thick pipe

What is thick-walled steel pipe

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What is thick-walled steel pipe

What is thick-walled steel pipe ?

Thick wall steel pipe , the steel pipe The diameter and wall thickness of the steel tube ratio is smaller than 20 is called the thick wall steel pipe. Mainly used for drilling, pipe for petrochemical industry Cracking tube , Boiler tube And bearings and car, tractor, aircraft with high precision tube structure.

Brief introduction

The general use of thick wall steel pipe hot rolling technology, if it is a unit of measure to distinguish words, then, generally, the wall thickness / diameter equal to 0.05 is a watershed of thick wall steel pipe and thin-walled steel pipe, wall thickness / diameter of less than 0.05 is greater than the thickness of thin-walled steel tube, steel pipe, in use for for thin-walled steel pipe. The blank and thick wall steel pipe used in hollow parts. The use of pressure and pipeline.
Thick wall steel pipe is mainly used in tap water engineering, petrochemical industry, chemical industry, electric power industry, agriculture and city construction. Used for liquid delivery: water supply and drainage. Gas transportation: gas, vapor, liquefied petroleum gas. For structural purposes: as piling pipe, tube for bridge; pier, road and building structure.
Texture of material

Commonly used materials for domestic 10# 20Mn 42CrMo 36CrMo 40Cr 20Cr: 15CrMo 12Cr1Mov Q235A, Q235B 1Cr17, 00Cr19Ni11, 0Cr13, 1Cr18Ni9, 0Cr18Ni11Nb, 16Mn, 45#, 20#, L245, L290, Q345, X42, X46, X70, and X80.

Standard parameters
Tensile strength

The tensile strength of thick wall steel pipe

Size deviation

According to the national standard GB/T17395 “ seamless steel pipe The size, shape, weight and tolerances “of size deviation requirements, can be divided into standardized and non standardized two, four grades.

Wall thickness deviation

Standard wall thickness allowance

Non standard wall thickness allowance

Outside diameter tolerance

Strength grade

  • 1) to Nominal pressure Said the grade or provisions of the pressure temperature ratings Pipe fitting According to the prescribed standards, a pressure temperature rating as the benchmark, such as GB/T 17185;
  • 2) standard provides only a nominal fitting thickness connected with the pipe, according to the standard provisions of the applicable benchmark grade pipe pressure temperature ratings, such as GB14383


  • 3) only provides fittings size standards, such as GB12459, GB 13401, the bearing strength should be determined by confirmatory test.
  • 4) other, should be pressure design or analytical method according to the relevant provisions to determine the use of reference. In addition, determine the pipe strength, also should not be lower than that of the whole pipeline system the most severe conditions may arise in the operation under pressure.
  • Welding technology

    Welding method
    Thick wall steel pipe welding first clean the welding joints of oil, paint, water, rust, and then according to the thickness of the groove, thick in some, thin is smaller (grinding), and then the product gap, is generally a rod or wire diameter 1- 1.5 times, if groove accidentally opened a can be appropriate to stay small. Tack welding of at least 3, 4 general good work. The welding time should be the best starting point more than half of welding, the lowest point of a centimeter, as from the opposite connection. If the wall thickness of steel pipe, should be stratified, at least two layers, the first layer of whole ring welding can weld second layer.
    Technological process
    Billet, heating, perforation, three roll cross rolling, rolling or extrusion, tube to tube diameter (or reducing), cooling, straightening, pressure test (or testing), mark .

    How To Heat Treat Seamless Small-diameter Thick-walled Steel Pipe

    Small-diameter thick-walled seamless pipes are steel pipes with a small ratio of outer diameter to wall thickness. How should such steel pipes be heat treated?

