What are the differences between casing and tubing?
What is casing pipe?
Casing pipe, also called “encasement pipe,” is used in underground construction. Casing pipes safeguard many kinds of utilities, like water mains, electrical high-voltage lines, natural gas lines and fiber-optic communication lines from damage. These utilities need protection from human activity and natural elements. The construction of deep foundations also makes use of steel casing pipes.
Casing pipe is used in different types of horizontal underground boring, where the pipe is jacked into an augered hole in segments and then connected together by welding or by threaded and coupled ends, or other proprietary pipe connectors. The steel casing pipe can also be set up and welded into a “ribbon” and then directionally pulled through a previously drilled hole under highways, railroads, lakes and rivers.
|Types of steel tubes||Outer Diameter||Wall Thickness|
|Cold-rolled tubes||Tube sizes(mm)||Tolerances(mm)||Tolerances(mm)|
|API SPEC 5CT||J55||C||Si||Mn||P||S||Cr||Ni||Cu||Mo||V|
|Grade||Type||Total elongation under load (%)||Yield strength (min)||Yield strength (max)||Tensile strength min Mpa||Hardness Max (HRC)||Hardness Max (HBW)|
Oil casing is used to support the oil, gas wells of steel pipe, in order to ensure the drilling process and the completion of the entire well after the normal operation. Each well has several layers of casing depending on the drilling depth and geology. Casing down to use cement cementing, it and the tubing, drill pipe is different, can not be reused, a one-time consumption of materials. Therefore, the casing of the total consumption of more than 70% of the wells. Casing according to the use can be divided into: catheter, surface casing, casing technology and oil casing.
The production of casing pipes are from steel smelted in electric furnaces, treated with synthetic slag and cast by continuous casters. This steel-making process guarantees the attainment of chemically pure steel, given the phosphor and sulfur contents. This provides highly ductile, malleable and corrosion-resistant pipes, which can operate at low temperatures in a number of corrosive media. Steel grades and heat-treatment regime application allows production of high-strength pipe.
Steel casing pipes should have minimum yield strength of 35,000 psi. Casing pipes need to have smooth walls and be exceptionally straight and round. Casing pipe and joint construction should be of uniformly thick steel to avoid any matter leaking from the casing. The outside diameter, size and wall thickness should conform to ASTM Designation A252. Use pull-on or wrap-around rubber varieties of “casing end seals” to seal the ends of the steel casing pipe. Apply corrosion-proofing water-based paint to the exterior pipe surface to safeguard against atmospheric corrosion during shipping and storage.
In accordance with the requirements of ANSI/AWS D1.1, all welding should be performed by qualified welding operators. Complete one reduced section tension test specimen for each lot of 1,000 feet of each size and wall thickness. Verify that the tensile strength is not less than 95 percent of the minimum strength specified for the grade of steel used, except when waived by the customer. No hydrostatic testing is required. Examine all connections to make sure they are free of injurious defects at the time of shipment. Otherwise, prior to shipping, reject and repair that section.
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.
Production Standard, Grade, Steel No:
- API 5L PSL1 L175/A25, L210/A, L245/B, L290/X42, L320/X46, L360/X52, L485/X70
- PSL2 L245R/BR, L290N/X42N, L320N/X46N, L360N/X52N, L415/X60N
- API 5CT PSL1, PSL2, PSL3, H40, J55, K55, N80
- GB/T 9711.1 L175, L210, L245, L290, L320, L360
- GB/T 9711.2 L245NB, L290NB, L360NB
- GB/T 9711.3 L245NC, L290NC, L360NC
Delivery Condition: Annealed, Normalized, Normalized and Tempered
API Spec 5CT Casing pipe
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.
Standard: API SPEC 5CT
API 5CT pipe Size (mm):
- Outer Dimensions: 6.0mm – 219.0mm
- Wall Thickness: 1.0mm – 30 mm
- Length: max 12000mm
Application: gas, water and oil transportation in both oil and natural gas .
