Difference Between LSAW and HSAW Pipes

- Aug 30, 2019-

Difference Between LSAW and HSAW Pipes



Longitudinally Submerged Arc Welding, shorthand for LSAW


Helical submerged arc welding (spiral) steel pipe is the full name of HSAW pipe.


1 welding technology in terms of: 

spiral welded pipe and straight seam welded pipe welding method is consistent, straight seam steel pipe, inevitably, there will be a lot of the t-shaped weld, so the probability of weld defects is also greatly improved, and the t-shaped seam welding residual stress is larger, the stress state of the weld metal are often in a three-way increases the possibility of a crack.In addition, according to the technical provisions of submerged arc welding, each welding seam should have an arc ignition place and an arc extinguishing place, but each straight seam welding pipe cannot reach this condition when welding the circular seam, so there may be more welding defects at the arc extinguishing place.



2. When the pipe is under internal pressure, two main stresses are usually generated on the pipe wall, namely, radial stress  and axial stress.The synthetic stress at the weld , where, the spiral Angle of the weld.



3. The weld of spiral steel tube is the spiral angle, so the synthetic stress at the spiral weld is the main stress.Under the same working pressure, the wall thickness of spiral pipe with the same diameter can be reduced than that of straight seam welded pipe.According to the above characteristics, when the spiral steel pipe bursts, because the normal stress and synthetic stress on the welding seam are relatively small, the bursting port generally does not originate from the spiral welding seam, and its safety is higher than that of the straight seam welded pipe.When there is a parallel defect near the spiral weld, the expansion risk of the spiral weld is not as high as that of the straight weld due to the low stress of the spiral weld.Because the radial stress is the maximum stress existing on the steel pipe, the welding seam bears the maximum load when it is in the direction of vertical stress.That is, the straight seam bears the largest load, the circumferential weld bears the smallest load, and the spiral seam is between the two.



4. Static pressure blasting strength: through relevant comparative tests, it is verified that the yield pressure of spiral steel pipe and straight-seam welded pipe is basically consistent with the measured and theoretical values of blasting pressure, with the deviation close.But no matter the yield pressure or blasting pressure, the spiral steel pipe is lower than the straight seam welded pipe.The blasting test also showed that the annular deformation rate of the blasting mouth of spiral steel pipe was significantly higher than that of straight seam welded pipe.It is proved that the plastic deformation capacity of spiral steel pipe is better than that of straight welded pipe, and the blasting mouth is generally limited to one pitch, which is caused by the strong restraint effect of spiral weld on the expansion of the crack.



5. Toughness and fatigue strength: the trend of pipeline development is large diameter and high strength.With the increase of the diameter of steel pipe and the increase of the steel grade used, the trend of the cusp stability extension of ductile fracture becomes larger.According to the test of the related research institution in the United States, although the spiral steel pipe and the straight seam welded pipe are the same grade, the spiral steel pipe has higher impact toughness.



6. The pipeline is subject to random alternating loads during the actual operation.It is important to know the low cyclic fatigue strength of steel pipe to judge the service life of pipeline.



7. According to the measurement results, the aromatic strength of spiral steel pipe is the same as that of seamless pipe and resistance welded pipe. The test data are distributed in the same area as that of seamless pipe and resistance welded pipe, but higher than that of general submerged arc welded pipe.


Product Description
Product Name
welded spiral steel pipe
Material
Q235A, Q235B, Q345, L245, L290, API5L X42,X52,X60,X70,X80, OCr13,1Cr17,00Cr19Ni11,1Cr18Ni9,0Cr18Ni11Nb,ST37.0,
ST35.8,ST37.2,ST45,ST52,ST52.4,STP G38,STP G42,STPT42,STS49, etc...
Standard
SY/T5037-2000, GB/T9711.1-1997, GB/T9711.2, API-5L, SY/T5040-92, ASTM A53,A106, DIN1626,DIN1629,DIN2448,JIS G3452,JIS G3454,JIS
G3455, JIS G3456,JIS G3457,JIS G3461
Application
Mainly used in water engineering, petroleum and natural gas industry, chemical industry, agricultural irrigation, urban
construction,
Remark
1. Payment terms : T/T ,L/C 2. Terms of trade : FOB ,CFR,CIF ,DDP,EXW
3. Minimum order : 2 tons
4. Delivery time : Within 25 days.
Productivity
5000Tons per month.
Standard
GB/T9711.1 GB/T9711.2 SY/T5037 SY/T5040 API5L
Package
In bundles, Painting, Beveled edges, plastic caps ends, or as buyer's request.
Used
The pipes are widely used in natural gas, offshore oil piling, petroleum, chemical
After sale service
We do what we promised ,We promised what we will do .

