What is OCTG?

What is OCTG?

Oil Country Tubular Goods (OCTG), is a collection of rolled metal products, more commonly known as drill pipe, casing and tubing which are manufactured according to API specification. It used both onshore and offshoreiIn petroleum industry.

Oil Country Tubular Goods are used both onshore and offshore. In the industry, they are also referred to by the acronym OCTG (for “Oil Country Tubular Goods”).

  • Drill pipe is heavy seamless tube that rotates the drill bit and circulates drilling fluid. Pipe segments 30 ft (9m) long are coupled with tool joints. Drill pipe is simultaneously subjected to high torque by drilling, axial tension by its dead weight, and internal pressure by purging of drilling fluid.
  • Additionally, alternating bending loads due to non-vertical or deflected drilling may be superimposed on these basic loading patterns.
  • Casing pipe lines the borehole. It is subject to axial tension by its dead weight, internal pressure by fluid purging, and external pressure by surrounding rock formations. Casing is particularly exposed to axial tension and internal pressure by the pumped oil or gas emulsion.
  • Tubing is pipe through which the oil or gas is transported from the wellbore. Tubing segments are generally around 30 ft [9 m] long with a threaded connection on each end.

Drill pipe
Casing pipe
Tubing
Differences between PSL 1 and PSL 2
API Spec 5CT
API SPEC 5L

oil country tubular goods - What is OCTG?

Drill pipe

Drill pipe is a seamless tube that rotates the drill bit and circulates drilling fluid. It is hollow to allow drilling fluid to be pumped down the hole through the bit and back up the annulus. The annulus of an oil well is the space between any piping tubing or casing and the piping, tubing or casing immediately surrounding it. The presence of an annulus gives the ability to circulate fluid in the well. Drill pipe is subjected to high torque by drilling, axial tension by its dead weight and internal pressure by purging of drilling fluid.

Characteristic of casing pipe

Casing is important to oil drilling equipment, and its main equipment includes drill, core pipe and casing, drill collars and drilling small diameter steel pipe and so on.

The casing is used to support oil and gas wall of the pipe, to ensure that the drilling and completion of the process of the normal operation of the wells. Depending on the drilling each well depth and geological conditions, to use several layers of casing. Casing cementing go down after using it with tubing, drill pipe are different, can not be reused, a one-time consumable materials. Therefore, the total consumption of the casing is 70% of the oil well pipe. Casing can be divided according to usage: catheter, surface casing, casing and production casing. Casing is a large-diameter pipe, play a fixed oil and gas wells, or wellbore wall effect. The casing is inserted into the well hole, fixed with cement to prevent the formation and borehole spaced borehole collapse and to ensure circulation of the drilling mud to the drilling mined.

Casing is mainly used for drilling oil wells during drilling and after completion of the support wall to ensure that the conduct of the drilling process and completion of the wells after the regular oil casing normal operation. OCTG mainly used for oil and gas well drilling and oil and gas transportation. It includes oil drilling pipe, oil casing, pump tubing. Oil drill pipes are mainly used to connect the drill collar and drill and pass drilling power. Casing is mainly used for drilling and completion of the right wall of the support, to ensure that the conduct and completion of the drilling process after the normal operation of the wells. Pumping wells at the bottom of the tubing will mainly oil, gas transported to the ground.

Casing is to maintain the wells run lifeline. As different geological conditions, underground complex stress state, pulling, pressing, bending, torsional stress acting on the combined effect of the tube, which the casing itself, the quality of the higher requirements. Once the casing itself is damaged for some reason, could lead to the whole production wells, or even scrapped.

Drill Pipes with Welded Tool Joints

Drill Pipes with Welded Tool Joints - What is OCTG?

The drill pipes with welded tool joints are installed in the drilling string and are connected with the kelly bar in the top and with the drill collar and drill bit or tool in the bottom.

