Petroleum casing pipe thread seal joint
The utility model relates to the thread seal joint of petroleum casing pipe, and the sleeve pipe that is specially adapted to high-pressure gas well, deep-well connects the thread seal joint of usefulness.
Special screw thread on the sleeve pipe is in assembling and using process, stretched, under the comprehensive function of compounding pressure such as compression, external and internal pressure and flexural load, screw thread should have enough join strengths, and the tubing string that can guarantee to be threaded is in the long term seal integrity and the structural integrity of bearing under inside and outside hundreds of atm difference effects.A large amount of at present API standard garden screw threads that use and buttress thread (But-tress) joint all adopt screw thread to produce bigger interference in assembling and realize above-mentioned functions, partly there is the gap in thread engagement, in use can not obtain gratifying sealing, and very easily cause stress corrosion.The garden inipple can only bear the tension load that is equivalent to body rupture strength 60%～80%, though the buttress thread joint has higher join strength, but its sealing is very poor, thereby API standard garden screw thread and buttress thread joint, can't give full play to the performance of its tubing on high-level tubing.
A kind of transport pipe screw cap sleeve connector is now disclosed, though radius of curvature in the protruding garden of primary seal part double thread sealed department, and the size of the cone angle of internal thread is stipulated, improved the problem of sealability and stress corrosion resistant, but and do not have interchangeability between the API universal joint, for oil well designs, the preparation of accessory and maintenance are made troubles.
The purpose of this utility model is intended to overcome above-mentioned deficiency, and a kind of good airproof performance is provided, join strength height, a kind of petroleum casing pipe thread seal joint that can exchange with the API modular connection.
The utility model specific embodiments is along axial direction to form the cone seal part that the hermetic unit in protruding garden and a inwall at internal thread on form by one in externally threaded end in primary seal part, and outside thread end and one form along a spacing shoulder of sealing that forms on the internal thread inwall.Radius of curvature 20mm≤R≤the 80mm of the protruding garden of outside thread hermetic unit, the conical surface of the inwall of internal thread and 4.57 °≤α of axis angle≤10 °; In the end of the point of contact 4 of sealed department and spacing shoulder 3 apart from 5mm≤L≤8mm; Front and back at the point of contact 4 of primary seal are provided with ring screw fat storage chamber 5.
Because said structure keeps having with the API joint feature of interchangeability, and employing low stress design, its join strength kept higher level when it bore combined load, had good sealing property and joint efficiency, simultaneously to the radius of curvature and the angle in protruding garden, and spacing shoulder has been made certain limitation to the length of primary sealing area, make primary seal partly be the tangent plane sealing, owing to do not press in having, the sealing surface contact length is shorter when tightening like this, sealing surface is bonding when avoiding button, and has good lubricating condition.Because at the forward and backward thread compound storage chamber that is provided with of primary sealing area, improved the lubricating condition of sealing surface, avoid sealing surface bonding, simultaneously because of having and API screw thread interchangeability, for oil well designs, the preparation of accessory and maintenance provide convenience.
Now in conjunction with the following drawings, the thread seal to this sleeve pipe partly is described further.
Fig. 1 is the longitudinal sectional drawing of the utility model thread seal joint.
Fig. 1 is the structure example of a kind of inipple of showing by an inipple spare B (box cupling).The both sides of sealing adapter piece B are internal thread 2, the body A that is connected with 2
2The end be outside thread 1, constituted a joint.
In each joint structure of adapter piece B, there is one section threadless even surface the end in the outer garden week of outside thread 1, and it is shaped as protruding garden body.One section threadless smooth is arranged on the interior garden of female thread portion 2, be shaped as taper, thread head and internal thread inwall form the spacing shoulder 3 of sealing outside, are the interchangeability that keeps with API petroleum casing pipe inipple, and pitch, tooth-shape angle are identical with the trapezoidal partially general petroleum sleeve joint of API.
For providing good sealing property to screw thread, this joint has metal and metallic radial interference sealing surface, makes joint not have leakage-gap.Determined the curvature 20mm≤R≤80mm of externally threaded protruding garden hermetic unit in addition, the conical surface of inboard wall of internal thread and axis angle are 4.57 °≤α≤10 °, outside thread protruding garden sealing surface and internal thread conical seal (contact) face form tangent sealing (point of contact 4 shown in Figure 1) when making button like this, 4 place's joint sealing faces produce maximum interference at the point of contact, when pressing in joint bears, the area of contact of sealing surface increases with interior pressure, make primary sealing area have the sealability of height, pressure when last button because in not having, the sealing surface contact length is short, and sealing surface is bonding when avoiding button.Sealing surface stress is interfered and keeps sealing compact structure partly for avoiding shoulder stress, the end distance of having determined sealing surface point of contact 4 and spacing shoulder 3 is 5mm≤L≤8mm, because primary sealing area has fabulous sealing, spacing shoulder 3 is straight interior shoulder, locatees and resist high torsional interaction and auxiliary seal effect when joint is connected.Thread compound unnecessary in the joint can be stored in the 4 forward and backward ring screw fat storage chambeies 5 that respectively are provided with 2mm～4mm at the point of contact, has improved the sealing surface lubricating condition, avoids sealing surface bonding, reduces thread compound to sealing surface pressure and screw thread stress influence.Improved petroleum casing pipe screw thread of the utility model and SEALING FITTING, be applicable to Φ 127mm～Φ 339.7mm specification sleeve pipe, by theory analysis and experimental results show that, the join strength of the joint of this a kind of structure and gas sealing ability and tubing are suitable, and, joint is used in the heavy corrosion environment because joint has low stress.