Appearance Disadvantages of ERW Pipe

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Appearance Disadvantages of

ERW Pipe

The appearance defects of welded pipes include long knife bends, wavy bends, gnawed edges, scars, scratches, embossing, uneven head and tail, tower-shaped rolls, loose rolls, surface oxide scale, etc.

The appearance defects of welded pipes include long knife bends, wavy bends, gnawed edges, scars, scratches, embossing, uneven head and tail, tower-shaped rolls, loose rolls, surface oxide scale, etc.

1.Long knife curve

This is caused by the uneven deformation of the hot-rolled strip in the width direction on both sides during the cold rolling process. It bends to one side along the length of the hot-rolled strip on the horizontal plane, or is called a crescent bend. Hot rolled steel strip. Long knife-bent welded pipes can easily cause lap welding during production and processing, and the direction may shift or even rotate during forming.

2. Wavy bend

This is the continuous vertical bending of the edge part of the hot-rolled strip; it is caused by the uneven deformation of the center and edge along the width direction of the hot-rolled strip during cold rolling. The corrugated elbow will cause severe overlap welding during forming welding and cannot be processed, so it is not allowed to appear.

3. Bite the edge

This is the phenomenon of jagged unevenness on the edge of hot-rolled strip, which usually occurs on slit hot-rolled strip. The reason is that the disc scissors of the slitting machine are broken, dull or chipped. Hot-rolled strips with severe undercuts will have some cracks and gaps during electric welding, endangering the welding quality and reliability.

4. Scabs, indentations, scratches, uneven head and tail

Strain and embossing are caused by dirt sticking to the rolls during cold rolling. Scratches are caused by the hot-rolled strip being scratched by dirt on the roller table or floor during travel, especially when the cold-rolled strip is not oiled. The uneven head and tail are caused by the hot-rolled strip not being uncoiled and cut directly after cold rolling. This defect causes the appearance quality of the welded pipe to be unqualified and must be rejected or judged to be scrapped, which reduces the yield and qualification rate of the welded pipe.

5. Tower Roll

Pylon-shaped coils arrange ten hot-rolled steel strips from the inner ring to the outside to obtain hot-rolled steel strip coils, which are generally not allowed to exceed 50mm.

6. Loose rolls

Slightly loose coils can be used after sorting. Severely loose coils cannot be used because they cannot be sorted and must be cut into loose parts, which increases the consumption of metal materials and reduces the yield.
Cause: The packaging is not firm and does not meet the packaging requirements; poor operation during loading and unloading;

7. Surface oxide scale

1.Long knife curveThis is caused by the uneven deformation of the hot-rolled strip in the width direction on both sides during the cold rolling process. It bends to one side along the length of the hot-rolled strip on the horizontal plane, or is called a crescent bend. Hot rolled steel strip. Long knife-bent welded pipes can easily cause lap welding during production and processing, and the direction may shift or even rotate during forming.2. Wavy bendThis is the continuous vertical bending of the edge part of the hot-rolled strip; it is caused by the uneven deformation of the center and edge along the width direction of the hot-rolled strip during cold rolling. The corrugated elbow will cause severe overlap welding during forming welding and cannot be processed, so it is not allowed to appear.3. Bite the edgeThis is the phenomenon of jagged unevenness on the edge of hot-rolled strip, which usually occurs on slit hot-rolled strip. The reason is that the disc scissors of the slitting machine are broken, dull or chipped. Hot-rolled strips with severe undercuts will have some cracks and gaps during electric welding, endangering the welding quality and reliability.4. Scabs, indentations, scratches, uneven head and tailStrain and embossing are caused by dirt sticking to the rolls during cold rolling. Scratches are caused by the hot-rolled strip being scratched by dirt on the roller table or floor during travel, especially when the cold-rolled strip is not oiled. The uneven head and tail are caused by the hot-rolled strip not being uncoiled and cut directly after cold rolling. This defect causes the appearance quality of the welded pipe to be unqualified and must be rejected or judged to be scrapped, which reduces the yield and qualification rate of the welded pipe.5. Tower RollPylon-shaped coils arrange ten hot-rolled steel strips from the inner ring to the outside to obtain hot-rolled steel strip coils, which are generally not allowed to exceed 50mm.6. Loose rollsSlightly loose coils can be used after sorting. Severely loose coils cannot be used because they cannot be sorted and must be cut into loose parts, which increases the consumption of metal materials and reduces the yield.Cause: The packaging is not firm and does not meet the packaging requirements; poor operation during loading and unloading;7. Surface oxide scale

Casting defects can result from scale entering the weld zone between the edges of hot rolled strip. In addition, the compound flakes on the surface of the hot-rolled strip enter the forming machine and accelerate the damage of the forming roll. Hot-rolled strips with severe scale must be descaled.