TU 1324-137-0147016-01

This specification cover seamless steel pipes with upset ends and welded tool joints.
The drill pipes with welded tool joints are installed in the drilling string and are connected with the kelly bar in the top and with the drill collar and drill bit or tool in the bottom.
The pipes are to be used for drilling oil, gas and test wells, workover, and emergency service in relevant casing strings.
The climatic zone of use is from I1 up to II12 as per GOST 16350.
The tool joints to be welded to pipes are supplied in accordance with TU 3663-128-01470016-00.
The pipe integrated tool joints are considered to be repairable items.
The specified repair life (original life) of tool joints is not less than 1200 screw-unscrew cycles.
The sizes of drill pipes with welded tool joints and of tool-joint thread are in accordance with API standard, Spec. 7, and extend the range of drill pipes not covered by GOST R 50278-92.
The pipes have optimal values of ratio of torsional moments of tool joint and of pipe, also they have optimal moments of resistance box and pin, and of tensile strains of tool joint and pipe.
In pipe design, the optimal values of pipe end upset coefficients were selected; it results in good pipe characteristics in respect to reduced mass of pipe.

The pipe end upset can be external (EUE), internal (IUE) or combined.

The pipes are manufactured at four length groups:

Pipe length, L, m:

Group 1 Group 2 Group 3 Group 4
5,9…6,3 8,0…8,4 9,0…9,4 11,9…12,5
Standard pipe size Strength group Tool joint Thread
BN-60х7,11 D, E, L, M ZP-86-45 Z-73
BK-73х7 D ZP-86-45-1 Z-73
BK-73х9 D, E ZP-92-34 Z-73
BK-73х9 D, E, L, M ZP-105-45 Z-86
BN-73х9 D, E ZP-105-54 Z-86
BN-73х9,19 D, E, L, M ZP-105-51 Z-86
BV-89х8 D, E ZP-108-45 Z-86
BN-89х6,5 D, E ZP-121-76 Z-102
BN-89х8 D, E, L ZP-121-68 Z-102
BN-89х9,35 D, E ZP-121-68 Z-102
BN-89х9,35 L ZP-127-65 Z-102
BN-89х9,35 M ZP-127-62 Z-102
BN-114х8,56 D, E, L, M ZP-159-93 Z-133
BK-127х9,19 D, E ZP-162-95 Z-133
BK-127х9,19 D, E, L ZP-162-89 Z-133
Standard pipe size Reduced mass of pipe (L=9.3 m)
kg/1 rm)
Mtors. t.joint/
Mtors. pipe
Screw torsional moment of tool joint thread,
Nm
BN-60х7,11 10,4 0,9 3000
BK-73х7 12,8 1 3000
BK-73х9 15,8 0,9 4500
BK-73х9 16,5 1 6700
BN-73х9 16,2 1,1 5600
BN-73х9,19 16,7 0,9 5890
BV-89х8 18,9 0,9 6770
BN-89х6,5 15,7 1 6000
BN-89х8 18,9 0,9 8000
BN-89х9,35 20,9 1 8000
BN-89х9,35 21,7 0,9 9000
BN-89х9,35 21,9 0,9 10000
BN-114х8,56 26,9 1 19000
BK-127х9,19 31,1 1 27100
BK-127х9,19 32,1 0,9 22700

Casing pipe

Casing pipe is used to line the borehole, which is the actual hole dug into the ground to get to the oil. Like the drill pipe, it too is subject to axial tension. However, it differs in that while needing to handle internal pressure from the oil itself, there is also external pressure from the rock and sediment it has been bored into. It too is extremely heavy duty and crucial to OCTG.

Characteristic of casing pipe

Casing is important to oil drilling equipment, and its main equipment includes drill, core pipe and casing, drill collars and drilling small diameter steel pipe and so on.

The casing is used to support oil and gas wall of the pipe, to ensure that the drilling and completion of the process of the normal operation of the wells. Depending on the drilling each well depth and geological conditions, to use several layers of casing. Casing cementing go down after using it with tubing, drill pipe are different, can not be reused, a one-time consumable materials. Therefore, the total consumption of the casing is 70% of the oil well pipe. Casing can be divided according to usage: catheter, surface casing, casing and production casing. Casing is a large-diameter pipe, play a fixed oil and gas wells, or wellbore wall effect. The casing is inserted into the well hole, fixed with cement to prevent the formation and borehole spaced borehole collapse and to ensure circulation of the drilling mud to the drilling mined.