The main steel grade of API 5CT:
- API 5CT J55
- API 5CT K55
- API 5CT N80
- API 5CT L80
- API 5CT P110
Packing: Bare/bundles/crates/crate protection at the both sides of tubes or as per customers’ requirements .
This International Standard is applicable to the following connections in accordance with ISO 10422 or API Spec 5B:
- 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).
For such connections, this International Standard specifies the technical delivery conditions for couplings and thread protection.
For pipes covered by this International Standard, the sizes, masses, wall thicknesses, grades and applicable end finishes are defined.
This International Standard may also be applied to tubulars with connections not covered by ISO/API standards.
Chemical Composition of API 5CT
Mechanical Properties of API 5CT
|Steel Grade||Yield Strength (Mpa)||Tensile Strength (Mpa)|
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.
Site requirements for casing pipe operation
On site, downhole operations should be performed in accordance with API RP 5C1. Prepare and inspect casing pipe before use. Prepare thread grease and pliers with a torque control system to API BUL 5A2. Specific operational requirements are as follows.
(1) The newly delivered casing pipe shall be checked for any harmful defects specified in API Spec 5CT and shall be limited to the test methods and operating ranges specified in the standard.
(2) All casing pipe, whether new, used or repaired, shall be threaded at all times frequently with a protective wire. Whenever possible, the casing pipe shall be placed on a stone free, sand or dirty Mud (except for normal drilling mud) on a bench, plank or metal surface. If you accidentally drag the casing pipe into the soil, should re-clean the thread.
(3) For long oil and casing string, it is recommended to use sliding type elevator. Chuck and slip shall be clean, undamaged, and properly fitted. For heavy oil, casing string, extra long slips should be used and the chuck must be level.
(4) If the hoisting hook is used, check whether the bearing surface is unevenly worn or not. This wear and tear can cause the hoop side to rise and the coupling piece to come out of danger. When the load acts on the bearing surface, Load should be evenly distributed.
(5) Check the chucks on the chuck and elevator, and make sure they are released together. Otherwise, it is possible to dent or slip the tube.
What is tubing?
Tubing is used for many things, it is something that you can use over and over again and that is going to last when you need it to. With steel tubing, you generally get something that will be durable and rust proof as long as you put some sort of treatment over it and generally there is a coating that goes over it. Steel tubing is great for heavy-duty tubing that needs to be completed, it is something that you are going to be able to trust to last and get the job done.
Tubing is used to transport fluids and gases in a variety of pneumatic, hydraulic, and process applications.
Tubing are usually cylindrical in shape, but may have round, rectangular, or square cross-sections. Tubing is specified in terms of outside diameter (OD) and, depending upon the material of construction, either rigid or flexible. There are several basic types of products. Metal tubes are made of aluminum, brass, bronze, copper, steel, stainless steel, or precious metals. Plastic tubes are made of ethyl vinyl acetate (EVA), polyamides, polyethylene (PE), polyolefin, polypropylene (PP), polyurethane (PU), polytetrafluoroethylene (PTFE), polyvinyl chloride, or polyvinylidene fluoride (PVDF). Rubber tubes are made of natural compounds such as polyisoprene or synthetic materials such as silicone. Glass and quartz tubes are commonly available. Electrical tubing is designed to contain wires and minimize the risks posed by electrical hazards. Fiberglass tubing is impervious to many caustics and suitable for extreme temperatures. Mechanical tubing includes stronger cross-sections and is designed for structural applications. Medical tubing is usually sterilized and relatively small in diameter.
Selecting tubing requires an analysis of dimensions, performance specifications, opacity, finish and temper. Tubes are specified in English design units such as inches (in) or fractions of an inch, or metric design units such as millimeters (mm) or centimeters (cm). Inside diameter (ID) is a tube’s longest inside measurement. Outside diameter (OD) is a tube’s longest outside measurement. Wall thickness is another important factor to consider. Performance specifications for industrial tubes include pressure rating, maximum vacuum (if applicable), maximum bend radius, and temperature range. In terms of opacity, some tubes are clear or translucent. Others are solid or multi-colored. Polishing or pickling imparts a bright finish. Galvanized tubes are coated with zinc for improved corrosion resistance. Painting, coating, and plating are other common finishing techniques. Annealing improves machinability by removing mechanical stress and altering ductility. Half-hard tubes are manufactured to a Rockwell hardness range of 70 to 85 on the B scale for steel. Full-hard tubes are fabricated to a Rockwell hardness of 84 and higher on this same scale.
