SSAW Steel Pipe - Knowledge

Spiral welded steel pipe (SSAW steel pipe), Spiral submerged arc pipe

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Spiral steel pipe, also known as spiral welded pipe, is made by rolling low-carbon structural steel or low-alloy structural steel strip into a tube blank at a certain spiral angle (called forming angle), and then welding the tube seams. It can produce large-diameter steel pipes with narrower strip steel.

Features:
The production process of straight seam welded pipe (ERW/LSAW) is simple, with high production efficiency, low cost and rapid development. The strength of spiral welded pipe is generally higher than that of straight seam welded pipe. It can produce welded pipes with larger diameters with narrower billets, and can also produce welded pipes with different diameters with billets of the same width. However, compared with straight seam pipes of the same length, the weld length increases by 30~100%, and the production speed is lower. Therefore, most smaller diameter welded pipes use straight seam welding, while large diameter welded pipes mostly use spiral welding.

Standard & Class

Classfication	Standard	Main Products
Steel Pipe for Fluid Service	GB/T 14291	Welded pipe for mine fluid sevice
	GB/T 3091	Welded pipe for low pressure fluid service
	SY/T 5037	Spirally submerged arc welded steel pipe for pipelines for low pressure fluid service
	ASTM A53	Black and hot-hipped galvanized welded and seamless steel pipe
	BS EN10217-2	Welded steel tybes for pressure purposes - delivery technical conditions - part2: Electric welded non- alloy and alloy steel tubes with specified elevated temperature properties
	BS EN10217-5	Welded steel tybes for pressure purposes - delivery technical conditions - part5: submerged arc welded non-alloy and alloy steel tubes with specified elevated temperature properties
Steel Pipe for Ordinary Structure	GB/T 13793	Longitudinally electric resistance welded steel pipe
	SY/T 5040	Spirally submerged arc welded steel pipe piles
	ASTM A252	Welded and seamless steel pipe piles
	BS EN10219-1	Cold formed welded structural hollow sections of non-alloy and fine grain steels - part1: Technical delivert conditions
	BS EN10219-2	Cold formed welded structural hollow sections of non-alloy and fine grain steels - part2: tolerances dimmsions and sectional properties
Line Pipe	GB/T 9711.1	Steel pipe for pipeline transportation system of petroleum and natural gas industries(Class A steel pipe)
	GB/T 9711.2	Steel pipe for pipeline transportation system of petroleum and natural gas industries(Class B steel pipe)
	API 5L PSL1/2	Line pipe
Casing	API 5CT/ ISO 11960 PSL1	Steel pipe for use as casing or tubing for wells of petroleum and natural gas industries

