Stainless Steel Welded Pipe

Stainless steel welded pipe is manufactured by rolling stainless steel plate on a machine then welding the seam. A scarfing blade then removes the weld flash from the inside and outside of the pipe.

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Categories: Stainless pipe, Weld steel pipe

Description

A stainless steel welded pipe is cold rolled flat strip or sheet and then made circular using a bending machine. Stainless steel welded pipe can be welded with or without filler material utilizing a high source of energy. These pipes can be produced in customize sizes without any restrictions.

The SS welded pipe can work well in moderate corrosive environments due to the presence of welds. The economically welded stainless steel pipe is simpler to procure and produce. These pipes have a good surface quality and have a consistent wall thickness. Stainless steel welded round pipes are used in the transportation of water, oil, and gas in larger quantities.

Stainless steel welded pipe is manufactured by rolling stainless steel plate on a machine then welding the seam. A scarfing blade then removes the weld flash from the inside and outside of the pipe. Many processes heat treat the welding zone to make the seam less visible and provides a more complete finish to the pipe. With today’s stainless steel pipe making technology, welded pipe most often has tighter dimensional tolerances than seamless pipe. Using seamless stainless steel pipe or welded stainless steel pipe depends on tolerances, wall thickness and diameter ratio. With this in mind, seamless pipe is more expensive than welded pipe.

A wide range of effective production facilities offers you a large number of possibilities:

Corrosion resistant pipes with outer diameters from 15 to 2 032 mm (80 inch) and wall thicknesses up to 70 mm
Pipes are made from special alloys, titanium or clad materials
Pipes with demanding tolerance requirements
Pipes in special geometric shapes
Pipes according to internationally valid standards, including DIN, DIN EN, DIN EN ISO, NORSOK, API and ASTM

Duplex Welded Stainless Steel Pipe is in the application of Petrochemical and Chemical industry, Onshore and Offshore Oil & Gas field of exploration, production and processing, Pulp and Paper-making industry, Ship Buliding industry, Coal industry and etc.

The general features of our DSSP: superior corrision resistance, such as pitting corrosion, crevice corrosion, abrasion corrosion; better weldability and mechanical properties; excellent intergranular corrosion resistance and better cost- effectiveness.

Stainless steel can withstand corrosive or chemical environments due to its smooth surface.

NPS: 1/8″ through 24″

Schedules: 5, 10, 10S, 20, 30, 40, 40S, 80, 80S

Specifications: ASTM A312, ASME SA312

Inspection & Quality Control

With a complete set of advanced testing equipment, we have the following Regular Testing Items:

Chemical Composition Analyzing;
Metallographic Test ;
Mechanical Properties Test;
Hydraulic Test;
Non-destructive Test, including X-Ray Flaw Detection;
Dimensional Checking;

Flattening
Flare & Flange
Reverse Bend
Reverse Flattening
Tensile Strength
Hardness

Enquiry/Ordering Information

Material Grade
NB Pipe Size or Outside Diameter
Wall Thickness, Length – Random/Standard/Specific

Finish Required
Relevant Specification
Application/End use

Finishes

As welded
Welded & externally polished
Welded Annealed & Pickled

Welded Cold Drawn Annealed & Pickled
Welded Cold Drawn Annealed Pickled & externally polished
Other Finishes as per customers requirement

Also used in producing all kinds of conventional weapons, the barrel, artillery shells and so on.

Custom Grades of Stainless Steel Tube

Austenitic: 201, 304/304L, 316/316L, 317/317L, 347/347H, 321/321H, 904L
Ferritic: 409, 430, 439, 441, 434, 436, 444, 446
Martensitic: 403, 410, 410S, 414/L, 441, 418, 420, 440, 416
Duplex: 2205/S31803, S32750, S32760

Common Applications for Stainless Steel Tubing Stainless steel tubing has a number of uses in a wide variety of industries. It can be used during manufacturing in processing plants or can become part of a final product. Stainless steel tubing can also be used in pipelines to transport oil, gas, water, or chemicals.

Stainless steel welding technical requirements and quality assurance measures

For the ferritic stainless steels, grain growth in the heat affected zone, welding joint ductility and toughness sharp decline, brittle, easy to form cold cracks in the welding residual stress.

