Conversion from ASTM Standards 

Engineering specification is also a language, and standard specifications for material and processes are defined differently in each country in the world. To a new designer, steel grades might seem easy, where 316 stainless steel is one material and cast iron another, but there are variations in each of these categories of metal. Rumors abound about people receiving poor quality steels from other jurisdictions. It leaves some designers wondering if there is something intrinsic in the official standards in other countries that can lead to these complaints.

International standards do not translate, metal-for-metal, the way words might translate. When converting from one standard to another, it’s almost impossible to find identical compositions for a given type of metal. The question becomes: can you find an equivalent? This can be confusing, as each named metal grade has its own chemistry and production guidelines.

For people without a materials background, these differences can make the purchase of foreign-made metal seem iffy, like ordering an inferior knockoff. However, the quality of the grades of steel are as good, country to country. Understanding what makes a steel standard or specification can help a North American business navigate overseas production.

Steel Grades explained

Metal alloys are a mixture of different proportions of elements. A standard includes the chemistry, or “recipe” for the alloy, documenting what different elements should be melted into it. Specific instructions may also be given on melting temperature, cooling, and treatment.

Published standards also record the mechanical properties of a specified metal. If it has been made correctly, a metal should not only have the correct chemical analysis, but also perform within the correct range in mechanical tests.

Steels contain iron and carbon. Standards for each grade of steel specify the proportions by weight of each of these elements, as well as any additional elements alloyed with them. These additions may create different characteristics: for example, chromium is present in stainless steel to help prevent rusting.

In most consumer metal standards, the proportions of each element are given an acceptable range, rather than a precise number. For example, the ASTM 1050 grade steel is so named because it is approximately .50% carbon by weight. However, the tolerance for carbon percentage in the ASTM 1050 standard is .48-.55%. A similar Japanese specification sets carbon between .47-.53%, and allows for silicon and other trace elements, whereas the ASTM standard does not.

Steel specifications often provide ranges for carbon, manganese, silicon, phosphorus, sulfur, chromium, nickel, and molybdenum, and none set identical ranges for each element. It is for this reason that steel standards from different organizations are not precise matches: the tolerances merely overlap. If one steel specifies less than .007% sulfur content, and another allows up to .040%, are they different steels? Small changes do not matter in many situations but may be relevant depending on the metal’s intended use.

It is not just chemistry, but also processing, that changes the behavior of a metal. Metal is crystalline and forms grain microstructures as it cools. Chemistry, melting, cooling, and heat treatment all can change the grain of the metal. This directly influences tensile strength, hardness, and brittleness. Therefore, steel specification may also include the production steps needed to create particular microstructures, including martensite, austenite, or ferrite grains.

When making a substitution between one standard and another, a skilled metallurgist or engineer will evaluate comparable grades based on mechanical properties. The engineer considers what the final product needs to do, and in what conditions. Using their understanding of chemistry, the expected working load, and knowledge of the conditions the product will work in, they can find a steel for the product’s requirements in any standard. All recognized steel standards generally have equivalent rigor, making this translation possible.

It is not a difference in published standards that are the source of poor-quality foreign metals.

Manufacturing Processing Specification for Seamless pipe

Cold drawn (rolled) seamless steel pipe: round tube billet → heating → perforation → head → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → blank tube → heat treatment → straightening → Hydraulic test (inspection) → mark → storage.

Hot rolling (extrusion seamless steel pipe): round tube billet → heating → perforation → three-roll cross-rolling, continuous rolling or extrusion → pipe removal → sizing (or reducing diameter) → cooling → blank tube → straightening → water pressure Test (or flaw detection) → mark → into storage.

Detailed explanation of two Steel Pipe processes

The cold drawn steel pipe is made of hot-rolled steel coil as raw material, it's subjected to pickling to remove scale and then cold-rolled. The finished product is rolled hard roll. The cold work hardening caused by continuous cold deformation to make the strength and hardness of the rolled hard roll rise and tough. The plastic index is reduced, so the stamping performance will deteriorate and can only be used for parts that are simply deformed. Rolled hard rolls can be used as raw materials for hot-dip galvanizing plants because the hot-dip galvanizing units are provided with an annealing line. The hard roll weight is generally 6~13.5 tons, and the inner diameter of the coil is 610mm. Generally, cold-rolled rolled sheets and coils should be subjected to continuous annealing (CAPL unit) or hood furnace annealing to eliminate cold work hardening and rolling stress, and achieve the mechanical properties specified in the corresponding standards. The surface quality, appearance and dimensional accuracy of the cold-rolled steel sheet are superior to those of the hot-rolled sheet, also the thickness of the product is thinly rolled to about 0.18 mm, which is favored by the majority of users. Deep processing of products with cold-rolled steel coils as a substrate has become a high value-added product. Such as electro-galvanizing, hot-dip galvanizing, fingerprint-resistant electro-galvanizing, color-coated steel coils and vibration-damping composite steel sheets, PVC laminated steel sheets, etc, so that these products have excellent quality, high corrosion resistance and other excellent quality, which have been widely used. Cold rolled steel coils must be finished after annealing, cutting, tailing, trimming, leveling, leveling, rewinding, or longitudinal shear plates, etc. To conculde, cold rolled products are widely used in automobile manufacturing, home appliances, instrument switches, construction, office furniture and other industries. The weight of each package after the steel plate is 3 to 5 tons. The flat roll weight is generally 3~10 tons/vol. The inner diameter of the coil is 610 mm.

