LSAW Steel Pipe

Straight seam welded steel pipe (LSAW steel pipe), Double-sided submerged arc welding steel pipe (DSAW steel pipe), Longitudinal submerged arc welded steel pipe, high frequency straight seam welded pipe

LSAW (Longitudinal submerge arc welding) is a type of SAW pipe made of steel plates that were hot rolled by JCOE or UOE forming technology. JCOE technology represents the shaping and forming processes involved during manufacturing as well as the inner and outer welding and cold expansion carried out after welding.

Steel pipes are mainly produced by two different manufacturing methods, namely welded pipes or seamless pipes. LSAW - longitudinal submerged arc welding is a special welding technique used in the production of welded pipes, LSAW is usually the most economical solution when operating conditions require high wall thickness due to high internal or external pressure.

Grades of LSAW Steel Pipe:

For pipeline: API 5L GR A, GR.B, X42, X45, X50, X60, X60, X65, X70, X80

For piles: ASTM A252 GR 1, GR 2, GR 3

ASTM A53: GR A, GR B, GR C, GR D
BS 4360: Grade 43, Grade 50
EN: S275, S275JR, S355JRH, S355J2H

Application of LSAW Steel Pipe:
Used for oil/gas/water
Transmission
Engineering
Offshore projects.

When building high-strength, high-toughness, high-quality long-distance oil and gas pipelines, the steel pipes required are mostly large-diameter thick-walled straight seam submerged arc welded pipes. According to API standards, in large oil and gas pipelines, when passing through Class 1 and Class 2 areas such as high-cold areas, seabeds, and densely populated urban areas, straight seam submerged arc welded pipes are the only designated applicable pipe type.

Advantages of LSAW Steel Pipes:
1) High production efficiency: Compared with traditional long welded pipes, LSAW straight seam welded pipes have higher production efficiency.
2) Stable welding quality: The use of submerged arc welding technology can ensure the stability of welding quality.
3) High weld quality: The quality of the weld is high and can meet higher requirements.
4) Suitable for large-diameter welded pipes: LSAW straight seam welded pipes are suitable for the manufacture of large-diameter pipes.
5) Simple process control: Compared with other welding methods, the process control of LSAW straight seam welded pipes is relatively simple.

Sizes of LSAW Steel Pipe:

OD: 16"-72"