Welded austenitic stainless steel welding process is improper or inappropriate choice of welding materials, prone to intergranular corrosion, welding hot cracking and embrittlement of welded joints and a series of defects, a direct impact on the performance of welded joints and weld quality.

For the more common austenitic stainless steel, in the welding process in claim small line energy fast short arc welding, minimize weld overheating, in order to prevent overheating by weld generated coarse columnar grain structure, reducing the welding residual stress , thereby preventing the welded joint stress corrosion cracking and the hot crack generation. Because weld overheated decreases, correspondingly reduces the residence time of the weld metal in sensitizing temperature, intergranular corrosion of welded joints tend to decrease.

Manual tungsten arc welding then stainless steel, using ordinary DC TIG welding machine, welding machine in the best conditions allowed.

Due to the low thermal conductivity of austenitic stainless steel, in the same welding current than structural steel can be obtained a large depth of penetration. Weld in order to obtain a certain size in order to prevent overheating, the welding current should be smaller than when welding ordinary low-alloy steel from 10% -20%, and the fine diameter wire. This can achieve a desired depth of penetration, and also allows a relatively reduced cross section of the weld bead, and to help improve the crack resistance of the weld of the welding current is relatively reduced.

The new development trend of stainless steel welded pipe

Stainless steel welded pipes have gradually replaced seamless pipes and become the new favorite of industrial heat exchangers. In industry, stainless steel welded pipes are widely used, such as heat exchange pipes in heat exchangers, which require stainless steel welded pipes to achieve heat exchange function. Of course, some heat exchange tubes on the market still use stainless steel seamless tubes. But most of them use stainless steel welded pipes. Why?

1. Improvement of welding technology

Stainless steel welded pipes have been widely used in heat exchange, and their technology, quality and scale have also been greatly improved. As far as welding technology is concerned, the welding technology used has always been argon arc welding, plasma welding, combined welding and other welding methods to ensure the quality of stainless steel welded pipes. The improvement of stainless steel welded pipe welding technology also means that it can completely replace stainless steel seamless pipe for heat exchangers, boilers and superheaters.

2. Low cost and high efficiency

The production process of stainless steel seamless pipe is to heat the stainless steel strip (round tube blank) at high temperature in a furnace, and then punch holes with a punching machine. The whole process is expensive. The production cost of stainless steel welded pipe is relatively low, and the manufacturing efficiency is high. The welding process is easier to control the precision than the seamless pipe, the surface is smoother, and the construction speed is faster. Under the premise of mass production, the cost of stainless steel welded pipe is 20% lower than that of seamless pipe. And after welding, the quality of the joint is basically the same as that of wood. Therefore, stainless steel welded pipes can completely replace seamless pipes in industrial production.

At present, the domestic demand for stainless steel welded pipes is increasing year by year. Choosing stainless steel welded pipes can not only save costs, but also ensure quality.

Difference between Stainless Steel Spiral Welded Pipe, ERW, SAW, and EFW

A stainless steel spiral welded pipe is produced as coils of steel that are flattened after unwinding. Angled rollers are utilized to flatten a spiral welded stainless steel pipe. These pipes can be classified into the 3 common specifications, namely ERW, SAW, and EFW.

The Stainless Steel ERW Pipe is a specification that is produced as the material is cold rolled and welded longitudinally. The versatile SS ERW pipe makes use of low voltage current to melt and weld the pipe.

A Stainless steel Efw Pipe has the same forming and production capabilities as ERW pipes. However, they make use of high voltage current to weld the material. The efw stainless steel pipe is an excellent choice for welding it with dissimilar piping systems.

A SAW pipe is produced as an arc is created between the workpiece and the continuously fed electrodes. The SAW stainless steel spiral pipe is protected against weld contamination using a protective gas shield. This allows it to weld material with higher thicknesses.