Chemical Analysis and Mechanical Properties

Standard	Grade	Chemical Composition(max)%					Mechanical Properties(min)
Standard	Grade	C	Si	Mn	P	S	Tensile Strength(Mpa)	Yield Strength(Mpa)
API 5CT	h40	-	-	-	-	0.030	417	417
	J55	-	-	-	-	0.030	517	517
	K55	-	-	-	-	0.030	655	655
API 5L PSL1	A	0.22	-	0.90	0.030	0.030	335	335
	B	0.26	-	1.20	0.030	0.030	415	415
	X42	0.26	-	1.30	0.030	0.030	415	415
	X46	0.26	-	1.40	0.030	0.030	435	435
	X52	0.26	-	1.40	0.030	0.030	460	460
	X56	0.26	-	1.40	0.030	0.030	490	490
	X60	0.26	-	1.40	0.030	0.030	520	520
	X65	0.26	-	1.45	0.030	0.030	535	535
	X70	0.26	-	1.65	0.030	0.030	570	570
API 5L PSL2	B	0.22	0.45	1.20	0.025	0.015	415	415
	X42	0.22	0.45	1.30	0.025	0.015	415	415
	X46	0.22	0.45	1.40	0.025	0.015	435	435
	X52	0.22	0.45	1.40	0.025	0.015	460	460
	X56	0.22	0.45	1.40	0.025	0.015	490	490
	X60	0.12	0.45	1.60	0.025	0.015	520	520
	X65	0.12	0.45	1.60	0.025	0.015	535	535
	X70	0.12	0.45	1.70	0.025	0.015	570	570
	X80	0.12	0.45	1.85	0.025	0.015	625	625
GB/T 9711.1	L210	-	-	0.90	0.030	0.030	335	335
	L245	-	-	1.15	0.030	0.030	415	415
	L290	-	-	1.25	0.030	0.030	415	415
	L320	-	-	1.25	0.030	0.030	435	435
	L360	-	-	1.25	0.030	0.030	460	460
	L390	-	-	1.35	0.030	0.030	490	490
	L415	0.26	-	1.35	0.030	0.030	520	520
	L450	0.26	-	1.40	0.030	0.030	535	535
	L485	0.23	-	1.60	0.030	0.030	570	570
GB/T3091/ SY/T503	Q195	0.12	0.30	0.50	0.035	0.040	315	315
	Q215B	0.15	0.35	1.20	0.045	0.045	335	335
	Q235B	0.20	0.35	1.40	0.045	0.045	370	370
	Q345B	0.20	0.50	1.70	0.035	0.035	470	470
ASTM A53	A	0.25	0.10	0.95	0.050	0.045	330	330
ASTM A53	B	0.30	0.10	1.20	0.050	0.045	415	415
ASTM A252	1	-	-	-	0.050	-	345	345
	2	-	-	-	0.050	-	414	414
	3	-	-	-	0.050	-	455	455
EN10217-1	P195TR1	0.13	0.35	0.70	0.025	0.020	320	320
	P195TR2	0.13	0.35	0.70	0.025	0.020	320	320
	P235TR1	0.16	0.35	1.20	0.025	0.020	360	360
	P235TR2	0.16	0.35	1.20	0.025	0.020	360	360
	P265TR1	0.20	0.40	1.40	0.025	0.020	410	410
	P265TR2	0.20	0.40	1.40	0.025	0.020	410	410
EN10217-2	P195GH	0.13	0.35	0.70	0.025	0.020	320	320
	P235GH	0.16	0.35	1.20	0.025	0.020	360	360
	P265GH	0.20	0.40	1.40	0.025	0.020	410	410
EN10217-5	P235GH	0.16	0.35	1.20	0.025	0.020	360	360
EN10217-5	P265GH	0.20	0.40	1.40	0.025	0.020	410	410
EN10219-1	S235JRH	0.17	-	1.40	0.040	0.040	360	360
	S275JOH	0.20	-	1.50	0.035	0.035	410	410
	S275J2H	0.20	-	1.50	0.030	0.030	410	410
	S355JOH	0.22	0.55	1.60	0.035	0.035	470	470
	S355J2H	0.22	0.55	1.60	0.030	0.030	470	470
	S355K2H	0.22	0.55	1.60	0.030	0.030	470	470

