API Casing Pipe

In drilling technology, casing string is a long section of connected oilfield pipe that is lowered into a wellbore and cemented. The purpose of the casing pipe is as follows:

·       prevent the collapse of the borehole

·       prevent formation fluids from entering the borehole in an uncontrolled way

·       prevent fluids in the borehole (such as produced oil or gas, drilling mud etc.) from entering other formations

API casing pipe refers to primary specifications set forth in API Specification 5CT (ISO 11960). This API documents promulgate standards for the threaded end finish, the wall thickness (several are available in each size to satisfy various design parameters, and in fact are indirectly specified by standardized nominal weights per linear foot; thicker pipe obviously being heavier), and the strength and certain chemical characteristics of the steel material. the API publications provide performance minimums for longitudinal strength ("joint strength") as well as resistance to internal (bursting) and external (collapsing) pressure differentials.

The pipe segments (called "joints") are typically male threaded on each end and connected with short lengths of double-female threaded pipe called couplings. Some specialty casing is manufactured in one piece with a female thread machined directly into one end.

To ensure product quality, a number of on-line inspection equipment has been established to monitor composition analysis, non-destructive testing, measurement, drifting, hydrostatic testing and other critical elements of pipes.

In addition to on-line inspection and testing, full-time & professional quality inspection stations were also set up, which are responsible for the analysis, inspection and determination of process quality, quality of incoming raw material, physical and chemical properties of products and technical indexes, etc.

The production lines are composed of 4 major parts: iron-making, steel-making (billet), pipe-rolling and pipe finishing. 

• Smelting system

  The steel-making plants are equipped with electric arc furnace (EAF), ladle refining furnace (LF), vacuum degassing device (VD), vacuum oxygen degassing furnace (VOD), RH vacuum degassing furnace and continuous casting lines to meet the requirements of producing high purity and quality steel billets.

  The steel making works are equipped respectively with 150-ton, 90-ton, and 100-ton EAFs and can produce rounds billets of outside diameters 210~500 mm and square billets of 150 x 150 mm. Total annual billet capacity is 2.9 million tons.

  The feeding materials of the EAFs mainly consist of liquid iron and steel scrap. Liquid iron comes from blast furnace and made of high grade iron ore imported. It makes sure strict quality control starts from its own steel, especially important to stringent demands of customers for high quality on-time delivery.

  
• Pipe rolling system

  Main equipment:
  Rotary billet heating furnaces, piercing mills, rolling mills, reheating furnaces, sizing mills, cooling beds and NDE inspection systems.

  PQF stands for Premium Quality Finishing, which is the latest three-roll pipe rolling technology developed and supplied by SMS Meer, Germany, featured with the best control of dimensional tolerances, rejection ratio and productivity.

  
• Heat treatment system

  There are heat treatment lines installed for producing high grade pipes satisfying the most stringent applications, among which a brightening line and a solution annealing line treats stainless steel pipes, high alloy pipes and boiler tubes, making excellent product quality after treatment.

  
• Pipe finishing system

  Main equipment:
  CNC threading machines, chamfering machines, hydraulic testing machines, NDTs, saws, coupling screw-up machine, coupling phosphate line, up-setter, marking/measuring/weighing devices, and others.

  CNC threading machines: introduced from U.S.A., Belgium, Spain, Germany and Japan.

  
• Non-Destructive Tests

  Various NDT technologies are adopted for detection of transversal, longitudinal and lamination defects in the inner and outer surfaces of pipe body, pipe end and coupling, including electro-magnetic, ultrasonic, magnetic particle, eddy current, to ensure that all pipes supplied to the customers are of high quality.

A typical piece of casing might be described as 9-5/8" 53.5# P-110 LT&C Rg 3: specifying OD, weight per foot (53.5 lb/ft), steel strength (110,000 psi yield strength), end finish ("Long Threaded and Coupled"), and approximate length ("Range 3" usually runs between 40 and 42 feet).