Three Factors Revealing the Effectiveness of Iron and Steel Industry

This year, the effectiveness of China's steel industry achieved a comprehensive upgrade, what is the main reason? Prime Steel Pipe as the leading manufacturer and exporter of carbon steel pipe, including ERW steel pipe, LSAW steel pipe, SSAW steel pipe, seamless steel pipe, etc., we think the main reason are:

1. Domestic economy remain stable
First of all, the national economy remain stable, real estate, infrastructure, automotive and other related industries demand, become the biggest driving force of the steel industry. GDP growth 6.9% in the first half of 2017, for eight consecutive quarters to maintain the range of 6.7% -6.9%, of which real estate and infrastructure investment growth has rebounded.

2. Effective supply structural reform
Second, the supply structural reform and DE-capacity promotion effective changed the phenomenon of excess capacity. According to the data report, five years target of excess capacity of China's iron and steel industry is 100 million -1.5 million tons.

3. Steel enterprises cost reduction efficiency
In the first half of 2017, the country doing special rectification on the "ground of steel", banned, shut down more than 600 illegal production enterprises, involving about 120 million tons steel, it is good for develop steel industry. In the past, "ground steel" is made of scrap steel, after banned 'ground of steel', the price of scrap declined,  it is helpful for fix the shortage of hot metal business; while scrap energy consumption is low, can help companies save a lot of cost.


The Classification of Carbon Steel Pipe

The classification of carbon steel pipe includes multiple factors, such as production methods, cross-sectional shape, wall thickness and application. Next, Prime Steel Pipe will detailedly introduce the classification of carbon steel pipe for all of you.

Carbon steel pipe is classified by its production methods:

1. Seamless Steel Pipe - hot rolled seamless steel pipe, cold rolled seamless steel pipe, cold drawn seamless steel pipe.

2. Welded Steel Pipe - longitudinal welded pipe, spiral welded pipe, electric resistance welded pipe.

Carbon steel pipe is also classified by its cross-sectional shape. Its categories include:

1. Simple section steel pipe - round carbon steel pipe, square carbon steel pipe, rectangular carbon steel pipe, oval carbon steel pipe ect.

2. Complex section steel pipe - hexagonal carbon steel pipe with unequal edge, five plum shaped carbon steel pipe, double convex carbon stee pipe, double concave carbon steel pipe ect.

Carbon steel pipe is classified by its wall thickness:

1. Thin walled carbon steel pipe.

2. Thick walled carbon steel pipe.

Carbon steel pipe is classified by its application:

Carbon steel pipe can be used for thermal equipment, machinery industrial pipe, oil line pipe, geological drilling steel pipe, container steel pipe, chemical industry steel pipe, and other special purpose steel pipe.


The Classification of Seamless Steel Pipe

Seamless steel pipe is divided into two categories, including hot-rolled and cold-rolled seamless steel pipe.

Hot-rolled seamless steel pipe contains general steel pipe, low and medium pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, oil cracking pipe, geological pipe and other steel pipe.

In addition to the general steel pipe, cold-rolled seamless steel pipe also contains low pressure boiler steel pipe, high pressure boiler steel pipe, alloy steel pipe, stainless steel pipe, oil cracking pipe, other steel pipe, but also include carbon thin-walled steel pipe, alloy thin-walled steel pipe, stainless steel pipe, special-shaped steel tube.

The diameter of hot-rolled seamless pipe is generally greater than 32mm, wall thickness is 2.5-75mm, the diameter of cold-rolled seamless steel pipe can be 6mm, wall thickness can be 0.25mm, the diameter of thin tube can be 5mm, wall thickness is less than 0.25mm, Cold-rolled seamless steel pipe has higher dimensional accuracy than the hot-rolled seamless steel pipe.

The seamless steel pipe for general use: is made by 10,20,30,35,45 and other high-quality carbon steel, 16Mn, 5MnV and other low-alloy structural steel or 40Cr, 30CrMnSi, 45Mn2, 40MnB alloy steel by hot-rolled or cold rolled. The seamless steel pipe made by 10,20 and other low-carbon steel is mainly used for fluid transportation pipeline. The seamless steel pipe made by 45,40Cr and other carbon steel is mainly used to manufacture mechanical parts, such as cars, tractors force parts. The seamless steel pipe for general use should ensure strength and flattening test. The hot-rolled steel pipe is delivered in a hot-rolled state or a heat-treated state, cold-rolled steel is delivered in a heat-treated state.


What is The Meaning of API 5L Line Pipe?

General Information of API 5L Line Pipe:

Specifications for API 5L adhere to the International Organization for Standardization ISO 3183. The API 5L specification provides standards for pipe suitable for use in conveying gas, water, and oil in the natural gas and oil industries. The API SPEC 5L covers seamless and welded steel line pipe. It includes standard-weight and extra-strong threaded line pipe; and standard-weight plain-end, regular-weight plain-end, special plain-end, extra-strong plain-end, special plain-end, extra-strong plain-end pipe; as as well as bell and spigot and through-the-flow line(TFL) pipe.

Grades covered by this specification are A25 ,A ,B (and the following "X" Grades), X42, X46, X52, X56, X60, X65, X70, X80. The two digit number following the "X" indicates the Minimum Yield Strength (in 000's psi) of pipe produced to this grade.

Pipe manufactured to ASTM106 Grade A or B are not interchangeable with API 5L. Requirements to API 5L X grades are more stringent, rolled grades are not acceptable and rework is not allowed. Moreover, particular attention is given to toughness and toughness tests for sour services and higher pressure & temperature classes.

