Brief Introduction

BOHAI NKK Drill Pipe Co., Ltd. (BHNK) is a joint venture with CNPC

BOHAI Equipment Manufacture Co., Ltd., JEF Steel Corporation,

Marubeni-Itochu Steel Inc., and Metal-One Corporation as the shareholders.

BHNK was established in December, 1995 and the current number of personnel

is 252, among which there are 32 staff with senior technical title, and 2 resident

experts from Japan. BHNK went into production in 1997 and, till now, has

accumulatively yielded out 180,000 Metric Tons drill pipes.

BHNK Drill Pipe Specifications:

（1） API Standard，OD: 23/8＂— 65/8＂，Grade: E75、X95、G105、S135.

（2） Sulfur resistant drill pipe with C95S、C105SS grades.

（3） Double shoulder Tool Joint (DSTJ) drill pipe with high anti torque

ability.

（4） 5” EUE drill pipe jointly developed in conjunction with Tarim Oil

field, China.

BHNK, boasting advanced techniques and high automaticity, uses the

whole production line and technologies transferred from NKK (a leading

international supplier of drill pipe with over 30 years’ experience) with an

annual yield capacity of 35,000 Metric Tons.

钻杆生产工艺流程

Tool Joint Machining Line Friction Welding Line

Inside & outside Machining

Pipe End Machining

Thread Inspection

Friction Welding

Stress Reliving of Weld Line

Cutting of Bead

Quenching of Weld Line

Tempering of Weld Line

Weld Line Inspection

Weighing & Length Measuring

Make & Break Copper Plating

Threading

Quenching of Tool Joint

Tempering of Tool Joint

Hardness MPI

Hard-banding

Heat treatment to Tool Joint Threading

Friction Welding

MPI of Tool Joint Ultrasonic Inspection of Weld Line

Corporate Qualification

API 5DP

ISO 9001:2008

Drill Pipe

Drill Pipe with API Standards

Mechanical Properties of Pipe Body

Standard Grade

Yield Strength Tensile Strength

ElongationMIN

Average Impact Energy MIN MAX MIN

ksi（N/mm2） ksi（N/mm2） ksi（N/mm2） % fb-lbs（J）

APISpec 5D

Group 1 E-75 75 （517） 105 （724） 100 （689） API formula 40 （54）

Group 2 X-95 95 （655） 125 （8620 105 （724） API formula 40 （54） G-105 105 （724） 135 （931） 115 （793） API formula 40 （54） S-135 135 （931） 165 （1138） 145 （1000） API formula 40 （54）

Mechanical Properties of Tool Joint

Standard Grade

Yield Strength Tensile Strength

ElongationMIN

Average Impact Energy MIN MAX MIN

ksi（N/mm2） ksi（N/mm2） ksi（N/mm2） % fb-lbs（J）API

Spec7 120 （827） - 140 （965） 13 -

Throat（Miu）smooth and long

Sulfur-Resistant Drill Pipe

Mechanical Properties of Pipe Body

Grade

Yield Strength Tensile Strength

Hardness SSC Test

MIN MAX MIN HRC ksi（N/mm2） ksi ksi（N/mm2） MAX %

BNK C95SS 95 （655） 110 （758） 105 （724） 26 85

BNK C105SS 105 （724） 120 （827） 115 （793） 29 85

Mechanical Properties of Tool Joint

Grade

Yield Strength Tensile Strength

Hardness SSC Test

MIN MAX MIN HRC ksi（N/mm2） ksi ksi（N/mm2） MAX %

BNK TJ95 95 （655） 110 （758） 105 （724） 26 85

BNK TJ110 110 （758） 125 （862） 125 （862） 33 65

5”EUE Drill Pipe

Product Characteristics:

(1） The Shape of throat is changed to minimize stress concentration and lower the

frequency of fatigue failures on throat.

（2） The ID and upset area of Pin Tool Joint are upsized to reduce water horse power

loss of mug and enhance cycle efficiency.

（3） Special materials are used for tool joint and pipe body to improve the mechanical

properties of the drill pipe as a whole.

Comparison with normal drill pipe:

Correlation Table of Drill Pipe Dimensions： Unit：mm

Specification Tool Joint Weld Line Pipe Body

OD ID（PIN） ID（BOX） OD (Weld Line)

OD ID OD ID

5”EUE 171.5 88.9 101.6 136 136 100 127 108 5”Normal S135 168.3 69.9 88.9 130.2 130.2 94.7 127 108.6

Correlation Table of Drill Pipe Mechanical Properties:

Specification

Tool Joint Weld Line Pipe Body

Tensile Strength Yield

Strength Impact Energy

Single Impact Energy

Average Impact Energy

Mpa Mpa J J J 5”EUE ≥1000 931-1138 ≥45 ≥80 ≥90

5”Normal S135 ≥965 ≥827 ≥20 ≥38 ≥47

Von Mises Equivalent Stress Distribution on Upset Throat with API Standard

Von Mises Equivalent Stress Distribution on EUE Upset Throat