Seamless Pipes

PETROSADID is a leading supplier of seamless pipes providing an extensive selection of all grades and dimensions to the oil & gas, petrochemical, chemical and power industries. We work closely together with certified pipe manufacturers from around the world and have a huge range of different seamless pipes constantly on stock ranging from Hot Rolled to Cold Drawn pipes.

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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.

Seamless pipes are finished in accordance with customer needs regarding dimensional and wall thickness specifications as well as heat treatment for more demanding applications. In general a seamless pipe is manufactured in sizes from 1/8” to 24” according to current standards API, ASTM, and ASME.

In the production of steel pipes, steel is molded and reshaped with different machinery at different temperatures. One of the steel manufacturing processes is steel rolling, which involves metal stock passing through a pair of rolls. Rolling produces flat steel sheets of a specific thickness, and the process is classified according to the temperature at which the metal is rolled. If the temperature of the metal is above its recrystallization temperature, or the temperature at which the grain structure of the metal can be altered, then the process is termed as hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is termed as cold rolling.

Cold Drawn Seamless Pipe

Cold drawn seamless pipe is usually required where the end product is either safety and/or quality critical.

The method for making cold-drawn seamless pipes involves taking a round "billet" or bar of steel and boring it in the center, turning it, cutting it, heating it to make it more pliable, then "drawing" it (extruding or pulling it) to make it a longer and thinner pipe. As the pipe cools, "cold working" begins. Cold working involves pulling the pipe over a stationary die and a mandrel. This increases the pipe's hardness and improves its surface condition and grain structure while reducing the pipe to the desired size and thickness.

Hot-Rolled Seamless Pipe

Different from cold rolling which is performed below the recrystallization temperature, hot rolling is conducted above the temperature. Hot rolled seamless pipes offer higher torsional rigidity than cold rolled ones, thus it offers better torsional resistance than cold rolled tubes.

Advantages

Hot rolled seamless steel pipe can damage the cast microstructure of the steel ingot, refinement of the crystal grains of the steel, and eliminate the defects of the microstructure, so that the the steel organization compacting, improve the mechanical properties. This improvement is reflected in the rolling direction, so that the steel is no longer to a certain extent isotropic; pouring the formation of bubbles, cracks, and osteoporosis, under high temperature and pressure can also be welded together.

Disadvantages:

• After the hot rolling, the nonmetallic inclusions in the interior of a steel (mainly sulfides and oxides, as well as the silicate) was pressed into a sheet, stratified (laminated) phenomenon appears. The layering of the steel in the thickness direction by the pull performance deteriorated significantly, and may appear in the weld shrinkage interlayer tear. Weld shrinkage induced local strain often reach several times the yield point strain, the strain is much greater than the load caused;

• Residual stress caused by uneven cooling. The residual stress is the stress of internal self-phase equilibrium in the absence of external force, the hot-rolled steel of various cross-sectional has a residual stress such Usually steel sectional dimension is the greater, the greater the residual stresses. Residual stress is self-phase equilibrium, but the steel members in the performance external force or have a certain influence. Such as deformation, stability, anti-fatigue may adversely.

• Hot-rolled steel products, poor control of thickness and edge width. We are familiar with the thermal expansion and contraction, even if the beginning of the hot-rolled out are standard length, thickness, or there will be some negative final after cooling, this negative differential edge width wider the increasing thickness of the performance of the more obvious.

Highlights of the Seamless Pipes

Specification

• Pipe sizes are documented by a number of standards, including API 5L ANSI/ASME B36.10M in the US, and BS 1600 and BS 1387 in the United Kingdom. Typically, the pipe wall thickness is the controlled variable, and the Inside Diameter (I.D.) is allowed to vary. The pipe wall thickness has a variance of approximately 12.5 percent.

• Specifications for API 5L adhere to the International Organization for Standardization ISO 3183, standardizing pipeline transportation systems within the materials, equipment and offshore structures for natural gas, petroleum, and petrochemical industries. When authoring the standards, the technical committee recognized that there are two basic Product Specifications Levels (PSL) of technical requirements and therefore developed PSL 1 and PSL 2. PSL 1 is a standard quality for line pipe where PSL 2 contains additional chemical, mechanical properties, and testing requirements.

• PSL-1 is a loose standard quality for line pipe, whereas PSL-2 contains additional testing requirement, stricter chemical physicals, along with different ceiling limits of mechanical properties, and require Charpy impact testing conditions.

