What is a SSAW pipe?
Spiral submerged arc welded steel pipe is a kind of metal pipe with spiral seam welded by submerged arc welding technology.
SSAW pipe is made of hot rolled coiled steel by automatic submerged arc weld under normal atmospheric temperature. All the pipes are produced according to API Spec 5L, GB/T9711.1, GB/T9711.2, ASTM A252-89 standard. These pipes mainly used in petroleum and natural gas industry to transport flammable and non-flammable liquid and steel construction.
- (O.D×Wall Thickness)mm×Length(mm)
- 219-3200mm×5-30mm x 12000mm+500mm
In addition to above specification, the pipes can be produced according to customer’s requirements.
- ASTM A252-89 WELDE AND SEAMLESS STEEL PIPES PILES
- API SPEC 5L Specification for Line Pipe
- GB/T9711.1 Petroleum and natural gas industries—Steel pipe for pipelines—Technical delivery conditions
- SY/T5037 Spiral submerged arc welded pipe for low pressure liquid transportation
Q235-Q345, L175-L485, SS400, 16Mn, L290-L360 or according to the customer’s requirements.
Spiral welded steel pipes are widely used in Oil, Natural Gas, Water and other flammable & nonflammable liquid conveyance and distribution pipelines, steel structures for construction and other general purposes by means of their wide size range.
Pipe Coating: HDPE/ 3PE/ 3PP/ Pipe cement mortar lining
Mill Test Certificate: EN 10204/3.1B
Third party inspection: SGS, BV, Lloyds etc.
Classfication of SSAW Steel Pipe
|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|
|Standard||Grade||Chemical Composition(max)%||Mechanical Properties(min)|
|C||Si||Mn||P||S||Tensile Strength(Mpa)||Yield Strength(Mpa)|
|API 5L PSL1||A||0.22||–||0.90||0.030||0.030||335||335|
|API 5L PSL2||B||0.22||0.45||1.20||0.025||0.015||415||415|
|Standard||Tolerance of Pipe Body||Tolerance of Pipe End||Tolerance of Wall Thickness|
|Out Diameter||Tolerance||Out Diameter||Tolerance|
|API 5L PSL1/PSL2||OD<60.3||-0.8mm～+0.4mm||OD≤168.3||-0.4mm～+1.6mm||WT≤5.0||≤±0.5|
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.
- (1) Raw materials that strip, wire, flux. Must go through rigorous testing before being put into the physical and chemical.
- (2) Strip head and tail docking, using single or double wire submerged arc welding, in rolled steel by automatic submerged arc welding.
- (3) Before molding, the strip after flattening, cutting, trimming, planing, surface cleaning and transportation to the curved edge treatment.
- (4) The use of electrical contacts on both sides of the conveyor control the pressure cylinder pressure to ensure the smooth delivery of the strip.
- (5) The use of internal or external control roll forming.
- (6) The weld gap control device to ensure that the weld gap to meet the welding requirements, diameter, volume and the wrong side of the weld gap have been strictly controlled.
- (7) The welding and soldering are used outside the United States Lincoln welding machine for single or double wire submerged arc welding, to obtain stable welding specifications.
- (8) After welding the weld line continuous ultrasonic injury checked to ensure 100% coverage of non-destructive testing of spiral weld. If defective, automatic alarm and spraying tags, production workers so adjusting the process parameters, and remove defects.
- (9) The use of air plasma cutting machine to cut a single tube.
- (10) Cut into a single pipe, each batch of steel should be carried out strict inspection system, inspection of weld mechanical properties, chemical composition, fusion status, steel surface quality and after NDT inspection process to ensure that qualified pipe before they can formally put into production.
- (11) There is a continuous sonic flaw marks the site of the weld, manual ultrasonic and X-ray review, if there are defects after repair again after destructive testing until confirmation defect has been eliminated.
- (12) Steel butt weld and spiral weld intersects with D-type connector where the pipe all through the X-ray television or film examination.
- (13) Each pipe hydrostatic test pressure radial seal. Test pressure steel pipe pressure and time by computer testing device strictly controlled. Test parameters are automatically printed record.
- (14) Pipe end machining, so that the end vertical, blunt edge bevel and accurate control.
Spiral Seam Annealing Systems:
Outside Diameter Control
X-Ray Testing Online
Welding of hot rolled steel coils takes spiral form after passing through preforming and forming rolls. Excellent exterior weld quality at high production speeds is provided by double submerged arc welding process. Manufactured pipes are cut to the desired lengths at the exit of the pipe machine. Pipe ends are beveled by means of carbide machining for accurate on-site welding.
