Steel Pipes

Pipes are mainly of two types, seamless and with seam. Seamless pipe is manufactured from solid rounds by extrusion process in steel tube mills. The pipes with seam are made from plates, by rolling into cylindrical shape joining it by welding. It can be straight welded seam or spiral welded seam for long pipes.

Dependng on application and pressure ratings, pipes are made of different thicknesses called shedule.

GA for Pritam. But could you enlighten me more on the application of seamed pipes because most of the pipes I used to see are just seamless pipes regardless of pressure or shcedule.

Seamless pipe are best for any use but then comes the question of economics of the system. Many stadards allow use of welded pipe in non-critical services. Even API allows welded pipes in cross contry transportation of natural gas at pressure as high as 40 kg/cm2.

All cooling water services, service air lines, low pressure drains and vent lines in the process plants are some of the areas where welded pipes are used. On jetties oil loading /unloading lines are some of the servises where spiral welded pipes are common to see.

Thanks hien for GA. "could you enlighten me more on the application of seamed pipes because most of the pipes I used to see are just seamless pipes regardless of pressure or schedule." In fact, most of the pipes used in industry or elsewhere are welded pipes only. Because of much higher cost (about 40-60%), seamless pipes are used for very critical & specific applications like high pressure or hazardous fluids to be handled or where life & reliability of welded pipe is low. Many times it is difficult to visually identify the welded seam of the pipe because it is produced in automated shops and it does not look like normal weld seam. Most of the welded pipes are produced by "Electrical Resistance Welding" process, so they are called ERW pipes also. You can easily identify spiral welded pipe.

While seamless pipe can be extruded from a billet in an extruision press, The majority of steel seamless pipe was made in mills where it was created by rolling, not extruding. The mills I worked at used a piercer and rolls to create the pipe. This is different than extrusion.

Process path was 1) rehaeat cast round billets; 2) Piercing mill;3) Multi Stand Mandrel Mill; 4) Reheat furnace; 5) Sizing mill OR Stretch reducing mill.

It seems to most people that the piercer does in fact produce the center cavity; this is not true. the cavity is created by the center rupture formed by diametrically opposed pressure which makes one diameter shorter, whilre the one at right angles becomes longer, (roll to oval, spreading the metal). This takes place longwise and in opposite directions causing the the center to open up. THIS IS NOT EXTRUSION!

Extrusion is forcing of a billet into lengths of uniform cross section by forcing the metal to flow plastically through a die orifice.

Milo

"How many type of steel pipes (probably 02 - one is plain)?"

There are to basic ways to manufacture pipe: Extruded (producing Seamless pipe) and Roll & Welded pipe. The rolled and welded is done two ways (a) straight seam and (b) spiral seam.

"What are the names of these pipes in English and where we will apply them?"

The names of these two types of pipe is "Seamless Pipe" and "Welded Pipe"

Seamless pipe (carbon steel and alloy) is most often used in the processing part of a Chemical plant or Refinery where there is high temperature and high pressure.

Welded pipe is used in Water Treatment plants, Waste Treatment Plants and "Offsite" (Tankage) areas of Refineries and Chemical plants.