Manufacture/Inspection and Advantages of ERW Line Pipe

Electric resistance welding (ERW) pipes are manufactured by continuously roll-forming hot coil material into a pipe shape, and butt-welding the weld seam after heating/melting the coil edges using the Joule heat generated by passing a high frequency current through the edges. At the seam of the ERW butt weld (hereinafter, seam), the welding beads on the pipe inside and outside surfaces are removed by online, full-length grinding, followed by seam heat treatment to improve the weld microstructure.

After ERW linepipes are cut to the specified length, product pass through the quality assurance process, which includes hydrostatic testing, ultrasonic testing of the seam and pipe body, inspections of external appearance and dimensions, etc.

In general, ERW pipes have the following advantages.

(1) Because hot coils are used as the starting material, thin wall thickness pipe can be manufactured, and its thickness accuracy is good and the pipe has a smooth surface which is free of roughness, pits, etc.

(2) The pipemaking process is characterized by high productivity and high dimensional accuracy. As a result, lower costs can be expected in the pipe-laying process due to reduction of the work load in girth welding to join pipes, etc.

The Classification of Line Pipe

​Line pipe is manufactured from high-strength carbon steel, and is made to strict engineering and metallurgical specifications developed by the American Petroleum Institute (API). Here we will introduce the classification of line pipe.

Pipe mills produce two types of line pipe: seamless and welded. Seamless pipe is formed from a cylindrical bar of steel that is heated to a very high temperature and then is pierced with a probe to create the hole through the cylinder.  Rollers size the cylinder to produce the proper diameter and wall thickness. This technique is used to make small diameter pipe, from 0.5 inches to 24 inches in diameter.

Most pipe produced for interstate natural gas pipelines is the welded variety, because interstate systems require larger diameter pipe.  Pipe mills manufacture line pipe by forming a steel plate or coil into a cylindrical shape, and closing the seam using a welding process.  The mill evaluates the quality of the weld seam using ultrasonic and/or radiological inspection methods and pressure tests each joint of pipe to levels significantly higher than the eventual operating pressure of the pipeline.  

The pipe is further tested to ensure that it meets all requirements of steel chemistry, strength and toughness, and dimensional characteristics.  Mills that produce line pipe to API specifications meet the most stringent criteria for steel making and pipe production technologies to ensure safe, reliable pipeline service.  The gas pipeline industry maintains the manufacturing and test records of the pipe for the life of the pipeline.

Line Pipe

Line pipe is a type of steel pipe that is used for transporting materials through pipelines across the country. Line pipe can be used to transport petroleum, natural gas, oil, and water. It is a durable pipe that must meet certain specifications and regulations. This pipe typically has a high strength and durability in order to withstand high pressures. 

What is Line Pipe

Line pipe is a type of pipe that is manufactured from high strength carbon steel. It is typically made according to metallurgical specifications that were developed by the American Petroleum Institute (API). Line pipe can be used to build pipelines that transport a variety of resources including natural gas, oil, petroleum, and water. This pipe is available in a variety of diameters ranging from 2 inches to 48 inches. Line pipe can include either seamless or welded carbon steel or stainless steel piping. Because line pipe needs to withstand high pressures, there are important tests done on line pipe to ensure it meets all of the requirements of steel chemistry, strength, toughness, and dimensional characteristics. Using line pipe that meets the set criteria will ensure safe and reliable pipeline service.The size and diameter of line pipe that is required for a pipeline can vary based on the amount of gas or liquid that a pipe is intended to carry as well as the pressures that a line pipe must withstand. For example, in most cases a mainline, the principal pipeline that delivers natural gas, will require line pipe that is around 16 to 48 inches in diameter. Smaller pipelines that deliver gas to the mainline or take gas from a mainline can be constructed of 6 to 16 inch diameter line pipe. One can determine the necessary diameter required for a pipeline by considering the volume of gas or liquid that the line pipe will be carrying as well as the pressure at which this will be transported. The thickness requirements for line pipe are determined by the maximum operating pressure required for a pipeline. This is based on published standards and federal regulations. Following proper safety regulations when selecting and installing line pipe, will ensure proper pipeline operation and prevent dangerous or hazardous situations.

We are manufacturer of Line Pipes and supply high quality Line Pipes in both large and small quantities worldwide & offer you the best prices in the market.

