Liquified propane piping materials 2

[jonesey]

Does anybody have recommendations as to what piping materials to use for liquified propane ? I've heard that some companies specify the use of low temp carbon steels (LTCS) typically ASTM A333 Gr.6 for pipe, whilst some companies specify the use of carbon steel typically API 5L ?

 

[CRG]

What temp & pressure are you designing for? It does not take high pressure for the phase change at room temperature. I recognize the possibility of the piping system cooling as the liquid propane evaporates if the pressure drops. Design piping system (select appropriate material) for temp, pressure, and product that will in the system.

 

[SooCS]

The key issue is the charpy test requirement. A333 or API 5L either will work as long as the material is charpy tested to the min design temperature. A333 charpy test is the standard requirement, while API is optional except for selected material at 32 deg F. Thus may not be good enough for your application unless you specify the charpy test temperature requirement.

Normal operating condition for liquid propane may be at room temperature. However, during startup and depressizing condition, the temperature may drop below minus 20 oF. To prevent britle fracture, charpy test is recommended to ensure the material can withstand the min temperature.

 

[ornerynorsk]

Here in Frostbite Falls, Minnesota, we use copper outdoors, and transition to carbon steel pipe(astm a53f???) indoors. This is for commercial and residential installation (smaller lines, generally under 2 inch)

 

[dbevil]

We use normal carbon steel for all liquid propane service. The charpy requirements for steel are based on its strength under full pressure. If you depressure the pipe to get it cold, there is no load on the pipe and thus, there are no strength or charpy requirements. Just don't strike the cold pipe with a hammer until it warms up.

 

[fedespiegel]

SooCS

"...However, during startup and depressizing condition, the temperature may drop below minus 20 oF. To prevent britle fracture, charpy test is recommended to ensure the material can withstand the min temperature...."

Which is the recommendable temperature to do the test, to prevent the condition presented before?

Regards
Federico Spiegel

 

[TD2K]

Fedespiegel, you need to determine the minimum temperature you want the pipe to operate at without risk of brittle failure based on your expected operating conditions.

Let's say you consider the case of the pipe full of boiling propane at atmospheric pressure during startup or shutdown (or maybe low pressures during operation). The liquid propane will be about -40F if it is at atmospheric pressure. That would be the temperature you'd need to ensure the metal had sufficient toughness (which is what the Charpy test measures) to prevent brittle failure.

I'm currently putting in some small bore piping that can handle propane and it's just standard A-106 pipe, A-105 fittings, etc. This client choices to use this material rather than low temperature based on their experience.

 

[fedespiegel]

TD2K

Is there a way to correlate the results of the test at, let´s say, -5°C (23°F) to a lower temperature and still be valid?


Thanks for the quick answer

Best regards
Federico Spiegel

 

[TD2K]

I'm not the best person to ask this but I don't think so. The transistion from ductile to brittle is very rapid so I don't know how a correlation would work.

 

[fedespiegel]

That was what I thought. I was told that a correlation existed but I just cannot find it, if it exist.

Thanx

You´ve been very helpfull