• ASTM A 530/A 530M Specification for General Requirements for Specialized Carbon and Alloy Steel Pipe

Cost

• Hot rolling is typically not as costly or as expensive as cold rolling or cold drawing, as the steel is more malleable at a higher temperature. There is also one less step when producing the steel, which cuts back on the operating costs of producing the steel. The finish of the steel will not be as smooth or clean as cold rolled or drawn steel, and mechanical properties of the steel are typically not as good as steel in its cold drawn form. This often is not important for steel products that are produced in high quantity and do not need a clean external finish.

Size

• Outer Diameter：

Hot finish: 2" - 30",Cold drawn: 0.875" - 18"

• Wall Thickness：

Hot finish: 0.250" - 4.00",Cold drawn:0.035" - 0.875"

• Length：

Random Length, Fixed Length, SRL, DRL

• The European designation equivalent to NPS is DN (Diamètre Nominal/ nominal diameter). The pipe sizes are measured in millimeters.

For NPS of 4 and larger, the DN is equal to the NPS multiplied by 25 (not 25.4)

Heat Treatment

• Hot-finished pipe need not be heat treated.

• Cold-drawn pipe shall be heat treated after the final cold draw pass.

Test

• Chemical Component Analysis, Mechanical Properties (Ultimate tensile strength, Yield strength, Elongation), Technical Properties (Flattening Test, Flaring Test, Bending Test, Hardness Test, Blow Test, Impact Test etc), Exterior Size Inspection.

Materials

API 5L Gr. (B, X42, X52, X60, X65, X70, X80)

A53 Gr. B

A106 Gr. (A, B, C)

A335 (P1, P11, P12, P22, P5, P9, P91, P92)

A333 Gr. (3, 6)

A312 (TP304/304L, TP316/316L, TP321, TP321H, TP347, TP347H)

A312 (UNS S31254, UNS N08367, UNS N08925, UNS N08926)

A790 (UNS S31803 / S32205 – Duplex 2205)

A790 (UNS S32550/ S32750/ S32760 - Super Duplex 2507)

ASTM B 466

ASTM B 861 Gr. 2

Nickel 200/201 - B161

Alloy 400 - B165

Alloy 600 - B167

Alloy 625 - B705

Alloy 800H/ 800HT - B407

Alloy 825 - B423

Alloy 276 - B622

Standard

ASME 36.10, ASME 36.19 are the key specifications covering the standardization of dimensions of welded and seamless wrought steel pipe. ASME B16.25 covers the preparation of butt weld connections between pipes and ASME B16.49 covers the marking details.

ASME 36.10

This standard covers the standardization of dimensions of welded and seamless wrought steel pipe for high or low temperatures and pressures. Pipe NPS 12 (DN 300) and smaller have outside diameters numerically larger than corresponding sizes. In contrast, the outside diameters of tubes are numerically identical to the size number for all sizes.

The size of all pipe is identified by the nominal pipe size. The manufacture of pipe NPS ⅛ (DN 6) to NPS 12 (DN 300), inclusive, is based on a standardized outside diameter (O.D.). This O.D. was originally selected so that pipe with a standard O.D. and having a wall thickness that was typical of the period would have an inside diameter (I.D.) approximately equal to the nominal size. Although there is no such relation between the existing standard thickness - O.D. and nominal size - these nominal sizes and standard O.D.s continue in use as "standard." The manufacture of pipe NPS 14 (DN 350) and larger proceeds on the basis of an O.D. corresponding to the nominal size.

ASME 36.19

This Standard covers the standardization of dimensions of welded and seamless wrought stainless steel pipe for high or low temperatures and pressures.

Pipes NPS 12 (DN 300) and smaller have outside diameters numerically larger than their corresponding sizes. In contrast, the outside diameters of tubes are numerically identical to the size number for all sizes. The wall thicknesses for NPS 14 through 22, inclusive (DN 350-550, inclusive), of Schedule 10S; NPS 12 (DN 300) of Schedule 40S; and NPS 10 and 12 (DN 250 and 300) of Schedule 80S are not the same as those of ASME B36.10M. The suffix S in the schedule number is used to differentiate B36.19M pipe from B36.10M pipe. ASME B36.10M includes other pipe thicknesses that are also commercially available with stainless steel material.

API 5L

ANSI / API 5L specifies the manufacture of two product levels (PSL1 and PSL2) of seamless and welded steel pipe for the use of a pipeline in the transportation of petroleum and natural gas. For material use in a sour service application, refer to Annex H; for offshore service application, refer to Annex J of API 5L 45th Edition.