CO2 Corrosion Resistant Tubing and Casing

CO2 corrosion resistant tubing and casing is applicable in corrosion environments with CO2. At present, there exist serious CO2 corrosions in Chinese Tarim, Changqing, Sichuan, North China Jianghan and other main oilfields. Especially in Sichuan and Changqing oilfields, CO2-H2S-Cl integrated corrosion is more serious and complex. It has been researched that CO2 has strong causticity. Thus stainless anti-CO2 corrosion steel pipes with high content of Cr, Ni, Mo and other alloying elements are considered to be ideal CO2 corrosion resistant materials. However, since these materials contain large quantities of Cr, Ni, Mo and other expensive strategic elements, which greatly increases the cost of steel pipes, thus limits their widespread use in the oil and gas fields. Especially for China oil drilling industry, most oil fields are lean ore low permeable fields. The use of expensive stainless steel corrosion resistant tubing and casing brings large one-time investment and poor economy.

Complying with users’ actual requirements, JST finds out that there mainly exist CO2, H2S, Cl, Ca2+, Mg2+, S042-, HCO3  and other comprehensive corrosive environments in oil wells, and that the corrosion failure is mainly characterized by localized rapid perforation corrosion failure. We also carry out low-Cr steel CO2 corrosion research and successfully develop economic 3Cr JST series anti-CO2 corrosion steel pipe and CO2 corrosion resistance tubing and casing with independent intellectual property rights and good performance.Features

• 1. It is made of pure steel with the content of P equal or less than 0.015% and S equal or less than 0.008%.
  2. JST CO2 corrosion resistance tubing and casing has stable performance. After quenching, the cross-sectional area of steel pipes can acquire more than 98% martensitic structure. After tempering, it can form small and uniform tempering sorbite structure.
  3. This type of anti-CO2 corrosion steel pipe has resistance to stress corrosion and eliminates residual stress. The surface forms a highly stable corrosion-resistant oxide film with the thickness of one or several atomic layers.
  4. JST CO2 corrosion resistance tubing and casing has a uniform structure and even hardness. The grain size is even more than Grade 8.
  5. After heat treatment, this anti-CO2 corrosion steel pipe can extend its usage life. JST configures advanced heat treatment equipment, making furnace temperature is equal or less than 5℃ and ensuring stable heating temperature. We also configure the rotating spray cooling system to fully guarantee water quenching uniform cooling of steel pipes. There are two sets of Siemens electronic control six roller straightening machine to ensure the straightness of corrosion resistant tubing and casing after heat treatment.
  1) Normalizing
  A. Operation Method
  The anti-CO2 corrosion steel pipe is heated to above Ac3 or Accm 30 to 50 degrees, after heat preservation, it will be cooled down with the cooling rate slightly larger than annealing rate.
  B. Objective
  a. Reduce hardness and improve ductility of CO2 corrosion resistance tubing and casing, and improve cutting and pressure processing performance.
  b. Refine crystalline grain, improve mechanical properties of this anti-CO2 corrosion steel pipe, and prepare for the next working procedure.
  c. Eliminate internal stress in the cold and hot processing of CO2 corrosion resistance tubing and casing.
  2) Hardening and Tempering
  A. Operation Method
  Hardening and tempering refers to high-temperature tempering after quenching. This anti-CO2 corrosion steel pipe is heated to 10 to 20 degrees higher than the temperature while quenching, after heat preservation, it will do quenching and then do tempering at the temperature of 400 to 720 degrees.
  B. Objective
  a. Improve the cutting and processing performance of CO2 corrosion resistance tubing and casing and improve the processed surface finish (smoothness).
  b. Reduce the deformation and cracking while quenching.
  c. Obtain good mechanical properties.
  6. In order to improve the CO2 corrosion resistance of this anti-CO2 corrosion steel pipe, JST focuses on the low alloy steel and adds a small amount of elements blocking the anodic process (Cr, Mo, Ni, etc.) and elements facilitating the cathodic process and surface activity (Cu, Si, Al, etc.).
  7. JST corrosion resistant tubing and casing is manufactured to the most exacting quality standards. We hold a global ISO 9001 registration for our operations, which follow a uniform quality policy and apply a rigorous quality management system.
  8. We can supply anti-CO2 corrosion steel pipes in bare, uncoated condition or with OD/ID coatings such as bitumastic and coal tar epoxy coatings.

