Tubing casing

Tubing and casing pipe are essential tools for oil exploration. The tubing is a tube that is lowered into the casing of the well when the well is being produced normally. From the well, the oil flows through the oil pipe into the ground and enters the gathering process. In the coal mining well, the combination of oil pipe, sucker rod and deep well pump draws oil to the ground and enters the gathering process.

Chemical Composition of API 5L Pipe Grade PSL1

Grade		Chemical Composition
		C (Max)	Mn (Max)	P (Max)	S (Max)
A25	CL I	0.21	0.6	0.03	0.03
	CL II	0.21	0.6	0.03	0.03
A		0.22	0.9	0.03	0.03
B		0.28	1.2	0.03	0.03
X42		0.28	1.3	0.03	0.03
X46		0.28	1.4	0.03	0.03
X52		0.28	1.4	0.03	0.03
X56		0.28	1.4	0.03	0.03
X60		0.28	1.4	0.03	0.03
X65		0.28	1.45	0.03	0.03
X70		0.28	1.65	0.03	0.03

Mechanical Properties of API 5L Pipe Grade PSL1

Grade	Mechanical Property
	TENSILE ( Min)		YIELD ( Min)
	Psi X 1000	Mpa	Psi X 1000	Mpa
A	48	335	30	210
B	60	415	35	245
X42	60	415	42	290
X46	63	435	46	320
X52	66	460	52	360
X56	71	490	56	390
X60	75	520	60	415
X65	77	535	65	450
X70	82	570	70	485

Permissible dimension tolerance and variation for seamless and welded API 5L Pipe

Data	Grade A, B, A25	X42 through X80
NPS 2-1/2 and smaller --Seamless and Welded, %	32.5	27.5
NPS 3 --Seamless and Welded, %	30.5	27.5
NPS 4 through 18 --Seamless and Welded, %	27.5	27.5
NPS 20 and larger -- Welded, %	27.5	27.5
NPS 20 and larger -- Seamless, %	27.5	27.5

Chemical Composition of API 5L Pipe Grade PSL2

Grade	Chemical Composition
	C	Mn	P	S
	(Max)	(Max)	(Max)	(Max)
B	0.22	1.2	0.025	0.015
X42	0.22	1.3	0.025	0.015
X46	0.22	1.4	0.025	0.015
X52	0.22	1.4	0.025	0.015
X56	0.22	1.4	0.025	0.015
X60	0.22	1.4	0.025	0.015
X65	0.22	1.45	0.025	0.015
X70	0.22	1.65	0.025	0.015
X80	0.22	1.9	0.025	0.015

Mechanical propertiesof API 5L pipe grade PSL2

Grade	Mechanical Property
	Tensile		Yield		C. E. IMPACT ENERGY
	Psi x 1000	Mpa	Psi x 1000	Mpa	PCM	IIW	J	FT/LB
B	60 - 110	414 - 758	35 - 65	241 - 448	0.25	0.43	T/L 27/41	T/L 20/30
X42	60 - 110	414 - 758	42 - 72	290 - 496	0.25	0.43	T/L 27/41	T/L 20/30
X46	63 - 110	434 - 758	46 - 76	317 - 524	0.25	0.43	T/L 27/41	T/L 20/30
X52	66 - 110	455 - 758	52 - 77	359 - 531	0.25	0.43	T/L 27/41	T/L 20/30
X56	71 - 110	490 - 758	56 - 79	386 - 544	0.25	0.43	T/L 27/41	T/L 20/30
X60	75 - 110	517 - 758	60 - 82	414 - 565	0.25	0.43	T/L 27/41	T/L 20/30
X65	77 - 110	531 - 758	65 - 82	448 - 565	0.25	0.43	T/L 27/41	T/L 20/30
X70	82 - 110	565 - 758	70 - 82	483 - 565	0.25	0.43	T/L 27/41	T/L 20/30
X80	90 - 120	621 - 827	80 - 102	552 - 705	0.25	0.43	T/L 27/41	T/L 20/30

