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Eastern Steel Manufacturing Co.,Ltd is a leading manufacturer and distributor of seamless steel pipe, welded steel pipe, OCTG products and fittings. We supply first-step processing, semi-finished parts and finished parts to help our clients meet fabrication requirements beyond their capacity or to improve operations by moving forward the pre-production processing.
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Eastern Steel Manufacturing Co.,Ltd not only improve product production and sales services, but also provide additional value-added services. As long as you need, we can complete your specific needs together.
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Many years of large-scale project experience in various fields（Oil & Gas, Construction, Power Energy, Marine & Offshore, Water Treatment, Exploration & Drilling Services, Pipeline & Petrochemical etc.）, professional project team is responsible from receiving until the end of the project.
1. NC50 Connection Quick Specs
| Parameter | NC50 Specification |
|---|---|
| Connection Type | NC50 Numbered Connection |
| API Equivalent | 4-1/2 IF |
| Thread Type | 4-1/2 IF (API IF Series) |
| Threads Per Inch (TPI) | 4 |
| Common Drill Pipe Size | 5 in |
| Tool Joint OD | 6-5/8 in |
| Tool Joint ID | 2-3/4 to 3-3/4 in |
| Pipe Body Grades | E-75, X-95, G-105, S-135 |
| Drill Pipe Standard | API Spec 5DP |
| Typical Make-Up Torque | 25,600–30,700 ft-lb |
NC50 drill pipe(Numbered Connection 50 Drill Pipe) is a high-performance, wear-resistant drill pipe manufactured in accordance with API Spec 5DP and commonly equipped with the NC50 connection (API 4-1/2 IF equivalent). It is widely used in medium-depth and deep oil and gas drilling operations.
NC50 does not refer to the outer diameter of the drill pipe, but rather to the connection specification used in the tool joint. In practical applications, NC50 is most commonly paired with a 5-inch drill pipe outer diameter to achieve the best balance of strength, torque, and economy.
| Pipe OD (in) | Weight (lb/ft) | Grade | Tool Joint OD (in) | Tool Joint ID (in) | Tube ID (in) |
|---|---|---|---|---|---|
| 5 | 19.50 | E-75 | 6-5/8 | 3-3/4 | 4.276 |
| 5 | 19.50 | G-105 | 6-5/8 | 3-1/4 | 4.276 |
| 5 | 19.50 | X-95 | 6-5/8 | 3-1/2 | 4.276 |
| 5 | 19.50 | S-135 | 6-5/8 | 2-3/4 | 4.276 |
| 4-1/2 | 25.60 | E-75 | 6-5/8 | 3-1/2 | 4.000 |
| 4-1/2 | 25.60 | G-105 | 6-5/8 | 2-3/4 | 4.000 |
| 4-1/2 | 25.60 | X-95 | 6-5/8 | 3 | 4.000 |
| 4-1/2 | 25.60 | S-135 | 6-5/8 | 2-3/4 | 4.000 |
| OD (in) | Connection | Grade | Range | Wall (in) | Weight (lb/ft) | Adjusted Weight | TJ OD (in) | TJ ID (in) | Tube ID (in) | TJ Yield | Min MUT | Max MUT | Tube Tensile (lbs) |
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 5 | NC50 | G-105 | II | 0.362 | 19.50 | 24.11 | 6-5/8 | 3-1/4 | 4.276 | 51,200 | 25,600 | 30,700 | 436,149 |
| 5 | NC50 | S-135 | III | 0.362 | 19.50 | 22.39 | 6-5/8 | 2-3/4 | 4.276 | 63,400 | 31,700 | 38,000 | 560,763 |
| 5 | NC50 | S-135 | II | 0.362 | 19.50 | 24.11 | 6-5/8 | 3-1/4 | 4.276 | 51,200 | 25,600 | 30,700 | 560,763 |
Pipe Body Material: Seamless steel pipe;
Common Steel Grades: E-75, X-95, G-105, S-135;
S-135 steel grade, due to its high yield strength (≥135 ksi), has become the mainstream choice for deep wells.
Joints are typically made of AISI 4137 / 4140 / 4145H modified steel;
Quenching and tempering treatment;
Surface phosphating or copper plating treatment to improve anti-galling and wear resistance.
