API Pipe Classification 1

[mkuppe]

Hello all,

I'm requesting a clarification on the API 570 literature. I'm attempting to classify piping in a plant that produces 200 proof ethanol for fuel. For the most part everything is pretty clear but I'm getting mixed interpretations from others about certain piping circuits. For example, at the top of the rectifier column, 190 proof ethanol vapor is travelling through a pipe. The temperature of the product is above the boiling point (obviously) but well below the auto-ignition temperature. I'm inclined to believe that as per the guidelines in API 570 section 6.3.4.2b, this qualifies the pipe as a Class 1 since the atomospheric boiling point is below the operating temperature. However, I've had others tell me that this would be a Class 3 pipe, but I'm skeptical since we are operating well above the flash point. Any thoughts or clarification would be greatly appreciated. Thank you.

 

[mkuppe]

Also, would eductors fall into the piping category or would they lie somewhere else, as far as the API is concerned? I would guess an eductor would be classified as piping since it is basically just a section of venturi pipe, like a flow meter. Thanks again for the help.

 

[delling311]

Information required for classifying pipe may be found using the P&IDs, MSDSs,
NEPA-704 and Client Engineering Guideline Documents. Listed below is the
information needed from each source.
a) The P&IDs have the operating parameters for a given unit.
b) The MSDSs list the Hazard Rating for each product.
c) NFPA-704 defines the Hazard Rating for each product.

The the higher the rating, the higher the classification will be. Generally any hazard rating of 2 will be class 2. a hazard rating of 3 will be class 2. and a hazard rating of 4 is going to be class 1.

I've done many MI baselines at ethanol plants around the midwest. The overhead vapor line in distillation is generally considered PSM. Most of the lines in that unit will be class 2 because of their alcohol content. The only class 1 system in an ethanol plant is the anhydrous ammonia.

 

[mkuppe]

Thank you delling311. That helps a lot. Does the class 2 rating extend to the piping in the tank farm as well? The tank farm and loadout piping contains, at a minimum, 190 proof ethanol and is obviously flammable but API 570 says that tank farm and loadout piping is class 3. What are your thoughts?

 

[delling311]

I consider the alcohol lines outside of the distillation unit to be class 3. 1. they are up in a pipe rack and off-plot where they will generally not pose a danger to people. 2. 570 is pretty clear to include tank farm/loading piping in their description of class 3 piping.