We have a team of experienced professionals with years of experience in manufacturing.

Line Pipe Consumption Report in China

Line Pipe is mainly used for manufacturing oil and gas transmission pipelines. Oil and gas pipelines is most convenient and safest lines connecting the resource area and the market consumption area. The construction of oil and gas transmission pipeline will not only ease the railway transportation pressure and also help to protect the security of supplying oil and gas to the market. Most importantly, it help to improve the energy security capacity in China. 

We also imported liquid natural gas (LNG) from Russia and the Central Asian Coutries. In order

to deliver these natural gas to the main consumption areas, construction the transmission pipeline is essential. Today, the West-East Pipeline Project has been completed, in the future, China will construct Shaanxi-Beijing, the Sino-Russian natural gas pipeline (East, West Line), as well as Central Asia or Russia to Shanghai Natural Gas Pipeline and the ultimate "West-East Pipeline. 

In China, the crude oil, natural gas pipeline network have already been finished in a considerable scale, however, the refined oil pipeline is relatively cover 40%. Therefore, in the future, China plans to build 30,000 km pipeline which requires API 5L X65 pipe line with the outer diameter of 500mm and wall thickness below 10mm. In the next ten year, China will construct about 50,000 km of oil and gas pipelines, the average annual need for line pipe is nearly 5,000km. The annual requirements for steel pipeline for transmission natural gas is about 400 million tons.

With the develpment of pressure liquid pipeline deliery, oil and gas transmission line pipe is corresponding to the rapid development of high grade direction. In the internatioanl developed countries, API 5L X52 line pipe is widely used in 1960s, API 5L X60-X65 line pipe is commonly used for oil and gas transmission. However, in recent years, API 5L X70 line pipe is occupied th main market for oil and gas pipeline construction. In China, the most widely used line pipe is API 5L X52, X65, X70 line pipe with the outer diameter ranges from 1016mm to 1219mm, and the pressure rate is 10MPa. 

API Line Pipe Standard Introduction

LINE PIPE:

Line Pipe is one of the transportation method used for transporting oil, natural gas and water through pipeline to the oil and gas industry. 

Line Pipe Type: Seamless Steel Pipe, Welded Steel PipesLine Pipe Ends Type: Plain Ends, Threaded Ends, Socket EndsLine Pipe Connection Type: Welding Connection, Coupling Connection, Socket ConnectionAPI 5L Line Pipe Steel Grade: GR.B, X42, X52, X60, X65, X70, L245, L290, L320, L360, L450, L485
API 5L Line Pipe Specification: 

               -Seamless Steel Pipe Specification: Outside Diameter: 10.3mm ~ 1016mm, Wall Thickness: 1.7mm ~ 52mm;
              - ERW Steel Pipe Specification:  Outside Diameter: 21.3mm ~ 660mm, Wall Thickness: 1mm ~ 20mm;
              - LSAW Steel Pipe Specification: Outside Diameter: 406mm ~ 1626mm, Wall Thickness: 6.0mm ~ 75mm;
              - SSAW Steel Pipe Specification: Outside Diameter: 219mm ~ 4060mm, Wall Thickness: 3.2mm ~ 40mm;

   

API 5L LINE PIPE STANDARD:

ISO 3183 / API 5L Line Pipe Standard is one of the most significant international standards in the oil and gas pipeline industry. Nowadays, API 5L Line Pipe Standard is widely applied all over
the world. Jointly completed by ISO and American Petroleum Institution, the 44th Edition ISO 3187:2007 / API Spec 5L Line Pipe Standard has caused widespread impact internationally. The revision was launched in April 2010, collected and processed more than 400 comments all over the world. At the end of 2012, the edition API 5L Line Pipe Standard was formally approved,
and it was formally released on February 18, 2013. Compared with the previous edition, ISO 3183:2012 / API Spec 5L Line Pipe (45 edition) has added two technical appendices which are
Appendix M: European Onshore Natural Gas Pipeline PSL2 Steel Pipe Order and Appendix P: Threaded and Coupled Calculation Formula, Guide Bending and Charpy Impact Calculation
Background. Besides, in the new edition of API 5L Line Pipe Standard, there are few technological changes such as manufacturing processes, performance indicators, test methods.
The new API 5L Line Pipe Standard is more perfect and science after a lot of editorial changes and textual representation of adjustment. 