Standard & Grade

Normal standard

Item	ASTM A213/A213M		ASTM A312/A312M
Grade	TP304	TP304L	TP304	TP304L
	TP316	TP316L	TP316	TP316L
	TP317	TP317L	TP317	TP317L
	TP347	TP310S	TP347	TP310S
	TP309H*	TP310H*	TP317*	TP310H*
		TP321HΔ		TP321HΔ

Normal chemical composition of stainless steel

Grade	C (max)	Si (max)	Mn (max)	P (max)	S (max)	Ni	Cr
TP 304	0.08	0.75	2	0.04	0.03	8-11	18-20
TP 304H	0.04-0.10	0.75	2	0.04	0.03	8-11	18-20
TP 304L	0.035	0.75	2	0.04	0.03	8-13	18-20
TP 309S	0.08	0.75	2	0.04	0.03	8-13	18-20
TP 310S	0.08	0.75	2	0.045	0.03	12-15	22-24
TP 316	0.08	0.75	2	0.04	0.03	19-22	24-26
TP 316L	0.035	0.75	2	0.04	0.03	10-15	16-18
TP 316Ti	0.08	0.75	2	0.04	0.03	11-14	16-18
TP 317	0.08	0.75	2	0.04	0.03	11-14	16-18
TP 321	0.08	0.75	2	0.04	0.03	9-13	18-20
TP 321H	0.04-0.10	0.75	2	0.04	0.03	9-13	17-20
TP 347	0.08	0.75	2	0.04	0.03	9-13	17-20
TP 347H	0.04-0.10	0.75	2	0.04	0.03	9-13	17-20

Grade	Tensile Strength Min(Mpa)	Yeild Point Min(Mpa)	EL. Min(%)	Rockwell Max
TP 304	515	205	35	90
TP 304H	550	240	35	90
TP 304L	485	170	35	90
TP 309S	515	205	35	90
TP 310S	515	205	35	90
TP 316	515	205	35	90
TP 316L	485	170	35	90
TP 316Ti	515	205	35	90
TP 317	515	205	35	90
TP 321	515	205	35	90
TP 321H	515	205	35	90
TP 347	515	205	35	90
TP 347H	515	205	35	90

Heat treatment technology of stainless steel pipe surface

For the heat treatment technology of the surface of stainless steel pipes, non-oxidation continuous heat treatment furnaces with protective gas are generally used abroad for intermediate heat treatment and final heat treatment of finished products. As a bright surface without oxidation can be obtained, the traditional pickling process is eliminated. The adoption of this heat treatment process not only improves the surface of stainless steel pipes, but also overcomes the environmental pollution caused by pickling.

According to the manufacturer of stainless steel pipes, according to the current world development trend, bright annealing continuous heat treatment furnaces are basically divided into the following two types:

(1) Roller-type bright annealing heat treatment furnace.

This bright annealing furnace type is suitable for heat treatment of large-size and large-volume special-shaped stainless steel pipes, with an hourly output of above 1.0 Tons. The protective gases that can be used are high-purity hydrogen, decomposed ammonia and other protective gases. It can be equipped with a convection cooling system to cool the special-shaped stainless steel tube faster.

(2) Mesh belt type bright annealing heat treatment furnace.

This bright annealing furnace type is suitable for small-diameter thin-walled precision special-shaped stainless steel pipes. The hourly output is about 0.3 to 1.0 Tons. The length of the steel pipe can be up to 40m. It can also be used to process capillary tubes in coils. Equipped with convection cooling system for fast cooling. Using gas fuel or electric heating, various protective gases can be used. The stainless steel pipe after this furnace-type heat treatment has no scratches and good brightness surface.

Tensile test and hardness test of stainless steel pipe?

Tensile strength test is to make a sample of stainless steel pipe, pull the sample to break on a tensile testing machine, and then measure one or several mechanical properties, usually only the tensile strength, yield strength, elongation after fracture and section are measured Shrinkage. Tensile strength test is the most basic test method for mechanical properties of metal materials. Almost all metal materials require tensile test as long as they have requirements for mechanical properties. Especially for those materials whose shape is not convenient for hardness test, tensile strength test becomes the only means of testing mechanical properties.

The hardness test is to slowly press a hard indenter into the surface of the sample with a durometer under specified conditions, and then test the depth or size of the indentation to determine the hardness of the material. Hardness test is the simplest, fastest and easiest method in material mechanical property test. The hardness test is non-destructive, and there is an approximate conversion relationship between the material hardness value and the tensile strength value. The hardness value of the material can be converted into the tensile strength value, which has great practical significance.

