Piping terms and definitions
Piping terms and definitions
1.Material
1.1 steel grade
Steel grade
1.2 pipe grade
The name indicating the strength level of the steel pipe
1.3 carbon steel
Carbon steel refers to an iron-carbon alloy having a carbon content of less than 2% and a small amount of silicon, manganese, and impurities such as phosphorus and sulfur. The performance of carbon steel depends mainly on the carbon content. The carbon content increases, the strength and hardness of the steel increase, and the ductility, weldability and weldability decrease.
1.4 alloy steel
An iron-carbon alloy composed of an appropriate amount of one or more alloying elements added to ordinary carbon steel. Alloy steel has special properties such as high strength, high toughness, wear resistance, corrosion resistance, low temperature resistance and high temperature resistance.
1.5 stainless steel
Steel that resists atmospheric corrosion is called stainless steel, and steel that resists chemical medium corrosion is called acid-resistant steel. In general, steels containing more than 12% chromium have the characteristics of stainless steel.
1.6 electric furnace steelmaking
The steelmaking process, which uses electricity as the energy source and scrap steel as the main raw material, is generally said to be the steel produced by the alkaline electric arc furnace, which has excellent quality and uniform performance. Electric furnaces generally have electric furnaces of 30 tons, 50 tons, 70 tons and 100 tons.
1.7 convert steelmaking
The steelmaking process completed in the converter with liquid pig iron as the main raw material. The converter is currently the most commonly used steelmaking equipment, and generally has converters of 100 tons, 150 tons, 200 tons and 300 tons.
1.8 ladle refining
In order to obtain a higher purity steel liquid and a steel with superior performance, the molten steel in the converter or the electric furnace is moved to another container for the refining steel making process. Furnace refining is generally carried out in a "ladle" (LF) or a dedicated container outside the furnace.
1.9 vacuum refining
Vacuum refining refers to refining of molten steel in vacuum furnaces at or below atmospheric pressure. Vacuum refining can further improve the purity of molten steel.
2, mechanical strength
2.1 Tensile strength
The maximum resistance of metal materials to damage under tensile forces, symbol Rm, in MPa.
2.2 yield strength
The metal material begins to produce the lowest stress point at yield, the symbol Rel, in MPa.
2.3 impact property
The resistance of metal materials to external impact loads is usually expressed by V-notch impact energy, and the symbol Akv is in J.
2.4 elongation rate
In the tensile test, the percentage of the length increased by the gauge length after the sample is broken and the length of the original gauge length, symbol A.
2.5 hardness
Metallic materials resist the ability of hard objects to press into the surface.
2.6 Rockwell hardness
A diamond cone indenter is pressed into the surface of the steel, and a method for detecting the hardness value is obtained by measuring the residual increment of the indentation depth, which is represented by the symbol HBW.
2.7 Brinell hardness
A method of detecting the hardness value by pressing a steel ball of a certain diameter into the surface of the sample and measuring the diameter of the impression on the surface of the sample is represented by HBW.
2.8 Vickers hardness
A positive quadrilateral pyramid diamond indenter is pressed into the surface of the sample, and a method for detecting the hardness value is obtained by measuring the diagonal length of the indentation on the surface of the sample, which is represented by the symbol HV, and is used more in the metallographic examination.
2.9 hydrostatic test
A test method for measuring the compactness of steel pipes. Under the test pressure, the voltage regulation time is not less than 5s.
The test pressure calculation formula is: P=2SR/D
In the formula:
P—test pressure, in MPa (MPa), when P<7MPa, repair to the nearest 0.5MPa, when P≥7MPa, repair to the nearest 1MPa;
S—Steel wall thickness in millimeters (mm);
D—the nominal outer diameter of the steel pipe or the calculated outer diameter, in millimeters (mm);
R—allows stress, ASME stipulates that for carbon steel and ferritic alloy steel pipes, the stress generated by the test shall not be less than 60% of the minimum value of the known yield strength, and for the austenitic alloy steel pipe, it shall not be less than the minimum known yield strength. 50%; allowable stress should be calculated according to the corresponding standard.
