6 Stainless Steel Pipe Dimensions

[Marine Farinha]

Stainlesssteel pipe is a kind of hollow and longitude steel, economic steel section is round shape. Stainless steel pipe and tube has been widely used in oil, chemical industry, medical, food, light industry, equipment and apparatus and structural parts etc. In additional, when twisting and anti-twist intensity is equal, stainless steel is more lighter, so it used in equipment parts and projects structural. Also used to produce all kinds of conventional weapons, barrel, shells and so on. This kind of pipes divide into: stainless steel seamless pipes and stainless welded pipes. According by manufacturing process can divided into following basic types: hot-rolled, extrusion, cold-circular, hexagonal, equilateral triangle, octagonal and other special-shaped stainless steel pipe

The ASTM A312 standard specification for seamless, welded, and heavy cold worked austenitic stainless steel pipes. stainless steel pipe and tube is widely in sulfuric acid storage tank in the phosphate fertilizer industries. Fluorosilicic /acid reactor phosphoric acid plant; Chlorate Crystallizer in the production of fertilizer; Ventilation system in pharmaceutical factory; Solvent recovery filter, condenser, pipeline; Bleaching equipment and filter in the pulp and paper industry; pipelines and water collecting system in offshore platforms; multi-stage flash distillation, low-temperature multi effect desalination; seawater condenser for power plant and so on.

ASME SB677 specification covers the UNS N08904 (904L), UNS N08925, UNS N08926 (alloy 926), in seamless, of cold-drawn, and hot finished steel pipe and steel tube for the extremely corrosive services. The standard includes the material in carbon steel, and ferritic alloy steel, and austenitic stainless steel pipes and tube, 6% molybdenum alloy stainless seamless pipe and tube.

ASTM A789/ ASME SA789 covers seamless and welded ferritic/austenitic stainless steel tubing for general services. The standard also applied to duplex stainless steel tube material. All tubes in this standard shall be furnished with heat-treated condition according to specified temperature and quench conditions. When the final heat treatment is in a continuous furnace, or when heat treated condition is obitained directly by quenching after hot forming, the number of tubes of same size and from the same heat lot shall be determined from the prescribed sizes of the tubes.

ASTM A790/ ASME SA790 is standard specification for seamless and welded ferritic/austenitic stainless steel pipe. Including duplex stainless steel pipe material. The standard specification mainly covers seamless and longitudinal weld ferritic/austenitic steel pipe, that applied intended for general corrosive services, with particular emphasis on resistance to stress corrosion cracking. This kind of pipe shall be manufactured by seamless or automatic welding process, without adding filler metal in the welding processes. Heat analysis shall be made to determine the percentages of the chemical elements specified. Tensile test, hardening test, flattening test, hydrostatic tests and nondestructive test shall be performed to the specified requirements.

Corrosion resistance performances is the key feature for stainless tube. The commonly used types of steel involve ferritic and martensitic steel, that are predominantly made by adding chromium and manufactured through heat-treatment or to be annealed. There are austenitic stainless steel tubing products that are rich in chromium and nickel and they offer better resistance levels when used under the same conditions as compared to martensitic or ferritic materials.

Generally manufactured using solid chromium or a combination of nickel and chromium, including manufactured in seamless and welded stainless pipe. Such as electric fusion welded pipe (ERW) that find application in high-pressure usage; Large diameter stainless steel pipe (in welded and seamless) in case of corrosion of high-temperature applications.

Sanitary tubing usually in stainless material and referred standards is ASTM A270. In case the pipe or tube coming in direct contact with sensitive products like food, water, or drink, it is what we called sanitary tube. In these situations, sanitary tubing has good performances of corrosive resistance, no tarnish, and is easy to clean.

When the usage is in cylinders, bearings or other hollow formed parts, there is a usage for mechanical purposes. The tubing that is available can be manipulated easily and it results in a wide range of cross-sectional shapes, or even shapes that are round or the ones that need to fit in the cross-section. It finds widespread usage in case of mechanical tubing.

Octal is located in China recognized as a leading supplier, distributor, and manufacturer union in providing piping solutions for oil and gas company. Product ranges in Steel Pipe, Casing and Tubing, Steel Plate, Sucker Rod, Steel Pipe Fittings, Valves, and Equipment for pipelines.