The hot-rolled steel pipe is made of continuous casting slab or slab slab as raw material, heated by step-type heating furnace, descaled by high-pressure water and then enters the rough rolling mill. The rough rolling material passes through the cutting head and tail, and then enters the finishing mill to implement computer control. After the final rolling, it is subjected to laminar cooling and coiling, and becomes a straight hair roll. The head and tail of the straight hair roll tend to be tongue-shaped and fish-tail-shaped, the thickness and width are inferior.

The edges often have defects such as waves, folds, and towers. The weight of the coil is heavier and the inner diameter of the coil is 760 mm. (Generally, the tube industry likes to use it.) After the straight hair is wound through the cutting, trimming and multi-pass straightening, leveling and other finishing lines, then cutting or rewinding, it becomes hot rolling steel plates, flat hot rolled steel coils, slitting belts and other products. If the hot-rolled finishing roll it's pickled to remove the scale and oiled, the hot-rolled pickled sheet roll is formed. This product has a tendency to partially replace cold-rolled sheets, and the price is moderate, which is very popular among users.

About ASTM Seamless Steel Pipe

Seamless steel pipe for the use of engineering and construction is very widely, it is a hollow steel strip no seams, it is mainly used to transport liquids pipelines, different look and general steel,one of those heavy type steel, it has a strong resistance to corrosion, resistant to general corrosion.

Compared with other plastic seamless steel pipe having strong mechanical resistance, impact regardless of how high a temperature is not interested in the use of seamless steel pipe, it is mounted and the other pipe is the same, can replace other piped water and other liquids.

Seamless steel pipes are extensively applied for the nuclear device, gas, petrochemical, ship building and boiler industries. seamless steel pipes dominates 65% of market share in Chinese boiler industry.

Seamless steel pipe chemical analysis: the chemical composition of the material for chemical analysis, chemical composition to meet the standard requirements.

Seamless steel pipe pressure and hydrostatic test is for pressure tube by into the hydrostatic test, which do not maintain the prescribed pressure value not less than 5 seconds, not to disclose, the regular supply hydraulic pressure test is 2.45MPa pressure The pressure test is P = 0.5MPAa.

The corrosion test: industrial corrosion-resistant steel pipe according to standard regulations or agreement between the corrosion of steel pipe corrosion resistance test, no intergranular corrosion.

Features of Seamless steel pipe:

· First, the thicker the wall thickness of the solution, it is really more cost effective and wise, the thinner the wall thickness, and its processing costs will appreciate sharply;

· Second, from the process of the product determines its limitations, from the general seamless steel pipe with low accuracy: wall thickness uneven, low brightness tube appearance, fixed length of high cost, and pitting in the appearance of black spots is difficult to bring go;

· Third, testing and plastic must be off-line. So it really is in the higher pressure, high strength, mechanical structure of wood reflects its superiority.

Characteristics of seamless steel pipes are as follows:

· High precision can do small batch production.

· Smaller diameter.

· Weldability strong, high compression capability.

· Steel pipe superior performance, relatively dense metal.

· Steel Cross area is more complex.

· High precision cold drawn products, good surface quality.

Application of ASTM Seamless Steel Pipe

Seamless steel pipe has a wide range of uses, including structure, fluid transportation, low and medium pressure boiler, high pressure boiler, fertilizer equipment, oil cracking, geological drilling, diamond core drilling, oil drilling, ships, automobile half shaft sleeve pipe, diesel engine and so on, will use seamless steel pipe.

The use of seamless steel pipe can avoid leakage and other problems, ensure the use effect, improve the utilization rate of materials.

It can be seen that the application of seamless steel pipe mainly reflects three areas:

· One is the construction field, which can be used for underground pipeline transportation, including groundwater extraction when building.

· The second is the processing field, can be used in machining, bearing sleeve and other aspects.

· Three is the electrical field, including gas transmission pipeline, fluid pipeline for water power generation, etc.

ASTM Seamless Steel Pipe is different from welded steel pipe

Molding process of the steel tube：

2.seamless steel pipe is cylindrical ingot hot pull into a tube, so can not see the weld. 