    1. The repaired parts need to be normalized during the heat treatment process. The normalizing is a heat treatment process of heating the small-diameter thick-walled tubes of seamless steel tubes to 45 ° C above Ac3, and after cooling for a suitable time, in a static air. Structural parts requiring mechanical properties require quenching after normalizing to meet mechanical performance requirements. Medium and high alloy steels and large forgings require high temperature tempering after normalizing to eliminate the internal stress generated during normalizing.
    2. Annealing treatment of small-diameter thick-walled tubes of seamless steel tubes is a heat treatment process in which metals and alloys are heated to a suitable temperature for a certain period of time and then slowly cooled. After annealing, the sub-eutectoid steel is ferrite plus flaky pearlite; the eutectoid steel or hypereutectoid steel is granular pearlite. In summary, the annealed tissue is a tissue that is close to equilibrium.
    3. Over-eutectoid steel normalizing heating knife Acm or more, so that the original mesh-like cementite is dissolved into austenite, and then cooled at a faster rate to inhibit the precipitation of cementite in the austenite grain boundary , which can eliminate the network carbide and improve the structure of the hypereutectoid steel. Welded parts require normalizing of the weld strength to improve the weld structure and ensure weld strength.
    4. Some seamless steel pipe small-diameter thick-walled pipes produce partial martensite transformation during forging to form hard tissue. In order to eliminate this kind of bad organization, when it is normalized, it is heated and kept at a temperature of about 20 °C higher than the normal normalizing temperature for normalizing. The normalizing process is relatively simple, which is beneficial to the use of forging waste heat normalizing, which can save energy and shorten the production cycle. Normalized processes and improper handling also produce tissue defects, similar to annealing, and the remedies are basically the same.

    What Are The Heat Treatment Processes For Thick-walled Seamless Pipes?

    The surface heat treatment technology of the 45th thick-walled seamless steel pipe is constantly being innovated, and the current technology has been developed more and more sophisticated. Let’s take a look at several methods of 45-thick thick-walled seamless pipe processing.
    1. Surface hardening:
    Rapid heating of No. 45 thick-walled seamless pipe by different heat sources, when the surface temperature of the part reaches above the critical point (when the temperature of the 45# seamless pipe core is below the critical point), it is quickly cooled, so that 45# seamless The surface of the tube is hardened and the heart remains in its original tissue. The most widely used in the industry is induction heating and flame heating surface quenching.
    2. Chemical heat treatment:
    The 45# seamless tube is placed in a medium containing active elements to heat and keep warm, so that the active atoms in the medium penetrate into the surface layer of the 45-thick thick-walled seamless tube or form a coating of a compound to change the texture and chemical composition of the surface layer. Therefore, the surface of the part has special mechanical or physicochemical properties.
    3. Contact resistance heating quenching:
    Similar to the electric resistance welded pipe, a voltage of less than 5 volts is applied to the 45# seamless pipe through the electrode, a large current flows at the contact of the electrode with the 45# seamless pipe, and a large amount of resistance heat is generated, so that 45# is absent. The surface of the seam tube is heated to the quenching temperature, and then the electrode is removed, and the heat is transferred into the interior of the 45# seamless tube and the surface is rapidly cooled, that is, the quenching purpose is achieved.
    4. Electrolytic heating quenching:
    The 45th thick-walled seamless tube is placed in an electrolyte of an acid, alkali or salt aqueous solution, and the 45# seamless tube is connected to the cathode, and the electrolytic tank is connected to the anode. After the direct current is turned on, the electrolyte is electrolyzed, oxygen is released on the anode, and hydrogen is discharged on the seamless tube No. 45. Hydrogen forms a gas film around the 45# seamless tube, which becomes a resistor to generate heat. The surface of the 45th thick-walled seamless tube is rapidly heated to the quenching temperature, and then the electricity is cut off, the film immediately disappears, and the electrolyte becomes a quenching medium. , so that the surface of the 45# seamless pipe is rapidly cooled and hardened.
    5. Laser heat treatment:
    The application of laser in heat treatment began in the early 1970s, and then entered the production application stage from the laboratory research stage. When a focused high energy density (10 W/cm) laser illuminates the metal surface, the metal surface rises to the quenching temperature in a few hundredths of a second or even a few thousandths of a second.
    The above several heat treatment technologies are now more advanced technologies, and the performance requirements of the 45th thick-walled seamless pipe have been improved very well. Now the market development of the 45th thick-walled seamless pipe is getting better and better, I believe that follow-up The market for the 45th thick-walled seamless pipe will be even broader.