Because the tensile strength test is not easy to test, and it is convenient to convert the hardness to the strength, more and more people only test the hardness of the material and less test its strength. In particular, due to the continuous advancement of hardness tester manufacturing technology and innovations, it is now possible to directly test the hardness of some materials that could not be directly tested before, such as stainless steel tube, stainless steel sheet and stainless steel strip. Therefore, there is a tendency for hardness tests to gradually replace tensile tests.

Process

Our specialized process for seamless tubing manufacturing begins with either an extruded hollow tube or a solid bar drilled to our exacting specifications. The material is then reduced in size a number of times through various cold working techniques until it reaches the specific size, tolerances, and temper required by our customer. After each cold working cycle the tubes are cut, cleaned and heat treated in preparation for the next cold working step.

Cold finished stainless steel tube technology flow chart

Pilfering

Pilfering reduces the size of the tube across three dimensions – outside diameter (OD), internal diameter (ID) and wall thickness. We roll a die set with a tapered groove across the outside of the tube while supporting the inside diameter using a taper-matched, hardened steel mandrel.

In a single cold working step, we can achieve a significant reduction in cross-sectional area while minimizing material loss and, most importantly, improving the material’s microstructure. Seamless tubes constitute the majority of volume processed by tube reducing or pilgering.

Cold Rolling

Like pilgering, tube rolling also uses compression to reduce the size of seamless tubes. However, while pilgering uses a pair of grooved, tapered dies to work the metal over a tapered mandrel, tube rolling utilizes one or two sets of rolls with constant cross-section grooves on the circumference of the tube.

Generally, the process employs a cylindrical mandrel with little or no taper. The rolls are driven by rack and pinion gears of different radii along profiled cams, completing multiple 360º rotations around the tube.

Cold rolling is a very precise method of reducing very thin walled and/or smaller diameter tubes, and is often used as the final cold working step. By rolling, we’re able to achieve exceptional control over dimensional tolerances and surface finish while also minimizing material loss and improving the metal’s microstructure.

Because it uses compression, tube rolling is well suited to processing unique metals like titanium and zirconium alloys.
Our cold rolling capabilities include both classic 2-roll (single roll set) tube rollers and an advanced 3-roll approach.

Cold Drawing

Typically used as the first form of size reduction for seamless tubes, cold drawing reduces the diameter by pulling the tube through a die that is smaller than the tube. In order to fit the tube into the die, one end is ‘swaged’ or ‘tagged’ thereby reducing the diameter of the leading end before drawing. Next, the narrowed end is passed through the die and clamped to a drawing trolley which pulls the tube through the die. After drawing the ‘tag’ is cropped from the tube end prior to cleaning.

Three types of cold drawing techniques:

Sink drawing

This is the simplest of the three drawing methods, as there is no tooling to support the ID surface. The tube is drawn through a die made of polished tool steel or industrial diamond, thereby reducing its inside and outside diameters. Our specialized lubrication and application techniques, combined with our proprietary die profiles, enable the OD surface to become smoother as the tube is drawn. Since the inside diameter is not constrained, the wall thickness of the tube will normally increase during drawing, and the ID surface finish will normally become rougher during a sink draw.

Rod drawing

Rod drawing is our most commonly used cold draw method, primarily for intermediate or in-process drawing stages, where both the outside diameter and wall thickness are reduced at the same time.

The tube is loaded over a hardened steel mandrel rod and both are then drawn through a die. This squeezes the tube onto the rod, reducing the outside diameter and thinning the wall simultaneously. The die and mandrel determine the size of the drawn tube, which is then slightly expanded by applying pressure to the outside of the tube so that the rod can be removed. Since larger reductions in cross-sectional area can be achieved by rod drawing, this method is used for mid-process stages to reduce tube sizes prior to the final drawing cycle.

