Seamless Pipes: An Overview

Seamless pipes are one of the main classifications of pipes. Let’s make a brief introduce about they’re manufactured and some of the potential benefits they present.

Manufacturing.

What makes a seamless pipe seamless is how it’s manufactured.

In contrast to welded pipes, which are made by rolling a flat plate into the shape of a pipe and then welding the seam, seamless pipes are made by drawing a solid billet over a piercing rod. This forms a hollow inner shell and creates pipes without seams.

Ability To Withstand Pressure

It’s this lack of a seam that give seamless less pipes their greatest advantage: an improved ability to withstand pressure. 

In welded pipes, the seam is the point that’s most susceptible to failure. By definition, seamless pipes don’t have that weak point, allowing them to have equal strength around the entire pipe. This lack of a seam also makes pressure calculations easier, as you don’t have to take the weld quality into account.

Shape Uniformity

Manufacturing welded pipes involves a number of variables that can affect the shape of the pipe, including rolling the plate before the weld and adding heat during the welding process. These factors mean that the shape can not always be relied upon to be uniform.This is not the case for seamless pipes. Their manufacturing process eliminates many of those extraneous forces, meaning the pipes can be more uniformly round.

Ability To Bear Load

Pipes must support not only their own weight, but also the weight of the fluid flowing through them. Leaks often happen at the welded seams, which gives seamless pipes a leg up over welded pipes.

Magnetic of Carbon Steel Pipe

Residual magnetism causes and impact on quality of welding 

When the gas pipeline construction and repair welding operations, sometimes magnetic blow phenomena affect the welding process. Forming a magnetic blow is the result of the presence of residual magnetism in the pipe metal. Typically, the magnetic induction and magnetic remanence divided into two processes. Magnetic induction in plants often produce tube links, such as: metal smelting, using electromagnetic crane for loading and unloading, pipe parked or garaged in a strong magnetic field, the magnetization is completed nondestructive inspection method, the pipe is placed close to power lines and so strong. Processes often produce magnetic welding operations during the assembly and the use of a magnetic holder, fixture and took DC welding pipes, such as: prolonged contact is connected to a DC power supply electric wire, bare wire segment or short-circuit pipe welding clamp and so on. 
When welding with magnetic steel, often difficult to see the arc ignition, combustion undermine the stability of the arc, the arc of the deviation, the liquid metal and slag melt the spill from the weld pool in a magnetic field. In order to stabilize the welding process and improve the quality of the welded joint, the steel is magnetized to demagnetized before welding. It should be noted, to be welded steel pipe is difficult to achieve full demagnetization. Therefore, when the remanence is insufficient to affect the quality of welding, it allows welding. 

Magnetic elimination of carbon steel pipe process 

1 to determine the size and direction of the pipe left field; 
2 Select the degaussing method, system diagrams and technical means; 
3 butt welded steel pipe or at the degaussing degaussing with the selected method; 
4 After checking the amount of residual magnetism after degaussing, to see if it meets the requirements.

The Benefits of Seamless Steel Pipe

The seamless steel pipe manufacturing process starts with a solid, round steel billet. This billet is then heated to great temperatures and stretched and pulled over a form until it takes the shape of a hollow tube.  All steel pipe suppliers will tell, there are three great advantages to making a pipe in this way.

Increased Pressure Ratings

The greatest advantage of seamless steel pipes is their increased ability to withstand pressure. The weakest point in a welded steel pipe is the welded seam. But because a seamless steel pipe has not been welded, it doesn’t have that seam, making it equally strong around the entire circumference of the pipe.

It is also much easier to determine pressure calculations without being required to take weld quality into consideration.

Although seamless pipe can sometimes be more expensive than welded pipe, this increased ability to withstand pressure allows you to use pipes that are thinner and lighter, which can help cut down on expenses.

Uniformity of Shape

Because welded seam pipe is wrapped around another form before it is welded, and because welding adds heat, stress and other extraneous variables to the forming process, it can never be as round as seamless steel pipe.

Seamless steel pipe is a continuous extrusion of the alloy, meaning that it will have a round cross section that you can count on, which is helpful when you’re installing pipes or adding fittings.

Strength Under Loads

Seamless steel pipe can sometimes be more expensive than other forms of steel pipe, but it’s also more reliable.