    Weld reinforcement
    Steel pipe wall thickness is less than 12.5mm, the weld height is not greater than 3.0mm; tube wall thickness is greater than 12.5mm, the weld height is less than 3.5mm.
    Nominal diameter of not more than 168.3mm Steel pipe That should be straight or bending index according to the provisions of the agreement both sides of supply and demand;
    Steel pipe nominal diameter greater than 168.3mm, the bending degree greater than 0.2% of the length of steel pipe.
    The end of the steel tube wall thickness is greater than 4mm, the pipe end chamfering can be 30 +5 degrees to 0 degrees, left 1.6mm + 0.8mm, the pipe end slope is less than or equal to 5mm.

    Engineering requirements

    The thick walled tube real selection and corresponding provisions and regulations and the use of t hick walled tube In the actual use or use, must follow the provisions of relevant laws and regulations and norms, especially the extremely high hazard or conveying fluid medium, medium and high pressure gas pipelines and other flammable occasions. In this context, based primarily on the use and use conditions (pressure, temperature, fluid) to determine the type of pipe fittings. The following lists the relevant regulations / standard, for reference only.
    1) method of safety supervision of special equipment;
    2) Regulations on safety inspection of special equipment;
    3) the provisions of safety management and supervision over pressure pipelines;
    4) the provisions of quality supervision and safety supervision of special equipment;
    5) special equipment design / manufacturing / installation supervision and management regulations (draft);
    6) Pressure Pipe Safety Technology Supervision Regulation (draft);
    7) technical specification for industrial metal pipeline safety (draft);

    Safety and economy

    Structure type fittings used in the actual projects, in addition to the introduction, and other various kinds of fittings, to meet a variety of different conditions, especially in special conditions. In the engineering design and selection, the strength grade of pipe is high, the safety is high, but the engineering cost is larger, it will cause unnecessary waste.
    Considering the economic benefits, to meet the requirements of engineering design at the same time, reduce costs as much as possible, but tend to form a small number of varieties selected on the overall fitting results, which is disadvantageous to the construction site material management, regulation and design changes require materials with generation etc.. Therefore, the selection of pipe fittings, comprehensive safety and economy, as far as possible to reduce the fitting varieties suitable. In addition, the site construction conditions, construction level, procurement cycle factors such as pipe, also should be taken seriously in the selection of pipe fittings. The specific circumstances, should also consider the possibility of strengthening pipe joints, small caliber pipe and mitered elbow bending of the site.
    At the same time, for fitting the production capacity and product market supply, it is necessary to understand the situation.

    The existing problems

    • 1) Domestic standards are not perfect, not standard fittings and fittings should be type parameters of standard material standards including fittings. But in the material standards or regulations is not complete, or lack of goods such as Ting requirements and inspection rules, and the group that the quality requirements of quality and technical aspects. The pipe material standard of supporting the poor, often from their respective positions, rather than from the perspective of the whole pressure pipe standard system to develop. Used in engineering, Pipe There is no standard, but the corresponding forging or casting standard. The reality is the use of pressure vessel standard fittings forgings forging standard, no differences between the two considerations, such as welding, film inspection and other provisions.
    • 2) Pipe fitting The standard contents vary widely, consistent with a lack of systematic and cohesive contradictions, causing inconvenience to use.
    • 3) Standard test without fittings, only GB12459, GB13401 standard specifies the calculation of blasting test of seamless steel butt welding fittings and steel pipe fittings of the pressure of the other pipe fittings manufacturing quality assurance test standard or Standard No.

    Computing method

    The calculation formula of theoretical weight per meter
    Delivery time for the spiral steel pipe according to the actual weight of shipment or delivery according to theoretical weight
    The actual weight, time of delivery, the weight of the product is according to the weighing weight (weighing) delivery;
    Theoretical weight — at the time of delivery, the product weight is calculated by nominal size of the steel weight. The formula is as follows (required delivery according to theoretical weight, should be specified in the contract):
    Theoretical weight per meter of spiral steel pipe (steel density 7.85kg/dm3) formula: W=0.02466 (D-S) S
    Type: W– spiral pipe per meter of theoretical weight, kg/m;
    Nominal diameter D– pipe, mm;
    S– spiral pipe nominal wall thickness
    Seamless steel tube The weight of the formula: [( external diameter Thickness) * wall thickness of]*0.02466=kg/ meters (weight per meter)