2.10 flatten test
Verify the deformation of the steel tube to a specified size. The tests were carried out at room temperature. After the flattening test, cracks and cracks were not allowed in the samples. The flattening test of the actual steel pipe material shall comply with the corresponding standards.
2.11 bend test
Mechanical test when the material is subjected to bending loads. The bending test is mainly used to test the plasticity and surface quality of steel pipes. Generally, the bending test shall be carried out according to the requirements of the purchaser. After consultation between the supplier and the purchaser, the contract shall indicate that the steel pipe with an outer diameter of not more than 22 mm may be subjected to a bending test, and cracks or cracks are not allowed in the bend of the specimen after bending. The bending test of the actual steel pipe material shall comply with the corresponding standards.
2.12 drift test
It is to test the deformation performance of the pipe end expansion process. The general flaring test shall be based on the requirements of the purchaser, negotiated by both parties, and specified in the contract. For steel pipes with a wall thickness of not more than 8 mm, the flaring test may be performed. After the flaring, the sample shall not be cracked or cracked. The flaring test of actual steel pipe materials shall comply with the relevant standards.
2.13 high-temperature strength
The mechanical properties of the samples were tested at room temperature above room temperature. Generally, there are high-temperature short-time tensile properties, high-temperature hardness, and the like.
2.14 high-temperature creep
The metal slowly undergoes plastic deformation under long-term high temperature and constant stress (even if the stress is less than the yield strength at this temperature), and is represented by the symbol (MPa).
2.15 rupture life
The ability of a metal material to resist fracture under high temperature and long-term loads is indicated by the symbol (MPa).
3, tube making technology
3.1 pierce
The solid tube blank is pierced into a hollow capillary tube with a plug.
3.2 hot roll
Refers to the rolling of metal materials at high temperatures. The rolling force required for hot rolling is small, and the geometry of the rolled product is not accurate enough.
3.3 cold draw
A process for cold working a perforated capillary. Cold drawing generally requires multiple drawing, and there must be corresponding stress relief annealing between each drawing to ensure the smooth progress of the next drawing. The capillary is subjected to acid washing, phosphorization and saponification before cold drawing. Pickling is a method of cleaning metal surfaces. Generally, the perforated capillary tube is immersed in an aqueous solution such as sulfuric acid to remove an oxide film on the metal surface; phosphating is a chemical protective reaction to form a phosphate protective film on the metal surface; saponification is The surface of the metal is coated with a saponification liquid which reacts with the phosphating film to produce a metal soap film which acts as a lubricant during cold drawing.
3.4 cold roll
Refers to the rolling of metal materials at low temperatures. Before the cold rolling, the capillary tube needs to be pickled, phosphatized and saponified. The rolling force of the cold rolling is large, and the geometrical dimensions of the rolled product are accurate.
3.5 hot expand
A process in which the mother tube is heated to a plastic deformation temperature, and the outer diameter of the mother tube is enlarged by the mandrel, and the wall thickness is reduced.
3.6 heat treatment
A process in which materials are placed in a medium to heat, heat, cool, and control the properties of the material by altering the surface structure of the material or its internal structure.
3.7 dressing
Reprocessing to meet customer's required size and quality requirements.
3.8 straightening
Correcting the shape defects of metal plastic processing products is one of the important finishing processes.
3.9 shot cleaning
Generally, it refers to a finishing process in which the surface of a steel pipe is treated by compressed air to achieve a clean surface (except for scale, burrs, dirt, etc.), which causes compressive stress on the surface and improves the fatigue resistance of the steel pipe.
3.10 plain ends
The end faces of the steel pipe were cut into a plane at 90° to the axis of the steel pipe.
3.11 beveled
The end faces of the steel pipe are machined into a welding groove at a certain angle.
4, delivery status condition of delivery
4.1 Rolling state as-rolled
Delivery status without any special rolling or heat treatment.
4.2 normalizing normalizing
The steel is heated to 30 ° C ~ 50 ° C above the phase transition point, kept for a certain period of time, and cooled in still air to obtain a heat treatment process containing a uniform structure of pearlite.
