Drilling Technology & Well Drilling Standards

RK Pipe & Supply has been integrally involved in support of companies drilling for oil and gas since its founding.  We know the complexity of this endeavor.  Our team had deep experience in supplying new and used drilling equipment for virtually all parts of a drilling rig as shown in Figure 1.  Additionally, we specialize in supplying tubular and other products that are used in the drilling string.  As we work with most of the major equipment manufacturers in the world, our equipment adheres to the major standards as defined by the American Petroleum Institute (API) and the International Association of Drilling Contractors (IADC).

The DRILL STRING is the drill pipe with the tool joints attached. The drill stem consists of the drill string and all other attached members, including kelly, subs, drill collars, heavy weight, drill pipe, stabilizers, shock absorbers, reamers, and any other in-hole equipment used generally or part-time during drilling operations.

Image: Supplying all parts of a Drill String.  RK Pipe, leading supplier of new and used drill pipe, drilling equipment, and tubular products.

Tubular Product Standards

In the world wide oil industry today, an overwhelming majority of all tubular goods are manufactured to specifications developed and approved by the American Petroleum Institute. These specifications cover the mechanical properties of the steel, the details of manufacture and physical dimensions of the pipe. The latter include internal and external diameters, wall thickness and upset dimensions for each nominal size, weight and grade, as well as tool joint type, O.D. and I.D., and length. API Specification 5 and 7 cover pipe and the drill string.

High Strength Drill Pipe – Because of deeper drilling and higher stress levels, grades of drill pipe stronger than Grade E-75 have been developed. Grades and minimum tensile yield strengths are:

Drill Pipe Grade Minimum Tensile Yield Strength
X-95 95,000
G-105 105,000
S-135 135,000
V-150* 150,000


*V-150 is not a standard API grade but is listed as the next higher grade above S-135.

High-strength drill pipe requires heavier and longer upsets than those used on Grade E-75. Tool joints on high-strength drill pipe are designed to fit the same elevators as those used for the Grade E-75 assemblies.



___________Month    Year______________


Grade Symbol
E-75 E
X-95 X
G-105 G
S-135 S
V150 V



1 2 3 4 5
ZZ 6 70 N E

1-Company Symbol
ZZ Company (Fictional for example only. Various tool joint manufacturers’ symbols are illustrated in a chart in Section 1, Page 8.)

2-Month Welded

3-Year Welded

4-Pipe Manufacturer
N-United States Steel Company

5-Drill Pipe Grade  E-
Grade E-75 Drill Pipe

Mill Symbol Mill Symbol
Algoma  X  Armco  A
Dalmine  D American Seamless  AI
Kawasaki H  B&W  W
Nippon  I  British Steel  B
Mannesmann  M  J&L  J
 Seamless Tubes  B  Lone Star  L
 Tamsa  T  Ohio  O
 US Steel  N  Republic  R
 Vallourec  V  Sumitomo  S
 Used  U  TI  Z
 Tubemuse  TU  Voest  VA

Processor Symbol

Grant TFW TFW Wheeling Pittsburgh P
Omsco OMS Younston Y
Prideco PI

Note: Pipe mills may upset and heat treat their own drill pipe or they may have this done according to their own specifications. The mill’s assigned symbol should be used on each drill string assembly. Pipe processors may buy “green” tubes and upset and heat treat these according to their own specifications. In this case, the processor’s assigned symbol should be used on each drill string assembly. Note: These codes are provided for pipe manufacturer* identi¬fication and have been assigned at pipe manufacturer’s requests. Manufacturers included in this list may not be current API licensed pipe manufacturers. A list of man-ufacturers licensed to use of the API monogram can be obtained by calling API headquarters. *See API Spec. 5D. The “manufacturer” may be either a pipe mill or processor.

Image: Drill Pipe Chart.  RK Pipe, leading supplier of new and used drill pipe, drilling equipment, and tubular products.

Note A: Standard weight Grade E-75 drill pipe designated by an asterisk (*) in the drill pipe weight code will have no groove or milled slot for identification. Grade E-75 heavy weight drill pipe will have a milled slot only in the center of the tong space. Note B: Groove radius approximately 3/8 inch. Groove and milled slot to be 1/4 inch deep on 5 1/4 in. O.D. and larger tool joints, 3/16 in. deep on 5 in. O.D. and smaller tool joints. Note C: Stencil the grade code symbol and weight code number corresponding to grade and weight of pipe in milled slot of pin. Stencil with 1/4 in. high characters so marking may be read with drill pipe hanging in elevators. LPB = Pin Tong Space Length (See Table 4.2, API Spec. 7)


Image: Drill Pipe Equipment Manufacturers Drill Pipe Chart.  RK Pipe, leading supplier of new and used drill pipe, drilling equipment, and tubular products.

*These are registered Trademarks of each company