【 Weak current College 】 pipe standards introduced in common terminology

1) a generic term

① delivery status
Refers to the final delivery of the products of plastic deformation or the status of the final heat treatment. General delivery without heat treatment called hot-rolled or cold-drawing (rolling) State or manufacturing status; after heat treatment delivery of that State, or heat treatment under the heat of the category called normalizing (often), hardening and tempering, annealing, solid state. When ordering, order status indicated in the contract.

② by actual weight of the delivery or delivery by theoretical weight
Actual weight--the time of delivery, the product weight is the weight (and weighed) weight of delivery;
Theoretical weight--the time of delivery, the product weight is based on steel nominal size calculated by weight. The calculation formula is as follows (the weight of the delivery requirements according to the theory, indicate in the contract):
Pipe weight per metre of theory (steel density 7.85kg/dm3) calculation formula:
W=0.02466（D-S）S
Type: W--theoretical weight per m of steel pipe, kg/m;
D--pipe nominal outer diameter, mm;
S-pipe nominal wall thickness, mm.

③ guarantee conditions
Under current standards projects for inspection and ensure that they meet standard requirements, called guarantee conditions. Guarantee conditions are divided into:
A basic guarantee conditions, (also known as will guarantee conditions). Whether a customer is indicated in the contract. Shall be carried out according to the standards and to ensure that the test results meet standard requirements.
Such as chemical composition, mechanical properties, dimensional deviation, surface quality and testing, pressure experiment or flattening or flaring, process performance experiments are required insurance conditions.
B, agreements guarantee conditions: standard in addition to basic guarantee conditions, there are "according to the demand-side requirements, after consulting both supply and demand, and listed in the contract? quot; or when the demand-side requirements ... Should be indicated in the contract "; and the customer, on the basic guarantees in standard conditions with strict requirements (such as composition, mechanical properties, dimensional deviations, etc.) or an inspection item (such as the wall thickness of steel pipe ellipticity, does not equal). The above terms and requirements, in order, from both supply and demand, supply technical agreement signed and dated in the contract. Therefore, these conditions also known as Protocol guarantee conditions. There was agreement that the condition of the product, generally to the price increase.

④ batch
Standard in the "batch" means an inspection unit, i.e. the inspection lot. If the delivery unit unit, called delivery batches. When bulk delivery, a delivery group may include several inspection lot; when the delivery volume when an inspection lot can be divided into several batches of delivery.

The composition of "instalment" typically have the following requirements (see the related standards):
A, each batch shall be composed of the same grade (grade), same furnace (cans), or the same oven number, same size and same heat treatment system (furnace) of steel.
B, for high-quality carbon steel structure, fluid, can different furnace (pot) of the same brand, same size and same heat treatment system (furnace) of steel.
C, welded steel tubes each batch shall be composed of the same grade (grade), composed of the same specification of pipe.

⑤ high-quality steel and high-quality steel
In GB/T699-1999 and GB/T3077-1999 standards, its trademark followed by the word "A", as the high-quality steel, contrary to the generally high-quality steel.
High-quality steel in some or all of the following is greater than that of high-quality steel:
A range of element content, reduced;
B, reduce harmful elements (such as sulfur, phosphorus, copper) content;
C, guarantee a high purity (requires fewer non-metallic inclusion content);
D, guarantee a high mechanical and technological properties.

⑥ vertical and horizontal
Standard in longitudinal direction is parallel processing (that is, with processing direction); transverse denotes processing direction vertical (processing direction i.e. steel pipe axial).
Do impact energy experiment, vertical specimen orientation because of fracture and processing. Therefore calls the horizontal fracture; horizontal specimen fracture due to processing and parallel to the direction, therefore calls longitudinal fracture.

(2) steel pipe shapes, size terminology

① the nominal size and the actual size
A, nominal size: is the standard provisions is nominal, is users and enterprises looking for the ideal size is indicated in the contract size of order.
B, actual size: is the production process in actual size, this size is often greater than or less than the nominal size. This is greater than or less than the nominal dimensions of the phenomenon known as the deviation.

② deviation and tolerances
A, deviation: in the production process, because the actual size can be difficult to achieve nominal size requirements, that is often greater than or less than the nominal size, so the standard establishes the actual size and nominal size there is a difference between allowed. The difference is positive, called positive difference is negative the negative deviation of calls.
B, tolerance: standards of a plus or minus the sum of the absolute deviation value is called tolerance, also called "tolerance zone".
Deviation is directional, which means to "positive" or "negative" said; the tolerance is not directional, therefore, the deviation values are known as "tolerance" or "bear tolerance" is the wrong term.