    The key to the quality of the steel pipe wall thickness uniformity number of wall thickness, thick wall steel pipe wall thickness is out of control will directly affect the quality and use of steel pipe, thick wall steel pipe, large diameter thick wall steel pipe is generally used in all kinds of mechanical processing, thick wall parts processing, pipe wall thickness pipe of the uniform directly effect of quality of the machined parts, pipe wall thick wall steel tube is out of control, the overall quality of the steel pipe is not strictly. The site or warehouse to select appropriate sites and storage of thick wall steel pipe, should be selected in the clean, unobstructed drainage areas, away from the harmful gas or dust factories. To remove weeds and all debris on the ground to keep clean, thick wall steel pipe. Not in the warehouse with acid and alkali, salt, cement and other corrosive materials piled up together on thick wall steel pipe. Different varieties of thick wall steel pipe shall be stacked separately to avoid confusion, to prevent contact corrosion. Large steel, steel, steel, or large diameter thick wall steel pipe, forgings can be piled up in the open air.

    Small and medium sized steel, wire rod, steel, medium caliber thick wall steel pipe, steel wire and wire rope, can be stored in a well ventilated material shed, but must cover pad. Some small thick wall steel pipe, steel sheet, steel, silicon steel sheet, thin or small caliber thick wall steel pipe, cold rolling, cold drawn thick wall steel tube as well as high prices, easy corrosion metal products, can be stored in storage. The warehouse should be selected according to geographical conditions, generally the ordinary closed warehouse, the roof walls, doors and windows tightly, with ventilated warehouse. The Treasury requires sunny pay attention to ventilation, pay attention to keep off rain moisture, suitable storage environment. Reasonable stacking and first put stacking principle is solid in the stacking, to ensure the safety of the conditions, do stacking according to varieties, specifications, different varieties of materials to prevent confusion and mutual stacking, corrosion, the principle of prohibition in the stack near the corrosive goods store, the thick wall steel pipe. The steel piled up in the open air the following must be chock or stone, stack face slightly tilted to facilitate drainage, and pay attention to material placed straight, to prevent deformation caused by bending. The height of stack, the manual operation is not more than 1.2m, the mechanical operation of the stack is not more than 1.5m, the width is not more than 2.5m. between the stack and the stack should have a certain channel check road access is generally O.5m, depending on the material size and transport machinery and is generally 1.5

    2.Om. duo pad high, if the warehouse for Chaoyang cement floor pad high O.1m can; if the mud, to pad high O.2

    0.5m. If the open-air site, cement ground pad high O – 3 – O – 5m, 0.5

    O.7m. high mud sand cushion piled up angle steel and channel steel should be put down, the mouth down, steel should be put, I groove surface can not towards the thick wall steel pipe, to avoid water rust.

    Related Advantages Of Thick-walled Seamless Pipe Cold Extrusion Technology

    1. The thick-walled seamless pipe cold extrusion technology has the following advantages:
    2. Extrusion parts size accurate surface smoothness: At present, the cold extrusion parts developed in China generally have a dimensional accuracy of 8 to 9 grades. If the ideal lubrication is used, the precision is second only to the fine polished surface. Therefore, parts manufactured by the cold extrusion method generally do not need to be reworked, and a small amount only needs to be finished (grinding).
    3. Saving raw materials: The material utilization rate of cold extrusion parts can usually reach more than 80%. For example, the utilization rate of the piston machining material of the Jiefang brand automobile piston is 43.3%, and the material utilization rate is increased to 92% when the cold extrusion is used; and if the universal joint bearing sleeve is changed to cold extrusion, the material utilization rate is from the past. 27.8% increased to 64%. It can be seen that the production of mechanical parts by cold extrusion can save a lot of steel and non-ferrous materials.
    4. High productivity: The efficiency of producing mechanical parts by cold extrusion method is very high, especially in the production of large-volume parts, which can be several times, several times, or even several hundred times more efficiently produced by cold extrusion. For example, the cold extrusion method for automotive piston pins is 3.2 times higher than that for cutting, and the cold extrusion piston pin robot is currently used to further increase productivity. The productivity of a cold extrusion automaton is equivalent to the productivity of 100 ordinary lathes or 10 four-axis automatic lathes.

