Reducing Tee Description

SA probably refers to the ASME pipe grading such as ASME SA 234 or 815 etc.

I have never come across the NNLT, but often in specifications the letters NLT will appear, which generally means "Not Lighter Than" and allows you a degree of latitude in your selection provided the item is of no less quality and strength.

Please restate 'exactly' how it is referenced, in its entirety.

Baring any additional information thus far, SA could be related to Swedish Surface Prep Standards:

http://www.blastal.com/images/SSPC_Chart.pdf

Does that make sense based on your usage/source?

In another forum thread SA was determined to mean "Same As" indicating that the rating of the fitting(s) should be the same as that of the connecting pipes' schedule.

Wild guess at NNLT, Nominal Size 1, Nominal Size 2, Length, Thickness

It may refer to the sizes, NNLT would then mean that the outlet and the branch is normal and the other one is large.

Manufacturers are allowed to put any characters they need/want on their products.

The SA and NNLT are not standard ratings so they could have many different meanings depending on the particular manufacturer's coding.

SA could be South America (Country of origin)

NNLT could be their company standard for threading procedure used.

I suggest you contact the manufacturer and ask them what the characters mean if you want anything other than a WAG.

In my early days at Boeing just as computers had evolved the prints would state "PORM". The suppliers would call me up and ask what the hell that ment. Well we could not put +/- on the prints , at that time, so PORM ment plus or minus.

Never saw "NNLT" but is it possible that the term has some reference to a nuclear plant piping spec?

"SA" is the abbreviation for ASME specification.

"NNLT" doesn't seem to be a standard abbreviation or terminology for Pipe Fitting specification. You need to give more details on this.