3.4.3
Bulk Plant Emergency Shutdown
Equipment and Periodic Examination
Methods
One of the leading causes of accidental spills of propane is a
pull-away at a transfer area. The term pullaway refers to an
accident caused by a bobtail or transport “pulling away”
from the transfer point while the hoses are still connected. A
pull-away may break the hose or even pull out the piping
network, creating a large propane leak and possible fire. To
avoid these problems, most transfer areas use bulkheads
and emergency shut-off valves (ESVs).
In this module you will learn to identify:
(1) Operating characteristics of bulkheads
(2) Operating characteristics of emergency shut-off valves
(ESVs)
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page 1
Identifying Operating Characteristics of Bulkheads
Bulkheads— are located where the plant hoses connect to a large
piping network where transports & bobtails are loaded & unloaded.
•
Bulkheads are normally made from steel beams and reinforced
concrete, and often are surrounded by large steel or concrete
posts to prevent vehicles from colliding with the critical piping.
•
NFPA 58 and many state and local codes stipulate that a
stanchion should be able to withstand a force from any direction
sufficient to cause the worst mechanical or structural damage to
be on the vehicle side of the transfer point.
Bulkhead maintenance is limited to inspection of fittings, valves, and
stanchions for structural integrity and propane leaks, especially in the
event of a pull-away.
3.4.3 Student Book  © 2004 Propane Education & Research Council
Pages 1 & 3
Identifying Operating Characteristics of Bulkheads
Bulkheads
Figure 1a. Vertical Bulkhead
Figure 1b. Vertical Bulkhead
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page 2
Identifying Operating Characteristics of (ESVs)
Emergency Shut-Off Valves (ESVs) are (one type of) valves that
may be used to automatically stop the flow of propane in the event of a
pull-away.
NFPA 58 requires that the valves be installed in the liquid or vapor lines
of certain piping systems within 20 ft. of the junction of hose and rigid
piping. In some plants, ESVs are often installed at the bulkheads for
loading bulk trucks and unloading transports. In addition, they are
installed at the hose junctions on tank car unloading risers.
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page 3
Identifying Operating Characteristics of (ESVs)
Emergency Shut-Off Valves (ESVs)
NFPA 58
2004
New provisions for transfer area protection require the
installation of ESVs to protect against hose failure
resulting from a number of circumstances, including
ruptures, exposure to fire, and pullaways.
ESVs must incorporate a means of closing by:
•
Manual shut-off at the valve location
•
Manual shut-off from a remote station
•
Automatic shut-off by thermal (fire) actuation
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page 3
Identifying Operating Characteristics of (ESVs)
Types Of Emergency Shut-Off Valves
Mechanical Emergency Shut-off Valves
a. With Dust Cover
Courtesy of Rego Co.
b. Cutaway
Figure 2. Mechanical ESVs
3.4.3 Student Book  © 2004 Propane Education & Research Council
Pages 4 & 5
Identifying Operating Characteristics of (ESVs)
Mechanical Emergency Shut-off Valves— Because the main valve
disc is spring loaded and directly in the propane flow path, the valve also
functions as an excess flow check valve.
Courtesy of Fisher Controls Co.
Figure 3. Mechanical ESVs
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page
6
Identifying Operating Characteristics of (ESVs)
Mechanical Emergency Shut-off Valves
Courtesy of Rego Co.
Figure 4. Mechanical ESV-Vapor Application
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page
7
Identifying Operating Characteristics of (ESVs)
Mechanical Emergency Shut-off Valve Installations
Courtesy of Rego Co.
Figure 5a. Mechanical ESV Installations
3.4.3 Student Book  © 2004 Propane Education & Research Council
Pages
7&8
Identifying Operating Characteristics of (ESVs)
Mechanical Emergency Shut-off Valve Installations
Courtesy of Rego Co.
Figure 5b. Mechanical ESV Installations
3.4.3 Student Book  © 2004 Propane Education & Research Council
Pages
7&8
Identifying Operating Characteristics of (ESVs)
Mechanical Emergency Shut-off Valves with Pneumatic
Operators
Figure 6. Mechanical ESV with Pneumatic Operator
3.4.3 Student Book  © 2004 Propane Education & Research Council
Pages
8&9
Identifying Operating Characteristics of (ESVs)
Pneumatic Emergency Shut-off Valves – There are certain valves
available today which are truly pneumatic ESVs; that is, the pneumatic
operator is an integral, internal part of the valve.
Courtesy of Fisher Controls Co.
Figure 7a. Pneumatic ESV
3.4.3 Student Book  © 2004 Propane Education & Research Council
Pages
9 & 10
Identifying Operating Characteristics of (ESVs)
Pneumatic Emergency Shut-off Valves – There are certain valves
available today which are truly pneumatic ESVs; that is, the pneumatic
operator is an integral, internal part of the valve.
Courtesy of Fisher Controls Co.
Figure 7b. Pneumatic ESV
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page
10
Identifying Operating Characteristics of (ESVs)
Pneumatic Emergency Shut-off Valves
Courtesy of Fisher Controls Co.
Figure 8. Railcar/Pneumatic ESV
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page
11
Identifying Operating Characteristics of (ESVs)
Pneumatic Emergency Shut-off Valves
Courtesy of Fisher Controls Co.
Figure 8. Railcar/Pneumatic ESV
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page
11
Identifying Operating Characteristics of (ESVs)
Pneumatic Emergency Shut-off Valve Installations
•
The pneumatic tubing can be charged (pressurized) in a number
of ways.
•
Figure 9 shows a typical charging system using nitrogen, air, or
CO2, which includes a cylinder, shut-off valve and regulator.
•
Alternate means of charging could include an auxiliary charging
line from the plant air compressors or a tap off the plant service air
system.
•
Any reliable source of pneumatic pressure is acceptable as long
as it is filtered and regulated up to 50 psig.
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page 12
Identifying Operating Characteristics of (ESVs)
Emergency Shut-off Valve Maintenance
•
Manufacturer's literature details the requirements and procedures
for maintenance and repair.
•
An annually documented test of the ESV is required by NFPA 58.
•
ESVs should be inspected frequently for gas leakage at all body
seams, plus the connections to piping and hose.
•
The pneumatic control system should be checked frequently for
proper operation; check for leaks by pressurizing the system and
checking all connections with liquid leak detector or a soapy water
solution.
•
Conduct frequent tests of the closing feature of the ESVs under
simulated conditions.
3.4.3 Student Book  © 2004 Propane Education & Research Council
Pages 13 & 14
Identifying Operating Characteristics of (ESVs)
Figure 11. Tank Car Unloading Riser
3.4.3 Student Book  © 2004 Propane Education & Research Council
Page
15
Time to See If You Got the Key Points of
This Module…
• Complete the Review on page 16.
• See if you are ready for the Certification
Exam by checking off the
performance criteria on page 17.
3.4.3 Student Book  © 2004 Propane Education & Research Council
Pages 16 & 17