Hydrogen Transportation

5.2.5.1 Road Tanker Truck

As discussed in Section 4.3.3.3.1, the various mechanisms of the LH2 tanker truck failures may be caused by accident-initiated release and non-accident-initiated release. The study addresses only the accident-initiated releases, as these are expected to have the greatest potential damage and large hydrogen releases. Release from the safety valve is not considered to be an accident. Some typical truck accident scenarios include collisions with other vehicles, road debris, buildings, or animals; collisions with trains; and overturns. The release sizes range from the full loss of contents to small drips. Small drips usually result from valve and fitting leaks that are not associated with accidents. Thus, they are not considered in the study, which focuses on accident-initiated releases. The release sizes studied were catastrophic failure (i.e. the instantaneous release of the entire contents of the tank) and continuous release (resulting from tank leak or pipe rupture). Therefore, the accident scenarios considered for the LH2 tanker truck is shown in Table 5-6. Purple book [159] suggested that the effective hole diameter is about 50 mm (2 inches).

Table 5-6 List of accident scenarios considered for the LH2 tanker truck

Scena rios

Undesired events

Inner diameter (mm)

Release Direction

Type of

Bund Surface

Discharge Data

Type

Phase

Tank

Pipe

Hole

Flowrate (kg/s) or mass (kg)

Duration (s or inst.)

A

Tank rupture

Liquid

2500

-

-

N/A

4000

inst.

B

Tank leak

Liquid

2500

-

76.2

Down

N/A

30.4

131.7

C

Line rupture

Vapor

2500

50.8

50.8

Vertical

N/A

4.2

962.5

D

Line rupture

Liquid

2500

76.2

76.2

Horizontal

N/A

10.9

367

5.2.5.1 GH2 Pipeline

As discussed in Section 4.3.3.3.2, several types of pipeline failure incidents are considered. The generic pipeline failure modes are based on historical incident data and include the loss of containment events resulting from corrosion leaks, external mechanical interference (third party damage); construction defects, material defects, and other causes. The release sizes are generally categorized by hole sizes, such as pinholes (about 0.1 inches in diameter), holes (11.5 inches in diameter), and rupture (line size). Due to the fact that the pipe is underground and the material transported (i.e. hydrogen) is non-toxic, the pinholes were not considered in the study. The accident scenarios considered for the GH2 pipeline is shown in Table 5-7. The holes were taken to be 20% of the pipe diameter, and ruptures taken as the pipe cross-sectional area. Each of the selected release sizes will be analyzed for different failure causes.

Table 5-7 List of accident scenarios considered for the GH2 pipeline

Undesired events

Inner diameter (mm)

Discharge Data

Scena rios

Type

Phase

Tank

Pipe

Hole

Bund Surface

Flowrate (kg/s)

Duration (s)

A

Rupture

Vapor

-

150

150

Vertical

N/A

1.9

158

B

Hole (20%)

Vapor

-

150

30

Vertical

N/A

1.8

168

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