Casing is mainly used for drilling oil wells during drilling and after completion of the support wall to ensure that the conduct of the drilling process and completion of the wells after the regular oil casing normal operation. OCTG mainly used for oil and gas well drilling and oil and gas transportation. It includes oil drilling pipe, oil casing, pump tubing. Oil drill pipes are mainly used to connect the drill collar and drill and pass drilling power. Casing is mainly used for drilling and completion of the right wall of the support, to ensure that the conduct and completion of the drilling process after the normal operation of the wells. Pumping wells at the bottom of the tubing will mainly oil, gas transported to the ground.

Casing is to maintain the wells run lifeline. As different geological conditions, underground complex stress state, pulling, pressing, bending, torsional stress acting on the combined effect of the tube, which the casing itself, the quality of the higher requirements. Once the casing itself is damaged for some reason, could lead to the whole production wells, or even scrapped.

Applications of coating pipe:

coating pipe base metal is including spiral, straight seam pipe, seamless steel pipe, etc., which are widely used in pipeline projects in the field of petroleum, chemical, natural gas, heating, sewage treatment, water, bridges, steel structures, piling and other marine water.

Standard: 
DIN 30670: Polyethylene coatings of steel pipes adn fittings.
DIN 30678: Polythylene coatiing of steel pipes and fittings.
SY/T0413-2002: Technical standard of polythelene coating for buried steel pipeling. 

Anti-corrosion coating:
Various steel pipe external coating projects are currently implemented by our company including single-layer/double-layer FBE, 2PE,3PE,3PP and other anti-corrosion coatings with the performed standards such as DIN30670, DIN30671,DIN30678,CAN/CSA-Z245.21-M92,SY/T4013-2002 and SY/T0315-97 etc.

     Coating Type   Coating Layer  Coating thickness
Three layers polyethylene  Inside layer: epoxy (Green)      2.0 -4.5mm
 Mid layer: adhensive (White)
Outsidelayer:polyethylene (Black)
   Two layers polyethylene Inside layer: adhensive      2.0 -4.5mm
Outside layer: polythene
   Epoxy  Epoxy      200-400um
   Two layers epoxy Inside layer: expoxy (Green)      400-800um
Outside layer:intensity epoxy (sage green)
Three layers polyethylene Inside layer: expoxy (Green)  2.5 -3mm
Mid layer: adhensive (White)
Outside layer: polypropylene (White)

Types of anti-corrosion coating:

  1. FBE anticorrosive epoxy powder: FBE epoxy powder preservative structure: electrostatic spraying epoxy powder coating on the pipe surface, a film. The coating has a coating operation is simple, clean, good impact resistance and flexural properties of the coating, temperature resistance advantages.
  2. 2PE/3PE corrosion: 2PE/3PE corrosion structure: the steel surface electrostatic spraying epoxy powder and binder twine lateral lateral wound polyethylene coating, combined with three excellent performance, thereby significantly improving the overall quality of corrosion of the pipe. Resistant to chemical corrosion, cathodic stripping, resistance to mechanical damage performance.
  3. Coal tar epoxy: Coal tar epoxy structure: epoxy resin + filler made of coal tar pitch anticorrosive coating on the steel surface coated glass fabric as reinforcement corrosion layer formation, commonly used in the pipe wall corrosion . Thickness of 0.5 ~ 1.0mm. 

Process of coating pipe

20150628235257985798 - What is OCTG?

20150629194974967496 - What is OCTG?

Package & Transportation of coating pipe

20150616203357845784 - What is OCTG?20150616203341954195 - What is OCTG?

Tubing

Tubing is the pipe that goes inside the casing pipe. This is the pipe that the oil itself will eventually make its way out of. The most simplistic of the OCTG family, tubing pipes can usually be found in segments of about 9m (30 ft), with threaded connections on each end, which can be protected with drill pipe protectors during transportation and storage. These protectors also help protect against any corrosion that could happen during storage, which could cause major problems when tons of oil are being pumped through.

GOST 633-80 Tubing and Couplings

Tubing is used for oil and gas production. Tubing shall be made seamless, plain or upset and coupling with high-seal connections. Coupling-free connections are possible.

This standard applies to seamless steel tubing smooth and couplings, with upset ends and couplings are smooth vysokogermetichnye and couplings, as well as flush-joint pipe with upset ends, used for the exploitation of oil and gas wells.

