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.

Production Process of Seamless Steel Pipe

The production process of seamless steel pipe:

Seamless steel pipe mainly complete through the tension reducing diameter. The stretch

reducing process is hollow base material without mandrel continuous rolling process. Under the condition of guaranteeing the welding quality , the parent tube and pipe tension reducing diameter is the process of the whole welded pipe heated to above 950 degrees Celsius, then warp tension reducing mill (tension reducing mill, 24 times) rolled into a variety of diameter and wall thickness of the finished pipe. The hot-rolled steel pipe with this production process have essential difference to the ordinary high-frequency welded pipe, through metallographic organization and mechanical properties of the weld and the parent of the furnace heating can be achieved exactly the same. In addition, through multi pass tension reducing diameter rolling machine and automatic control make the dimensional accuracy of steel (especially the roundness and wall thickness precision pipe) is better than the same kind seamless pipe. 

Seamless Pipe Manufacturing

Our seamless pipe manufacturing process involves the following steps:

-Transformation of raw materials into steel bars (Electric arc furnace, ladle furnace, vacuum

degassing and continuous casting processes)

-Transformation of steel bars into mother pipe, which is manufactured in different types of rolling mills

Each product is manufactured in accordance with customer specifications, including heat treatment for more demanding applications. Our pipes are threaded and undergo non-destructive testing before delivery to the customer.

We also offer cold-drawing for pipes with the diameter and wall thickness required for use in boilers, superheaters, condensers, heat exchangers, automobile production and several other industrial applications.

Difference between Seamless and ERW Stainless steel pipe

Today, Prime Steel will discuss about the key difference between Seamless and ERW Stainless Steel Pipe

What is the Raw material required for manufacturing Seamless & ERW Stainless steel Pipes?

Seamless Steel Pipe is made from a solid round steel ‘billet’ which is heated and pushed or pulled over a form until the steel is shaped into a hollow tube. 

What is the Difference Between Seamless and ERW Stainless Steel Pipes?

Electric Resistance Welding (ERW) pipe is manufactured by rolling metal and then welding it longitudinally across its length. Seamless pipe is manufactured by extruding the metal to the desired length; therefore ERW pipe have a welded joint in its cross-section, while seamless pipe does not have any joint in its cross-section through-out its length.

In Seamless pipe, there are no welding or joints and is manufactured from solid round billets. The seamless pipe is finished to dimensional and wall thickness specifications in sizes from 1/8 inch to 26 inch OD. Applicable in for High-pressure applications such as Hydrocarbon Industries & Refineries, Oil & Gas Exploration & Drilling, Oil & Gas Transportation and Air and Hydraulic cylinders, Bearings, Boilers, Automobiles etc.

ERW (Electric Resistance Welded) pipes are welded longitudinally, manufactured from Strip / Coil and can be manufactured upto 24” OD. ERW pipe cold formed from a ribbon of steel pulled through a series of rollers and formed into a tube which is fused through a electric charge. It is mainly used for low/ medium pressure applications such as transportation of water / oil.  

What Technologies are used to manufacture Seamless & ERW Pipes?

Technologies for Production of Seamless & ERW Pipes “CPE” Technology” used for Seamless Pipes & Tubes Production up to 7-inches OD is the world renowned Technology. “Plug Mill” Technology used for Higher Dia. Seamless Pipes & Tubes Production from 7-inches to 14-inches,is the most reliable technology,in higher dia. Segment. High frequency Induction Welding Technology is used for ERW Pipes &Tubes upto 21-inchesOD.

How to Identify Seamless or ERW Stainless Steel pipes?

To identify that a pipe supplied is seamless or ERW, Simply read the stencil on the side of the pipe

If it is ASTM A53, Type S means seamless.

Type F is furnace but welded,

Type E is Electrical resist welded.

Thats how. It is the easiest way to identify wether pipe is seamless or ERW.

Heat Treatment of LSAW Steel Pipe After Welding

LSAW steel pipe after heat treatment is a new technology to eliminate residual stress. After the material is preheated before welding to heat treatment temperature and the butt welding process to maintain the temperature of the continuously heated member, after the welding is completed using its thermal insulation cotton allowed to cool slowly. This method can effectively reduce the welding residual stress and improve resistance to stress corrosion of metals.

Internal weld NDT since the large steel pipes in water supply project belongs, especially the

thickness t = 30mm steel is used as a pipe bridge, both to withstand water pressure inside, but also the burden of its own weight and the water formed by a steel pipe moment, so the welding quality requirements are particularly high. For pipe bridge with a thickness t = 30mm large-diameter pipe, the longitudinal seam and girth weld belong to a class, require 100% of X-ray film examination and 100% ultrasonic flaw detection; and thickness t = 24mm buried pipe, longitudinal seam welding belongs to a class for 20% of the X-ray film examination and 50% of the ultrasonic flaw inspection.

Post weld heat treatment can effectively reduce the welding residual stress, and heat treatment temperature is higher, residual stress better. Large-diameter pipe post weld heat treatment can effectively improve the stress corrosion resistance of large diameter pipe, the higher the heat treatment temperature, resistance to stress corrosion increased more significant. Diffusion method metal carbide coating technology is the workpiece placed in special medium, formed by diffusion of metal carbide layer of a few microns to tens of microns on the workpiece surface. Anti-corrosion anti-corrosion of buried large diameter steel pipe and clear tubes are used to hang galvanized wire, spraying compressive strength of not less than 30N / mm2 of cement mortar lining.

Drainage Pipeline

Drainage pipeline refers to collection systems that discharge sewage, wastewater and stormwater drainage pipes and ancillary facilities composed. Including dry pipe, manifolds and pipes leading to the treatment plant, or any other place, whether on the streets built, as long as they play the role of drainage pipes, drainage channels should be as statistics. Length of sewer drain by all, trunks, branch pipes and inspection wells, connection length and calculate well as import and export, excluding rainwater drains mouth to the connecting pipe between the pipe and open channel into the household. When calculating a single tube should be calculated, that is, in the same street where two or more side by side drains, drainage channels and should be the length of each calculation.

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Pipe Type 

Galvanized iron pipe is currently the largest amount of a material to use, because galvanized iron pipe corrosion caused by high levels of heavy metals in water, affect human health, the government sector in many countries and regions have begun to explicitly prohibit the use of galvanized iron pipes. At present, China is gradually phased out this type of pipe. 

Brass is a more traditional but the price is more expensive pipe material, durable and construction more convenient. In many imported sanitary products, brass is the first choice. Price is the most important reason affecting their usage, in addition to copper corrosion is on the one hand factor. 

Stainless steel tube is a more durable piping material. But its high price, and the construction process is relatively high, especially the strength of the material is hard, very difficult scene processing. Therefore, the probability of the renovation project was selected low. 

Plastic composite pipe is a pipe more popular in the market because of its light weight, durable and easy construction, which can be more suitable for use in bending home improvement. Its main drawback is used for hot water pipes in use, due to thermal expansion and contraction will cause long-term dislocation wall resulting in leakage.

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.