API Standard Joint Thread Type: NC26=2-3/8"'IF
Tools/Inch: 4
PIN DIA: 60.35mm
API Standard Joint Thread Type: NC31=2-7/8"IF
Tools/Inch: 4
PIN DIA: 71.31mm
API Standard Joint Thread Type: NC38=3-1/2"'IF
Tools/Inch: 4
PIN DIA: 85.06mm
API Standard Joint Thread Type: NC40=4'IF
Tools/Inch: 4
PIN DIA: 98.06mm
API Standard Joint Thread Type: NC44=4'IF
Tools/Inch: 4
PIN DIA: 98.42mm
API Standard Joint Thread Type: NC46=4'IF
Tools/Inch: 4
PIN DIA: 103.73mm
API Standard Joint Thread Type: NC50=4-1/2"'IF
Tools/Inch: 4
PIN DIA: 114.30mm
API Standard Joint Thread Type: NC56
Tools/Inch: 4
PIN DIA: 117.50mm
(1) NC50 Connection Performance — Box OD 6-3/8 in
| Pin ID (in) | Make-Up Torque (ft-lbs) | Torsional Yield (ft-lbs) | Pin Tensile Yield (lbs) |
|---|---|---|---|
| 2-3/4 | 30,290 | 50,484 | 1,551,700 |
| 3 | 30,290 | 50,484 | 1,416,200 |
| 3-1/4 | 30,290 | 50,484 | 1,268,900 |
| 3-1/2 | 26,674 | 44,456 | 1,109,900 |
| 3-3/4 | 22,361 | 37,269 | 939,000 |
(2) NC50 Connection Performance — Box OD 6-1/2 in
| Pin ID (in) | Make-Up Torque (ft-lbs) | Torsional Yield (ft-lbs) | Pin Tensile Yield (lbs) |
|---|---|---|---|
| 2-3/4 | 34,191 | 56,984 | 1,551,700 |
| 3 | 34,191 | 56,984 | 1,416,200 |
| 3-1/4 | 30,730 | 51,217 | 1,268,900 |
| 3-1/2 | 26,674 | 44,456 | 1,109,900 |
| 3-3/4 | 22,361 | 37,269 | 939,000 |
(3) NC50 Connection Performance — Box OD 6-5/8 in
| Pin ID (in) | Make-Up Torque (ft-lbs) | Torsional Yield (ft-lbs) | Pin Tensile Yield (lbs) |
|---|---|---|---|
| 2-3/4 | 38,036 | 63,393 | 1,551,700 |
| 3 | 34,520 | 57,534 | 1,416,200 |
| 3-1/4 | 30,730 | 51,217 | 1,268,900 |
| 3-1/2 | 26,674 | 44,456 | 1,109,900 |
| 3-3/4 | 22,361 | 37,269 | 939,000 |
b - Torsional yield values shown in yellow indicate the connection is box weak in torsion.
The torsional yield strength is based on a shear strength of 57.7% of the minimum yield strength
The tensile strength of the tool joint pin is based on 120,000 psi yield and the cross sectional area at the root of the thread 5/8" from the shoulder.
NC50 is generally recognized as the API numbered connection equivalent of the 4-1/2 IF connection.
In oilfield practice, the terms NC50 and 4-1/2 IF are often used interchangeably when referring to drill pipe tool joint connections, although dimensional verification is recommended for critical applications.
NC50 drill pipe pricing depends on factors such as steel grade, pipe dimensions, inspection requirements, and optional services like hardbanding.
For accurate pricing, it is usually evaluated based on specific project requirements.
| Feature | NC50 | NC52 |
|---|---|---|
| Connection Type | API Numbered Connection | API Numbered Connection |
| Common Application | Standard drilling operations | Higher torque drilling applications |
| Torque Capacity | High | Higher than NC50 |
| Drill Pipe Compatibility | Commonly used with 5" drill pipe | Commonly used with larger or high-torque drill strings |
| Interchangeability | May require crossover subs | May require crossover subs |
Q1. Is NC50 the drill pipe size or the thread type?
NC50 is an API Numbered Connection specification, not a drill pipe size. It is commonly used on 5-inch drill pipe and is generally considered equivalent to the API 4-1/2 IF connection.
Q2. What international standards does NC50 drill pipe conform to?
NC50 drill pipe generally needs to conform to the following API standards:
API Spec 5DP – Drill pipe manufacturing standards
API RP 7G / 7G-2 – Drill string design and connector parameters
API Spec 7-1 – Drill string connector materials and heat treatment
Compliant products generally provide API Monogram and MTC (Material Certificate of Conformity).
Q3. What materials are typically used for NC50 drill pipe connectors?
Common connector steels: AISI 4137 / 4140 / 4145H
Quenched and tempered (Q&T)
Surface treatment: Phosphating or copper plating to prevent seizing and wear
Q4. Is NC50 the same as 4-1/2 IF?
Yes. NC50 is generally regarded as the API numbered connection equivalent of the 4-1/2 IF thread and is commonly used on 5-inch drill pipe.
Q5. What is the make-up torque for an NC50 connection?
Depending on the tool joint configuration, the recommended make-up torque for NC50 connections typically ranges from 25,600 to 38,000 ft-lb.
Q6. What are the thread specifications of an NC50 connection?
NC50 belongs to the API IF thread series and has 4 threads per inch (TPI). It is widely used in oil and gas drilling applications requiring high torsional strength.
NC50 drill pipe is a cost-effective mainstream drilling solution, achieving a good balance between strength, torque, cost, and maintainability, and is widely compatible with API standards. The system enjoys high recognition in the global oilfield services market.
Read more: API Drill Pipe Thread Types or Drill Pipe Weight Chart and Calculation
E-mail: sales@eastern-steels.com
