1、Category of pipes and tubes

1、Categorization according to manufacturing method

（1） seamless pipe——hot rolled pipe, cold rolled pipe, cold drawn pipe, extrusion tube, pipe jacking
（2） welded tube
（a） categorization according to techniques——arc welded tube, resistance welded tube（high-frequency, low-frequency）, gas welded tube, furnace butt welded tube
（b） categorization according to weld seam——straight welded tube, spiral welded tube

2、Categorization according to section shape
（1）simple section steel pipe -- round pipe, square pipe, ellipse pipe, triangular pipe, hexagonal pipe, lozenge pipe, octagonal pipe, semi-circular pipe, other
（2） sophisticated section steel pipe -- non-equal hexagonal pipe, cinquefoil pipe, biconvex pipe, biconcave pipe, melon seed shaped pipe, conic pipe, corrugated pipes, watchcase pipe, other
   
3、 Ccategorization according to wall thickness -- thin-walled pipe, thick-walled pipe

4、 Categorization according to usage -- steel pipe for piping, hot working equipment pipe, mechanical industry pipe, petroleum pipe, tube for drilling, container pipe, chemical pipe, special use pipe, other

2、Seamless pipe

Seamless pipe is a long steel material with hollow section and without joint seam. Because of the hollow section, it is widely used for liquid and gas delivering pipes, such as petroleum delivering pipe, natural gas delivering pipe, utility gas delivering pipe, water pipe, and solid material delivering pipe, etc. Compared with solid steel such as round rod, weight of pipe is lighter with the same bending strength and torsional strength. Seamless pipe is an economic section steel, and it is widely used for manufacturing structural elements and mechanic parts, e.g., petroleum drill stem, automobile transmission axle, bicycle frame, and steel scaffold at construction site, etc. Using steel pipe to manufacture circular parts, can improve the material yield，simplify the manufacturing procedures, and save materials and processing man power, e.g., nowadays pipes have been widely used to make rolling bearing ferrule, and jack case, etc. Furthermore, pipe is a necessary material for making different kinds of routine weapons, e.g., rifle and gun barrels are all made of steel pipes. Pipes can be classified into round pipe and shaped pipes according to the shape of the cross section. Circle has the largest area with a given circumference, therefore, round pipes can delivery more liquid or gas. Besides, the stress over circular section is quite uniform when it is bearing interior/exterior radial pressure, therefore, most of pipes are round pipes. However, round pipes have some limitations, too, e.g., the tensile strength of round pipes is not as high as that of squared pipe or rectangular pipe when it is subjected to plane bending. Therefore, some agriculture equipment frame, and steel furniture are using squared or rectangular pipes. Pipes with other different cross section shapes can be used for different purposes.
   
1. Structural seamless steel pipe (GZ/T8162-1999) is seamless pipe used for ordinary structures and mechanical structures.
   
2.Liquid/air delivering seamless pipe (GB/T8163-1999) is ordinary seamless pipe used for delivering water, oil, and gas, etc.
   
3. Low/medium pressure boiler seamless pipe (GB3087-1999) is quality carbon structure steel hot rolled and cold drawn (rolled) seamless pipe, which is used for manufacturing super heated vapor piping and boiling water piping of different structural low/medium boilers, and super heated vapor piping, big fume piping, small fume piping, and arch tubing for locomotive boilers.

4. High-pressure boiler seamless pipe (GB5310-1995) is seamless pipe made of quality carbon steel, alloy steel, or heat resistant stainless steel, which is used for manufacturing heating furnace piping for high pressure boilers.
   
5. Fertilizer equipment high-pressure seamless pipe (GB6479-86) is quality carbon structural steel or alloy steel seamless pipe, which is used for chemical equipments and piping with working temperature of -40~400 ℃ and working pressure of 10~30 Ma.
   
6.Petroleum cracking seamless pipe (GB9948-88) is seamless pipe used for furnace piping, heat exchanger, and piping of petroleum refineries.
   
7. Drilling pipe (YB235-70) is the steel pipe used by geology departments to perform rock drilling, which can be classified according to their use into drilling stem, drill collar, rock core barrel, cannula, and sedimentation pipe, etc.
   
8. Diamond core drilling seamless pipe (GB3423-82) is the seamless steel pipe used for drill stem, rock core barrel, and cannula for diamond rock core drilling.
   
9.Petroleum drilling pipe (YB528-65) is the seamless pipe used for petroleum drilling which is thickened at both ends from inside or outside. The pipe can be classified into threaded pipe and non-threaded pipe. Threaded pipe is connected by connectors, while non-threaded pipe is connected to the joints of tools with butt welding.
   
10. Ship carbon seamless pipe (GB5213-85) is the carbon seamless pipe for manufacturing grade I pressure resistant piping, grade Ⅱ pressure resistant piping, and boilers and super-heaters for ships. Carbon steel seamless pipe is with a wall working temperature not exceeding 450℃， while alloy steel seamless pipe exceeding 450℃.
   
