Maybe to us light weight means ... plastic.
When asking engineering questions, you must be far more specific with the words you use when writing your questions.
I meant to say Lt. wt. steel fittings (elbows, reducers etc) of different sizes.
I am asking to know what the longitudinal seam factor would be. For instance seamless or ERW = 1 as longitudinal factor. Thanks
There is no change in anything whether the fitting is seamless or welded for the same material.
Most people try not to get the longitudinal seam lined up on connecting pipe / fittings, but other than that I don't know where you would use a factor like that on a fitting
Remember - More details = better answers
Also: If you get a response it's polite to respond to it.