③ delivery length
Delivery length also known as user requirements for length or contract length. The standard length for delivery in the following provisions:
A, usually length (also known as the non-fixed length length): where length is the length of the standard provisions within and no fixed length requirements, are known as usual length. For example, structural pipe standards: hot (squeeze. expansion) steel pipe 3000mm ~ 12000mm; drawing (rolling) steel pipe 2000mmm ~ 10500mm.

B, lengthLength: length length length should be generally, is within the scope of the contract in a fixed-length dimensions. But the actual operation are cut absolute length length is unlikely, therefore, standard provisions for length length allowed is deviation value.
Structural tube standard is:
Production length length length of tube than usual tubes yield drop large production companies fare request is reasonable. Increase the enterprise is not entirely consistent, usually on the basis of a benchmark price increase of 10%.

C, double length length: double length length length should be generally, the contract should specify single foot length and total length in multiples of the Constitution (e.g. 3000mm× 3 multiples of 3 3000mm, total length to 9000mm). Actual operation, should be based on the total length plus allows positive 20mm, plus every single foot length should be kept cut cushion. Structural tube, for example, provisions remain cut cushion: outside diameter ≤ 5 ~ 10mm 159mm; outer diameter > 10 ~ 15mm 159mm.
If the standard deviation of non-double length length and cutting margin requirement should be determined by supply and demand sides, consultations and indicate in the contract. Times the length scales with fixed length length, will give the production enterprise yield significantly reduced, thus producing enterprise is reasonable fare, the fare increases with the length length increases in basically the same.

D, scope length: the length of the range in the ordinary length, when a user requests a fixed length of the range, in the contract notice.
For example: typically has alength of 3000 ~ 12000mm and scope length length 6000 ~ 8000mm or 8000 ~ 10000mm.
Visible range is longer than length and generous double length length requirement, but the length of the stringent than usual, also production enterprises to bring yield reduction. Therefore manufacturers fare is justified, the increase in the basic prices increase on average 4%.

④ wall thickness are not
Pipe wall thickness is not possible throughout the same, in the cross-section and longitudinal tube wall thickness is not on the objective existence, namely the phenomena such as uneven thickness. In order to control this heterogeneity in some pipe standards set forth in the wall thickness is not allowed to index, as a general rule not exceed 80% of the wall thickness tolerances (after consultation with both supply and demand).

⑤ ellipticity
In circular pipe cross-section on the outer diameter of phenomena, that is, there are not necessarily mutually perpendicular maximum outer diameter and minimum outside diameters, the maximum outer diameter and the difference between the minimum diameter is oval degrees (or out-of-roundness). In order to control the ellipticity, steel pipe standards provides the oval of the General provisions allowing indicators, not more than 80% tolerance for the outside diameter (after consultation with both supply and demand).

⑥ bending
The length of the tube in a curve, on a number of its degree of curvature curve is called. Standard in bending is generally divided into the following two ways:
Local curvature: A, a metre long ruler by amount in the maximum bending of steel tubes, measuring its chord height (mm), which is the local curvature, numeric value with a unit for mm/m, represents a method such as 2.5mm/m. This method also applies to pipe ends are curvature.
B, full-length total curvature with a piece of string, from both ends of the tube, measuring pipe tensile bending Department Max chord height (mm), and then converting development degree (in m), a percentage of the length of the tube length bending.
For example: pipe length 8m, measured maximum chord height 30mm, the tube length bending should be:
0.03÷8m×100%=0.375%

⑦ oversize
Oversize or dimensions exceed the standards of tolerance. Here's the "size" mainly refers to the outer diameter and wall thickness of steel tubes. Usually someone put oversize habit called "tolerance in line", to equate deviation and tolerance is not known, you should call close "/" deviation. Here's deviation might be "positive" or "negative", rarely in the same batch of steel pipe in the positive and negative deviations are off-color ".

(3) chemical analysis terms

Chemical composition of steel is the relationship between the steel quality and end-use performance of one of the important factors, and also the preparation of steel products, as well as the final product is based mainly on heat treatment system. Therefore, the technical requirements of steel standards, often first establishes the applicable grade steel products (steel grade) and chemical composition, and the inclusion of standards in tabular form, is a production enterprise and customer acceptance of steel and steel products important constituents.