This is because it has greater strength under loading. Empty pipe must always support its own weight, but when a pipe is filled with material–or under load–it must also support that weight as well. Pipe failures and leaks in welded pipes usually occur at the welded seam. But because seamless pipe doesn’t have that seam, it isn’t subject to those failures.

These benefits make seamless steel pipes the preferred material in an array of commercial pipe applications, including ship building, pipelines, oil rigs, oil field equipment, pressure vessels, machinery parts and offshore rigs. An additional benefit of seamless pipes is that they perform well in harsh conditions, which means that they can be used in extremely cold or hot environments.

If you’re considering seamless steel pipes for your next commercial pipe project, please get in touch with us and request a quote. As a leading international steel pipe supplier, we can provide you with the products you need and quickly ship your order to anywhere in the world.

The quality of ERW steel pipe can be affected by the raw materials

We know the quality of the raw materials have a deep influence on the quality of the ERW steel pipe, but how? Below we will discuss how the quality of steel trips influence the quality of ERW steel pipe during the production.

1.Why the mechanical properties of the steel trips can affect the quality of ERW steel pipe?

For ERW steel pipe, the commonly used steel type is carbon steel. The steel standard and grade includes API 5L GR.B -X70, ASTM A53 GR.A/B/C, ASTM A500 GR.A/B/C etc.

If the strip yield point and tensile strength is too high, it will cause difficulties during the steel strip forming. Specially for producing thick wall ERW steel pipe, cracking is easy to happen during pipe welding due to the large resilient materials, large deformation stress. When the tensile strength of steel strips exceeds 635 MPa and elongation less than 10%, cracking can be happen during the welding process. When the tensile strength is less than 300MPa, the strip material in the molding process can easily have a wrinkled surface, because the low tensile strength means soft physical properties. Therefore, the mechanical properties have great influence on the quality of ERW steel pipe. Particularly, the tensile strength of the material effectively controlled the quality of the ERW steel pipe.

2.How the impact on the steel strips surface defects influence the quality of ERW steel pipe?

The steel strips surface defects includes common camber, wavy edge slitting etc. Camber and

wavy are generally appeared in the cold rolled strip rolling process, it is controlled by the  improper reduction. During the ERW steel pipe forming process, camber will cause steel strips deviation or flip.

Uneven strip edge is generally appeared in the slitting, the slitting machine causes the disc blade blunt or sharp result. Because of the uneven strip edge, the steel strips might have unexpected crack which affect the stability of the welding quality.

3.Why the steel strip geometry will influence the quality of ERW steel pipe?

When the width of steel strips is less than the tolerance, the pressing force will be reduced. It will cause unstable welding seam or welding seam cracking. When the width of steel strips is greater than the tolerance, the squeeze pressure increased, it will cause burrs or lap welding and other welding defects. Therefore, the fluctuations of the steel strips width, can affects the accuracy of the outer diameter of the steel pipe. Also, it can seriously affect the quality of the surface of the steel pipe.

The fluctuation of the steel strip thickness can affect the accuracy of the finished steel pipe thickness. If the steel strips have vary thickness, it will cause unstable pressure force and welding temperature during the steel pipe welding process, in the end it resulting in unstable quality ERW steel pipe welding. Therefore, before steel pipe welding, we need to check each roll of steel strips surface quality as well as the geometry of each roll. For those does not meet the quality standard steel strips, we will not used for the production of ERW steel pipe to avoid unnecessary losses.

The factors affect the ERW steel pipe quality during production

In order to ensure the quality of ERW steel pipe during the production process, we need to analysis which factors will affect the product quality. Through a deep data collecting from our

 Φ76mm high frequency welding unit for a month, we believe that the ERW steel pipe quality will be affected by raw materials, welding process, the roll adjustment, roll material, equipment failure, the production environment etc. Among these factors, the raw materials accounted for 32.44%, welding process accounted for 24.85%, the roll adjustment accounted for 22.72%. These three factors are the main factors affect the ERW steel pipe quality during the production. While the roll material, equipment failure, and the production environment are the three factors only accounted for 19.99% which is defined as the less important factors. Therefore, during the ERW steel pipe production process, we need to focus on the factors matters which are raw materials, welding technology and roll adjustment.

Characteristics of Hollow Section When Roll Forming

Cold-formed steel, cold-formed rectangular tube through the one-way roller contacts the outer tube forming the outer wall so that the strip bending moment, bending line will produce cold-formed compression, the compression effect makes bend lines longitudinally elongated, bent accumulation of the metal appears thicker, which is cold-formed compression / thickening effect.

