Manufacturing Of Large Diameter Pipes For Oil And Gas

By:•Faraz Shaukat•Gohar Rehman Sani•Humble Khalid Tareen

HISTORY Pipes for water supply began to be

used around 2500 B.C. The Chinese transported water

through bamboo. The age of iron began about 1000

B.C. The Age of Steel was born in 1855 in

England

PROPERTIES OF STEEL PIPE

Steel has salient properties that can be utilized to advantage in buried pipelines. The following are desirable requirements of buried, pressurized pipe.

These requirements can be achieved by welded steel pipe:

• Strength• Ease of installation• High-flow capacity• Leak resistance• Long service life• Reliability and versatility• Economy

STEPS INVOLVED IN MANUFACTURING

Ingot production Producing blooms and slabs Sheet Forming Shaping Welding Surface Operation

INGOT PRODUCTION

In order to form flat products such as plates and sheets, or long products such as bars and rods, ingots are shaped between large rollers under enormous pressure.

Molten steel is made by melting iron ore and coke (a carbon-rich substance that results when coal is heated in the absence of air) in a furnace, then removing most of the carbon by blasting oxygen into the liquid. The molten steel is then poured into large, thick-walled iron molds, where it cools into ingots.

PRODUCING BLOOMS AND SLABS

To produce a bloom, the ingot is passed through a pair of grooved steel rollers that are stacked. These types of rollers are called "two-high mills." In some cases, three rollers are used. The rollers are mounted so that their grooves coincide, and they move in opposite directions.

SHEET FORMING Blooms are converted into billets by putting

them through more rolling devices which make them longer and more narrow.

These billets are further converted into slabs through same process of rolling.

Slabs are also reworked. To make them malleable, they are first heated to 1,204°C. This causes an oxide coating to form on the surface of the slab. This coating is broken off with a scale breaker and high pressure water spray. The slabs are then sent through a series of rollers on a hot mill and made into thin narrow strips of steel called sheets.

DESIGNSeamless

Seamless tubes are typically more light weight

used for bicycles and transporting liquids

Welded•Seamed tubes are heavier and more rigid.•used for things such as gas transportation, electrical conduit and plumbing

DESIGN Longitudinal

Metal sheet is bend into tubular form then welded in straight line.

Stress concentration at welded part increases.

Spiral•Rollers bend sheet into helical form•Then welded into spiral shape•Homogeneous stresses allover.

PIPE MANUFACTURING

Then rollers bend these sheets into helical form.

Inside, and later, outside welding is performed by an automatic submerged arc process.

The molten weld and the arc zone are protected from atmospheric contamination by being “submerged” under a blanket of granular fusible flux consisting of lime, silica, manganese oxide, calcium fluoride, and other compounds.

POST PIPE MANUFACTURING

PROCESS Coating Hydrostatic testing Ultrasonic inspection Leakage

CONCLUSION Steel is used in manufacturing because it is

Economical,Leak Resistance,Easy to install,Long service life and reliability.

Seamless Pipes are not used because they are light weight and large diameter seamless pipes cannot be produced.

Longitudinal welded Pipes are not used because of stress concentration at one point,due to which pipe fails early

Spiral welded pipes are used because of uniform stress allover.