After the pipe is conveyed to hydrostatic testing and off-line ultrasonic testing and/or real time X-ray inspection, the pipe will be subject to final inspection for the compliance to customer requirements.
Starting from incoming control up to the final inspection stage; entire process is monitored and supported by computerized system. Traceability is achieved by input controls and barcodes through entire production lines.
Lincoln Welder Welding
SSAW pipe mills
High Frequency Welding
- Edge Planing Machine: Planing machine, which is made mounts, active seats, conveying, pneumatic platen mechanism, screw drive mechanism and knife mechanism, compressed air station, hydraulic station and electric control system, etc., screw drive mechanism is mounted on a fixed activities within the seat and seat.
- Edge Milling Machine: Milling Machine planing machine as an alternative to products with high efficiency,high precision, low power consumption advantages. For beveling various shapes carbon steel plates are particularly suitable. General 5-40mm thickness, 15-50 degrees arbitrary regulation.
- Pipe Cutting Machine: Automatic pipe cutting machine can automatically clamp the material, feed, feeding, size setting, stop and work a set number of metering unctions.
- Butt Welding Machine: Also called current welder welder or resistance butt welding. By a resistance between the two contact surfaces of the workpiece, by a low voltage high current moment, the contact surface of two mutually abutting metal instantaneous heating to melt and fuse.
- Pinching Machines: Pinching machines,including machines,rails,fixed clamping block,activities clamping block and cylinder;the machine table surface provided with the rail and the fixed clamping block the rail in close proximity to one end of the stationary clamping block.
- Hydraulic Test Machine: Hydraulic test machine is a sewing after the equipment. Equipped with automatic gas booster pump gas drive, you can easily achieve the output pressure is adjustable and controllable. Advanced technology, reasonable structure design. With small size, light weight, looks nice features.
Because ssaw steel pipe can be made by a coil width continuous forming welding production, easy automation, and using double-sided automatic submerged arc welding type, there are a variety of testing method to check weld quality assurance checks. Therefore, when laying oil pipelines, spiral welded pipe has been widely used. However, in forming the welding process, the process by mistake or due to other reasons mature operation, resulting in a variety of pipe defects generated.
Lack of fusion
No penetration weld means between the base metal and the base metal, not the spaces left by the arc melting, the double-sided spiral welded pipes produced generally in the middle of the weld. Due to the use of double-sided spiral submerged arc welded pipe, it is not automatic weld penetration welded joints of the causes, which is too small for the gap, too small welding current and welding speed is too fast, or if improper wire angle welding arc is caused by partial blow When it is not prone to partial penetration.
Porosity and slag
Porosity in the weld pool is absorbed much of the high temperature gas and the cooling gas in the melting of the metal in a sharp decline in the residual gas is too late to escape, which is formed in the weld metal. Porosity can be divided into isolated pores, pore density, porosity and worm holes chain, are generally a number of factors can lead to gas welding process are the cause of porosity. Gas pores in the weld formed primarily of hydrogen and carbon monoxide, which ray intensity attenuation tends to zero, therefore, appears as black holes is greater than the background image porphyritic blackness, blackness generally larger, image clarity is easy to identify.
Crack is harm serious welding defects, as well as the common defects in welding seam. Cracks in the welding stress-induced embrittlement and other factors together, the binding force of welded joints of metal atoms localized destruction and the formation of the new interface (the gap). Cracks can be classified according to their causes hot cracking, cold cracking, reheat cracking, lamellar tearing, stress corrosion cracking. As the spiral welded pipe is generally of high quality carbon steel and low alloy steel materials, welding and heat treatment after the process is no longer carried out, so most of the thermal cracking and cold crack.
The difference between single-sided and double-sided welding of ssaw steel pipe
The influence of ssaw steel pipe production process factors on the quality of single-side welding double-sided forming welds mainly includes welding current, welding speed, number of welding layers, electrode type and electrode diameter.
