Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L15/00—Screw-threaded joints; Forms of screw-threads for such joints
  • F16L15/001—Screw-threaded joints; Forms of screw-threads for such joints with conical threads
  • F16L15/003—Screw-threaded joints; Forms of screw-threads for such joints with conical threads with sealing rings
• • E—FIXED CONSTRUCTIONS
  • E21—EARTH OR ROCK DRILLING; MINING
  • E21B—EARTH OR ROCK DRILLING; OBTAINING OIL, GAS, WATER, SOLUBLE OR MELTABLE MATERIALS OR A SLURRY OF MINERALS FROM WELLS
  • E21B17/00—Drilling rods or pipes; Flexible drill strings; Kellies; Drill collars; Sucker rods; Cables; Casings; Tubings
  • E21B17/02—Couplings; joints
  • E21B17/08—Casing joints
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16L—PIPES; JOINTS OR FITTINGS FOR PIPES; SUPPORTS FOR PIPES, CABLES OR PROTECTIVE TUBING; MEANS FOR THERMAL INSULATION IN GENERAL
  • F16L15/00—Screw-threaded joints; Forms of screw-threads for such joints
  • F16L15/04—Screw-threaded joints; Forms of screw-threads for such joints with additional sealings

Definitions

• Tapered pipe threads have been used for many years for connecting and sealing the ends of pipes in many industries, such seals being primarily dependent on the use of a paste like sealing compound to seal leak paths inherent between conventional mating pipe threads.
• US Patent 2,907,589 explains the susceptability of the Hydril connector to damage, in columns 1 and 2, which may leak due to a variety of reasons.
• the same patent discloses another plastic seal ring and although "end clearance may he provided to allow for dirt and sand or for machining tolerances" no definite room is provided for thermal expansion of the plastic ring. Such a condition may provide an erratic tendency to seal, giving a false assurance in a dangerous situation.
• US Patent 2,980,451 discloses a plastic ring deposed intermediate the engaged threads and confined so as to "extrude” the plastic, clearly allowing for no thermal expansion of the plastic and allowing for a progressive relaxation of the plastic seal which in the presence of changing temperatures and pressures, in time allows leakage.
• OS Patent 3,047,316 also allows for extrusion of a plastic ring but makes no provision for sealing of the plastic ring after thermal bulk contraction occurs.
• US Patent 3,572,777 and 3,100,656 show soft seals trapped by the end of the male connector but make no provision to protect the soft seals against: blowout by external pressure; erosion and wear from internal abrasive fluid flow.
• the present invention provides a threaded pipe connection that ensures greater contact pressure between the mating threads at each end of the engaged thread length than the average contact pressure between the entire length of the engaged threads.
• a seal area is accomplished near the least diameter end of the engaged threads to thereby gain a higher rating against internal fluid pressure.
• a seal area against external fluid pressure is accomplished near the greatest diameter of the engaged threads to thereby prevent external fluid pressure from acting against a lesser thickness of the male thread, to thereby which in turn gain a higher rating against external fluid pressure.
• a plastic seal ring may be provided near the small diameter end of the engaged threads within an annular space sufficiently larger in volume than the plastic seal ring so as to allow for thermal expansion without extruding the seal ring by thermal expansion.
• Figure 1 is a fragmentary section of a conventional threaded pipe connection wherein tolerances allow for perfect matching of the tapers.
• Figure 2 is the same as Figure 1 except tolerances allow the male thread to have a steeper taper than the female thread.
• Figure 3 illustrates a conventional male pipe thread made up hand tight into a female thread formed according to the present invention.
• Figure 4 is the same as Figure 3 except the connection has been made up power tight, to the operating position.
• Figure 5 is the same as Figure 4, but with an annular space and plastic seal ring added in accord with the present invention.
• Figure 6 is an alternative embodiment of the present invention shown in the hand tight position.
• Figure 7 is a third embodiment of the present invention shown in the hand tight position.
• FIG 8 is the same as Figure 6 except the connection has been made up power tight.
• Figure 9 is an enlarged fragmentary section of Figure 5 to better detail the plastic seal one turn before full power tight makeup.
• Figure 10 depicts the plastic seal of Figure 9 after full power tight makeup.
• Coupling 12 comprises a continuous thread as at 14 which may include three different sections 16, 18 and 20, each having a different taper angle.
• Section 18 may have a taper angle substantially the same as does the male pipe thread 10
• section 16 may have a slower taper than does the male pipe thread and section 20 may have a faster taper than does the male pipe thread.
• a maximum sealing effect against internal fluid pressure may be formed at the smallest engaged thread diameter as at 22 and that a maximum sealing effect against external fluid pressure may be formed at the largest engaged thread diameter as at 24, by practice of the present invention.
