Design Factor for liquids line in HCA

[LearnerN]

Newbie question: I've heard before that the design factor for a hazardous liquids line in an HCA is 0.5, but I can't find this in the CFR or where this came from. Can someone direct me to the right resource? Thank you.

 

[BigInch]

It can be 0.5 for gas pipelines, however there is not a specific legally required DF for HCAs for liquid lines. DF is 0.72 unless otherwise agreed, or specified by the permitting authority having jurisdiction in the HCA, for example such as the BLM. Not to say that more conservative DF may be appropriate, given the state of things in general these days.

How did the question arise?

 

[LearnerN]

Thanks for the info, BigInch, and that makes a lot of sense especially of the CFR and such. The question arose just because I've heard this before but never could find the specific reference, but at least it's more conservative.

 

[LearnerN]

The specific issue I have in mind is a liquids line in mostly rural areas.

 

[BigInch]

403.2

The value of F used in this Code shall be not greater
than 0.72. Where indicated by service or location,
users of this Code [highlight #FCE94F]may elect[/highlight] to use a design
factor, F, less than 0.72.

Do Note that in Appendix covering [highlight #FCE94F]OFFSHORE[/highlight] LIQUID PIPELINES, DF is 0.60 for platform piping and risers.

 

[LittleInch]

I'm no expert on CFR, but a cursory glance shows that the issue of HCA is a gas pipeline system issue and not mentioned in the liquids section.

Therefore you are probably trying to prove a negative and can't find anything because it doesn't exist.

Sounds to me like a typical expression by someone who has "heard of it" and "its in the code", without ever being specific about where they heard it or which code and which section. Happens a lot.

AFAIK, HCA is not a concept used for liquid lines which stay liquid at atmospheric pressure (i.e. not LPGs).

For liquid pipelines you can decide to use a DF <0.72 t your discretion and determined by the particular situation. Many choose to do this at e.g. road crossings or directional drills where any corrosion (internal or external) would be difficult to repair.

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[BigInch]

B31.4 does cover Liquid Petroleum Gas
and other hydrocarbon products, anhydrous ammonia and slurries transported "predominantly" as a liquid.
Addressing your vapor pressure concern is a consideration for radius of hazardous cloud determination.

See the special provisions for LPG
Mainline valve spacing 434.15.2
Inspection intervals 451.5 (2 X typical liquid line)
Integrity Safety Precautions 451.6
454 Emergency Management
Running Pumps during Emergencies
Vapor Cloud range determination