As industrial applications have evolved and grown more complex, the piping products and systems that serve them have had to keep pace.

While many pipe manufacturing methods exist, the most prominent discussion in the industry compares electric resistance welded (ERW) vs. seamless (SMLS) steel pipe.

Both ERW and seamless steel pipe manufacturing methods have been in use for decades; over time, the methods used to produce each have advanced. So which is better?

Manufacturing welded pipe

Welded pipe starts out as a long, coiled ribbon of steel called a skelp. The skelp is cut to the desired length, resulting in a flat rectangular sheet. The width of that sheet&#;s shorter ends will become the pipe&#;s outside circumference, a value that can be used to calculate its eventual outside diameter.

The rectangular sheets are fed through a rolling machine that curls the longer sides up toward one another, forming a cylinder. In the ERW process, high-frequency electrical current is passed between the edges, causing them to melt and fuse together.

An advantage of ERW pipe is that no fusion metals are used and the weld seam cannot be seen or felt. That&#;s opposed to double submerged arc welding (DSAW), which leaves behind an obvious weld bead that must then be eliminated depending on the application.

Contact us to discuss your requirements of Erw Steel Pipe. Our experienced sales team can help you identify the options that best suit your needs.

Additional resources:
Everything You Need To Know About Pipe Clamps

Welded pipe manufacturing techniques have improved over the years. Perhaps the most important advancement has been the switch to high-frequency electric currents for welding. Prior to the s, low-frequency current was used. Weld seams produced from low-frequency ERW were more prone to corrosion and seam failure.

Most welded pipe types require heat treatment after manufacture.

Manufacturing seamless pipe

Seamless piping begins as a solid cylindrical hunk of steel called a billet. While still hot, billets are pierced through the center with a mandrel. The next step is rolling and stretching the hollow billet. The billet is precisely rolled and stretched until it meets the length, diameter and wall thickness as specified by the customer order.

Some seamless pipe types harden as they&#;re manufactured, so heat treatment after manufacturing is not required. Others do require heat treatment. Consult the specification of the seamless pipe type you&#;re considering to learn whether it will require heat treatment.

Historical perspectives and use cases for welded vs. seamless steel pipe

ERW and seamless steel piping exist as alternatives today largely due to historical perceptions.

Generally, welded pipe was considered inherently weaker because it included a weld seam. Seamless pipe lacked this perceived structural flaw and was considered safer. While it&#;s true that welded pipe does include a seam that makes it theoretically weaker, manufacturing techniques and quality assurance regimens each have improved to the extent that welded pipe will perform as desired when its tolerances aren&#;t exceeded. While the apparent advantage is clear, a critique of seamless piping is that the rolling and stretching process produces an inconsistent wall thickness compared to the more precise thickness of steel sheets destined for welding.

The industry standards that govern the manufacture and specification of ERW and seamless steel pipe still reflect those perceptions. For example, seamless piping is required for many high-pressure, high-temperature applications in the oil & gas, power generation and pharmaceutical industries. Welded piping (which is generally cheaper to produce and is more widely available) is specified across all industries as long as the temperature, pressure and other service variables do not exceed parameters noted in the applicable standard.

In structural applications, there&#;s no difference in performance between ERW and seamless steel pipe. While the two can be specified interchangeably, it wouldn&#;t make sense to specify for seamless when cheaper welded pipe works equally well.

Good purchasing practice for welded and seamless steel pipe

An important note to make as piping products are specified for a project is that the specification books (such as those provided by ASTM, ASME, ANSI and API, among others) that engineers use to guide the specs they write only list pipe grades without referencing whether they&#;re produced via ERW or seamless pipe manufacturing. Not all grades can be produced by both means.

For example, a potential mix-up can occur if an engineer specifies welded pipe with a large outside diameter and wall thickness without knowing it would be impossible to manufacture it. This error would likely go unnoticed until a purchase order is placed, at which time a pipe supplier would notify the customer that the order couldn&#;t be fulfilled as written.

Also, a good grasp of industry standards could lead to cost savings. The A106 and A53 carbon steel pipe standards are a good example. In this article, we discuss how pipe complying with the former must be seamless while pipe complying with the latter can either be seamless or welded. For example, if an engineer must follow the A53 standard on a given project, he or she may still have the flexibility to choose which type to specify based on the specifics of the application.

Show us your specs, request a quote and get your pipe fast

American Piping Products stays fully-stocked with the best inventory of welded and seamless steel piping products in the industry. We source our stock from mills around the world, ensuring buyers get the pipe the need faster regardless of any applicable statutory restrictions.

In our steel pipe buyer&#;s guide, we&#;ll help you navigate the piping procurement process from start to finish to ensure you get what you need as quickly as possible when it&#;s time to buy. If a piping purchase is in your near future, request a quote. We&#;ll provide one that gets you exactly the products you need&#;fast.

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