API 5L LINE PIPE PSL1 & PSL2:

API 5L Line Pipe Standard has put forward specific requirements on the manufacturing of seamless and welded steel pipe including two steel pipe specification level (PSL1 and PSL2). API 5L
Line Pipe is widely used for petroleum and natural gas industry pipeline transportation systems, but this API 5L Line Pipe criterion is not suitable for the cast iron pipe. PSL is the abbreviation
of Product Specification Level which is the quality level of API 5L Line Pipe. API 5L Line Pipe has two standards which are PSL1 and PSL2. Although these two standard only have one word
difference, the content is very different. PSL2 is a higher quality level than PSL1. Both standard level have different levels of inspection requirements, chemical composition requirements,
mechanical properties requirements, mechanical properties requirements. When making order follow the API 5L Line Pipe Standard, the purchaser need to indicate the level of standard
(PSL1 or PSL2) regard of the basic contract terms such as product specification, steel grades, order quantity etc. In general condition, if the contracts do not mention the standard level,
the manufacturer will produce in accordance with the standard of PSL1. To be more specify, the differences are including:

        1. Pipeline Hydro-static Test should be done piece by piece, and the API 5L Line Pipe Standard does not specify to allow non-destructive alternative hydro-static testing.
        2. Impact performance test is necessary for PSL2 standard, while PSL1 is not necessary for this type of test.         3. Non-destructive Test should be applied for PSL 2 standard pipe piece by piece, while for PSL1 standard is not required. 

API 5L Line Pipe Standard is similar to the Chinese Standard GB/T9711. API 5L Line Pipe PSL1 is equivalent to the GB/T9711.1. Compared with API 5L Line Pipe PLS1, API 5L Line Pipe
PSL2 standard level requires more impact energy experiments, so the production time and production cost for the manufacturers will increase. Besides, API 5L Line Pipe PSL2 standard
requires a higher quality level of raw materials for producing steel pipes, the raw materials ordering time will be longer than the PSL1 standard steel pipe raw materials. Moreover, in order
the reach the quality standard of PSL2 and also control the production cost of the factory, the manufacturer will set up a higher level of minimum order quantity for the purchasers. For
API 5L Line Pipe PSL2, some time purchasers will request for following NACE standard which means during the production the manufacturers have to add hardness and acid resistance test
for the pipes to reach a even higher quality level of steel pipes. 

Tolerance of Outside Diameter

Standard	Out Diameter	Tolerance of Pipe End	Tolerance of Pipe Body
API 5L	219.1～273.1	+1.6mm, -0.4mm	±0.75%
	274.0～320	+2.4mm, -0.8mm	±0.75%
	323.9～457	+2.4mm, -0.8mm	±0.75%
	508	+2.4mm, -0.8mm	±0.75%
	559～610	+2.4mm, -0.8mm	±0.75%

Tolerance of Wall Thickness

Standard	Grade	Out Diameter	Wall Thickness
API 5L	A	219.1～457	+15%, -12.5%
	B	508～610	+17.5%, -12.5%
	X42-X80	508～610	+19.5%, -8%

 Chemical Analysis & Mechanical Properties

Standard	Class	Grade	Chemical Analysis(%)				Mechanical Properties(min)(Mpa)
			C	Mn	P	S	Tensile Strength	Yield Strength
API 5L	PSL1	B	0.26	1.20	0.030	0.030	414	241
		X42	0.26	1.30	0.030	0.030	414	290
		X46	0.26	1.40	0.030	0.030	434	317
		X52	0.26	1.40	0.030	0.030	455	359
		X56	0.26	1.40	0.030	0.030	490	386
		X60	0.26	1.40	0.030	0.030	517	414
		X65	0.26	1.45	0.030	0.030	531	448
		X70	0.26	1.65	0.030	0.030	565	483
	PSL2	B	0.22	1.20	0.025	0.015	414	241
		X42	0.22	1.30	0.025	0.015	414	290
		X46	0.22	1.40	0.025	0.015	434	317
		X52	0.22	1.40	0.025	0.015	455	359
		X56	0.22	1.40	0.025	0.015	490	386
		X60	0.22	1.40	0.025	0.015	517	414
		X65	0.22	1.45	0.025	0.015	531	448
		X70	0.22	1.65	0.025	0.015	565	483
		X80	0.22	1.85	0.025	0.015	621	552