Fluid service (B31.3) of Milk Lime ? 2

[drakkkko]

Hello,

I need to confirm if Milk Lime is Fluid Service Category M or Category D.
Pipes line Temperature= 75 °C (167 °F); P= 122 KPa.

Thanks in advance!

 

[bimr]

The definition of Category M Fluid Service is as follows. Note that for purposes of emphasis, it has been broken into subparts, all of which must be satisfied for the service to meet the definition of Category M (ASME B31.3, para. 300.2):
•"A fluid service
•in which the potential for personnel exposure is judged to be significant and
•in which a single exposure of a very small quantity
•of a toxic fluid,
•caused by leakage,
•can produce serious irreversible harm to persons on breathing or bodily contact,
•even when prompt restorative measures are taken."

Note that toxic means, by its dictionary definition, poisonous.

The B31.3 Fluid Service concept considers the fluid contained within the pipe and the particular set of operating circumstances as well as the safeguards that will be in place (see B31.3, Appendix "G").

If you look at the logic flow chart (Figure M300, Guide to Classifying Fluid Services) provided by B31.3 in Appendix "M", you will see a clear path of logic in determining that a "Toxic" fluid may be contained in a piping system that is classified "Normal Fluid Service".

When the Owner specifies the Fluid Service for the piping system, the fluid contained within the pipe and the particular set of operating circumstances as well as the safeguards that will be in place must be considered.

A very important point, the ASME B31 Code for Pressure Piping, B31.3, Process Piping does not classify lime milk piping systems or any other piping systems. Only the Owner can do that (using the guidance provided in the B31.3 Code). It is the owner's responsibility to determine the fluid service category.

Referring to B31.3, Appendix M, Figure M300, one can follow the logic that would be used to determine the system fluid service. "Can a single exposure, caused by leakage, to (of) a very small quantity of the fluid produce serious irreversible harm as defined under Category M Fluid service?" The answer is no.

You will find that the frequency of systems being correctly labeled "Category M Fluid Service" under B31.3 is about the same frequency as you will see "Lethal Service" vessels under the ASME B&PV Code. The majority of owners would not classify this piping as Class M. If I were the owner, I would opt to make the system "Normal Fluid Service".