Use classification of steel pipe:

1.water gas pipe is commonly used welded steel pipes, transport fluid and gas called, to feel the pressure, so are relatively thick wall. 

2.The conduit is to wear a wire and thin-walled tube. At that time only the standard, no one production. In fact, the eighties and nineties of gas pipes with water.

3.Galvanized iron pipe is galvanized welded steel pipe. Galvanized inside and outside, water can be transported. Let Electric used when threading. General are relatively thin wall. Now on the market is poor. Elbow bend angle to blast hole.

Difference between seamless and seam pipe

Seamless pipe is formed at one time during rolling. Welded steel pipes need to be welded after rolling, generally with spiral welding and straight welding. The performance seamless tube is better, and of course the price is higher.

Steel pipe is a kind of hollow long steel, which is used as a pipeline for conveying fluids, such as petroleum, natural gas, water, gas, steam, etc. In addition, when the bending and torsional strength are the same, the weight is light, so it is also widely used. Used in the manufacture of mechanical parts and engineering structures. Also used to produce a variety of conventional weapons, barrels, shells and so on.

· Concentricity: The process of manufacturing seamless pipe is a hole punched out in a stainless steel billet temperature of 2200 ° f the, in this high temperature, the tool steel by stamping and drawing softens and spirally from Kongzhong Cheng-shaped out. So that the wall thickness of the pipe is not uniform and high eccentricity. Thus astm allows seamless pipe wall thickness than a slit tube wall thickness difference. Precision cold-rolled plate (width of 4-5 feet per roll) made a slit tube. These cold rolled sheet is usually the largest wall thickness difference is 0.002 inches. The steel sheet was cut into a width πd, where d is the outer diameter of the pipe. Seam pipe wall thickness tolerance is very small, and the entire circumference of the wall thickness is very uniform. 

· Welding performance: Average seam pipe and seamless pipe the chemical composition has a certain difference. The production of seamless steel component is only astm the basic requirements. Produce seamless tube steel with the chemical composition suitable for welding. For example, silicon, sulfur, manganese, oxygen and triangle ferrite and other elements can be mixed according to a certain proportion in the welding process with an easy transfer heat weld, so that the entire weld penetration. The lack of the above chemical composition of the steel, seamless, for example, in the welding process will produce a variety of factors of instability, is not easy to weld and welding impervious. 

· Grain size: usually, the grain size of the metal and the heat treatment temperature and to maintain the same temperature for the time. Therefore, annealed seam and seamless pipes are the same grain size. If the slit pipe with minimum cold treatment, grain size smaller than the grain size of the weld metal of the weld, and otherwise, the grain size is the same. 

· Strength: the strength of the pipe depends on the alloy composition, which contains the same alloy and the same heat treatment of seamless and seamed pipe strength are the same in essence. After tensile test and three-dimensional vibration test, tear seam pipe occurs almost exclusively in a place away from the welding point or heated areas. This is because the weld impurities less and the nitrogen content is higher, and thus the strength of the weld is better in other parts. ASME Boiler and Pressure Vessel Association, however, that a slit tube can only afford 85% of the license pressure, which is mainly due to the collection of data as early as welding equipment in use today have improved. ASME requirements 100% by ultrasonic test tube joints can be fully exposed to the license pressure. Similarly, Europe and Asia also provides through the eddy current test tube joints to guarantee the performance of the welding quality, eddy current testing require the approval of the legal procedures and permit institutions. The trent eddy current testing by the permission of the Swedish Ministry of Energy. The ASME think current loss is smaller quality performance is based on a slit tube. 

· Corrosion resistance: corrosion resistance, good or bad is also vary depending on the composition of the alloy. The same chemical composition fully heat-treated seamless and the seam pipe corrosion resistance. ASTM provide supplementary test can prove the corrosion resistance of the weld is equal to or better than the metal being welded. Incomplete seam tube welding heat treatment in acidic chloride environment, corrosion will be accelerated, but only need corrosion test is, in fact, their environment is not so bad. Bending and extension: extension of the welding at the following tests can be specified by ASTM Verification: bend 45 °, then bent to 90 °, then flattened along the weld seam pipe Repeat the above steps; then turned so that the weld bending diameter up to 180 °. Weld quality standards adopted by the tear or intergranular separation are not allowed in the case of 40 times magnification. Pipe bending radius is controlled by the composition of the alloy, the general minimum bend radius for 2d. Conditions of the welding seam in a neutral or a state of compression. Moreover, the piping should be annealed to reduce its hardness, thereby improving the bending performance. 

· Price: Price seam pipe is usually only half of the seamless. 

· Wall thickness and diameter: thickness and diameter value of small thin-walled tube preferably by welding production. Thickness and diameter large thick-walled tube is best made with the stamping method.