O.D.		W.T.							Length(m)
Inch	mm	Min.Yield Strength(Mpa)
Inch	mm	245(B)	290(X42)	360(X52)	415(X60)	450(X65)	485(X70)	555(X80)
16	406	6.0-14.0	6.0-13.0	6.0-12.0	6.0-11.0	6.0-10.5	6.0-10.0	6.0-9.0	6.0-12.3
18	457	6.0-15.0	6.0-14.0	6.0-13.0	6.0-12.0	6.0-11.5	6.0-11.0	6.0-10.0	6.0-12.3
20	508	6.0-16.0	6.0-15.0	6.0-14.0	6.0-13.0	6.0-12.5	6.0-12.0	6.0-11.0	6.0-12.3
22	559	6.0-17.0	6.0-16.0	6.0-15.0	6.0-14.0	6.0-13.5	6.0-13.0	6.0-12.0	6.0-12.3
24	610	6.0-18.0	6.0-17.0	6.0-16.0	6.0-15.0	6.0-14.5	6.0-14.0	6.0-13.0	6.0-12.3
26	660	6.0-19.0	6.0-18.0	6.0-17.0	6.0-16.0	6.0-15.0	6.0-15.0	6.0-14.0	6.0-12.3
28	711	6.0-20.0	6.0-19.0	6.0-18.0	6.0-17.0	6.0-16.5	6.0-16.0	6.0-15.0	6.0-12.3
30	762	7.0-21.0	7.0-20.0	7.0-19.0	7.0-18.0	7.0-17.5	7.0-17.0	7.0-16.0	6.0-12.3
32	813	7.0-22.0	7.0-21.0	7.0-20.0	7.0-19.0	7.0-18.5	7.0-18.0	7.0-17.0	6.0-12.3
34	864	7.0-23.0	7.0-22.0	7.0-21.0	7.0-20.0	7.0-19.5	7.0-19.0	7.0-18.0	6.0-12.3
36	914	8.0-24.0	8.0-23.0	8.0-22.0	8.0-21.0	8.0-20.5	8.0-20.0	8.0-19.0	6.0-12.3
38	965	8.0-25.0	8.0-24.0	8.0-23.0	8.0-22.0	8.0-21.5	8.0-21.0	8.0-20.0	6.0-12.3
40	1016	8.0-26.0	8.0-25.0	8.0-24.0	8.0-23.0	8.0-22.5	8.0-22.0	8.0-21.0	6.0-12.3
42	1067	8.0-26.0	8.0-25.0	8.0-24.0	8.0-23.0	8.0-22.5	8.0-22.0	8.0-21.0	6.0-12.3
44	1118	9.0-27.0	9.0-26.0	9.0-24.5	9.0-23.5	9.0-22.8	9.0-22.0	9.0-21.0	6.0-12.3
46	1168	9.0-27.0	9.0-26.0	9.0-24.0	9.0-23.5	9.0-22.8	9.0-22.0	9.0-21.0	6.0-12.3
48	1219	9.0-28.0	9.0-27.0	9.0-25.4	9.0-24.0	9.0-23.5	9.0-23.0	9.0-22.0	6.0-12.3
52	1321	9.0-28.0	9.0-27.0	9.0-25.4	9.0-24.2	9.0-23.5	9.0-23.0	9.0-22.0	6.0-12.3
56	1422	10.0-29.0	10.0-28.0	10.0-26.0	10.0-24.5	10.0-23.8	10.0-23.0	10.0-22.0	6.0-12.3
60	1524	10.0-29.0	10.0-28.0	10.0-26.0	10.0-24.5	10.0-23.8	10.0-23.0	10.0-22.0	6.0-12.3
64	1626	10.0-30.0	10.0-29.0	10.0-27.0	10.0-25.4	10.0-24.8	10.0-24.0	10.0-23.0	6.0-12.3
68	1727	10.0-30.0	10.0-29.0	10.0-27.0	10.0-25.4	10.0-24.8	10.0-24.0	10.0-23.0	6.0-12.3
72	1829	10.0-30.0	10.0-29.0	10.0-27.0	10.0-25.4	10.0-24.8	10.0-24.0	10.0-23.0	6.0-12.3

Tolerance of Outside Diameter and Wall Thickness of LSAW Steel Pipe

Types	Standard
	SY/T5040-2000	SY/T5037-2000	SY/T9711.1-1977	ASTM A252	AWWA C200-97	API 5L PSL1
Tube end OD deviation	±0.5%D	±0.5%D	-0.79mm～+2.38mm	<±0.1%T	<±0.1%T	±1.6mm
Wall thickness	±10.0%T	D<508mm, ±12.5%T	-8%T～+19.5%T	<-12.5%T	-8%T～+19.5%T	5.0mm
		D>508mm, ±10.0%T				T≥15.0mm, ±1.5mm

Chemical Composition and Mechanical Properties of LSAW Steel Pipe

Standard	Grade	Chemical Composition(max)%					Mechanical Properties(min)
		C	Mn	Si	S	P	Yield Strength(Mpa)	Tensile Strength(Mpa)
GB/T700-2006	A	0.22	1.4	0.35	0.050	0.045	235	370
	B	0.2	1.4	0.35	0.045	0.045	235	370
	C	0.17	1.4	0.35	0.040	0.040	235	370
	D	0.17	1.4	0.35	0.035	0.035	235	370
GB/T1591-2009	A	0.2	1.7	0.5	0.035	0.035	345	470
	B	0.2	1.7	0.5	0.030	0.030	345	470
	C	0.2	1.7	0.5	0.030	0.030	345	470
BS En10025	S235JR	0.17	1.4	-	0.035	0.035	235	360
	S275JR	0.21	1.5	-	0.035	0.035	275	410
	S355JR	0.24	1.6	-	0.035	0.035	355	470
DIN 17100	ST37-2	0.2	-	-	0.050	0.050	225	340
	ST44-2	0.21	-	-	0.050	0.050	265	410
	ST52-3	0.2	1.6	0.55	0.040	0.040	345	490
JIS G3101	SS400	-	-	-	0.050	0.050	235	400
	SS490	-	-	-	0.050	0.050	275	490
API 5L PSL1	A	0.22	0.9	-	0.03	0.03	210	335
	B	0.26	1.2	-	0.03	0.03	245	415
	X42	0.26	1.3	-	0.03	0.03	290	415
	X46	0.26	1.4	-	0.03	0.03	320	435
	X52	0.26	1.4	-	0.03	0.03	360	460
	X56	0.26	1.1	-	0.03	0.03	390	490
	X60	0.26	1.4	-	0.03	0.03	415	520
	X65	0.26	1.45	-	0.03	0.03	450	535
	X70	0.26	1.65	-	0.03	0.03	585	570

