PRIME STEEL PIPE: lsaw steel pipe manufacturer

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2016/06/29

Difference between Hot Stretch Reducing Pipe and LSAW Steel Pipe

Difference between hot stretch reducing pipe and LSAW steel pipe are basically has the following two points:

1, Resulting in differnce on product quality due to the different processes, hot stretch reducing

also carried out a process after high-frequency welding process that lsaw steel pipe can not found ------ Longitudinal are no clear line inside and outside burrs. Burr presence will affect the tube fluid - flow, burr block the normal flow of fluid, resulting in a whirlpool. According to principles of fluid mechanics, welding must increase local compression, discontinuity make pipe safety factor is also greatly reduced, hot stretch reducing steel production process - fully taken into account the existence of the risk of burrs, to limit burr removal, making it uniform thickness, no difference in the appearance and seamless. So from this point of view, hot stretch reducing pipe joints also completed the transition seamless.

2, Weld quality directly determines the quality of welded pipe, seamless pipe is welded with the greatest difference lies. Longitudinal after the high-frequency welding, straight seam set carbon can not be eliminated, weld and the parent just join together and not completely fused into one - could not stand the test of time and pressure. Hot stretch reducing high-frequency welding steel pipe after heating to go through the whole, the overall annealing temperature of 800 degrees, and then open the change process, after which a series of processes, the weld and the parent organization performance - has been the same for the complete melting one, well done from the seam to a seamless transition.

2016/06/16

Quality Problems of LSAW Steel Pipe

In the LSAW steel pipe production process, because the primary process is in a hot state, so the heating operation is resolution product quality is very important process.

The heat with the furnace, according to their results, and reheating furnace is divided into two kinds; the former is used to billet heated from room temperature to the processing temperature; the latter is used in the process in the blank reheated to the required processing temperature.

Heating will be wrong in the outer surface of the tube surface may exhibit cracks, folds and migraine pain and other waste reason.

Furnace There are many ways, but the primary use is a ring furnace. This furnace has an annular hearth, it can slowly change the direction of the diameter of the blank along the bottom of the load from the entrance, a reversal can be used at the outlet of the heating and soaking temperature to the rule kind of stove. This operation is the key blank is heated uniformly heated to a temperature suitable for processing. Because a great impact on the quality of the perforation, that is, when the temperature of the process piercing is an important condition affecting the quality, it is generally the temperature of the billet piercing working is to manipulate.

2016/03/09

Insulation corrosion process on LSAW Steel Pipe

Applying insulation corrosion process on LSAW Steel Pipe is to slow down or prevent the chemical out of the media so as to ensure the steel pipes can be applied in different environment condition for a certain period of time.

LSAW Steel Pipe insulation corrosion performance advantages are as below:

1. Good insulation properties. The heat loss is only 25% of the traditional double submerged arc welded pipe. In the long run, it can save a lot of energy, reduce energy costs significantly.

2. Highly waterproof and corrosion resistance. The insulation corrosion LSAW Steel Pipe can be directly buried in the ground or water without attached trench. It is simple and rapid construction, and also low total cost.

3. Double submerged arc welded pipe still have good corrosion resistance and impact resistance at low temperatures. It can be directly buried permafrost.

4. The application life time can up to 30 to 50 years. Proper installation an use can double submerged arc welded pipe maintenance cost low.

5. It is allow to set alarm system. It is allowed to realize the leakage fault detection and accurate fault location and automatic alarm indication.

2016/02/29

Difference between Hot Stretch Reducing Pipe and LSAW Steel Pipe

Difference between hot stretch reducing pipe and LSAW steel pipe are basically has the following two points:

1, Resulting in differnce on product quality due to the different processes, hot stretch reducing also carried out a process after high-frequency welding process that lsaw steel pipe can not found ------ Longitudinal are no clear line inside and outside burrs. Burr presence will affect the tube fluid - flow, burr block the normal flow of fluid, resulting in a whirlpool. According to principles of fluid mechanics, welding must increase local compression, discontinuity make pipe safety factor is also greatly reduced, hot stretch reducing steel production process - fully taken into account the existence of the risk of burrs, to limit burr removal, making it uniform thickness, no difference in the appearance and seamless. So from this point of view, hot stretch reducing pipe joints also completed the transition seamless.

2, Weld quality directly determines the quality of welded pipe, seamless pipe is welded with the greatest difference lies. Longitudinal after the high-frequency welding, straight seam set carbon can not be eliminated, weld and the parent just join together and not completely fused into one - could not stand the test of time and pressure. Hot stretch reducing high-frequency welding steel pipe after heating to go through the whole, the overall annealing temperature of 800 degrees, and then open the change process, after which a series of processes, the weld and the parent organization performance - has been the same for the complete melting one, well done from the seam to a seamless transition.

Transverse Cracks Maintenance of LSAW Steel Pipe

Transverse crack after lsaw steel pipe measures rework appear, specifically:

1. Confirm defect
All welds 100% UT inspection, crack marked location, length, depth and direction. If the entire weld has defects, the proposed dig out the entire re-submerged arc weld, partial repair is recommended SMAW.

2, Planing preheat
Preheating temperature is 110-170 ℃, preheating temperature weld both sides of the detection position is not less than 150mm, the heating is within the range of from defects around 500mm.

3, Gouging
Gouging out both ends of the range of cracks, weld integrity is not less than 50mm Outbound middle gouging, gouging ends gently to smooth the transition, the transition surface and a vertical line at least greater than 45 °. Gouging carbon rod angle should be at 60 ° or less, particularly in the crack to arrive at an angle as small as possible.