    Processing performance of thick-walled Seamless Steel Pipe

    1. Thick-walled seamless steel pipe castability (castability): refers to the ability of metal materials to obtain qualified castings by casting. Casting properties mainly include fluidity, shortening and segregation. Fluidity refers to liquid metal filling molds. Capability, shortening refers to the degree of volume shortening when the casting is condensed. Segregation refers to the non-uniformity of the chemical composition and arrangement of the metal during the cooling and condensation process due to the difference in crystallization.
    2. Thick wall seamless steel tube forgeability: refers to the metal material can change the shape without cracking during pressure processing. It can be hammered, rolled, stretched, twisted in hot or cold state. Pinch and other processing. The quality of forgeability is primarily related to the chemical composition of metal materials.
    3. Thick-walled seamless steel pipe machinability (cuttability, machinability): refers to the ease with which a metal material becomes a qualified workpiece after being machined by a tool. The machinability is good and the surface roughness of the workpiece is usually processed. It is measured by the cutting speed and the degree of wear of the tool. It is related to many factors such as the chemical composition, mechanical function, thermal conductivity and degree of work hardening of the metal material. It is usually roughly judged by the hardness and the resistance for the machinability. Generally speaking, the higher the hardness of the metal material, the harder it is to cut. The hardness is not high, but the resistance is large and the cutting is difficult.
    4. Weldability (weldability): refers to the customary function of metal materials for welding processing. Firstly, it refers to the difficulty of obtaining high-quality welded joints under certain welding process conditions. It contains two aspects: Combined function, that is, under certain welding process conditions, the certain metal constitutes the sensitivity of welding defects, and the second is the application of the function, that is, the certain metal welding joints have the applicability to the application requirements under certain welding process conditions.

    Bearing Capacity Of Thick-walled Seamless Steel Tubes

    The outstanding feature of thick-walled seamless steel pipe is its strong pressure resistance, and it can be transported by various liquids and gases. So how is the carrying capacity of thick-walled seamless steel pipes improved? The following is a detailed introduction for everyone.
    In layman’s terms, thick-walled seamless steel tubes can carry weight indirectly. It is generally believed that cabinets are also best not to hang on light-weight walls, but for light-weight walls that have been tiled, because cement can enhance the load-bearing capacity of the wall, the cabinet can be hung on the wall even without special treatment. . However, for the sake of insurance, it is best to deal with the wall. The method of treatment is to first coat a thick-walled seamless steel pipe on the wall, then smooth it with cement mortar, and finally seal it with gypsum board.
    However, the safest method is to use a special hanger to secure the thick-walled seamless steel cabinet to the floor. Thick-walled seamless steel tubes carry relatively high pressure and are widely used in the construction bottom and transport liquids. From the perspective of his performance, the demand for thick-walled seamless steel tubes and the market will become stronger and stronger. Here are some reasons why thick-walled seamless steel pipes often burst:
    The hot-rolled rolling position of thick-walled seamless steel tube steel is 38, 118m away from the strip head, mainly located in the middle of the strip.

    1. It is speculated from the shape of the large hole of the rolling crack that the crack starts in the middle of the width of the strip. The reason is that the rolling force and the shearing force cause the crack to stretch and form a macroscopic macroscopic hole.
    2. The seamless steel pipe in the cold rolling production process interrupted the fracture surface smooth, no obvious surface defects before and after the fracture.
    3. Observing the microscopic morphology of the fracture, the typical dimple-like ductile fracture morphology is observed. At the same time, the fracture is layered, the central dimple is larger, the dimple is reduced at the near surface, and the crack exhibits divergence mainly center fracture. The extended fracture morphology has a deep fracture depth at the center, and it is speculated that the layered morphology of the fault zone is closely related to the central segregation.