Chemical Composition of CO2 Corrosion Resistance Tubing and CasingCO2 corrosion is closely related with material Cr content and CO2 partial pressure and temperature in oil and gas wells. Cr is the most effective element to prevent CO2 corrosion because it can rapidly form a dense and thin Cr203 passivation film on the metal surface. As the Cr content increases, the CO2 corrosion resistance effect of this anti-corrosion steel pipe is enhanced. CO2 partial pressure is the main factor to affect the corrosion rate. CO2 corrosion rate accelerates with the increase of CO2 partial pressure. In general, as the temperature rises, the corrosion rate of materials also increases. The chemical composition of JST CO2 corrosion resistance tubing and casing meets the following table:

Grade	Model	Max. or Tolerance Range (wt %)
		C	Si	Mn	P	S	Cr	Mo	Ni	Cu
80	JST80-1Cr				0.018	0.008	0.5-1.5
	JST80-3Cr				0.018	0.008	2.5-3.5
	JST80S-3Cr JST80SS-3Cr				0.015	0.005	2.5-3.5
	JST80S-13Cr				0.015	0.005	12.0-14.0	0.50	0.50	0.25
90	JST90-3Cr				0.018	0.008	2.5-3.5
	JST90S-3Cr JST90SS-3Cr				0.015	0.005	2.5-3.5
95	JST95-3Cr				0.018	0.008	2.5-3.5
	JST95S-3Cr JST95SS-3Cr				0.015	0.005	2.5-3.5
	JST95-13Cr				0.018	0.008	12.0-14.0	3.0	6.0	0.5
	JST95S-13Cr				0.015	0.005	12.0-14.0	3.0	6.0	0.5
110	JST110-13Cr				0.018	0.008	12.0-14.0	3.0	6.0	0.5
	JST110S-13Cr	0.04			0.015	0.005	12.0-14.0	3.0	6.0	0.5

Mechanical Properties of Anti-CO₂ Corrosion Steel Pipe

Grade	Model	Yield Strength		Tensile Strength (MPa)	Elongation	Impact Toughness	Max. Hardness
		min	max	min			HRC
80	JST80-1Cr JST80-3Cr	552	758	689	Calculate according to API 5CT formulas.	According to API 5CT Requirements for N80	23
	JST80S-3Cr JST80SS-3Cr	552	655	655
	JST80S-13Cr					According to API 5CT Requirements for L80
90	JST90-3Cr	621	724	689		According to API 5CT Requirements for C90	25.4
	JST90S-3Cr JST90SS-3Cr
95	JST95S-3Cr JST95SS-3Cr	655	758	724		According to API 5CT Requirements for T95	25.4
	JST95-3Cr JST95-13Cr JST95S-13Cr
110	JST110-3Cr JST110-13Cr JST110S-13Cr	758	965	862		According to API 5CT Requirements for P110	32

Note: 1.JST80-1Cr, JST80-3Cr, JST80S-13Cr, JST90-3Cr, JST95-3Cr, JST95-13Cr, JST95S-13Cr, JST110-3Cr and JST110-13Cr CO2 corrosion resistance tubing and casing can be used in corrosion environments with CO2. (PCO2≥0.02MPa).

• 2.JST80S-3Cr, JST80SS-3Cr, JST90S-3Cr, JST90SS-3Cr, JST95S-3Cr, JST95SS-3Cr and JST110S-13Cr anti-CO2 corrosion steel pipes are applicable in low corrosion environments with CO2 and a small amount of H2S.

Technical Parameters Parameters refer to the specification table of tubing and casing.

Product Maintenance For this type of anti-CO2 corrosion steel pipe, there are mainly five protection measures for CO2 corrosion, including fluid dynamics method, electrochemical protection, pipe surface treatment, pipe selection and adding corrosion inhibitor.

Established in 1984, Jiangyin Changjiang Steel Tube Making Factory has been engaged in manufacturing tubing and casing for about 30 years. We mainly supply structure pipe, fluid pipe, high pressure boiler pipe, API pipe, marine pipe, alloy pipe, line pipe, etc. Our products are extensively used in metallurgy, port, ship-breaking, manufacturing, real estate, chemical engineering, transportation and other industries. JST corrosion resistance tubing and casing (such as anti-CO2 corrosion steel pipes) are well appreciated for their advanced design, sophisticated manufacturing, excellent quality and full service.