LSAW steel pipe Manufacturing Process:

Longitudinally Submerged Arc Welded Process Flow
LSAW (Longitudinally Submerged Arc Welded Steel pipes) in leaflets plate as raw material, the steel plate in the mold or molding machine pressure (volume) into using double-sided submerged arc welding and flaring from production.

The LSAW process of welded pipe includes UOE and JCOE.
UOE LSAW pipe forming process:
The three main forming processes of UOE LSAW steel pipe forming process include: steel plate pre-bending, U forming and O forming. Each process adopts a dedicated forming press to complete the three processes of pre-bending the edge of the steel plate, U forming and O forming in sequence to deform the steel plate into a circular tube.

JCOE LSAW pipe forming process:
Forming: After several steps of stamping on the JC0 forming machine, first half of the steel plate is pressed into a "J" shape, then the other half of the steel plate is pressed into a "J" to form a "C" shape, and finally pressurized from the middle to form An open "0"-shaped tube blank is formed.

The specific process steps of LSAW steel pipe are as follows:

1. Plate Probe: This is used for manufacturing the large diameter LSAW joints right after it enters the production line which is the initial full-board ultrasonic testing.
2. Milling: The machine used for milling does this operation through two-edged milling plate to meet the requirements of the plate width and the sides parallel to the shape and degree.
3. Pre-curved side: This side is achieved by using a pre-bending machine on the pre-bending plate edge. The plate edge needs to meet curvature requirement.
4. Forming: After the pre-bending step, in the first half of the JCO molding machine, after stamped steel, it is pressed into a “J” shape while the on the other half of the same steel plate it is bent and pressed into a “C” shape, then the final opening forms an “O” shape.
5. Pre-welding: This is to make a welded pipe steel a straight seam after it has been formed and then use gas welding seam (MAG) for continuous welding.
6. Inside weld: This is done with a tandem multi-wire submerged arc welding (about four wire) on the inner part of the straight seam welded steel pipe.
7. Outside Weld: Outside weld is the tandem multi-wire submerged arc welding on the outer part of the LSAW steel pipe welding.
8. Ultrasonic Testing: Outside and inside of the straight seam welded steel pipe and both sides of the base material are welded with 100% inspection.
9. X-ray inspection: X-ray industrial TV inspection is carried out on the inside and outside using image processing system to make sure there is detection sensitivity.
10. Expansion: This is for accomplishing submerged arc welding and straight seam steel pipe length hole diameter so as to improve the steel tube’s size precision and improve the distribution of stress in the steel tube.
11. Hydraulic test: This is carried out on the hydraulic test machine for steel after expanding by-root test for ensuring the steel pipe meets the standard requirements with the machine having an automatic recording and storage capabilities.
12. Chamfering: This involves the inspection carried out on the steel pipe at the end of the whole process.

Production equipment of LSAW steel pipe:

Plate edge milling machine
The milling machine mills the two sides of the plate to exacting standards in order to meet width, edging and groove shape specifications.

Edge crimping machine
The crimping machine crimps the edges of the plate to form the required curvature.

Tack welding machine
The two edges of the open seam pipe are brought together by the tack welding machine. then welded by the tack welder using a metal active - gas arc welding("MAG" )process.

Forming machine
Utilizes the "JCO" process to bend and form the crimped steel plate into a steel pipe.

Interior welding machine
The interior longitudinal seam of the pipe is welded from the inside by fixing 4 welding heads while moving pipe and using submerged-arc welding process.

End facing machine
The machine levels the pipe end with rotating cutter heads to ensure that required groove and edge specifications are met.

Hydrostatic tester
Using end face sealing technology eliminates blind zones during hydrostatic testing. The tester is also equipped with automatic recording and storing functions.

Expanding machine
The pipe is subjected to full-length expansion to increase the precision of the pipe dimensions and to improve the internal stress distribution.