Grade Range	A25 Through X70	Gr B Through X80	Table 1
Size Range	0.405 Through 80	4-2/1 Through 80	Table 1
Type Of Pipe Ends	Plain-End, Threaded-end, Bevelled-End, Special Coupling Pipe	Plain-End	Table 1
Seam Welding	All Methods Continous Welding Limited to Grade A25	All Methods Except Continous And Laser Welding	Table 1
Electric Welds: Welder Frequency	No Minimum	100 Khz Minimum	5.1.3.3.2
Heat Treatments of Electric Welds	Required For Grades > X42	Required For All Grades (Gr B Through X80)	5.1.3.3.1; J.3.3.2:6.2.7
Chemistry: Max C For Seamless Pipe	0.28% For Grades > Gr B	0.0024	tables 2a, 2b
Chemistry: Max C For Welded Pipe	0.26% For Grades > Gr B	0.0022	tables 2a, 2b
Chemistry: Max P	0.0003	0.0003	Tables 2a, 2b
Chemistry: Max S	Only When Purchases Specifies Sr18	0.0002	Tables 2a, 2b
Carbon Equivalent	None	Maximum Required for Each Grade	4.2:4.3:6.1.3: Sr15.1
Yield Strength, Maximum	None	Maximum for Each Grade	tables 3a, 3b
UTS, Maximum	None Required	Maximum For Each Grade	Tables 3a, 3b
Fracture Toughness	Only When Purchaser Specifies Sr4	Required For All Grades	6.2.6; 9.3.5: 9.8.4; 9.10.7;
Non-destructive Inspection of Seamless Pipes	Permitted	sr4 Mandatory	table 14 9.7.2.6
Repair By Welding of Pipe Body, Plate And Skelp	Permitted By Agreement	Prohibited	5.3.2;9.7.6: B.1;b.2
Certification	Certificates When Specified Per Sr15	Prohibited	4.3;9.7.4.4;9.7.6;b.1.2;b.4
Traceability	Traceable Only Until All Tests are Passed Unless Sr15 Is Specified	Certificates (Sr15.1) Mandatory	12.1
		Traceable After Completion of Tests (Sr15.2) Mandatory	5.6

API 5L tubing generally refers to pipeline–API 5L line pipe, line pipe is a ground spare oil, steam, water, transported by pipeline to the oil and gas industry pipeline include seamless and welded steel tubes, the tube end is flat, threaded and socket ends its connection for welding, collar connections, socket connections, and so on.

API 5L Pipe comes in Seamless and Welded steel line pipe for pipeline transportation systems in the petroleum and natural gas industries. API 5L Pipe is suitable for conveying gas, water, and oil.

The two digit number following the “X” indicates the Minimum Yield Strength (in 000’s psi) of pipe produced to this grade.

Manganese sulphides are typical inclusions in all manganese alloyed steels. Because they tend to segregate resulting in reduced impact strength, sulphure content needs to be minimized. We specify maximum 0.007%.

The requirements that define different levels of standard technical requirements for PSL-2 and PSL-3, for all Grades except H-40, L-80 9Cr and C110, are contained in Annex H.

Peotroleum and natureal gas industies – Steel pipes for use as casing or tubing for wells.

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.

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	0.02	0.015	0.15	0.2	0.2	/	/	0.02
API 5CT  K55	0.34-0.39	0.20-0.35	1.25-1.50	0.02	0.015	0.15	0.2	0.2	/	/	0.02
API 5CT N80	0.34-0.38	0.20-0.35	1.45-1.70	0.02	0.015	0.15	/	/	/	0.11-0.16	0.02
API 5CT  L80	0.15-0.22	1	0.25-1.00	0.02	0.01	12.0-14.0	0.2	0.2	/	/	0.02
API 5CT J P110	0.26-035	0.17-0.37	0.40-0.70	0.02	0.01	0.80-1.10	0.2	0.2	0.15-0.25	0.08	0.02

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

API 5CT is applicable to following connections which complied with API SPEC 5B:

• SC: Short round thread casing
• LC: Long ound thread casing
• BC: Buttress thread casing
• NU: Non-upset tubing
• EU: External upset tubing
• IJ: Integral tubing connections

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.

Flat-end pipe

Flat end pipe is a pipe supplied with unmachined threads, and It may upset or not , but it shall comply with all requirements of a specific steel grade in this standard.

