This invention relates to tubing having threaded ends with multiple seals.
Prior art United States patents are officially referenced and cross-referenced in Class 285, Pipe Joints or Couplings, subclasses 333, Threaded Drill Pipe Types, and 334, Similar Types Having Flat Crest Threads.
Examples of patents found there are:
______________________________________ 3,100,656 3,822,902 3,508,771 2,102,072 3,658,368 2,111,627 4,085,951 3,167,333 2,104,799 2,181,343 3,687,493 4,244,607 ______________________________________
U.S. Pat. No. 3,100,656, describes a threaded tubing joint with a shoulder seal, a tapered seat seal has an inward recess holding a plastic ring which is axially compressed.
U.S. Pat. No. 3,508,771 shows a tapered pipe joint with a shoulder seal 9, 10 and tapered seat seal 11 and a sealing ring between threads and a seat seal. The sealing ring 8 does not have a round cross-section. The threads may have a sealing profile as shown in FIGS. 5 and 6.
The seal receiving groove 21 in the inner tapered surface shown in FIG. 2 is of interest in U.S. Pat. No. 3,658,368.
The annular sealing ring 24 in U.S. Pat. No. 4,058,951 is of interest, but the ring has a generally square cross-section as shown in FIGS. 6, 7 and 8.
U.S. Pat. Nos. 2,104,799, 3,687,493 and 3,822,902 show sealing rings having round cross-sections.
Sealing rings as shown in U.S. Pat. Nos. 2,102,072, 2,111,627 and 3,167,333 are axially compressed.
U.S. Pat. Nos. 2,181,343 and 4,244,607 have thread configurations of interest.
The threaded tubing may be used in conditions of substantial pressure differentials between the inside and outside of the tubing and may be used in situations where it is undesirable to permit combination of fluids between the inside and outside of the tubing. Fluids in or around the threaded tubing may have propensities to move around conventionally sealed tubing.
A need persists for threaded tubing having multiple seals which complement each other and prevent communications of fluids between inside and outside of the tubing.