    Application Of Thick-walled Seamless Steel Pipe

    The term seamless steel pipe is believed to be familiar to many people. It is not well understood that it is only a detailed classification. Because the types and types of steel pipes are numerous and numerous, the number of pipes including plastics has reached tens of thousands in the world. These pipes are used in various ways, and every pipe from the sewer to the city plays a role. The most important role, the process development, makes thick-walled steel pipes, which are smaller than 20 diameter, into hot-selling pipes.
    Many people may be unfamiliar, but they use this material in many channels. For example, buildings such as some other industries use seamless steel pipes because the walls of thick-walled seamless steel pipes are thick and durable. Widely used. Thick-walled steel pipes can also be used as sewage pipes. It can also be used as oil pipes. Nowadays, the underground passages of the city are indispensable for thick-walled steel pipes. Steel pipes are also used to build mobile scaffolding. Because the quality of thick-walled steel pipes is very good, more and more industries are starting. Pay attention to this material.
    In the construction of cars or corridors, thick-walled steel pipes are often used for their small advantages. Many of our automobile exhaust pipes are made of thick-walled steel pipes, although many plastic pipes are used in construction. The disadvantage of the plastic pipe is obvious, the age and oxidation resistance are absolutely inferior to the steel pipe. That is to say, human development has been inseparable from the new building materials of steel pipes. Stainless steel has been popular for many years. Manufacturers have made series of stainless steel products such as thick-walled steel pipes according to the principle of stainless steel durability, which is considered to be a major part of the human tube industry. progress.
    The development prospects of thick-walled steel pipes are good, because the construction of big cities is inseparable from it. In the future, there will be more industrial land to use as a necessary material for engineering, and its role is slowly changing. Serving human beings is the mission of thick-walled steel pipes. Our lives have also become more abundant with the addition of thick-walled steel pipes, and the convenience and convenience it provides are very real. It can be seen that thick-walled steel pipes have slowly entered various industries and entered our lives.

    What is thick-walled steel pipe? Thick wall steel pipe, the steel pipe The diameter and wall thickness of the steel tube ratio is smaller than 20 is called the thick wall steel pipe…

    Nominal Pipe Size

    What is Nominal Pipe Size ?

    Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. The name NPS is based on the earlier “Iron Pipe Size” (IPS) system.

    That IPS system was established to designate the pipe size. The size represented the approximate inside diameter of the pipe in inches. An IPS 6″ pipe is one whose inside diameter is approximately 6 inches. Users started to call the pipe as 2inch, 4inch, 6inch pipe and so on. To begin, each pipe size was produced to have one thickness, which later was termed as standard (STD) or standard weight (STD.WT.). The outside diameter of the pipe was standardized.

    As the industrial requirements handling higher pressure fluids, pipes were manufactured with thicker walls, which has become known as an extra strong (XS) or extra heavy (XH). The higher pressure requirements increased further, with thicker wall pipes. Accordingly, pipes were made with double extra strong (XXS) or double extra heavy (XXH) walls, while the standardized outside diameters are unchanged. Note that on this website only terms XS & XXS are used.

    Pipe Schedule

    So, at the IPS time only three walltickness were in use. In March 1927, the American Standards Association surveyed industry and created a system that designated wall thicknesses based on smaller steps between sizes. The designation known as nominal pipe size replaced iron pipe size, and the term schedule (SCH) was invented to specify the nominal wall thickness of pipe. By adding schedule numbers to the IPS standards, today we know a range of wall thicknesses, namely:

    SCH 5, 5S, 10, 10S, 20, 30, 40, 40S, 60, 80, 80S, 100, 120, 140, 160, STD, XS and XXS.

    Nominal pipe size (NPS) is a dimensionless designator of pipe size. It indicates standard pipe size when followed by the specific size designation number without an inch symbol. For example, NPS 6 indicates a pipe whose outside diameter is 168.3 mm.

    The NPS is very loosely related to the inside diameter in inches, and NPS 12 and smaller pipe has outside diameter greater than the size designator. For NPS 14 and larger, the NPS is equal to 14inch.

    For a given NPS, the outside diameter stays constant and the wall thickness increases with larger schedule number. The inside diameter will depend upon the pipe wall thickness specified by the schedule number.

    Pipe size is specified with two non-dimensional numbers,

    • nominal pipe size (NPS)
    • schedule number (SCH)

    and the relationship between these numbers determine the inside diameter of a pipe.

    Stainless Steel Pipe dimensions determined by ASME B36.19 covering the outside diameter and the Schedule wall thickness. Note that stainless wall thicknesses to ASME B36.19 all have an ” S ” suffix. Sizes without an ” S ” suffix are to ASME B36.10 which is intended for carbon steel pipes.

