Tubing or Tubbing: How To spell?
The word Tubing is misspelled against Tubbing, a noun meaning "A lining of timber or metal around the shaft of a mine; especially, a series of cast-iron cylinders bolted together, used to enable those who sink a shaft to penetrate quicksand, water, etc., with safety."
Tubbing has double "bb" is mispronounced as "b"Remember double 'BB' in between the strings Tu & ing which should not be misspelled with single 'B'
Wrong Spelling:  Tu-b-ing  Correct Spelling:  Tu-bb-ing 
Check more misspelled words of Tubbing to spell it correct.