Product with API Threads

Steel grade H40, J55, K55 or M65 casings are available in short or long threads. However, if the purchaser requests a long threaded casing, it should be specified on the order.

Rounded Nose

The “round” or “bullet-nose” type of pipe end may be provided by the manufacturer or specified by the purchaser to replace the conventional corner breaks on the threaded ends of external upset tubing. The improved end should be rounded so that the coating is applied and the inner and outer surfaces are rounded and smooth, without sharp corners, burrs.

Threading

Product threading, gauging practice and thread inspection shall be in accordance with API Spec 5B. The product end shall not be hammered, but may be slightly shaped to meet the requirements of thread machining. For steel grades of C90 and higher strength, such forming shall only be carried out with the consent of the purchaser.

Workmanship of ends

All product ends shall be free of burrs on the inside and outside edges. And sand blasting shall be applied to both male and female threads of C110 steel grade.

The purpose of this specification is to provide standards for pipe suitable for use in conveying gas, water, and oil in both the oil and natural gas industries. Ferropipe applies this specification to both seamless and welded steel line pipe. Ferropipe supplies pipe with plain-ends, with ends suitable for threading as well as pipe with ends prepared for use with special couplings.

The American Petroleum Institute specification API 5L addresses seamless and welded steel line pipe for pipeline transportation systems in the petroleum and natural gas industries. API 5L is suitable for conveying gas, water, and oil.

Specifications for API 5L adhere to the International Organization for Standardization ISO 3183, standardizing pipeline transportation systems within the materials, equipment and offshore structures for natural gas, petroleum, and petrochemical industries.

Product Specification Level (PSL) AMERICAN PETROLEUM INSTITUTE has further divided the grades in accordance with the Product Specifications Levels (PSL) of technical requirements and therefore developed PSL 1 and PSL 2. Requirements that apply to only PSL 1 or only PSL 2 are designated. Whereas Requirements that are not designated to a specific PSL apply to both PSL 1 and PSL 2.

• PSL 1 is a standard quality for line pipe, These line pipe can be supplied in Grades A25 through X70.
• PSL 2 contains additional chemical, mechanical properties, and testing requirements, PSL 2 has mandatory requirements for carbon equivalent, notch toughness, maximum yield strength, and maximum tensile strength. These and other differences are summarized in Appendix J. These line pipe can be supplied in Grades B through X80.

Pipe manufactured as Grade X60 or higher shall not be substituted for pipe ordered as Grade X52 or lower without purchaser approval. followed by the first two digits of the specified minimum yield strength in U.S. Customary units.

An API 5L line pipes manufactured in two varieties PSL 1 and PSL 2. But what is PSL? PSL stands for Product Specification Levels. PSL stands for Product Specification Levels.

Pipes are used in different type of environment such as corrosive and non-corrosive. Pipes used in severe corrosive environment required material that can withstand such process condition. On other hands for normal services, a standard quality level pipe will also serve the purpose.

The difference between PSL1 And PSL2 pipes - Chemical properties

PARAMETER	PSL1	PSL2
Chemistry: Max C for Seamless pipe	0.28% for grades ≥ B	0.0024
Chemistry: Max C for Welded pipe	0.26% for grades ≥ B	0.0022
Chemistry: Max P	0.03% for grades ≥ A	0.0003
Chemistry: Max S	0.0003	0.0002
Carbon equivalent:	Only when purchaser specifies SR18	Maximum required for each grade

Three elements change when requirements change from PSL1 to PSL2.

First Is Carbon.

Maximum Carbon for Seamless PSL1 pipe is 0.28% for the grade B & higher. For all grades of PSL2 pipes maximum carbon is 0.24%.

Similarly, for welded PSL1 pipe Maximum Carbon is 0.26% for the grade B & higher. For all grades of PSL2 welded pipes maximum carbon is 0.22%.

The Second Element Is Phosphorus.

For PSL1 pipe, Maximum Phosphorus is 0.03% for the grade A & higher. For all grades of PSL2 pipes, maximum Phosphorus is 0.03%. So, the only difference is a grade lower than A.

The Third Element Is Sulphur.

For PSL1 pipe, Maximum Sulphur is 0.03%. For PSL2 pipes maximum Sulphur is 0.02%.