11. Automotive semi-axle housing seamless tube (GB3088-82) is quality carbon structural steel or alloy structural steel hot rolled seamless tube used for manufacturing automotive semi-axle housing tubes and driving axle housing tubes.
   
12.Diesel engine high pressure fuel pipe (GB3093-86) is the cold drawn seamless pipe for manufacturing the high pressure tube for diesel engine sparge system.
   
13.Hydraulic and pneumatic cylinder seamless pipe with accurate inner diameter (GB8713-88) is cold drawn or cold rolled precision seamless pipe with accurate inner diameters used for manufacturing hydraulic and pneumatic cylinders.
   
14. Cold drawn or cold rolled precision seamless pipe (GB3639-83) is the cold drawn or cold rolled precision seamless pipe with high precision of dimensions and good surface cleanness and smoothness used for mechanical structures, hydraulic equipments. Using precision seamless pipe to manufacture mechanical structures or hydraulic equipments, can greatly save the mechanical processing man power, improve material yield, and improve product quality as well.

15. Structural stainless steel seamless pipe (GB/T14975-1994) is the hot rolled (extrusion, expansion) and cold drawn (rolled) seamless stainless steel pipe widely used for manufacturing corrosion resistant piping , structural elements, and parts for the industry of chemical engineering, petroleum engineering, light weaving, medicine, food, and mechanics, etc.

16. Hydraulic delivering seamless stainless steel pipe （GB/T14976-1994） is the hot rolled (extrusion, expansion) and cold drawn (rolled) seamless stainless steel pipe used for hydraulic delivering.

17. Seamless shaped pipe is referred to all seamless pipes with non-circular cross section shape, other than round pipes. It can be categorized according to the dimension of pipe cross section profile into uniform wall thickness seamless shaped pipe (code name is D), non-uniform wall thickness seamless shaped pipe (code name is BD), non-uniform diameter seamless shaped pipe (code name is BJ). Seamless shaped pipe is widely used for different kinds of structural elements, components and parts for tools and mechanical instruments. Compared with round pipes, the shaped pipe is usually of greater moment of inertia, section modulus, and bending/torsion resistance, and it can greatly decrease the weight of structures, and save steel materials in the mean time.

3、Welded steel pipe

Welded steel pipe is also referred to as welded pipe, which is made by welding the formed steel plate or strip rolls. The manufacturing technique of welded pipe is simple, with high production efficiency and a wide range of categories and specifications, the investment on equipment is also low. However, usually the strength of welded pipe is lower than seamless pipe. Since the 1930’s, welding quality has been constantly improved as a result of the rapid development of quality steel strip tandem rolling technology and welding / testing technology, and more and more types of welded pipes are available in the market withwider range of specifications, therefore, seamless pipes has been replaced by welded pipes in more and more fields. Welded pipes can be categorized according to the seam into line welded pipes and spiral welded pipes. The production technology of line welded pipe is simple, with high production efficiency and low cost, therefore, it develops fast. Spiral welded pipes usually have greater strength than line welded pipes do, and pipes with large diameter can be manufactured by line welding narrow ingot materials. It’s also possible to produce pipes with different diameters with the ingot materials of the same width. However, the welding seam length is 30-100% longer than that of the line welded pipe of identical pipe length. The production speed is also low. Therefore, pipes with small diameters are normally produced by line welding, while pipes with large diameters spiral welding.
   
1. Low pressure hydraulics delivering welded pipe （GB/T3092-1993） , also referred to as commercial welded pipe, or black pipe. It’s used for delivering low pressure hydraulic matter such as water, gas, air, fuel, and steam, etc., among other purposes. The pipes can be categorized according to the wall thickness into commercial pipes and strengthened (thickened) pipes；or according to the end form into non-threaded pipes (naked pipes) and threaded pipes. The specification of pipes is denoted by the nominal caliber （mm）, which roughly equals to the inner diameter, usually ininches, such as 11/2. The low pressure hydraulics delivering welded pipes are also widely used as the raw pipes for producing the low pressure hydraulic delivering galvanized welded pipes, except for delivering liquid and gas directly.

2. Low pressure hydraulic delivering galvanized welded pipe （GB/T3091-1993） is also referred to as galvanized electrical welded pipe, or white pipe. It’shot-dipped galvanized welded (protected welded or electrical welded) pipe used for delivering low pressure hydraulics such as water, utility gas, air, fuel, and steam / warm water, etc., among other purposes. The pipes can be categorized according to wall thickness into commercial galvanized pipes and thickened galvanized pipes; or according to the end forms into non-threaded galvanized pipes and threaded galvanized pipes. The specification of pipe is denoted by the nominal caliber （mm）, which is roughly the inner diameter, usually in inches, such as 11/2.
   
3. Commercial carbon steel cable sleeve tube （GB3640-88）is the tube used to protect the electrical cables in industrial and civil construction engineering, and electrical installation engineering for equipments.
   