1) The advantage of cold-formed is small rebound, forming accurate, and as long as the roller type accurately, inside corner molding R more accurate. The advantage is that it can be cold-formed side bent when you can not be cold-formed, for example, square and rectangular tube top / side synchronous bending and finishing. You can also cold-formed bent R <0.2t inside corners and walls without fracture.

2) There is a disadvantage of cold-formed stretching / thinning effects. It will produce cold-formed bends stretch, stretching effect of the longitudinal length of the bend lines shortened; second, cold bending of the metal due to stretching and thinning. The disadvantage is cold-formed in the top / side of sync when cold-formed, since the upper and lower rollers while generating pressure, easy molding force beyond the critical point, causing instability concave edge, and can also affect the stable operation of units and forming quality.

The Story From the Financial Dept in Shinestar Group

In the corridor , you can always see the people rushed back to the office with a briefcase at lunch time. Who are they? They are our cute colleagues who work at financing department. They must to bank to take document in the morning and back to office to finish the process , but time is tight so they always have no time to have lunch.  

The financing department is a warm and harmonious team,which are made up of six young and

sunshine girls. Songyan , the manager of Financing department , a intellect, courageous and resolute girl.Li Jiangnan is the girl who hard-working and patience, careful girl, the smart and hard-working girl-Wang liyu , the less talking girl- Leng xiaoqian.

They have composed the Song of Youth with the diligent and achievements, this story is performed everyday in this office which is full of vigor.

Traveling long distances, and time for the race

The work of financing cooperation department  is a delicate and difficult task, it acts the bank settlement business and finance for the group and subordinate 16 subsidiaries .The area in changsha, hunan province as the center, but also include Hubei province,Tianjin city, Jiangxi province subsidiary bank business. Dealing with finance business, the loan may only be for one main body of the group , but the submitted data contains nearly all of the group's affiliates.

It is about 343km from Changsha to Nanchang,it may takes half an hour high-speed rail 

and one hour car journey to arrived  destination- Nanchang Economic and Technological 

Development Zone Industrial Park Baishuihu Changbei steel market.Owing the time is limited,Li Jiangnan need to put the dozens of file in order in a day,and than take the earliest high-

speed rain to Nanchang the next morning,so she had to stay in the bank  during the lunch breaks.and do the work as soon as possible,after she finished all the work,it is near the night.

it is a great challenge for person's spirit and physical strength work in this fast-paced and high -intensity atmosphere.but  co-financing unit colleagues need  to face every day and they have already accustomed.

Cold or Heat, Everything was done well.

Shinestar has 16 subsidiary company , float capital over 10 billion each year, it is not easy to running so much money well in today's downturn economic. Scheduling, financing, loans ..., each segment are serious and important, the lifeblood of Shinestar is in the hand of financing department which can not allow even a small mistake.

Song yan, joint in Shinestar Group at 2008, was a normal staff in Financing Department, after years hard-working , she was promoted to the manager of Group Finance Department. Years of experience in the finance management , which makes Song yan familiar with the company's operations and offer great help for external communication .

In order to do a good job in every loan, regardless of cold or summer, they often follow up on the banks to deal with multiple subsidiaries of loans at the same time. In snowy winter morning, Song Yan and Li Jiangnan go to the grass-roots branches and meet customer manager, prepare the loan company and related company information and deliver to the higher lending center audit. Before going to work in the afternoon, in order to rush to another deposit related bank, they continue on their way at noon without rest, and then return to the center from the lending margin deposit bank, submit a single run margin deposit and other information. Due to the banking business is busy, working overtime to squat in the bank after 18:00 still unable to finish the audit of all the day, Song Yan and Li Jiangnan can only wait until the next day to go to the bank to continue the review.Such examples are numerous in them, they regardless of cold, tirelessly runs. The wind is big, the road is far, but could not prevent the group of young people's passion and light.  

After intense work in the busy, they still keep the passion of learning. A bit of progress every day, it is this group of young people's motto. Discuss working together, their ideas, they put forward their own problems, looking for work together, and in your own work more attention, also enhance the tacit understanding between each other, for the next work node to bring more convenience.

They chose Shinestar, select the financing cooperation department, even in the most difficult moments, don't abandon, don't give up; they have devoted all efforts and enthusiasm. This is their business, but also their dreams; They pay obscurity, finally gratifying return. We feel from them, it is not only a man should have the dedication and Shinestar served, more pride and glory as a people Shinestar obtained. Ordinary jobs, ordinary people, but it is not ordinary youth, this is a story of our financing department.