Applications and benefits of API 5L Line Pipe:

1. API 5L line pipe is preferred in long pipelines due to its inexpensiveness, so it is widely used in gas, water and oil transportation.
2. API 5L line pipe can resist to crack propagation, so it used to pipeline steel.
3. Line Pipe and Sour Service Line Pipes.


Production Equipments of Precision Welded Pipe

In the process of three typical production methods, the main pipe equipment, pipe forming unit cold drawing machine, cold rolling unit and cold reducing unit, has a decisive role in the formation of precision welded pipe. But the equipment types of precision pipe pipe is much, the range of that is big, and technical performance requirements are different. If we want to meet the quality requirements of precision welded pipe, we must be suitable configuration.

1. On the manufacturing stage of precision welded pipe:

Strip preparation - Desktop rack or chain conveyor
Uncoiler - Cantilever or Double Cone Uncoiler
Straightening of steel - Roller leveling machine
Shear - oblique cutting shears
Butt welding machine
Live sets of materials - live sets (box, cage, spiral, tunnel, etc.)
Milling edge planing edge - milling edge planing machine
Forming - continuous forming machine (roll, row roll, FF forming, etc.)
Welding - high frequency induction or contact heating welding equipment
Clear burrs - inside and outside deburring devices (both inside and outside)
Weld heat treatment - IF linear induction heating device (or steel pipe heat treatment)
Cooling - air cooling and cooling water jacket
Sizing - continuous sizing machine (roll)
Nondestructive testing - Ultrasonic or eddy current flaw detection
Flying shear - flying shear (stamping, rolling, sawing, milling, etc.)
Straightening - Roller Straightening Machine (5 ~ 7 Roll)
Cut off the flat head - cutting machine and the head machine and step into the bench
Eddy current testing - eddy current flaw detector (instead of hydraulic pressure test)
Water pressure test - hydraulic pressure test machine (single or multi-type)

2. On the cold drawn and cold rolling stage of precision welded pipe:

Rolling head - rolling head or hammer machine
Intermediate heat treatment - continuous roll annealing furnace
Pickling, cleaning - pickling, washing tanks and flushing facilities
Phosphating, saponification - phosphating, saponification tank
Cold drawing - cold drawing unit
Lubrication - Lubricating pond
Cold Rolling - Roller Cold Rolling Mill
Heat treatment of the finished product - Protection atmosphere Heat treatment furnace (chamber or roll)

3. Cold reduction stage of precision welded pipe:

Cold reduction - cold reduction unit (two or three roller type cold reduction unit frame according to the total amount of deformation configuration)

As the precision welded pipe varieties, specifications, technical requirements are different, the production process and processes are not the same, some processes take a long time, some processes less time, so the production process prone to uneven, and the need for a buffer link, In order to make the smooth progress of production, to minimize the weak links, about 90% of the precision welded pipe products have to go through the middle of the warehouse to balance production capacity.


The Characteristic of Seamless Precision Steel Tube

Precision steel pipe is a kind of steel pipe that inside and outside of the wall are without oxidation layer, withstand high pressure without leakage, high precision, high finish, cold bending is not deformed, flaring, flattening no cracks and so on. The main advantage of seamless precision steel tube is characterized by a smaller diameter, high precision, high precision, good surface quality, better performance, more dense metal. It has strict requirements on the pipe body bore, the outer wall size and the tolerance and roughness. Seamless precision steel pipe is mainly used for mechanical structure, hydraulic equipment, hydraulic and pneumatic cylinder manufacturing.

The characteristic of seamless precision steel tube:

1. Finished tube size accuracy, internal and external diameter can be accurate to within 0.05mm.
2. Internal and external surface finish is good.
3. There is no oxide film on the inner and outer surfaces of the precision tube after cold rolling.
4. Precision pipe flaring, flattening no cracks, cold bending is not deformed, can withstand high pressure.
5. Performance is superior, can make a variety of complex deformation and mechanical deep processing.

The uses of seamless precision steel pipe:

1. Precision tube for automobile manufacturing, precision pipe for automobile parts, precision tube for precision equipment, Precision pipe for boiler equipment.
2. Motor shell with precision tube, motor shell, DC motor tube.
3. Industrial processing categories: machinery manufacturing with precision pipe, machine tool processing with precision tube, bearing pipe with precision pipe, processing machinery parts, etc. High pressure tubing, hydraulic cylinder.
5. Other: electrical gas transmission, water power pipes and so on.


Low-frequency Electric Resistance Welding

Low-frequency electric resistance welding (LF - ERW), is an obsolete method that was used to weld seams in oil and gas pipelines. It was phased out in the 1970s but as of 2015 some pipelines built with this method remained in service.

Electric resistance welded pipe (ERW steel pipe) is manufactured by cold-forming a sheet of steel into a cylindrical shape. Current is then passed between the two edges of the steel to heat the steel to a point at which the edges are forced together to form a bond without the use of welding filler material. Initially this manufacturing process used low frequency A.C. current to heat the edges. Over time, the welds of low frequency ERW pipe was found to be susceptible to selective seam corrosion, hook cracks, and inadequate bonding of the seams, so low frequency ERW is no longer used to manufacture pipe. This low frequency process was used from the 1920s until 1970. In 1970, the low frequency process was superseded by a high frequency ERW process which produced a higher quality weld. So the high frequency process is still being used to manufacture pipe for use in new pipeline construction. In the production of ERW steel pipe manufactured by Prime Steel Pipe, high-frequency ERW process is widely used, so that we can guarantee the quality of welding seam and produce high quality ERW steel pipe.