PRIME STEEL PIPE: submerged arc welded steel pipe

Showing posts with label submerged arc welded steel pipe. Show all posts

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.

2016/01/14

Order---SSAW Steel Pipe shipped to Nigeria

Product: SSAW steel pipe, Spiral Submerged Arc Welded, Carbon Steel
Standard: API 5L PSL1 GR.B
Specification: 1000mm*20mm*29.2meters
Surface: 3PE anti-corrosion coated
Ends: Plain End
Quantity: 896 Tons
Production Time: 35 days
Destination: Nigeria info@primesteeltube.com