The rabbit hole is deep, and confusing smile

We've found these marks on U.S. doubles, and we have good evidence the marks do NOT mean Sanderson Bros. made the tubes
S.B. & Co - Sanderson Brothers & Co.; follow by
G – Gautier?
In 1882, Gautier Steel was a division of Cambria Iron Co., Allegheny Co., PA. Dudley G. Gautier was president of the Philadelphia Steel & Forging Co. and D.G. Gautier & Co. was listed as an agent for both Sanderson Brothers & Co. and Tacony Iron Works (1881-1910) of Philadelphia.
T – Tacony?
P – Sanderson‘s Pittsburgh Works?
C – Sanderson‘s Cumberland (Maryland) Works? or Carpenter Steel Company, establish in 1889 in Reading, PA which used a ‘C’ to mark their bar steel?

Here is an Ithaca Flues with the same mark



Long version is here
https://docs.google.com/document/pub?id=17ixogftgITEblNUWtmFBv96ZvgjK6eFell8GsAWd-KI

https://sites.google.com/a/damascusknowledge.com/www/home