Galvanized Steel

Galvanized steel is simply steel coated with zinc. After going through a process called galvanizing, in which steel is coated with zinc and a normal steel becomes a galvanized steel. This process is performed to avoid steel from rust and corrosion.

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Galvanized steel has thousands of industrial applications, especially marine

products. They are commonly used in marine applications because in that case the pipe fittings are subject to tough and wet conditions. It is not a new concept, in fact, it is being used from early times. Till 1850, over ten million tons of zinc was used to protect steel. There is a misconception about the galvanized steel.

Many people think that galvanized is a better product, but it is expensive and increases the overall cost. In fact, galvanized steel becomes less expensive when combined with its long life span. Galvanized steel studs cost almost half the price as compared to wooden studs that are most commonly used in buildings. Galvanized pipes are not used for  underground lines. It is relatively better to use for hot water lines, however, it also works good for cold water lines. Avoid using galvanized pipe fittings for gas supply lines as natural gas can cause the zinc to come off and cause blockages in the system.

Galvanized pipe fittings generally comes in size ranging from diameter of 1/8" to 20". These pipes are great value for money. No doubt galvanized steel pipes have various advantages, however, it has disadvantages also. One disadvantage is that the zinc coating can hide problems and defects beneath the coating which would otherwise be visible. And there are few more.

The important thing to remember is that whatever you choose, choose smartly. There is nothing on this planet that has only advantages, But there are things that have more advantages than disadvantages which makes them relatively better choice.

Pipe External Corrosion

Pipe external corrosion

1, Single FBE corrosion (FBE) Single-layerFBE Coating Epoxy powder layer because of its excellent corrosion resistance,insulation resistance and long service life and become an advanced anti-corrosion coating of the outer pipe. Sub-ordinary nature (thickness: 300 ~ 400um) andenhanced (thickness: 400 ~ 500um) two kinds.

2, Double FBE corrosion (2FBE)

Double epoxy powder coated outer coating is a composite structure,consisting of anti-corrosion epoxy powder primer and epoxy powder resistant tome chanical damage the surface layer of a coating film is completed. Normal sex(thickness ≥ 620um); enhanced (thickness ≥ 800um)

3, Two polyethylene / polypropylene anticorrosion (2PE/2PP)

Two polyethylene / polypropylene layer with good corrosion resistance,insulation resistance, long service life and resistance to mechanical damage. Sub-normal and enhanced thickness according to pipe size varies: Common Min1.8mm; enhanced minimum 2.5mm.

4, Three layer polyethylene / polypropylene anticorrosion (3PE/3PP)

Three layer polyethylene / polypropylene layer with excellent corrosion resistance, insulation resistance, longer service life and a certain degree of resistance to mechanical damage of the coating has been widely used in various large-scale projects of the corrosion in the pipeline. Common type and strengthened type two, thickness of the pipe size varies: Common minimum thickness 1.8mm; enhanced minimum thickness of 2.5mm.

Welded Pipe Manufacturing

Three types of welding processes:

Electric Resistance Welding: During ERW, a high frequency electrical current is transmitted to

the material by means of copper sliding contacts so that the abutting edges initiate fusion as they come into contact.

Longitudinal Submerged Arc Welding: In LSAW, the butt joint of the pipe is welded in at least two phases, one of which is on the inside of the pipe. The welds are made by heating with an electrode arc between the bare metal electrodes. Pressure is not used. Filler metal for the welds is obtained from the electrodes.

Spiral Submerged Arc Welding: Spiral SAW allows large diameter pipes to be produced from narrower plates or skelps. During this process, the weld pool is protected against oxidation by a flux produced from the electrode fed separately onto the weld.

Special Demands of Galvanized Steel Pipe Production Line

The galvanized steel pipe production lines have special requirements, especially for the production environment, it is nesscary to production quality and efficiency improvement. Particularly, galvanized steel need a stable enviroment to production.

First, Ensure that the production line for delicate work processes, equipment, heating,

ventilation, drainage, etc., all work are revolves around the ritual of quality. As long as the quality of the galvanized steel is good, all other factors can be achieved.