Special O-rings and the available pipe dimensions make the pressing system the right choice for an extremely wide range of applications. The following applications each relate to the combination of the Geberit Mapress seal ring with the Geberit Mapress Stainless Steel system pipe CrNiMo.

The Geberit Mapress Stainless Steel pressfittings which are suitable for gas installations are equipped with a yellow seal ring made of HNBR. They can be distinguished from other fittings through their yellow marking and yellow protection plug.

Pipe dimensions vary based on the schedule and material. There is quite a bit that goes into the dimensions, but you can use the table of contents if you want to skip all of that and jump directly to the pipe size charts.

Nominal Pipe Size (abbreviated NPS) is a North American standard for identifying pipe sizes. Technically, the NPS is non-dimensional and only roughly refers to the diameter of the pipe. However, from NPS 14 and above, the NPS value matches the outside diameter of the pipe. Nominal Pipe Sizes apply to all materials of pipe. When specific pipes are specified, the NPS, Schedule, and material are required.

Outside of North America, pipes are identified by Diametre Nominel (DN), which is a dimensionless value that roughly equates to the outside diameter of the pipe in mm. The DN dimensions must conform to ISO Standard 6708.

While the Nominal Pipe Size identifies the outside diameter of the pipe, more information is needed to identify specific pipes. A pipe's schedule is the thickness of the pipe wall, which directly affects the interior dimension and weight of the pipe. Wall thickness is important because it determines the amount of internal pressure that the pipe can withstand. The schedule number is roughly calculated as: Schedule = 1000 x (P/S) where P is the internal service pressure of the pipe (psig) and S is the ultimate tensile strength of the pipe material (psi).

In addition to the schedule numbers, you will often see Standard (STD), Extra Strong (XS), and Double Extra Strong (XXS). These were original terms used prior to the schedule system that was implemented in 1927. It was originally intended for these to be phased out, but they occasionally appear. Stainless Steel pipe schedules append an "S" to the end of the schedule number, for instance Schedule 40S.

The two most common schedule sizes seen in buildings are Schedule 40 and Schedule 80. However, some process piping, utility facilities, and civil piping may require higher schedule numbers depending on the pressures used.

On the other hand, tubes are structural members and are measured with an exact outside diameter. Tubing is measured by the exact outside diameter and the wall thickness (WT). The manufacturing tolerances are much tighter than in pipes.

It is important that all local codes and standards are adhered to. Please consult a professional architect, engineer, consultant, or agency for advice about specific projects, buildings, conditions, codes, and/or regulations.

In March 1927 the American Standards Association authorized a committee to standardize the dimensions of wrought steel and wrought iron pipe and tubing. At that time only a small selection of wall thicknesses were in use: standard weight (STD), extra-strong (XS), and double extra-strong (XXS), based on the iron pipe size (IPS) system of the day. However these three sizes did not fit all applications. Also, in 1939, it was hoped that the designations of STD, XS, and XXS would be phased out by schedule numbers, however those original terms are still in common use today (although sometimes referred to as standard, extra-heavy (XH), and double extra-heavy (XXH), respectively). Since the original schedules were created, there have been many revisions and additions to the tables of pipe sizes based on industry use and on standards from API, ASTM, and others.[3]

Stainless steel pipes, which were coming into more common use in the mid 20th century, permitted the use of thinner pipe walls with much less risk of failure due to corrosion. By 1949 thinner schedules 5S and 10S, which were based on the pressure requirements modified to the nearest BWG number, had been created, and other "S" sizes followed later. Due to their thin walls, the smaller "S" sizes can not be threaded together according to ASME code,[4] but must be fusion welded, brazed, roll grooved, or joined with press fittings.

Based on the NPS and schedule of a pipe,[5] the pipe outside diameter (OD) and wall thickness can be obtained from reference tables such as those below, which are based on ASME standards B36.10M and B36.19M. For example, NPS 14 Sch 40 has an OD of 14 inches (360 mm) and a wall thickness of 0.437 inches (11.1 mm). However, the NPS and OD values are not always equal, which can create confusion.

For a given NPS, the OD stays fixed and the wall thickness increases with schedule. For a given schedule, the OD increases with NPS while the wall thickness stays constant or increases. Using equations and rules in ASME B31.3 Process Piping, it can be shown that pressure rating decreases with increasing NPS and constant schedule.[a]

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