Plug drawing

This type of drawing is used to achieve the best possible surface finish and the greatest control over both dimensions and final temper. The outside diameter and wall thickness of the tube are both reduced during plug drawing, as the tube travels through a die and over a stationary plug/mandrel made of high grade tool steel. The plug or mandrel has a polished surface and is attached to a fixed back rod, which is carefully positioned within the drawing die. The tube is loaded over the mandrel/back rod. As the tube passes through the die, the burnishing action of the metal flowing over the stationary plug imparts a high tolerance surface finish inside the tube.

When properly lubricated and prepared, the ID will show very few flaws and finishes of 16 RMS or better can be achieved. Plug drawing is normally chosen for the final draw stage because it achieves a high quality surface finish, exceptional dimensional control, and positive influence on tensile strength requirements.

Annealing

Annealing is used to soften the metal before further cold working or fabrication processes, and improves the overall metallurgical microstructure of the tube. During tube reduction or cold drawing, it can become hard and somewhat brittle. To be able to draw the tube again, stresses formed during cold working need to be removed to return the material to its normal state.

During annealing the tube is heated to a controlled temperature (up to 2100°F) and soak time. Through this process the tube remains in shape, but the grains in the structure of the tube reform into a regular unstressed pattern. The resulting annealed tube is softer and suitable for redrawing.

Our closely controlled annealing and heat treat processes are audited regularly by our nuclear, medical, and aerospace customers.

Straightening

Drawing and annealing generally results in some degree of bowing, producing a slight bend in the tubing. We use multiple roll mechanical straighteners in the first stage of finishing. The straightener applies pressure and flex to the product in order to remove bends or bows, resulting in a straightness level of 0.010” per foot, or better. Straightening can introduce slight changes to the size and mechanical properties of the tubing, so these aspects are very carefully controlled during the process.

Marking: SunnySteel, material grade, standard, specification, heat no.
Surface Treatment: Bright annealed, polished outside and inside surface.
Package: knitting strip bundle, wooden box or steel box
Mill test certificate: according to EN 10204 3.2
Inspection: Third party inspection, or by clints

Packing

There are probably hundreds of different methods for packing stainless pipe, and most of them have merit, but there are two principles that are vital for any method to work prevent rusting and Sea transportation security.

We inventory stainless steel grades that are readily used in manufacturing such as 304, 304L and 316/L to harder to find items such as 309H, 330 or 405 stainless.

the wooden boxes packing for stainless products

Application

Stainless steel pipe (tube) has excellent characteristics of corrosion resistance and smooth finishing. Stainless steel pipe (tube) is commonly used in demanding equipment like automobiles, food processing, water treatment facilities, oil and gas processing, refinery and petrochemicals, breweries and energy industries.

Stainless steel tube is typically measured by its outer diameter and can be used in a variety of applications including a number of structural applications. Stainless steel tubing is extremely durable and able to withstand corrosion. This tubing will not rust, even if exposed to the elements, heat, and other extreme conditions. Because of these factors, stainless steel tubing can be used for a wide variety of applications.

The stainless steel tubing that is supplied by SunnySteel can used in a variety of industries, including:

Considering the importance of outside and inside surface of stainless steel tubes for fluid power industry, Our mills are providing tubes that are free from scale, rust, seams, laps.

Machinery Parts
Food and Beverage Processing
Pharmaceutical
Biotechnology
Automotive

Marine
Construction
Chemical
Oil and Gas

the main requirement for stainless steels is that they should be corrosion resistant for a specified application or environment. The selection of a particular “type” and “grade” of stainless steel must initially meet the corrosion resistance requirements.

Additional mechanical or physical properties may also need to be considered to achieve the overall service performance requirements.

Inquiry

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FAQ

Q: How long is your delivery time?
A: The delivery time of customized products is generally 25 35 days, and non customized products are generally shipped within 24 hours after payment.

Q: Do you provide samples? Is it free?
A: If the value of the sample is low, we will provide it for free, but the freight needs to be paid by the customer. But for some high value samples, we need to charge a fee.

Q: What are your payment terms?
A: T/T 30% as the deposit,The balance payment is paid in full before shipment

Q: What is the packaging and transportation form?
A: Non steaming wooden box and iron frame packaging. Special packaging is available according to customer needs. The transportation is mainly by sea.

Q: What is your minimum order quantity?
A: There is no minimum order quantity requirement. Customized products are tailor made according to the drawings provided by the customer.