Casing and tubing

Seamless steel tubes for oil casing and tubing application for onshore and offshore Oil & Gas applications in the domains of Exploration, Production and Processing.


API SPEC 5CT Standard of American Petroleum Institute

This International Standard is applicable to the following connections in accordance with ISO 10422 or API Spec 5B:


Seamless steel tubes for oil casing and tubing in oil wells

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

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.

Diamensional tolerances:
Types Outer diameter Wall thickness
Cold-rolled tubes Tube sizes(mm) Tolerances(mm) Tolerances(mm)
<114.3 ±0.79 -12.5%
≥114.3 -0.5%,+1%
Mechanical properties of API SPEC 5CT:
Models of steel tubes
Tensite strength(MPa)
Yield strength(MPa)
J55 ≥517 379-552 -
K55 ≥517 ≥655 -
N80 ≥689 552-758 -
L80(13Cr) ≥655 552-655 ≤241HB
P110 ≥862 758-965 -

Chemical composition of API SPEC 5CT:
Models of steel tubes Chemical compositions (%)
C Si Mn P S Cr Ni Cu Mo V Als

0.34-0.39 0.20-0.35 1.25-1.50 ≤0.020 ≤0.015 ≤0.15 ≤0.20 ≤0.20 - - ≤0.020

(36 Mn2V)
0.34-0.38 0.20-0.35 1.45-1.70 ≤0.020 ≤0.015 ≤0.15 - - - 0.11-0.16 ≤0.020
L80(13Cr) 0.15-0.22 ≤1.00 0.25-1.00 ≤0.020 ≤0.010 12.0-14.0 ≤0.20 ≤0.20 - - ≤0.020

0.26-0.35 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
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).

Tech & Service of Seamless pipe

Seamless pipes are extensively applied for the nuclear device, gas, petrochemical, ship building and boiler industries. Seamless pipes dominates 65% of market share in Chinese boiler industry.

How to make seamless pipe(seamless pipe process)?
Hot Piercing Workshop
Piercing process
The cross roll piercing and pilger rolling process in the size range from approx. 250 to 660 mm outside diameter.
Precision cold drawn steel tube production process
Pipe weld cracks
often follow different mechanisms can be divided into two types of thermal cracking and cold cracking.
How to calculate a steel pipe and tube theoretic weight
Calculate a steel pipe?
Pipe fittings are necessary to join together pipes, or to change the direction of an existing pipe.
Pipe beveling
Pipe beveling is the process where an angle is formed between the edge of the end of a pipe or tube and a plane perpendicular to the surface.
Steel pipe cutting machine
Pipe cutting
Cutting tools have a grinding wheel piece cutting machine (also known as toothless saw), hand saw, cutter and other hand tools.
Packing the steel pipes
There are probably hundreds of different methods for packing a pipe, and most of them have merit, but there are two principles that are vital for any method.


Our team are highly trained and experienced in servicing and producing all types of steel supplies. Whether you've got a large construction project, or need parts for industrial machinery, our team of steel fabrication consultants will ensure that your project is provided with the parts you need, when you need them.

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