① steel melting components
General standards in chemical composition is the melting components. It is the steel smelting is complete, the chemical composition of the casting of the medium-term. To have a certain representation, that is, on behalf of the furnace or cans of average composition, sampling standard methods, the liquid steel into the sample mold, small ingots on a plane or drill sampling, in accordance with the provisions of the standard (GB/T223) for analysis, the results must conform to the standard range of constituents, and is also the basis of customer acceptance.

② finished components
The finished component called validation and analysis components, from the provisions on thefinished steel products (GB/T222) drillthrough or scrap of planing sampling, and in accordance with the provisions of the standard (GB/T223) for analysis of chemical composition. Steel in mold and plastic deformation, later because steel alloying elements in the uneven distribution of (segregation), thus allowing the finished product composition and scope of standard components (melting) discrepancies between the deviation value shall conform to GB/T222.

Steel production components mainly for the use or acceptance of the quality inspection departments using steel quality, production enterprises generally not do analysis of finished product (except as required by the user), but should ensure that finished products meet the standard requirements of.

③ the arbitral analysis
Because both laboratory analysis of the sameThe result of a significant difference and beyond two laboratories allow analysis of error, or a production company and sector, demand-side and supply-side on the same sample or the same analysis of finished steel products have differences, can be used by third-party analysis with rich experience of authority (such as the Chinese iron and Steel Institute or a commodity inspection eligible Inspection Department) for further analysis, namely that of the arbitral analysis. The results of the analysis of arbitration shall be final judgment.

(4), mechanical properties of terminology
Mechanical performance of steel products is to ensure that the final performance of steel (mechanical properties) of key indicators, it depends on the chemical composition of steel and its heat treatment system. In steel standards, according to the different usage requirements, establishes the tensile properties (tensile strength, yield strength and yield point, elongation) as well as hardness, toughness and indicators, as well as user requirements of high and low temperature performance, etc.

① tensile strength (σ b)
Specimens in the drawing process, pull off when the most vigorously (Fb), out to sample the cross-sectional area (So) from stress (σ), known as the tensile strength (σ b), N/mm2 (MPa). It represents the metal materials in the tension field resistance capacity of maximum. Formula:
Type: Fb--specimen pull off, when the most vigorously, N (n);
So--the original sample, mm2 cross-section.

② yield point (σ s)
With yield phenomenon of metal materials, sample drawing procedure in force does not increase (constant) is still able to elongate the stress that when the yield point. To force a drop occurs, you should distinguish between upper and lower yield point. Yield point in N/mm2 (MPa).
Upper yield point (σ s u): specimen yield and force first decline before the maximum stress;
The yield point (σ s l): when excluding the initial transient effects, yield the minimum of stress.
Yield point calculation formula is:
Type: Fs--sample drawing procedure yield strength (constant), N (n);
So--the original sample, mm2 cross-section.

③ fractured elongation (σ)
In the tensile test, the test sample after its scale distance, the length and the percentage of the gauge length, known as elongation. To σ represents, in%. Formula:
Type: L1-sample scale distance of la break length, mm;
L0--sample the original scale distance length, mm.

④ section shrinkage (ψ)
In the tensile test, after its sample la necking at maximum cross sectional cut amount and percentage of the original cross-sectional area, known as section shrinkage. Expressed in units of ψ. Calculated as follows:
Type: S0--sample raw cross-sectional, mm2;
S1--sample la after reducing the minimum cross-sectional, mm2.

⑤ hardness indicators
Metal material resistance hard objects the ability to pressure, surface, called the hardness. According to the test method and the scope of application, the hardness can be divided into Brinell hardness, Rockwell hardness, Vickers hardness, shore hardness and microhardness and high hardness. For tubes commonly have Brinell, Rockwell, Vickers hardness.

A, Brinell hardness (HB)
With a diameter of steel balls or carbide ball to the test force (F) onto the design surface, the provisions of the time after the removal of the test, the measurement of the surface of the specimen creasing diameter (L). Brinell hardness values is to test force divided by the indentation of a spherical surface area. To HBS (ball), N/mm2 (MPa).
The calculation formula is:
Type: F--into the metal surface of the test specimen, N;
D--testing steel ball diameter, mm;
D--the average diameter, mm for indentation.
Determination of Brinell hardness more accurate and reliable, but generally only applies to HBS 450N/mm2 (MPa) of metal materials, hard steel or a thin sheet does not apply. Standard in steel tube, the most widely used Brinell hardness, often to indentation to indicate that the diameter d hardness of the material that is both intuitive and convenient.