The spiral steel pipe is a spiral seam steel pipe with a steel coiled plate as a raw material, which is often extruded and formed by welding with an automatic double-wire submerged arc welding process. The spiral steel pipe feeds the strip steel into the welded pipe unit, and after being rolled by multiple rollers, the strip steel is gradually rolled up to form a round tube blank with an open gap. 3mm, and make the two ends of the welding port flush.

Material Q235A, Q235B, 10 #, 20 #, Q345 (16Mn), L245 (B), L290 (X42), L320 (X46), L360 (X52), L390 (X56), L415 (X60), L450 (X65), L485 (X70), L555 (X80) L290NB / MB (X42N / M), L360NB / MB (X52N / M), L390NB / MB (X56N / M), L415NB / MB (X60N / M), L450MB (X65), L485MB (X70), L555MB (X80) .

Production process

(1) The raw materials are strip coil, welding wire and flux. Before input, it must undergo strict physical and chemical tests.

 (2) The head and tail of the steel strip are connected by single-wire or double-wire submerged arc welding. After being rolled into steel pipes, automatic submerged arc welding is used for welding. (3) Before forming, the strip steel is leveled, trimmed, planed, surface cleaned and transported, and pre-bent. 

(4) The electric contact pressure gauge is used to control the pressure of the oil cylinder on both sides of the conveyor to ensure the smooth transportation of the steel strip. 

(5) Using external control or internal control roll forming. 

(6) The weld gap control device is used to ensure that the weld gap meets the welding requirements, and the pipe diameter, the amount of misalignment and the weld gap are strictly controlled. 

(7) Both internal and external welding adopt American Lincoln electric welding machine for single-wire or double-wire submerged arc welding, so as to obtain stable welding quality. 

(8) All welded seams are inspected by online continuous ultrasonic automatic flaw detector to ensure 100% coverage of non-destructive testing of spiral welds. If there are defects, it will automatically alarm and spray marks, and the production workers will adjust the process parameters at any time according to this, and eliminate the defects in time.

(9) Use air plasma cutting machine to cut the steel pipe into single pieces. 

(10) After cutting into a single steel pipe, each batch of steel pipes must undergo a strict first inspection system to check the mechanical properties, chemical composition, fusion state, surface quality of the steel pipe and non-destructive inspection to ensure the qualification of the pipe making process Only then can it be officially put into production. 

(11) The parts with continuous sonic flaw detection marks on the welding seam are manually reviewed by ultrasonic and X-ray. If there are defects, after repairing, they will undergo nondestructive inspection again until it is confirmed that the defects have been eliminated. 

(12) Tubes with butt-welded welds of steel strips and D-joints that intersect spiral welds are all checked by X-ray TV or filming.

 (13) Each steel tube undergoes a hydrostatic pressure test, and the pressure is radially sealed. The test pressure and time are strictly controlled by the steel pipe hydraulic microcomputer detection device. Test parameters are automatically printed and recorded. 

(14) Mechanical processing of the pipe end, so that the verticality of the end face, the bevel angle and the blunt edge are accurately controlled

Company Profie

Cangzhou Steel Pipe Group (CSPG)Co.,Ltd.

No.92 JieFang East Road ,Cangzhou City, Hebei,P.R.China.

With the sense of responsibility, customer-centered, market-oriented, service-oriented, spot supply as the main body, good reputation, excellent business quality, integrity, conscientious work, perception of society and the spirit of Bianjin, we are committed to creating a win-win, easy and convenient large-scale integrated steel procurement for customers Platform.

The company upholds the enterprise tenet of integrity-based and customer-oriented, constantly strengthens internal management and builds an elite team, and will: all for users throughout the whole process of economic management, for this purpose, to provide customers with high-quality products and excellent services.


FAQ
1. Q: Are you a factory or a trading company?
A: We not only have our own factories but also have shares in some other enterprises.
2. Q: Can you provide samples?
A: Yes, if the sample is available in stock.
3. Q: Can you arrange the shipment?
A: Sure, we have permanent freight forwarder who can gain the best price from most ship company and offer professional service.
4. Q: What is the delivery time?
A: It is based on the order, normally 15 - 20 days after receiving the deposit or L/C at sight.
5. Q: Do you have quality control?
A: Yes, we have gained BV, SGS authentication.
6. Q: What are your payment terms?
A: 100% irrevocable L/C at sight. Or T/T, 30% advance, and balance against the copy of B/L within 3-5 days.
7.Q: What is your MOQ?
A: 10 tons for common size, or mix sizes for a 20 GP container.