4, Polished
Polished to no black, polished surface after the transition should be smooth, there should be no sharp pit.

5, PT
After cooling to an appropriate temperature do penetrant testing (PT).

6, Polishing
PT based on test results, for grinding, grinding to no red line so far.

7, MT
After grinding to do magnetic particle testing (MT), confirmed that no residual crack, or should continue to polish until the MT is not detected until cracks.

8, Preheat
Recommended preheating temperature is 110-170 ℃, preheat temperature detection position of both sides of the weld is not less than 150mm, 500mm weld heating within the range of distances.

9, Welding
Welding operations carried out in accordance with the instructions, the bead width not exceeding 15mm, can lanes on the lane. Can SMAW or automatic submerged arc welding process.

10, After welding, insulation, slow cooling

11, Post-weld heat treatment
PWHT is mainly diffusion of hydrogen, lower residual stress after welding for stiffness weldment have devoted to "eliminate the hydrogen treatment," "stress relief heat treatment." Recommended heat treatment system are: immediately after completion of welding heat to 200 ℃ with a ceramic blanket, power off after slow cooling insulation 2h.

12, After the welding detection
After welding is completed 48h, according to the requirements of NDT inspection to confirm repair qualified.

Requirements of Large-caliber LSAW Steel Pipe Performance to Construction

In addition to large-caliber lsaw steel pipe as a structural material generally has good mechanical and process performance, but also has the use of stainless steel corrosion environment, maintaining the appearance of fine excellent characteristics, but also with acid and alkali resistance, high stainless steel pipe temperature, low temperature resistance, excellent magnetic properties, wear and other functions. Stainless steel pipes and other metal materials have been widely used in construction projects also has the following characteristics compared.

1) Large Diameter Longitudinal has a high specific strength and specific stiffness. Specific strength and stiffness of structural engineering in the selection of materials two basic parameters. Strength is the ratio of strength and weight, high-strength steel for the 52 different types of stainless steel pipes in different state than the intensity of the heat treatment may be in the range of 46 to 152, while the aluminum alloy commonly used is 48, copper alloy 17 zinc alloys 16.9. Specific stiffness elastic modulus (Young's modulus) E ratio and proportion of material of high strength steel was 25.5, ferritic stainless steel pipe of 25.6, austenitic stainless steel pipe of 25.3, 25.5 aluminum, copper alloy one of 12.1, 14.1 zinc alloy, stainless steel pipe also shows the structure of "lightweight materials" ideal material.

2) Good high temperature strength and low temperature toughness. Compared with ordinary carbon steel, large diameter longitudinally welded pipes of high temperature performance is much better, so they have better fire performance, common carbon steel at about 400 ℃ loses its load-bearing function, and stainless steel pipe before structural damage can withstand up high temperature of 700 ℃, reportedly suffered 9/11 and the collapse of the US plane hit a skyscraper is due to a large number of aviation gasoline combustion and the temperature is too high resulting in complete loss of load-bearing steel structures function collapse, stainless steel pipe having a good impact toughness, especially at low temperatures more than ordinary carbon steel is much better, you can ensure durability and safety of the building structure, steel structure when subjected to external force (such as collisions, earthquakes, etc.) and curved, structural strength stainless steel pipe becomes very high. Stainless steel pipe manufacturer

3) Good processing performance. Large-caliber Longitudinal plastic, ductile, excellent molding capability, ease of molding, made of thin-walled structures, and can be molded at the same time strengthened, when the structural member after the molding process appear more safeguard its overall performance important.

4) Stainless steel pipe long service life. Depending on the use of the environment, the rational use of stainless steel pipe built engineering structures has a long life, no or very little need for maintenance features, from building life cycle cost analysis, ordinary steel needs an overhaul every 25 years or replace, The large diameter longitudinally welded pipes was Bainiantaiji, compared with the life cycle of various building materials of stainless steel pipe lowest cost, for large-caliber Longitudinal member due to local change and replace, the recycling rate is high, large-caliber Longitudinal itself The recycling rate of up to 100%.

2016/01/27

Pre-welding process for LSAW Steel Pipe

LSAW steel pipes (UOE, JCOE) manufacturing processes, welding processes are set to continuous advance. Its role is to be finalized after the tube forming, shaping and positioning within the weld seam on the back cover, in order to ensure the pipe dimensions and is conducive to tube welded pipe to improve quality and production efficiency.

Pre-welding process
After forming the tube by the next roller conveyor transported to a pre-welder's torch, rising rotating roll, rotate to adjust an open position to weld at the top of both sides of the pressure on the pressure roller and the pressure roller so that the tube seam, drop gun and adjust the tracking of the weld seam, open the protective gas and cooling water, start welding, welding condition monitoring, welded to the tube end welding arc stops (automatic delay stop gas), lift the gun and the top pressure rollers, pipe welder pre sent , pipe ends and welding defects.

Pre-welding process characteristics
Pre-welding using Ar + CO2 mixed gas shielded arc welding, continuous welding seam on the back of the tube to move at a faster speed. Since the bevel angle, tube shape, the tube along the longitudinal direction of the opening and both sides of the plate edge distortion factors of inequality, forming the seam after seam quality is not stable, larger changes. Need to change the tube seam welding, the arc of a steady state, the weld position deviated from the case and other real-time tracking and adjusted accordingly. Thus presoldered have welding speed, impact seam quality factors, changes and adjustments randomness and other characteristics. info@primesteeltube.com