Tolerance of Outside Diameter and Wall Thickness

Standard	Tolerance of Pipe Body		Tolerance of Pipe End		Tolerance of Wall Thickness
Standard	Out Diameter	Tolerance	Out Diameter	Tolerance	Tolerance of Wall Thickness
GB/T3091	OD≤48.3mm	≤±0.5	OD≤48.3mm	-	≤±10%
	48.3	≤±1.0%	48.3	-
	273.1	≤±0.75%	273.1	-0.8～+2.4
	OD>508mm	≤±1.0%	OD>508mm	-0.8～+3.2
GB/T9711.1	OD≤48.3mm	-0.79～+0.41	-	-	OD≤73	-12.5%～+20%
	60.3	≤±0.75%	OD≤273.1mm	-0.4～+1.59	88.9≤OD≤457	-12.5%～+15%
	508	≤±1.0%	OD≥323.9	-0.79～+2.38	OD≥508	-10.0%～+17.5%
	OD>941mm	≤±1.0%	-	-	-	-
GB/T9711.2	60	±0.75%D～±3mm	60	±0.5%D～±1.6mm	4mm	±12.5%T～±15.0%T
	610	±0.5%D～±4mm	610	±0.5%D～±1.6mm	WT≥25mm	-3.00mm～+3.75mm
	OD>1430mm	-	OD>1430mm	-	-	-10.0%～+17.5%
SY/T5037	OD<508mm	≤±0.75%	OD<508mm	≤±0.75%	OD<508mm	≤±12.5%
SY/T5037	OD≥508mm	≤±1.00%	OD≥508mm	≤±0.50%	OD≥508mm	≤±10.0%
API 5L PSL1/PSL2	OD<60.3	-0.8mm～+0.4mm	OD≤168.3	-0.4mm～+1.6mm	WT≤5.0	≤±0.5
	60.3≤OD≤168.3	≤±0.75%	168.3	≤±1.6mm	5.0	≤±0.1T
	168.3	≤±0.75%	610	≤±1.6mm	T≥15.0	≤±1.5
	610	≤±4.0mm	OD>1422	-	-	-
	OD>1422	-	-	-	-	-
API 5CT	OD<114.3	≤±0.79mm	OD<114.3	≤±0.79mm	≤-12.5%
API 5CT	OD≥114.3	-0.5%～1.0%	OD≥114.3	-0.5%～1.0%	≤-12.5%
ASTM A53	≤±1.0%		≤±1.0%		≤-12.5%
ASTM A252	≤±1.0%		≤±1.0%		≤-12.5%

SSAW steel pipe is the raw material of strip coil, often temperature extrusion molding, automatic double-wire double submerged arc welding process made of spiral seam pipe. Spiral steel pipe will strip into the pipe unit, the multi-roll rolling, strip rolled up, forming a circular gap opening gap, adjust the squeeze roll reduction, the weld gap control in the 1 ~ 3mm, and make both ends of the weld flush.

Manufacturing process of SSAW steel pipe:

(1) Raw materials are strip steel coil, welding wire and flux. They must undergo strict physical and chemical inspection before being put into use.
(2) The head and tail of the strip steel are butt-jointed by single-wire or double-wire submerged arc welding. After being rolled into a steel pipe, automatic submerged arc welding is used for repair welding.
(3) Before forming, the strip steel is leveled, trimmed, planed, surface cleaned, conveyed and pre-bent.
(4) An electric contact pressure gauge is used to control the pressure of the oil cylinder on both sides of the conveyor to ensure the smooth conveying of the strip steel.
(5) Externally controlled or internally controlled roller forming is adopted.
(6) A weld gap control device is used to ensure that the weld gap meets the welding requirements. The pipe diameter, misalignment and weld gap are strictly controlled.
(7) Both internal and external welding are performed by single-wire or double-wire submerged arc welding using an American Lincoln electric welder to obtain stable welding specifications.
(8) All welds are inspected by online continuous ultrasonic automatic flaw detectors to ensure 100% non-destructive testing coverage of spiral welds. If there are defects, an automatic alarm will be sounded and a mark will be sprayed. The production workers can adjust the process parameters at any time to eliminate the defects in time.
(9) The steel pipes are cut into single pieces by an air plasma cutting machine.
(10) After cutting into single steel pipes, each batch of steel pipes must undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion status, surface quality of the welds and non-destructive testing to ensure that the pipe making process is qualified before it can be officially put into production.
(11) The parts with continuous ultrasonic flaw detection marks on the welds are re-inspected by manual ultrasonic and X-ray. If there are defects, they are repaired and then subjected to non-destructive testing again until it is confirmed that the defects have been eliminated.
(12) The butt welds of the strip steel and the pipes where the T-joints intersect with the spiral welds are all inspected by X-ray television or film.
(13) Each steel pipe is subjected to a hydrostatic test, and the pressure is radially sealed. The test pressure and time are strictly controlled by a steel pipe water pressure microcomputer detection device. The test parameters are automatically printed and recorded.
(14) The pipe end is machined to accurately control the end face verticality, groove angle and blunt edge.