 9 Sec 3
• Is the vaporizer designed for a minimum metal
temperature of -40 F? – Ci 9 Sec 3
• Does the vaporizer outlet have a pressure relief
valve? – Ci 9 Sec 4
• Is there a program in place to monitor NCl3
levels? – Ci 9 Sec 5 and Ci 152 Sec 5
49

Process Safety Information (d)
(Bulk Container Unloading)
• Are there a remotely operated or automatically
actuated emergency shutoff valves to isolate
both sides of flexible hoses? – Ci 57 Sec 3, Ci 66 Sec 9
• Are there at least 2 remote shutoff valve
operators? – Ci 57 Sec 3
• Is there a tank motion detector that closes
shutoff valves? – Ci 57 Sec 3
51

Process Safety Information (d)
(Bulk Container Unloading) cont.
• Does the padding system include backflow
prevention? – Ci 49 Sec 7
• Are Cl2 hoses constructed of compatible
materials? – Ci 6 App A
53

Process Safety Information (d)
(Storage Systems)
• Is the Cl2 tank protected with a pressure relief device?
– Ci 5 Sec 5
• Are there emergency shutoff devices on the liquid lines?
– Ci 5 Sec 5
• Is there a pressure sensing device on the tank?
– Ci 5 Sec 5
• Does the tank have a reliable level device?
– Ci 5 Sec 5
• Are all tank openings (nozzles) on the tank top?
– Ci 5 Sec 4
• Does the tank have sufficient spill protection?
– Ci 5 Sec 6
54

Process Safety Information (d)
(General Process)
• Are process areas monitored for chlorine?
– Ci 1 Sec 7
• Are indoor chlorine areas properly
ventilated?
– Ci 1 Sec 7
• Are process vessels equipped with relief
devices?
– Ci 9 Sec 5
55

Process Safety Information (d)
(Scrubbers) cont.
• Is there a means to process chlorine gas
vented from equipment and piping?
– Ci 89 Sec 1
• Can the scrubber handle the most probable
release scenario?
– Ci 89 Sec 3
• Does the scrubber have passive capability or
emergency power?
– Ci 89 Sec 4
• Is the scrubbing medium appropriate?
– Ci 89 Sec 2
57

Process Safety Information (d)
(Scrubbers) cont.
• Is the scrubbing solution monitored to
confirm continued capability?
– Ci 89 Sec 2
• Is the scrubbing vent monitored?
– Ci 89 Sec 4
• Is there adequate backflow prevention?
– Ci 89 Sec 4
58

Process Safety Information (d)
(Packaging / Processing)
• Are there chlorine monitors in packaging
and processing areas with appropriate
limits?
– Ci 1 Sec 7
• Are the materials for the sodium
hypochlorite piping appropriate?
– Ci 96 Sec 4
59

Process Hazard Analysis
1910.119 (e)
• Is there chlorine monitoring at the railcar
unloading site?
– Ci 64 Sec 3
• Has the facility investigated the potential
for nitrogen trichloride to accumulate?
– Ci 9 Sec 5, Ci 152 Sec 5
60

Operating Procedures
1910.119 (f)
(Bulk Container Unloading)
• Do procedures include the following:
– PPE for chlorine loading/unloading/line
breaking?
– Ci 1 Sec 5, Ci 85 Sec 12
– Requirements for unloading lines and air
padding lines purged to a scrubber, evacuated,
disconnected, and capped?
– Ci 1 Sec 3, Ci 49 Sec 11, Ci 66 Sec 9, Ci 79 Sec 79
61

Operating Procedures (f)
(Packaging / Processing)
• Do procedures include the following:
– Appropriate steps for evacuating and filling cylinders
and ton containers?
– Ci 162 Sec 6
– Leak testing containers before filling?
– Ci 17 Sec 3
– Proper evacuation of lines before disconnecting?
– Ci 17 Sec 3
– Appropriate torque setting of valves and packing
nuts?
– Ci 17 Sec 4
62

