An overview of the buckle type

Table of Contents

Buckle type is the most common basic knowledge in tools, and it is also a difficult part to distinguish. The buckle type is very important to the field engineer. If you do not know the buckle type, there will be many problems in material, preparation and operation command, which may affect the progress of field operation and cause unnecessary losses.

oil casing thread
oil casing thread

1. Type of oil casing thread

API thread types include: BTC (partial ladder thread), LTC (long round thread), STC (short round thread), NU (TBG unthickening tubing thread), EUE (external thickening tubing thread), XC (direct casing thread), IJ (integral joint tubing thread) and other types of API thread.



Tenaris Series: Tenaris NK3SB, Tenaris ER

Hunting series: Hunting Seal Lock Boss, Hunting Seal Lock HT, Hunting Seal Lock APEX

Baosteel series products: BGT1, BGC

Other patent thread: Tiangang, WSP-1T, WSP-2T, NSCC, NSCT, etc

2, tubing commonly used thread

  • 1) NewVAM

This type of buckle is characterized by a rectangular section, equal spacing of pitch, small taper, no external thickening. Seen at the end of the production slip sleeve in the workshop.

  • 2) EU(External upset) is getting thicker

The EU connection is an externally thickened tubing connection. In the process of recognizing the variable buckle joint on the shop shelf, three other signs related to EU will be found. EUE(External Upset End) indicates the thickened end, EUP(External Upset Pin) indicates the thickened male buckle, and EUB(External Upset Box) indicates the thickened female buckle.

  • 3)NU(Non-upset) is not thickened externally

NU indicates a tubing connection without external thickening. In addition to the lack of thickening, there is another difference between NU and EU. Nu is usually 10 buttons per inch and EU is usually 8 buttons per inch. Where NUE represents the non-thickened end or the end is not thickened. Again, E means End.

3. Common buckle type of drill pipe

REG and IF buckles are commonly found in drill pipe. Others such as FH are not found in the tool shop.

According to experience:

REG buckle and IF buckle are generally 5 buckle /in and 4 buckle /in, but greater than 4-1/2 “even 4 buckle /in is REG buckle, that is to say greater than 4-1/2” are generally REG buckle, less than 4-1/2 “IF buckle more.

Common buckle type of drill pipe
Common buckle type of drill pipe
  • 1) REG(API Regular Thread) Regular threads in the API standard

In other words,Thread used in regular drill pipe joints. This type of thread has been used to connect the internal thickened drill pipe to form the diameter of the joint of the drill pipe is less than the internal diameter of the thickened end of the drill pipe, and the diameter of the thickened end of the drill pipe is less than the internal diameter of the drill pipe. REG buckle is more delicate, IF the buckle is rough, the reason is that the buckle density per unit length is different.

  • 2) IF(API Internal Flush) Indicates the API internal flush type

The thread used for the internal flat drill pipe joint. This type of thread is used to connect the externally thickened or externally thickened drill pipe to form the inside diameter of the drill pipe joint. The inside diameter of the thickened end of the drill pipe is equal to or similar to the inside diameter of the drill pipe pipe.

  • 3) FH(API Full Hole)API standard in the hole button type

As the name suggests, it is as big as an eye. What about that eye? Refers to the bore diameter of drill pipe joint and the bore diameter of the thickened end of drill pipe. Not the bore diameter of the drill pipe, which is usually smaller than that of the drill pipe.

Summary of steel grade of oil casing

Common buckle type of drill pipe
oil casing

Oil casing is usually composed of two parts, one is the pipe body and the other is the collar. There are many kinds of oil casing steel grades. For the convenience of field use and differentiation, they are usually distinguished by color. Some commonly used colors are listed below. See the table below for details:

steel gradeCoupling colorTube body strip color
C-75,9Crblue+2yellowblue+2 yellow
C-75,13Crblue+1yellowblue+1 yellow

Where the steel grade numbers represent 1000Psi, for example N-80 indicates a minimum yield strength equal to 80,00psi equal to approximately 55.16MPa.

Common flush buckle types are the HYDRILL CS, HYDRILL 511, TSWP, and FL-4S available in 2-7/8 “and 4”.

  • 1. The HYDRILL CS is 1.9 “and externally thickened, the HYDRILL 511 is 2-7/8” and thin to thick, and the TSWP is 4 “and sealed for double shoulders.
  • 2. FL-CS are shared with 2-7/8 “and 4” flusher.
  • 3. In addition, milling shoes and other tools also have TSWP buckle.
  • Screen tube, blind tube buckle type

BTC, for the side ladder buckle, the common size is 5-1/2 “, 6-5/8 “, 7 “and so on.

STC, short round grain, common sizes are 4-1/2 “, 5-1/2 “, 6-5/8 “, 7 “, 7-5/8 “, etc.

LTC, long round buckle, common sizes are 4 “, 4-1/2 “, 5-1/2 “, 7 “and so on.

Special buckle type

Special buckle for sealing unit

ACME buckle type, common sizes are 3.25 “, 4 “(3-5/8”), 4.75 “, 6 “.

Tubular buckle type

The LP buckle has a triangular section, similar to the EU, but it has a sharp feeling to the touch.

LP buckle is commonly used in high pressure manifold, common sizes are 2 “and 3”.

A surname

Common are 1502, 1602.

Casing milling pipe


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