- Welding current: The proper choice of the welding current size directly affects the final welding quality. Excessive welding current can increase the productivity and increase the penetration depth, but it is prone to defects such as biting and welding, and increases the tendency of stomata. In particular, when the vertical welding operation is difficult to control the molten pool, the occurrence of welding defects, arc length increases, the welding current is too small, the penetration depth is reduced, prone to defects such as incomplete penetration, poor fusion, slag inclusion, and disconnection. During the training, for those students who have just come into contact with welding, this is a difficult problem to grasp. During the single-sided welding of the board and board, the primary welding current is large, resulting in the back of our board there are many different sizes of welding. Bottom welding is too small, resulting in an unfused defect in our welding. This defect can directly lead to a significant reduction in weld quality, which is one of the important defects in industrial production.
- Welding speed: Welding speed is the main parameter to express the efficiency of welding production. Reasonable choice of welding courier is especially important for ensuring welding quality. The welding speed is too fast, so that the temperature of the bath is not enough, which may cause defects such as incomplete penetration, non-fusion, poor weld formation, and the like. The welding speed is too slow, so that the high temperature for a long time, the width of the heat affected zone increases, the grain of the welded joint becomes coarser, the mechanical properties decrease, the deformation of the weldment increases, and at the same time, the welding speed is too low and the thickness of each layer increases, resulting in slag backflow, the formation of slag inclusions and other defects. Cover welding speed.
- Improper selection of welding layers. The number of single-side welding double-sided forming welding layer also has a certain influence on the quality of the weld, each layer thickness is too large, the plasticity of the weld metal is detrimental, and the slag in the welding process is easy to reverse flow, resulting in slag and not Fusion and other defects, but the thickness of each layer is not too small, so as not to cause poor fusion on both sides of the weld.
- The shape of the electrode and the diameter of the electrode. The properties of the weld metal are mainly determined by the melting of the electrode and the weld metal. Therefore, whether the choice of wire type is appropriate or not is an important factor affecting the quality of the weld. In addition to the influence of the diameter of the electrode on the acoustic field rate, it also has a certain influence on the quality of the welding. The diameter of the electrode is too large and the underlying layer is under ground. The weld pool is difficult to control and it is easy to produce weld defects. What kind of base metal, choose the welding material with the same properties as the base metal. The choice of welding diameter is too large. We can hardly weld a good weld on the back of the test plate.
Difference Between LSAW Steel Pipe and SSAW Steel Pipe
Difference between LSAW steel pipe and SSAW steel pipe are followings below:
- The welding process is concerned: a consistent spiral welded pipe and Longitudinal welding, straight seam steel pipe will inevitably have a lot of T-weld, and therefore the probability of the existence of welding defects has greatly improved, and welding residual T welds stress is large, the weld metal are often in three-dimensional stress state, increases the likelihood of cracks. Furthermore, according to the provisions of submerged arc process, each weld shall have the arc at the place and extinction, but in each Longitudinal seam welding ring, unable to meet the conditions, which may have a place in the extinction more weld defects.
- When the pressure in the pipe to withstand, typically produces two main stress on the wall, that the radial and axial stress δ . Weld resultant stress δ, wherein the helix angle of the weld.
- Spiral Weld Pipe degree helix angle is generally, therefore synthetic spiral weld stresses are the principal stresses. Under the same operating pressure, spiral pipe of the same diameter than the Longitudinal wall thickness can be reduced.
- The hydrostatic burst strength: by the relevant comparison test, to verify the yield pressure and burst pressure measured and theoretical values spiral pipe and Longitudinal basic agreement, deviation close. But neither the yield stress or burst pressure, spiral pipe were lower than Longitudinal. Blasting test also shows spiral steel hoop blasting mouth deformation rate significantly greater than the Longitudinal. It was thus confirmed, spiral pipe plastic deformation than Longitudinal, blasting the mouth is generally confined to within a pitch, which is spiral weld for expansion gap played a powerful role in binding due.
- Toughness and fatigue strength: pipeline development trend of large diameter, high strength. With the increase of the diameter of the pipe, the steel grade increase, resulting in greater the ductile fracture tip steady expansion trend. Spiral pipe and Longitudinal although the same as a level, but the spiral steel pipe has a high impact toughness.
- Because of the transfer line output volume changes: in actual operation, the pipe is subjected to random alternating loads of action. Learn low cycle fatigue strength of steel, judging life of the pipeline is of great significance.
- Press the measuring result: fatigue strength spiral steel seamless and ERW pipe with the same test data and seamless pipe distribution and resistance in the same area, while Longitudinal submerged arc than the average higher.
Source: China SSAW Steel Pipe Manufacturer – Yaang Pipe Industry Co., Limited (www.pipelinedubai.com)
(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)
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