• the seal as at 22 reduces the outward fluid pressure load on section 18 of the coupling to a minimum value and increases the outward fluid pressure load on the male thread to increase thread contact pressure to thereby allow a higher pressure rating for the connection and also provide for an enhanced axial tensile strength of the connection because all threads are in full intimate contact and the full engaged thread height is insured as in 16.
• the seal as at 24 prevents . - external fluid pressure from moving to a smaller diameter of the male thread, as to section 18, to thereby force inwardly on a thinner section of pipe and thereby reduce the pressure rating against external fluid pressure.
• O.D. long thread 8 round API oil field casing thread may have the following dimensions: .625"+.002 length of section 16; 1.696"+.002 length of section 18; ..975+.030 or -.002 length of section 20; a 5.40237 pitch dia at the left end of section 16; a 5.3649 pitch diameter at the left end of section 18 and a 5.2589 pitch diameter at the left end of section 20.
• a taper equal to the API pipe taper of .0625"/" would be formed in section 18; a slower taper, .0600"/” would be formed in section 16 and a faster taper, .0938"/" would be formed in section 20.
• the conventional sealing compound may not be sufficient to seal off imperfections between the engaged threads.
• the pipe coupling may be formed with an annular space as at 26 of Figure 5 by removing a portion of the female thread in section 20.
• a suitable seal ring of plastic or the like 27 may then be placed in the annular space before assembly of the connection so as to be deformed by and to seal against the male member during make up of the connection. So that the plastic seal ring 27 will not be extruded when the connection experiences an increase in operating temperature, the annular space should be made sufficiently large so as to allow for thermal expansion of the ring.
• Figure 9 illustrates plastic ring 27 within space 26 before full power tight makeup.
• Conical surface 42 formed on the male member adjacent the end .thereof, is shown contacting but not moving, preformed cooperating conical surface 44 of ring 27.
• Annular space 26 is partially defined by end surfaces 46 and 48 and conical surfaces 50 and 52, all formed within coupling 12.
• Surfaces 50 and 52 have a common circle of intersection as at 54 which contacts outer conical surface 56 of ring 27 before power tight makeup, thereby defining annular space 58 between portions of surface 46, 50 and 56 and defining annular space 60 between portions of surfaces 48, 52 and 56. Therefore, before power tight makeup, ring 27 substantially fills annular space 26 except for annular spaces 58 and 60. Ring 27 also projects radially inwardly from space 26, to conical surfaces 44 and 60 so as to provide sufficient ring volume to cooperate with surface 42 so as to provide proper compression of ring 26.
• Ring 27 may be made of any suitable material such as Teflon impregnated with glass to achieve the strength, chemical resistance and other characteristics required for the. service intended.
• FIG. 6 Another embodiment of the present invention is illustrated in Figure 6 wherein coupling 30 is formed with female threads 32 which have a curved instead of a conical taper, the instantaneous taper being a minimum at the female thread of largest diameter 34 and increasing to a maximum taper angle as at 36. Taper angles at 34 and 36 may be the same respectively as tapers in sections 16 and 20 of Figure 3.
• FIG. 7 A variation of the embodiment of Figure 6 is shown in Figure 7 wherein the coupling has a single conical taper and the pipe has a curved taper 40 to accomplish the same end result as described above.
• Figure 4 A similar variation, not shown, may be made of Figure 4 wherein the coupling was formed with a single conical taper and the male thread was formed with three sections having a taper near its end slower than the coupling taper, an adjacent taper the same as the coupling taper and a third tarper faster than the coupling taper.

Landscapes

• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Mining & Mineral Resources (AREA)
• Life Sciences & Earth Sciences (AREA)
• Geology (AREA)
• Fluid Mechanics (AREA)
• Environmental & Geological Engineering (AREA)
• Physics & Mathematics (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Geochemistry & Mineralogy (AREA)
• Gasket Seals (AREA)
• Joints With Pressure Members (AREA)

Applications Claiming Priority (1)

Publications (1)

Family

ID=22182356

Family Applications (1)

Country Status (4)

Families Citing this family (5)

Family Cites Families (4)

• 1984
  • 1984-12-06 MX MX205240A patent/MX162665A/es unknown
  • 1984-12-06 EP EP85900398A patent/EP0203919A1/en not_active Withdrawn
  • 1984-12-06 WO PCT/US1984/002023 patent/WO1986003570A1/en unknown
• 1985
  • 1985-02-22 CA CA000474990A patent/CA1257629A/en not_active Expired

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events