Other than these three elements, for PSL2 pipe meeting, the Carbon equivalent is mandatory whereas for PSL1 pipe it is only required if the purchaser has specified SR18. SR18 means Supplementary Requirement No.18.

The difference between PSL1 & PSL2 pipes - Mechanical properties 

PARAMETER	PSL1	PSL2
Yield strength, maximum	None	Maximum for each grade
UTS (Ultimate Tensile Strength) maximum	None	Maximum for each grade
Fracture toughness	None required	Required for all grades

For PSL2 pipe there is a limit on Maximum Yield & Ultimate Tensile Strength whereas for PSL1 pipe meeting the minimum requirements are sufficient. The second requirement that is mandatory for PSL2 pipe is Fracture toughness which is not required for the PSL1 pipe.

The difference between PSL1 & PSL2 pipes - Manufacturing

PARAMETER	PSL1	PSL2
Grade Range	A25 through X70	B through X80
Size range	0.405″ through 80″	4.5″ through 80″
Type of ends	Plain end, Threaded end,Bevelled end special coupling pipes	Plain end
Seam welding	All methods: continuous welding limited to A25	All methods: except continuous welding and laser welding
Electric welds: welder frequency	No minimum	kHz minimum 100
Heat treatment of electric welds	Required for grades >X42	Required for all grades (B through X80)

Here in this table, ou can see the differences between PSL1 & PSL2 Pipes Manufacturing. PLS1 pipes are available in grade A25 through X70 whereas PSL2 pipes are available in Grade B through X80.

PSL1 pipes are available through size 0.405” to 80” whereas smallest diameter pipe available in PSL2 is 4.5” and the largest diameter is 80”.

PSL1 pipes are available in different types of end such as Plain end, Threaded end, Bevelled end, special coupling pipes whereas PSL2 pipes are available in only Plain End.

All kinds of welding method are acceptable to manufacture PSL1; however, continuous welding is limited to Garde A25. For PSL2 welded pipes, except continuous welding and laser welding, all other welding methods are acceptable.

For electric weld welder frequency for PSL2 pipe is minimum 100kHz whereas there is no such limitation on the PLS1 pipe. Heat treatment of electric welds is required for all Grades of PSL2 pipes whereas for PSL1 pipe, it is required for grades higher than X42.

Inspection And Defect Repair

PARAMETER	PSL1	PSL2
Non-destructive inspection of Seamless	Only when purchaser specifies SR4	SR4 mandatory
Repair by welding of pipe body plate, and skelp	Permitted	Prohibited
Repair by welding of weld seams without filler metal	Permitted by agreement	Prohibited

Non-destructive inspection of a seamless pipe is mandatory for PSL2 pipe whereas for PLS1 pipe it is supplementary requirements.

Repair of pipe body plate and skelp by welding is not allowed in PSL2 pipes whereas it is allowed in PSL1 pipes. Similarly, weld repair without filler metal is not allowed in PSL2 pipes whereas it is allowed with purchaser's permission in PSL1 pipes.

Certification & Traceability

PARAMETER	PSL1	PSL2
Certification	Traceable only until all tests are passed	Certificates (SR15.1) mandatory
Traceability	Traceable only until all tests are passed unless SR15 is specified	Traceable after completion of tests (SR15.2) mandatory

For PSL1 pipes, Traceability & Certification is not required beyond the point it passes all the required test whereas, for PSL2 pipes, Traceability & Certification is mandatory. This is all about the difference between PSL1 and PSL2 pipes. In short PSL1 pipes are standard quality pipe for normal services and PSL2 pipes are higher quality pipe than PSL1.

Grades

The grades covered by this specification are the standard Grades A25, A, B, X42, X46, X52, X56, X60, X65, X70 and X80; and any intermediate grades (grades that are higher than X42, intermediate to two sequential standard grades, and agreed upon by the purchaser and manufacturer). PSL I pipe can be supplied in Grades A25 through X70. PSL 2 pipe can be supplied in Grades B through X80. Class II (CI II) steel is rephosphorized and probably has better threading properties than Class I (CI l). Because Class II (CI II) has higher phosphorus content than Class I (CI l), it may be somewhat more difficult to bend. Pipe manufactured as Grade X60 or higher shall not be substituted for pipe ordered as Grade X52 or lower without purchaser approval.