For example: 120HBS10/1000130: diameter 10mm steel ball in 1000Kgf (9.807KN) test force, keeping the 30s (seconds) measured Brinell hardness value 120N/mm2 (MPa).

B, Rockwell hardness (HK)
Rockwell hardness testing with Brinell hardness test, is indentation test methods. The difference is that it is measuring the depth of the indentation. That is, in preliminary Yong test force (Fo) and total test force (F) the role of the head (magic factory cone or ball) into the specimen surface, the provisions of the time, remove the main test, a measurement of the residual indentation depth increments (e) calculate the hardness values. Its value is a number without a symbol HR said that the ruler has A, B, C, D, E, F, G, H, K, and so on nine of the ruler. Which are commonly used in the steel hardness test is generally A ruler, B, C, HRA, HRB, HRC.

Hardness value calculated using the following formula:
When using A and C ruler test, HR = 100-e
When to useB ruler test, HR = 130-e
-E--residual indentation depth increment its assorted lines to provide unit 0.002mm said, that is, when the pressure head axial displacement of one unit (0.002mm), i.e. the equivalent of a number of Rockwell hardness changes. E value, the greater the hardness of the metal becomes low, while the higher hardness.
Scope of application of the above three rulers are as follows:
HRA (diamond cone pressure head) 20-88
HRC(Diamond cone pressure head) 20-70
HRB (diameter 1.588mm steel ball Indenter) 20-100

Rockwell hardness test is currently applied to a wide range of methods, including HRC in the use of steel pipe standards after Brinell hardness HB. Rockwell hardness can be applied to measuring the very soft to very hard metal materials, it makes up for Brinell method is not a simple compared to Brinell method, you can directly from the hardness machine dial readout hardness values. However, because of its small indentation, the hardness value less accurate Brinell method.

C, Vickers hardness (HV)

Vickers hardness test is also an indentation test method is a relative angle to 1360 of surface is pyramid of Diamond Head to the selected test force (F) onto the test surface, the provisions of the time after the removal of the test, measuring the length of two diagonal line indentation.

Vickers hardness value is test force divided by the surface area of the indentation, the calculation formula is:
Type: Vickers hardness HV--N/mm2, (MPa);
F-test force, N;
D--indentation the arithmetic mean of the two diagonals, mm.
Vickers hardness test force F used as 5 (49.03), 10 (98.07), 20 (196.1), 30 (294.2), 50 (490.3), 100 (980.7) Kgf (N), six levels, can measure hardness values in the range 5-1000HV.

Represents the method, for example: 640HV30/20 indicates 30Hgf (294.2N) test keep the 20S (seconds) for determination of Vickers hardness value 640N/mm2 (MPa).
Vickers hardness method can be used fordetermination of very thin metal materials and surface hardness. It has the Brinell, Rockwell method of the main advantages, while overcoming their weaknesses of basic, but not as convenient for Rockwell method. Vickers in pipe standards are rarely used.

⑥ impact strength indicators
Impact strength is reflected in the metal come oh external shocks load resistance, general impact toughness values (ak) and impact energy (Ak) indicated that their units are the J/cm2 and J (JOULE).

Impact toughness or impact energy test (hereinafter referred to as "impact test"), is divided into different test temperature and room temperature, low temperature and high-temperature impact test three; if the specimen notch shape can be divided into "V"-shaped gap and "U"-shaped notch impact test.

Impact test with a certain size and shape (10 × 10 × 55mm) specimen (the length of the Middle Office is "U" or "V"-shaped gap, the gap depth 2mm) on the test machine against shock loading under gap broken experiment.
A, shock absorption power Akv (u)--has a certain size and shape of the metal style, under the effect of the impact load absorbed by the break time. Unit is the joule (J) or Kgf.m.
B, impact toughness values akv (u)-shock absorbing work divided by sample gap at the bottom of the cross-sectional area. Unit is the Joule/cm2 (J/cm2) or kilogram force-m/cm 2 (Kgf.m/cm2). Formula:
Type: Akv (u)--specimen broken when the absorption of reactive power, Kgf.m (J);
S--sample gap at the bottom of the cross sectional area office, cm2.

Room temperature impact test temperature of 20 ± 50C; low-temperature impact test temperature range < 15 ~-1920C; high-temperature impact test temperature range of 35 ~ 10000C.

Low-temperature impact test the cooling medium is non-toxic, security, non-corrosive metal and not at the test temperature of solidification of liquid or gas. If ethanol (alcohol), carbon dioxide, solid (dry ice) or liquid nitrogen fog gas (liquid nitrogen).