The use of galvanized steel is very widespread, especially in natural gas pipes, heating and other high strength and quality of the pipeline industry, galvanized steel pipe has a obvious advantages than others. If the galvanized used as plumbing, a large amount of rust inner tube after several years of use, the outflow yellow water pollution not only to ware but also mixed with not smooth inner wall of the breeding of bacteria. And corrosion  leads to high heavy metal content in the water, badly harm to human health.

In order to make galvanized steel with a bright white appearance and good corrosion resistance, in addition to hot dip galvanizing process, you can also use electric galvanizing process.

Low,Medium and High Carbon Steel

The world of carbon steels can be challenging to wrap your head around. There are many different options to choose from, and each type of steel has different benefits. The main differentiating factor is the amount of carbon that is mixed with iron during production. Other materials, mainly metals, can be added to change the physical properties. Notably, chromium is added to form stainless steel, while other  big picture, there are three distinctions between carbon steels: low, medium, and high.

Low carbon steel

Low carbon steels such as 302, 304 or 316 grades of stainless are typically used in applications which require high degrees of corrosion resistance but do not require a hardened surface. The carbon content of these steels typically range between 0.03-0.08%, and consumers typically use these grades of stainless (often without thinking about it) in kitchen equipment, silverware or almost any grade of un-plated steel used in food preparation. It’s great because it can survive the dishwasher without rusting, but it cannot be case hardened due to the very low carbon content.

While it can be used to make linear shafting, it isn’t suitable for loaded ball contact. So if a linear ball bushing were to be used on a soft 304 stainless steel shaft, for example, the balls in the bearing would quickly impact the shaft surface, resulting in visible ball tracking on its surface and a drastic reduction in both bearing and shaft life. It can, however, be used in conjunction with polymer, plain-style bearings which provide great options for both corrosion resistance and self-lubrication. For the right applications, a 300 series stainless steel linear shaft presents a great option for withstanding tough environmental conditions! 

Medium carbon steel

Medium carbon steels include grades with carbon contents ranging from 0.25% to 0.60% of the steel mass. Medium carbon grades are typically employed in conjunction with alloys such as chromium, nickel and molybdenum to produce high strength, wear resistance and toughness. Products using medium grades of carbon steel include gears, axles, studs and other machine components that require optimal combinations of strength and toughness.

Medium carbon steels have good machining characteristics, and one of the more popular grades used in machined steel product is AISI 1045.   AISI 1045 can also be hardened by heating the material too approximately 820-850C (1508 -1562 F) and held until the material reaches a uniform temperature. It should be soaked for one hour per 25 mm section of material and subsequently cooled in still air. 

High carbon steel

High carbon steels are those with carbon contents between 0.60% and 1.4% of the overall weight. The alloys in this particular category constitute the strongest and hardest within the three groups, but they are also the least ductile. These steels are used in a range of different mechanical, cutting and bearing applications as it can be hardened through heat treating and tempering. Additional alloys can be added to this steel category in order to generate different characteristics. Chromium and Manganese, for example, are used in the composition of 52100 steel and aid in the hardening process while enhancing the steel’s resistance to corrosion. Since 52100 is one of the steel grades frequently used to manufacture linear shafting, precise control of the case depth can be critical to generate a shaft with both a hardened surface (for loaded ball contact) and an un-hardened inner core which prevents the shaft from becoming brittle.

Steel alloys are given designators by organizations such as the American Iron and Steel Institute (AISI) and the American Society for Testing and Materials (ASTM) for easier classification and identification. AISI typically follows a four digit system, where the first two digits indicate the alloy, and the second two digits denote the carbon content. ASTM uses an “A” to denote ferrous materials, followed by an arbitrarily assigned number for each alloy.

Regardless of the system used, this standardization allows cross talk between designers, engineers, and builders to ensure the proper material is being selected and used in engineering projects. It also makes looking up physical properties of alloys very easy, as a simple search with the identification number produces the correct information.

The Best Welding Way to Weld Steel Pipe

The best way to welding steel pipe:

First of all, cleaning the oil, paint, water, rust ect. on welded steel pipe,  then opening groove

according to the wall thickness , larger open on thick wall, smaller open on thin wall (grinder), then the gap on pipe, usually the diameter of the rod or wire is 1-1.5 times, if you do a mistake and largered the groove , then smaller the gap. Tack welding at least three points, four points better in general work.

When welding should be finish in half and half, the best start point should one centimeter higher than the lowest point which is good for connection.  If the pipe wall thickness, it should be layered, at least two layers, the first layer full circle after welding can weld the second layer.