Pipe manufactured to ASTM106 Grade A or B are not interchangeable with API 5L. API 5l X grades have a more specific requirement as compared to API 5L. Rolled raw materials; weld repairs etc are not allowed due to high yield requirements. Apart from these general requirements, HIC, SOUR NACE compliance is a must due to combination of High Pressure and High temperature applications with toughness requirements.

Dimensions

The sizes used herein are dimensionless designations, which are derived from the specified outside diameter as measured in U.S. Customary units, and provide a convenient method of referencing pipe size within the text and tables (but not for order descriptions). Pipe sizes 23/8 and larger are expressed as integers and fractions; pipe sizes smaller than 23/8 are expressed to three decimal places. These sizes replace the “size designation” and the “nominal size designation” used in the previous edition of this specification. Users of this specification who are accustomed to specifying nominal sizes rather than 00 sizes are advised to familiarize themselves with these new size designations used in this specification, especially the usage in Tables 4, 5, and 6A.

PSL I pipe can be supplied in sizes ranging from 0.405 through 80. PSL 2 pipe can be supplied in sizes ranging from 4’/2 through 80. Dimensional requirements on threads and thread gages, stipulations on gagging practice, gage specifications and certification, as well as instruments and methods for inspection of threads are given in API Standard 5B and are applicable to threaded products covered by this specification. It includes plain-end, threaded-end, and belled-end pipe, as well as through-the-flow line (TFL) pipe, and pipe with ends prepared for use with special couplings.

Thread Parameters	Tubing		Casing
	2 3/8"to 2 7/8"	3 1/2"to 4 1/2"	5"and above
Taper	1:16
Thread Pitch	8 TPI	6 TPI	5 TPI

Advantages:

The connection with standard coupling can reach to the strength of pipe body.
High seal reliability, it can provide a considerable internal pressure resistance with the pipe body.
Anti galling design
Minimum energy losing

Thread Parameters	Tubing		Casing
	2 3/8" to 2 7/8"	3 1/2" to 4 1/2"	5" to 7 5/8"	8 5/8" and above
Taper	1:16
Thread Pitch	8 TPI	6 TPI	5 TPI	4 TPI

Advantages:

Excellent against bending / compressive and torsion properties
Reliable gas-tightness under any combination load
Easy to use and maintenance

Thread Parameters	tubing	casing
	2 3/8" to 4 1/2"	5" and above
Taper	1:16	1:10
Thread Pitch	6TPI

Advantages:

Excellent gas-tight sealing
With maximum clearance （100% plush with pipe body）
Easy to use and maintenance

Thread Parameters	Specification
	2 3/8" to 4 1/2"
Thread from	Cylindrical thread form
Thread Pitch	6TPI

Advantages:

Strongly anti galling performance, longer using life
Excellent resistance to H2S stresses corrosion.
Better sealing performance
Quickly speed of making up
The thread connection strength is same with pipe body.
High anti torque strength, high anti bending and strongly anti compression abilities.

Thread Parameters	Specification
	2 3/8" to 5"	5 1/2" to 7"
Thread form	Cylindrical thread form
Thread Pitch	8 TPI	4TPI

Thread Parameters	Specification
	2 3/8" to 4 1/2"
Thread from	Cylindrical thread form
Thread Pitch	4TPI

Advantages:

Strongly anti galling performance, longer using life
Excellent resistance to H2S stresses corrosion.
Better sealing performance
The thread connection strength is same with pipe body.
High anti torque strength, high anti bending and strongly anti compression abilities.

The API 5CT standard covers seamless and welded casing and tubing pipes for oil and gas transportation.Casing pipes are available in the following materials: H-40, J-55, K-55, N-80, L-80, C-90,T-95 ,P-110, Q-125.