4. Electrically line welded pipe （YB242-63） is the pipe with welding seamparallels to the longitudinal axis of the pipe. Usually it can be categorized into metric electrical welded pipe, electrically welded thin-walled pipe, and transformer coolant pipe, etc.
   
5. Pressure bearing hydraulic delivering spiral submerged arc spiral welded pipe (SY5036-83) is the spiral welded steel pipe manufactured as follows: firstly, use hot rolled steel strip roll as the tube blank, then formit spirally under room temperatures, and then weld it into the product by the double-sided submerged arc welding technique. It is used for delivering pressurized hydraulics.The pipe has a good pressure bearing ability, with good welding performances. All kinds of rigorous scientific tests and examinations have proved that the use of this type of pipes is safe and reliable. The pipes are of big caliber, with high delivering efficiency, and it can save investment on piping placement.It is mainly used for piping delivering petroleum and natural gas.
   
6. Pressure bearing hydraulic delivering high-frequency spiral welded pipe (SY5038-83) is the high-frequency spiral welded pipe which is produced as follows: firstly, use hot rolled steel strip roll as the tube blank, then spirally form it under room temperatures, and then weld it into the product by high frequency overlap welding. It is used for delivering pressurized liquids and gas. The pipe has a strong pressure bearing ability, and it is with good plasticity so that it is easy for welding and processing. All kinds of rigorous scientific tests and examinations have proved that it is safe and reliable to use this type of pipe. The pipe is with large caliber and high delivering efficiency, and it can save investment on placing piping. The pipe is mainly used for pipe lines delivering petroleum and natural gases.

7. Commercial low pressure hydraulic delivering submerged arc spiral welded pipe (SY5037-83) is the submerged arc welded pipes produced as follows: Firstly, use hot rolled steel strip roll as the tube blank, then spirally form it under room temperatures, and then weld it into the product by double sided automatic submerged arc welding or single sided welding. It is used for delivering commercial low pressure hydraulics such as water, utility gas, air, and steam, etc.
   
8. Commercial low pressure hydraulic delivering high frequency spiral welded pipe（SY5039-83） is the high frequency spiral welded pipe produced as follows: Firstly, use hot rolled steel strip roll as tube blank, then spirally form it under room temperatures, and then weld it into the product by high frequency overlap welding. It is used for delivering commercial low pressure liquids or gas.
   
9． Pile spiral welded pipe (SY5040-83) isproduced as follows: Firstly, use hot rolled steel strip roll as the tube blank, then spirally form it under room temperatures, and then weld it into the product by double sided submerged arc welding or high frequency welding. It is used for foundation pile steel pipes for construction structures, docks, and bridges, etc.

4、 Plastic lined steel composite pipe, large caliber coated pipe
   
Plastic lined steel composite pipe is produced as follows: Firstly, use hot-dipped galvanized steel pipe as the base, then coat plastic onto the inner wall (or exterior wall when needed) by melted powder-spraying coating technology, which is of extraordinary properties. Compared with galvanized pipes, this type of pipe has such advantages as corrosion resistant, rust-free, begriming free, smooth surface, clean, poison-less, and long lifetime, etc.. According to the tests, the lifetime of a plastic lined steel composite pipe is over 3 times that of a galvanized pipe. Compared with plastic tube, a composite pipe has such advantages as high mechanical strength, pressure resistance, and good heat resistance, etc. The base material is steel; therefore, there is no such problems as embrittling and aging. It can be widely used for delivering tap water, utility gas, and chemical products, etc. for delivering engineering and household heating engineering，and is a replacement or upgrading for galvanized pipe. The installation of it is basically the same as that of traditional galvanized pipe, and the pipe appearance and size are basically the same, furthermore, it can be used to replace large caliber plastic lined aluminum composite pipe to deliver tap water, therefore, it is well received by users, and has become one of the new products with the best competence in the pipe market.
   
Coated steel pipe is produced by coating plastics onto the large caliber spiral welded pipe and high frequency welded pipe, with a maximum pipe opening diameter up to 1200 mm. It is possible to coat plastic layers with different properties according to the requirements, such as PVC, PE, and EPOZY, etc. The coating layer is well bonded to the wall, and the pipe has such advantages as strong corrosion resistance, strong acid resistance, strong base resistance, and other chemical corrosion resistance, being poison-less, being rust-free, friction resistance, impact resistance, strong osmosis resistance, smooth pipe surface.Any stuff can not stick to the surface of the pipe, therefore, transportation resistance is decreased, the delivery efficiency and volume rate are improved, and the pressure loss during the delivery is decreased. The coating has no solvent in it, and will not leach out chemicals, therefore, it will not contaminate the material being delivered; therefore, pureness and hygiene of the material to be delivered is guaranteed. It can be used under cold or hot conditions cyclically or in alternating turns in the range between -40℃ to +80℃, without aging or chapping problems, therefore, it can be used under stringent conditions as can be found in freezing areas.
   
Large caliber coated steel pipe is widely used in the engineering fields of tap water, natural gas, petroleum, chemical engineering, medicine, communication, power, and marine, etc..