Training - 1910.119 (f)
(employees and contractor)
• Have employees been trained on
(Ci 1 Sec 5):
– Operation of chlorine equipment and
container handling
– Properties and physiological effects of
chlorine
– Equipment failure and leak reporting
procedures
63

Training (g) (Employees and
Contractor) cont.
• Location, purpose and use of emergency
equipment, fire fighting equipment, fire
alarms, and shutdown equipment.
• Use of emergency kits A, B, or C if used at
the site
• Locations, purpose and use of safety
equipment
• Location, purpose, and use of specialized
first aid equipment.
64

Pre-startup Safety Review
1910.119 (i)
• Is new or replacement piping properly
cleaned and inspected for chlorine
service? – Ci 6 Sec 11
65

Mechanical Integrity
1910.119 (j)
• Do procedures require leaks to be repaired
before allowing operations to begin or continue?
– Ci 1 Sec 4, Ci 49 Sec 11, Ci 66 Sec 9
• Have lubricants been checked for compatibility
( j(6))? – Ci 6 Sec 3
• Is the emergency shut-off system tested
routinely? – Ci 57 Sec 3
• Are chlorine hoses tested and replaced on a
preventive maintenance basis? – Ci 6 App A
66

67

Mechanical Integrity (j)
• Is the piping system routinely inspected?
(Ci 6 Sec 12)
– Flange bolt condition and tightness
– Valve packing leaks
– Valve operation
– Insulation condition
– Paint condition
– Condition of supports
– NDT for piping inspections
68

Mechanical Integrity (j)
• Are underground piping systems protected
by cathodic protection? – Ci 60 Sec 3
• Are chlorine storage tanks scheduled for
inspection? – Ci 5 Sec 8
• Are pressure relief valves scheduled for
periodic inspection? – Ci 5 Sec 9
• Are there procedures for inspection of
valves? – Ci 17 Sec 4
69

Mechanical Integrity (j)
• Are there scheduled routine external and
detailed internal inspections of the
vaporizer? - Ci 9 Sec 8
– Gaskets and valves for leaks
– Insulation for damage and signs of leaks
– Proper function of steam traps
– Proper function of all instruments
– Condition of supply equipment
– Coating condition
– General housekeeping to guarantee safe evacuation
70

Honeywell - Baton Rouge
Incident Timeline
• Chlorine cooler failed
• Liquid chlorine entered the coolant system
• Coolant pumps failed
• Chlorine is released to atmosphere
72

Honeywell Baton Rouge
Incident Timeline cont.
• 3:05 am – Operator notices leak, Cl2 gas
enters the control forcing operators to leave
• 3:25 am – Plant evacuated, authorities
notified
• 3:30 am – Vapor cloud mitigation water
sprays turned on
• 7 am – Equipment secured and release
stopped
73

74

75

76

Honeywell Citations
• j(4)(i) – failure to inspect, test, or otherwise
evaluate air supply pipes for the control
room ventilation system
• e(3)(i) – PHA did not address possible
failure of the brine pumps
• e(3)(iii) – PHA did not address the
engineering and admin controls such as
providing a device to monitor for chlorine
in the control room
77

Honeywell Citations (cont.)
• e(3)(iv) – PHA did not provide description
of the consequences for deviations
• d(3)(i)(e) – PSI did not include design info
on the control room positive pressure
system
• d(3)(i)(f) – PSI did not contain info on the
RAGAGEP for the ventilation system
78

Honeywell Citations (cont.)
• f(1)(i)(D) – Operating procedures did not
address emergency shut down
procedures and condition that would
require an emergency shut down related
to the coolant system
• f(1)(ii)(B)- Operating procedures for the
coolant system did not cover how to
handle the deviation for chlorine entering
the system
79

Honeywell Citations (cont.)
• l(1) – MOCs were not completed for a
previous coolant change or when the
positive pressure ventilation system was
installed in the control room
• m(4) – There was no investigation report
for a previous failure of heater tubes that
lead to contamination of the brine system
80

Closing
81