J55 and N80 are a common part of the oil casing material. However, these two materials are some differences

The difference between the J55 and N80

• Yield strength of the N80 is higher than the J55 up to 173 – 206 MPa.
• On the same area of ​​the sample, the elongation of N80 is higher than J55.
• Under the same size, the same sample orientation, the same minimum sample size, J55 grade couplings, coupling stock, coupling material, semi-finished and coupling attachment material can absorb lower than N80 steel grade.
• The nondestructive testing methods of seamless pipe,coupling stock, welded tube with J55 and N80 is differeent.
• J55 and N80 steel grade is not the same color: length greater than or equal 1.8m, J55 painted a bright green, N80 painted a red;
• J55 chosen by the manufacturer, or organize according to the order specified length normalized (N), normalizing and tempering (N & T) or quenching and tempering (Q & T). N80 is a whole, full-length heat treatment is mandatory. By the manufacturer selected for normalizing (N) or normalizing and tempering (N & T) + quenching (Q).

Functions:

1. The thread and coupling of this steel casing pipe are specially processed which have smooth surface area without any burr, tear or other flaws. These defects might have a bad influence on the products’ strength and connection.

2. The mechanical homes of this product are greater than that of the J55 and K55 types. This steel casing pipe can be used to some more complicated development in much deeper holes. It can be used for the exploitation of middle-level oil and gas.

3. Due to the great efficiency of N80 material, this casing tube is extensively utilized in natural gas and coal bed methane extraction along with in geothermal wells.

4. The sizes of this pipes vary from 41/2″ to 20″. All pipes are produced strictly in accordance with API requirements.

N80 steel casing pipe is an essential tool used in oil well drilling (Other crucial tools consist of drill pipe, core barrel, casing, drill collar, little size steel tube utilized in drilling, and so on). The thread and coupling of this steel casing pipe are specially processed which have smooth surface area without any burr, tear or other problems.

Depending on the different condition and the depth of the well,we should use the different steel grades.The corrosion resistance of the casing is also required under the corrosive environment. In the case of complex geological conditions, the casing has to be resistant to collapse.Most casing steel grades are largely of the same chemical composition. What gives each grade its distinct properties is the kind of heat treatment applied. Casing grades mainly differ in their yield strength, tensile strength, and hardness.

J55: A commonly used grade for most wells when it meets the design criteria. Some operators recommend it be full-length normalized or normalized and tempered after upsetting when used in carbon dioxide or sour service (ring-worm corrosion problems); however, such heat treatments increase costs. J55 has been the “standard” grade for tubing in most relatively shallow (< 9,000 ft) and low-pressure (< 4,000 psi) wells on land.

N80: A relatively old grade with essentially open chemical requirements. It is susceptible to H 2 S-induced SSC (acronym). It is acceptable for sweet oil and gas wells when it meets design conditions. The quenched-and-tempered heat treatment is preferred. The N80 grade is normally less expensive than L80 grades.

1. The yield strength of N80-1/Q is 173-206Mpa higher than that of J55.

2. J55 and N80-1/Q seamless pipes, coupling blanks, and non-destructive testing methods for welded pipe bodies are different.

3. The same specifications, the same sample orientation, the same minimum sample size, the absorption energy of J55 steel grade coupling, coupling blank, coupling material, coupling semi-finished product and accessory material is lower than N80-1/Q steel grade of.

4.The elongation of N80-1/Q is higher than that of J55 on the same sample area.

5. The distance of welded tube on flattening test board is different.

6. The mark or symbol of the product steel grade is different: the symbol of J55 is “J”, the symbol of N80-1 is “N1”, and the symbol of N80-Q is “NQ”.

7. The heat treatment process of J55 and N80-1/Q is different:

• J55: Selected by the manufacturer or according to the order, full length normalized (N), normalized + tempered (N & T) or quenched + tempered (Q & T).
• N80-1: Overall and full length heat treatment is mandatory. Normalized (N) or normalized + tempered (N & T) by the manufacturer
• N80-Q: Quenching (Q)

8. The steel grade color code of J55 and N80-1/Q is different: the length is greater than or equal to 1.8m, J55 is painted bright green, N80-1 is painted red, N80-Q is painted red, one bright green; the whole coupling , J55 oil casing painted bright green, N80-1 / Q painted red; ribbon, J55 tubing colorless, J55 sleeve a white, N80-1 colorless, N80-Q green.

9. The hydrostatic pressure test is different.

10. The requirements for PSL-2/3 of J55 and N80-1/Q are different.