Submerged arc welding pipe, SAW pipes

SAW is normally operated in the automatic or mechanized mode, however, semi-automatic (hand-held) SAW guns with pressurized or gravity flux feed delivery are available.

SAW pipes

Submerged arc welding (SAW) is a common arc welding process.

The process is normally limited to the flat or horizontal-fillet welding positions (although horizontal groove position welds have been done with a special arrangement to support the flux).

SAW pipe is made of hot rolled coiled steel by automatic submerged arc weld under normal atmospheric temperature. All the pipes are produced according to API Spec 5L, GB/T9711.1, GB/T9711.2, ASTM A252-89 standard. These pipes mainly used in petroleum and natural gas industry to transport flammable and non-flammable liquid and steel construction.

SAW means submerged arc weld ,it can be classified into LSAW and SSAW

Size range:

The pipes are supplied according to appropriate standards as well as customer specifications in a large variety of steel grades and dimensions.

Execute Standard:

Specific requirements on execution, tolerances, lengths, and mechanical & chemical properties are offered on request.

Material:

Pipe Coating: HDPE/ 3PE/ 3PP/ Pipe cement mortar lining

In addition to above specification, the pipes can be produced according to customer’s requirements.

Mainly usage:

Spiral welded steel pipes are widely used in Oil, Natural Gas, Water and other flammable & nonflammable liquid conveyance and distribution pipelines, steel structures for construction and other general purposes by means of their wide size range.

SAW Welded Pipe Manufacturing Method

In single seam SAW pipe, wedding is done with the help of submerged arc welding process. In this method, a welding arc is submerged in welding flux. A Continues solid filler wire is fed from the outside. The pipe is welded first inside and then from the outside.

In the case of double seam saw pipe first two halves are joined by tack weld which is called fit-up. Double seam saw pipe is havening a two weld seam opposite to each other. Both the seams are welded from inside and outside of the pipe. In the case of high thickness pipe, multiple pass welding is done.

In a spiral saw pipe, steel plate from the de-coiler is formed in a spiral loop. This spiral loop is then welded from inside and outside of the pipe. Because of the method of manufacture, a wide variety of diameters can be produced. Spiral saw pipes are used for low-pressure services.

Whereas straight saw pipes are used for medium to high-pressure services. Spiral saw pipes are less costly compared to straight saw pipe.

Once the welding is completed heat treatment is carried out on the weld or on the full body of pipe, this depends on the thickness of pipes. Weld seams are also subjected to various non-destructive testing such as RT & UT to ensure the soundness of the weld material.

Once all NDT is completed pipes are hydro tested to ensure strength and ability to remain leak proof under pressure. In the last stage of inspection, the pipe is checked visually and dimensionally by competent inspection engineer. He will ensure that pipe is meeting the code, standard, and specification requirements. Once the Inspection engineer cleared the pipe, it will mark as per the standard requirements & send for the packaging.

Difference between ERW and SAW steel pipe

As ERW steel pipe and SAW steel pipe in the pipe during forming, welding and process is different, so that two kinds of steel pipe in the performance there are some differences.

ERW steel pipe surface quality is superior to spiral submerged arc welded pipe, ERW steel pipe surface is smooth, smooth, beautiful, SAW steel pipe internal and external weld reinforcement. 

ERW steel pipe weld defect types is less than the saw steel pipe. Saw steel pipe with solvent deposited, more types of defects, in addition to volume defects, there are wire-line trap. ERW steel pipe weld defects only wire-line and straight welds, the inspection process easy to follow, and the defects in the maximum reflection at, once the lack of implicit, ultrasonic reflecting the strong, easy to detect. 

ERW steel pipe related to saw steel pipe in residual stress ratio is low. Since ERW pipe deformation in the deformation process more fully, coupled subsequent sizing flat oval, elliptical vertical changes and necking, making ERW pipe residual stress becomes smaller. Physical testing showed that the same specifications, the same material ERW pipe after incision along the axis, the axial and transverse incisions smaller displacement than the spiral submerged arc welded pipe. 

ERW Pipe overall performance of the same, when the pipe becomes defective, steel scrap judgment, allow welding. SAW steel pipe allowed, and pipe welding performance and overall performance is inconsistent, welding place prone to stress corrosion cracking. Experiments show that stress corrosion fatigue test ERW pipe spiral submerged arc welded pipe length than life.



Weled steel pipe specification, Standard and identification

Welded steel pipe (steel pipe manufactured with a weld) is a tubular product made out of flat plates, known as skelp, that are formed, bent and prepared for welding.

Galvanized pipe process characteristics

What is Galvanized Steel Pipe? Galvanized steel can be made into a strong plumbing or tubing material -- one that resists corrosion from exposure to water or the elements. It has been used used for water-supply pipes or as a strong tubing for outdoor applications.

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