3.4.3 Student Book © 2004 Propane Education & Research CouncilPage 1 3.4.3 Bulk Plant Emergency Shutdown Equipment and Periodic Examination Methods One

3.4.3 Student Book © 2004 Propane Education & Research Council Page 1

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 Pages 1 & 3

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.


Identifying Operating Characteristics of Bulkheads

Bulkheads

Figure 1a. Vertical Bulkhead

Figure 1b. Vertical Bulkhead


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.



Emergency Shut-Off Valves (ESVs)

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.

NFPA 58

2004

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



Types Of Emergency Shut-Off Valves

Mechanical Emergency Shut-off Valves

a. With Dust Cover b. Cutaway Figure 2. Mechanical ESVs

Courtesy of Rego Co.



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.

Figure 3. Mechanical ESVs

Courtesy of Fisher Controls Co.



Mechanical Emergency Shut-off Valves

Figure 4. Mechanical ESV-Vapor Application




Mechanical Emergency Shut-off Valve Installations

Figure 5a. Mechanical ESV Installations




Mechanical Emergency Shut-off Valve Installations

Figure 5b. Mechanical ESV Installations




Mechanical Emergency Shut-off Valves with Pneumatic Operators

Figure 6. Mechanical ESV with Pneumatic Operator



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.

Figure 7a. Pneumatic ESV




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.

Figure 7b. Pneumatic ESV




Pneumatic Emergency Shut-off Valves

Figure 8. Railcar/Pneumatic ESV




Pneumatic Emergency Shut-off Valves

Figure 8. Railcar/Pneumatic ESV




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.



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.



Figure 11. Tank Car Unloading Riser


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.

Documents

3.4.3 Student Book © 2004 Propane Education & Research CouncilPage 1 3.4.3 Bulk Plant Emergency Shutdown Equipment and Periodic Examination Methods One