  • GOST 633-80 D (Casing and Tubing) = API 5CT H-40
  • GOST 633-80 D (Casing and Tubing)= API 5CT J-55
  • GOST 633-80 D (Casing and Tubing) = API 5CT K-55
  • GOST 633-80 E (Casing and Tubing)= API 5CT N-80
  • GOST 633-80 E (Casing and Tubing) = API 5CT L-80
  • GOST 633-80 L (Casing and Tubing)= API 5CT C-90
  • GOST 633-80 L (Casing and Tubing)= API 5CT C-95
  • GOST 633-80 M (Casing and Tubing)= API 5CT P-110
Tubing to this standard shall be manufactured in two grades B and A depending on accuracy and quality level.
Size range of tubing, types of connections for the two grades are given in Table 1.

Table 1 size range of tubing grades A & B

gost 8633 table1 - What is OCTG?
Limit dimensional and mass tolerance are given below:
gost 8633 table2 - What is OCTG?

Technical requirements:

Outside and inside tube surface shall be free of cracks, laps, discountinuities, cavities and inclusions.

Small indentations, scratches on insignificant scale of production origin are permissible if they leave the wall thickness wihtin specified limits.

The run-out sections from upset part to tube body shall be smooth and gradual; wall thickness shall be within the specifed limits. Up set part of 85 mm length from the ends shall be free of defects.

Chemical composition of steel is not specified except that phosphorus and sulphur contents shall not exceed 0.045% each.

Mechanical properties of tubing and coupling metal are give in table 2.

Mechanical properties of tubing and coupling metal Table 2

gost 8633 table2 2 - What is OCTG?

Surfaces of threads and sealing shall be zinc-coated or phosphate-treated. All tubing except grade TBO shall be delivered with coupling (power-tight makeup) and anti-corrosion and sealing compounds applied. For transportation tubing and couplings shall be pointed for corrosion protection. Special internal coationgs on tubing grade A shall be applied on request.

Thread profile for plain and upset-end tubing is shown in Figure 1.

Fig. 1. Round thread profile for tubing.
Round thread dimensions for grades B and A are given below. gost 8633 figure1 - What is OCTG?

Thread sizes are give in Table 3, 4, 5 and 6.

Table 3 Sizes, mm of round thread for plain-end tubing grades B and A

gost 8633 table3 - What is OCTG?

Symbols for table 3

gost 8633 table3 1 - What is OCTG? 

Limit tolerances for nominal sizes are given below. Pitch, mm:- on 25,4 mm length ±0,75- on full-profiled thread ±0,120Taper, mm on 100 mm thread length:pipe body (+0,66) – (0,22)coupling (+0,22) – (0,36)

Table 4 Size, mm of round thread for external-upset tubing grades B and A

gost 8633 table4 - What is OCTG?

Symbols for table 4

gost 8633 table4 2 - What is OCTG?

High-seal thread connections type NKM.

Thread profile for tubing.

Thread profile for nominal bore 60 to 102 mm is shown in Fig.2; for nominal bore 114mm see Fig. 3. Thread dimension are given in Table 5.Fig.2. Thread profile (type NKM 60-102)a- coupling; upset end;b – tube; nipple.Fig.3. Thread profile (type NKM 114)a – coupling;b – tube.Bevel C can be replaced by rounding to 0.2 mm radius.

For dimensions of connectiong parts, see Fig. 4 and Table 6.

Fig.4. Thread ty NKM.
Limit thread tolerances are given in Table 7.

Thread interference measured as the distnace from the reference plane of the thread gauge to tube end shall be 20-1.2 mm for nominal bore 60 to 102 mm and 24-2.5 mm for nminal bore 114 mm.

Thread interference for galvanized or phosphate-treated coupling measured by a thread gauge shall be 5.0-1.2 mm for nomianl bore 60 to 102 mm and 6.0-2.5 mm for nominal bore 114 mm.

For power make-up of tubing and galvanized or phosphate-treated coupling thread interferences are given below:

gost 8633 power make up - What is OCTG?

Power make-up of tubing and couplings shall guarantee complete contact of tube end and the thrust surface of the coupling. Tubing grade B may have a gap of 0.5mm between the above suraces.