Tubing differs in terms of features, applications, and materials transported. Some tubes are coiled, conductive, corrugated, explosion-proof, finned, multi-element or multi-layered. Others are reinforced, spark resistant, sterilized, seamless, welded, or welded and drawn. General-purpose tubing is suitable for a variety of applications. Specialized products are used in aerospace, automotive, chemical, cryogenic, food processing, high purity, high temperature, high viscosity, medical, pharmaceutical and petrochemical applications. Depending on the application, industrial tube is used to transport coolants, hydraulic fluid, salt water, slurries, or water. Slurry tubing is rated to resist the abrasion associated with its transport.
Standard: API Spec 5 CT
Weight, (T & C)
where:N = Non-Upset tubing (T & C)U = External Upset tubing (T & C)Weight per unit calculation formula:w = (O.D. – W.T.) x W.T. x 0.0246615 (kg/m)w = (O.D. – W.T.) x W.T. x 10.68 (lb/ft)
Chemical req uirements
Mech anical requirements
|C||Mn||Ni||Cu||P||S||Si||Tensile strength||Yield limit||Elongation A min.|
|N80||–||–||–||–||0,03||0,03||–||min.689||552-758||to the wall|
Range I: 6,10-7,32 meters; (20,0-24,0 ft)Range II: 8,53-9,75 meters; (28,0-32,0 ft)
PROTECTION Unprotected or external varnishedEach pipe is provided with plastic protectors at both ends
MARKING Die stamping or/and paint stenciled according to standard or per customer requestTechnical details can be also marked on tags attached to each bundle.
DELIVERY In bundles of maximum 2500 Kg, tied in minimum four places with steel strips.
MILL TEST REPORTMill test reports are issued to customer requirements.Usually they comply with EN 10204 – 3.1.B (DIN 50049 – 3.1.B)
Boiler Tubings are known for their resistance to corrosion and tolerance for withstanding temperature variations. We also undertake customization of these tubes to meet the specific requirements of our clients.
Boiler tubing is used in these industries:
- Steam Boilers
- Power Generation
- Fossil Fuel Plants
- Electric Power Plants
- Industrial Processing Plants
- Cogeneration Facilities
Waste HeatBoiler Tube in the following Spec/Grades:
- ASTM A178 Grade A, C, D
- ASTM A192
- SA210 / A210 – Grade A1, C
- SA213 / A213 – Grades (limited sizes) T-5, T-9, T-11, T-22, T-91
- BS3059-I 320 CFS
- BS3059-II 360, 440, 243, 620-460, 622-490, S1, S2, TC1, TC2
- EN10216-1 P195TR1/TR2, P235TR1/TR2, P265TR1/TR2
- EN10216-2 P195GH, P235GH, P265GH, TC1, TC2
- DIN17175 ST35.8, ST45.8
- DIN1629, DIN1629 ST37.0, DIN1629 ST44.0, DIN1629 ST52.0
- JIS G3454 STPG370, STPG410
- JIS G3461 STB340, STB410, STB440
- GB5310 20G, 15MoG, 12CrMoG, 12Cr2MoG, 15CrMoG, 12Cr1MoVG, 12Cr2MoWVTiB
- GB9948 10, 20, 12CrMo, 15CMo
Inspection and Test:
- Chemical Composition Inspection, Mechanical Properties Test (Tensile Strength,Yield Strength, Elongation, Flaring, Flattening, Bending, Hardness, Impact Test), Surface and Dimension Test, No-destructive Test, Hydrostatic Test.