    The International Standards Organization (ISO) also employs a system with a dimensionless designator.
    Diameter nominal (DN) is used in the metric unit system. It indicates standard pipe size when followed by the specific size designation number without a millimeter symbol. For example, DN 80 is the equivalent designation of NPS 3. Below a table with equivalents for NPS and DN pipe sizes.

    NPS 1/2 3/4 1 1&#188 2 3 4
    DN 15 20 25 32 40 50 65 80 90 100

    Note: For NPS ≥ 4, the related DN = 25 multiplied by the NPS number.

    Do you now what is “ein zweihunderter Rohr” ? . Germans means with that a pipe NPS 8 or DN 200. In this case, the Dutch talking about a “8 duimer”. I’m really curious how people in other countries indicates a pipe.

    Examples of actual O.D. and I.D.

    Actual outside diameters

    • NPS 1 actual O.D. = 1.5/16″ (33.4 mm)
    • NPS 2 actual O.D. = 2.3/8″ (60.3 mm)
    • NPS 3 actual O.D. = 3½” (88.9 mm)
    • NPS 4 actual O.D. = 4½” (114.3 mm)
    • NPS 12 actual O.D. = 12¾” (323.9 mm)
    • NPS 14 actual O.D. = 14″(355.6 mm)

    Actual inside diameters of a 1 inch pipe.

    • NPS 1-SCH 40 = O.D.33,4 mm – WT. 3,38 mm – I.D. 26,64 mm
    • NPS 1-SCH 80 = O.D.33,4 mm – WT. 4,55 mm – I.D. 24,30 mm
    • NPS 1-SCH 160 = O.D.33,4 mm – WT. 6,35 mm – I.D. 20,70 mm

    Such as above defined, no inside diameter corresponds to the truth 1″ (25,4 mm).
    The inside diameter is determined by the wall thickness (WT).

    Facts you need to know !

    Schedule 40 and 80 approaching the STD and XS and are in many cases the same.
    From NPS 12 and above the wall thickness between schedule 40 and STD are different, from NPS 10 and above the wall thickness between schedule 80 and XS are different.

    Schedule 10, 40 and 80 are in many cases the same as schedule 10S, 40S and 80S.
    But watch out, from NPS 12 – NPS 22 the wall thicknesses in some cases are different. Pipes with suffix ” S ” have in that range thinner wall ticknesses.

    ASME B36.19 does not cover all pipe sizes. Therefore, the dimensional requirements of ASME B36.10 apply to stainless steel pipe of the sizes and schedules not covered by ASME B36.19.

    Remark( s ) of the Author.

    The Story Behind Nominal Pipe Size March 9, 2006
    • A question was put to the PM Engineer (PME) staff (one of SUPPLY HOUSE TIMES sister magazines) asking how nominal pipe size came to be. Here is the answer provided by PME Editorial Director Julius Ballanco.
    • The person directly responsible for the nominal pipe size was a gentleman by the name of Robert Briggs. Briggs was the superintendent of the Pascal Iron Works in Philadelphia. In 1862, he wrote a set of pipe specifications for iron pipe, and passed them around to all of the mills in the area.
    • Realize that in 1862, the United States was engaged in the Civil War. Each pipe mill made its own pipe and fittings to its own specifications. Briggs tried to standardize the sizing, which would also help the war effort. The pipe and fittings would be interchangeable between mills. This was rather novel in 1862.
    • The pipe standards went on to become known as the “Briggs Standards”. They eventually became the American Standards, and finally the standards used for modern day pipe.
    • The current ASTM A53 Steel Pipe Standard uses basically the Briggs Standard for pipe sizes 1/2 inch through 4 inch. You will notice that after 4 inches, pipe starts to get closer to the actual dimension used to identify the pipe.
    • So, you are probably asking, where did the sizes come from ?. Well, they were the sizes of the dies used in Pascal Iron Works. Briggs made everyone adjust to him. Hence, the name “nominal” pipe size came about, meaning “close to” or “somewhere in the proximity of” the actual dimension.

    I found the story behind Nominal Pipe Size on Supplyhouse Times

    Nominal Pipe Size What is Nominal Pipe Size ? Nominal Pipe Size (NPS) is a North American set of standard sizes for pipes used for high or low pressures and temperatures. The name NPS is ]]>