Table 5 Thread dimensions for tubing with high-seal type NKM and pup type NKB connections of grades B and A 
gost 8633 table5 - What is OCTG?
Table 6 Dimensions of high-seal thread connections for tubing

gost 8633 table6 - What is OCTG?

Symbols for table 6

gost 8633 table6 2 - What is OCTG?

Pup joints.

For thread profile and dimensions see Fig.2 and Table 5; details of dimensions are given in Fig.5 and Table 8. For limit tolerances, see Talbe 7.

Thread interference for the male and measured by using respective thread gauges haveing complete and incomplete thread profiles shall be 18+1.2 mm.

Fig. 5. Thread type NKB.

Table 7 Limit tolerances for thread types NKM and NKB, mm 
gost 8633 table7 - What is OCTG?

Thread interference for the gemale end measured by repective thread gauge shall be 5-1.2 mm. 

Table 8 Size of tubing with pup joints grades B and A, mm

gost 8633 table8 - What is OCTG?

Symbols for table 8

gost 8633 table8 2 - What is OCTG?

Wall thickness variation of both male and female ends shall not exceed 1.0 mm.

Thrust belt width shall be sa given below:

gost 8633 table8 3 - What is OCTG?

Threads of couplings shall be coaxial within 0.75 mm in the end plane and within 3 mm on one meter legnth. Plain end coaxiality may be increased to 1.0 mm if this parameter on one meter legnth is 2.0 mm.

Thread sufaces, thrust belts on tubes and couplings shall be free from burrs, pits, discountinuities and other defects affecting strength and sealing properties. 

Thread surface roughness shall not exceed 20 m. 

Wall thickness variation of couplings and threaded tube ends grade NKB shall not exceed 0.1 mm for nominal bores 27 to GOST 17410-78.

Grade D and K shall be supplied without non-destuctive examination on special agreement.

Select differences between PSL 1 and PSL 2

This is summarized information from API Specification 5L.

 Data

PSL1

PSL2

CVN impact (Charpy) testing

None required

Required for all grades

Nondestructive inspection of seamless

Only when purchaser specifies   SR4

SR4 mandatory

Certification

Certificates when specified per SR15

Certificates (SR 15.1) mandatory

Traceability

Traceable only until all tests are passed, unless SR15 is specified

Traceable after completion of tests (SR 15.2) mandatory

Hydrostatic Test

Required    

Required

Note: Please refer to the specific Standard or Specification or contact us for more details.

API Spec 5CT

API Spec 5CT – Specification 5CT/ISO 11960, Specification for Casing and Tubing, Eighth Edition, Petroleum and natural gas industries-Steel pipes for use as casing or tubing for wells.

The main steel grade of API 5CT:

  • API 5CT J55
  • API 5CT K55
  • API 5CT N80
  • API 5CT L80
  • API 5CT P110

Chemical Composition

Grade C≤ Si≤ Mn≤ P≤ S≤ Cr≤ Ni≤ Cu≤ Mo≤ V≤ Als≤
API 5CT J55 0.34-0.39 0.20-0.35 1.25-1.50 0.020 0.015 0.15 0.20 0.20 / / 0.020
API 5CT  K55 0.34-0.39 0.20-0.35 1.25-1.50 0.020 0.015 0.15 0.20 0.20 / / 0.020
API 5CT N80 0.34-0.38 0.20-0.35 1.45-1.70 0.020 0.015 0.15 / / / 0.11-0.16 0.020
API 5CT  L80 0.15-0.22 1.00 0.25-1.00 0.020 0.010 12.0-14.0 0.20 0.20 / / 0.020
API 5CT J P110 0.26-035 0.17-0.37 0.40-0.70 0.020 0.010 0.80-1.10 0.20 0.20 0.15-0.25 0.08 0.020

Mechanical Properties of API 5CT

Steel Grade Yield Strength (Mpa) Tensile Strength (Mpa)
API 5CT J55 379-552 ≥517
API 5CT K55 ≥655 ≥517
API 5CT N80 552-758 ≥689
API 5CT L80 552-655 ≥655
API 5CT P110 758-965 ≥862

API Spec 5CT standard replaced by:

