- Thread type and code
1. Oil pipe
1) Flat oil pipe (not thickened) NU (TBG or NUE)
2) Externally thickened oil pipe EU (UPTBG or EUE)
3) Integral joint oil pipe IJ (IJ TBG)
2. Casing
1) Long round threaded casing LG (LCSG or LTC)
2) Short round threaded casing STC (CSG or STC)
3) Trapezoidal threaded casing BC (BCSG or BTC)
4) Straight threaded bushing XC (XCJG)
3. Drilling tools
1) Digital connector NC(NC10-NC77)
2) Regular connector REG (2 3/8REG-8 5/8REG)
3) Internal flat connector IF (2 3/8IF-5 1/2IF)
4) Through-eye connector FH(3 1/2FH-6 5/8FH)
Note 1: The inner flat type and the through-eye type are gradually being phased out;
Note 2: 4FH-NC40 interchangeable
2 7/8IF-NC31 interchangeable
3 1/2IF-NC38 interchangeable
4IF-NC46 interchange
41/2-NC50 interchangeable
The exchange only has the same pitch diameter of the base surface, which does not affect the screwing and matching. However, the tooth shapes are different and the performance is also very different, so they cannot be equivalent.
4. Special buckle type
The main foreign special buckles that have been used in our country include: French Vallourec Company VAM buckle, German Mannesmann Company BDS buckle, Japanese NKK Company NK3SB buckle, Japanese Nippon Steel Company NSCC buckle, Japanese Kawasaki Company FOX buckle, Japan Sumitomo's TM buckle, Argentinian Stega's SEC buckle, Tenaris' double-level buckle, etc. These buckle types are also special buckles commonly used in the world.
- Tooth shape characteristics
1. Oil pipe and round thread casing
The thread is a circular thread (the tooth top and bottom are arc-shaped):
Taper is 1:16 (3/4"TPF)
The tooth profile angle is 60°
The tooth flank angle is 30°
The pitch is 3.175mm (8 threads/inch) and 2.54mm (10 threads/inch)
The tooth height is 1.810mm (8 teeth/inch) and 1.412mm (10 teeth/inch)
2. Trapezoidal casing
Taper is 1:16 (3/4" TPF, 13 3/8" and below)
Taper is 1:12 (1" TPF, 16″ and above)
The thread pitch is 5.08mm (5 teeth/inch)
The tooth profile height is 1.575mm
The tooth profile angle is 13°
The tooth flank angle is 3°
Note: 13 3/8″ and below, the thread top and bottom are parallel to the busbar; above 16″, the thread top and bottom are parallel to the axis.
3. Direct-connected casing
It is a special buckle, rarely encountered, and will not be introduced.
4. Drilling tools
Taper is 1:6, 1:4 or 1:8 (2" TPF, 3" TPF or 1.5" TPF)
The pitch is 6.35mm (4 threads/inch), 5.08mm (5 threads/inch), 4.233mm (6 threads/inch)
Tooth profile heights are 3.095, 3.083, 2.993, 3.743mm, etc.
The tooth profile angle is 60°
The tooth flank angle is 30°
4. Special buckle
We currently provide special buckles: BECO, CET, HEF, WFJ, WECO, PH6 and MOD ACME with taper, with different tapers and tooth shapes.