- Oil-dip, Varnish, Passivation, Phosphating, Shot Blasting
Tubing and Casing are usaged for Conveying gas and oil in both the oil and natural industries according API SPEC 5CT and ISO11960. With the normal steel grade API 5CT H40, API 5CT J55, API 5CT K55, API 5CT N80, API 5CT N80, API 5CT M65, API 5CT L80, API 5CT L80, API 5CT L80, API 5CT C90, API 5CT C90, API 5CT C90, API 5CT C90, API 5CT C95, API 5CT T95, API 5CT T95, API 5CT T95, API 5CT T95, API 5CT P110, API 5CT Q125, API 5CT Q125, API 5CT Q125.
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.
Petroleum and natural gas industries —Steel pipes for use as casing and tubing for wells.
This standard specifies the technical delivery conditions for steel pipes (casing, tubing, plain-end casing liners and pup joints), coupling stock and accessories and establishes requirements for three Product Specification Levels (PSL-1, PSL-2, PSL-3). The requirements for PSL-1 are the basis of this standard. The requirements that define different levels of standard technical requirements for PSL-2 and PSL-3, for all Grades except H-40 and L-80 9Cr, are contained in Annex H.
For pipes covered by this standard, the sizes, masses and wall thicknesses as well as grades and applicable end-finishes are listed in Tables C.1 to C.3 and Tables E.1 to E.3. By agreement between the purchaser and manufacturer, this standard can also be applied to other plain-end pipe sizes and wall thicknesses.
The main chemical compositions(%) of Tubing and Casing:
a product uses oil quenching, L80 grade carbon content of the upper limit may be increased to 0.50%.
b If the wall thickness
c If the product oil quenching, the C95 grade carbon content limit may be increased to 0.55%.
d If the wall thickness
NL-Not limit, but must show the element content in the product by reported.
Mechanical Properties of Tubing and Casing：
a Dispute, the Rockwell hardness of the laboratory should be used as the arbitration.
b Hardness limit is not specified, but according to the provisions of 7.8 and 7.9 in the most amount of change as production control.
TEUL: Total elongation under load
SWT: Specified wall thickness
HRC Allowable hardness change
What are the differences between casing and tubing?
Casing is generally a steel pipe installed in wellbore and is cemented in place to prevent Wellbore collapse, cross flow of fluids between different reservoirs and to control abnormal formation pressures. Tubings are usually run inside casing (cased hole) and serves as a conduit through which oil and gas is produced. It is basically a tube inside casing which is used to produce reservoir fluids.
Casings usually from20″ to7″ which are run after drilling hole size of24″,171/2″ ,121/2″ and81/2″ after running casing string cementing job is done to make a cement barrier for zonal / reservoir isolation so that channeling of reservoir fluid may be prevented. Casing is very necessary for smooth drilling operations in deep and ERD wells so that hole collapsing may be got rid of.
Tubings are run after drilling. Tubings are of 51/2 to 23/8″ in well completions to safe and cost effective maintenance of wells in production phase of well. Thru tubing we safely and efficiently produce wells according to reservoir volume and nature.
What is the difference between “Pipe” and “Tube” ?
Pipe is used for conveying fluid for mass transfer applications, whereas tube is used for conveying fluid with heat transfer applications.
A pipe is a tube with a round cross section conforming to the dimensional requirements for nominal pipe size as tabulated in ANSI B36.10. A tube is a hollow product of round or any other cross section having a continuous periphery. Tubes can be used in structural applications.
Pipe is made seamless or rolled and welded (sometimes referred to as ERW pipe) . The pipe sizes up to 12′ has a nominal size which is close but not the same as the actual O. D. Pipe in sizes 14″ and larger have an O. D. the same as the nominal size
Tubing is normally “cold drawn” seamless with the O.D. the same as the size designation (i.e.: 1″ inch tubing has an O. D. of 1 inch) . You can get different pressure ratings of 1″ tubing by changing the wall thickness. Thus the I. D. is smaller
In Pipe OD is fixed and ID varies with Schedule whereas in Tubes ID is fixed and OD varies with Thickness (Tubes are specified based on the ID)
Tube application in: boilers, heat exchangers, radiators, etc.
Source: China Steel Tubing Manufacturer – Yaang Pipe Industry Co., Limited (www.pipelinedubai.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.)
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