  • API Spec 5CT – Specification 5CT/ISO 11960, Specification for Casing and Tubing, Eighth Edition, Petroleum and natural gas industries-Steel pipes for use as casing or tubing for wells
  • This product references:
  • API Spec 5B – Specification for Threading, Gauging, and Thread Inspection of Casing, Tubing, and Line Pipe Threads (US Customary Units) (Includes March 2004 Addendum)
  • ISO 10422:1993 – Petroleum and natural gas-industries; threading, gauging, and thread inspection of casing, tubing and line pipe threads; specification
  • This product replaces:
  • API 5CT – Specification for Casing and Tubing (U.S. Customary Units)
  • ISO 11960 was prepared by Technical Committee ISO/TC 67, Materials, equipment and offshore structures for petroleum, petrochemical and natural gas industries, Subcommittee SC 5, Casing, tubing and drill pipe.

casing tubing - What is OCTG?

Seamless steel tubes for oil casing and tubing in oil wells

Model N0.of steel tubes:

J55,N80,L80,P110 etc.

  • short round thread casing (STC);
  • long round thread casing (LC);
  • buttress thread casing (BC);
  • extreme-line casing (XC);
  • non-upset tubing (NU);
  • external upset tubing (EU);
  • integral joint tubing (IJ).

This International Standard specifies the technical delivery conditions for steel pipes (casing, tubing, plain end casing liners and pup-joints) and accessories.

API SPEC 5L

PSL C, a    Mna P        S  Si V Nb

Ti

Other CEIIW CEpcm
1 0.24 1.40 0.025 0.015 0.45 0.10 0.05 0.04 b,c .043 0.025
2 0.28 1.40 0.03 0.03 b b b

API SPEC 5L is a international standard specifies requirements for the manufacture of two product specification levels (PSL 1 and PSL 2) of welded steel pipes for use in pipeline transportation systems in the petroleum and natural gas industries.

Manufacturing processes of OCTG include (all dimensional ranges are approximate)

  • Continuous mandrel-rolling process and the push bench process for sizes between 21 and 178 mm OD.
  • Plug mill rolling for sizes between 140 and 406 mm OD.
  • Cross-roll piercing and pilger rolling for sizes between 250 and 660 mm OD.

These processes typically do not allow the thermomechanical processing customary for the strip and plate products used for welded pipe. Therefore, high-strength seamless pipe must be produced by increasing the alloying content in combination with a suitable heat treatment such as quench & tempering.

octg figure 1 - What is OCTG?
Schematic deep well completion

Meeting the fundamental requirement of a fully martensitic microstructure even at large pipe wall thickness requires good hardenability. Cr and Mn are the main alloying elements used to produce good hardenability in conventional heat-treatable steel. However, the requirement for good sulphide stress cracking (SSC) resistance limits their use. Mn tends to segregate during continuous casting and can form large MnS inclusions that reduce hydrogen induced cracking (HIC) resistance.

threaded casing and tubing - What is OCTG?
OCTG includes threaded casing and tubing that are used in equipping and operating oil and gas wells.

Higher levels of Cr can lead to formation of Cr7C3 precipitates with coarse plate-shaped morphology, which act as hydrogen collectors and crack initiators. Alloying with Molybdenum can overcome the limitations of Mn and Cr alloying. Mo is a much stronger hardener than Mn and Cr, so it can easily recover the effect of a reduced amount of these elements.

Source: China OCTG Pipes Manufacturer – Yaang Pipe Industry (www.metallicsteel.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@metallicsteel.com

Please notice that you might be interested in the other technical articles we’ve published:

  • WHERE TO BUY HIGH QUALITY STEEL PIPES
  • ADVANTAGES OF DUPLEX STAINLESS STEEL PIPE AND SELECTION
  • Where to get high quality alloy steel pipes
  • Distinguish Inferior Steel Pipes
  • WHERE TO GET HIGH QUALITY HEAT EXCHANGER TUBES
  • WHERE TO GET HIGH QUALITY CARBON STEEL PIPES
  • Steel pipe

References:

  • www.yaang.com
  • https://www.steeljrv.com
Summary
what is octg - What is OCTG?
Article Name
What is OCTG?
Description
Oil Country Tubular Goods (OCTG), is a collection of rolled metal products, more commonly known as drill pipe, casing and tubing which are manufactured according to API specification. It used both onshore and offshoreiIn petroleum industry.
Author
Publisher Name
www.metallicsteel.com
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