4.3 Annealing
The steel is heated to a certain temperature, kept for a certain period of time, and then slowly cooled after heat to obtain a heat treatment process close to the equilibrium structure.
4.4 Full annealing full annealing
The steel is completely austenitized and then slowly cooled to obtain an annealing process close to the equilibrium structure.
4.5 isothermal annealing isothermal annealing
Heating the steel to a temperature above the phase transition point, after a suitable period of time, cooling to a certain temperature in the pearlite transformation temperature zone and isothermally maintaining the austenite transformation into pearlite structure, and then cooling in air.
4.6 stress relief annealing
Annealing is performed to remove residual stress existing in the steel pipe due to plastic deformation processing, welding, or the like.
4.7 quenching quenching
The steel is heated to a temperature above the phase transition point, kept for a certain period of time, and then quickly cooled to the heat treatment process of the martensite structure.
4.8 Tempering tempering
After the steel is hardened, it is heated to a temperature below the Ac1 point, kept for a certain period of time, and then cooled to room temperature for heat treatment.
4.9 tempering hardening and tempering
Heat treatment process of quenching + high temperature tempering
4.10 solution treatment
Mainly for the austenitic stainless steel and high-temperature alloy, the alloy is heated to a high temperature single-phase zone, and the heat treatment process of rapid cooling after a certain time of heat preservation.
5, geometric size size
5.1 nominal size nominal dimension
The nominal size specified in the standard is the ideal size desired by the user and the manufacturer, as well as the order size indicated in the contract.
5.2 actual size actual dimension
It is the actual size obtained during the production process, which is often larger or smaller than the nominal size.
5.3 Outer diameter out diameter
The diameter of the outer circumference of a circular steel pipe, also known as the average outer diameter, is indicated by the symbol OD.
5.4 inner diameter
The diameter of the inner circle of a circular steel pipe, also known as the average inner diameter, is indicated by the symbol ID.
5.5 wall thickness
The distance between the outer and inner circles of the steel tube is indicated by the symbol WT.
5.6 tolerance
The sum of the absolute values of the positive and negative deviations specified in the standard is called the tolerance, also known as the “tolerance zone”.
5.7 Allowable deviations permitted variations
In the process of raw tea, since the actual size is difficult to achieve the nominal size requirement, that is, it is often larger or smaller than the nominal size, the standard specifies that a difference is allowed between the actual size and the nominal size. A positive deviation is a positive deviation, and a negative value is a negative deviation.
5.8 bending degree straightness
The steel pipe is curved in the longitudinal direction, and the degree of curvature is called the degree of curvature, also called flatness. The standard specifies the measurement in bends per meter and full-length bends.
5.9 Tube End Size End-of-pipe size
In order to facilitate the connection between the steel pipes, the dimensions of the length of the steel pipe at the ends of 100 mm (4.0 in) are required, such as the pipe end thread, the pipe end groove, and the pipe end diameter tolerance requirements. The American Petroleum Institute (API) standards place special requirements on pipe end processing.
5.10 usual length random length
Also known as non-fixed length, where the length is within the length specified by the standard and there is no fixed length requirement, it is called the normal length.
5.11 length of cut length lengthen
The length of the fixed length should be within the usual length and is a fixed length dimension required by the contract. However, it is not possible to cut the absolute length in the actual operation, so the standard deviation length is specified for the length of the rule.
5.12 double length length multiple length
The length of the double ruler should be within the normal length. The length of the single ruler and the multiple of the total length should be indicated in the contract (for example, 3000mm × 3, that is, 3 times 3000mm, the total length is 9000mm). In practice, the allowable positive deviation of 20 mm should be added to the total length, plus the remaining allowance for each single-length length.
5.13 Range length range length
The length of the range is within the usual length and is the length of a fixed range required by the user.
6, nondestructive examination
6.1 Ultrasonic flaw detection
A non-destructive test method for inspecting internal defects of materials using the effects of differences in acoustic properties of materials and internal defects on ultrasonic propagation, denoted by the symbol UT.
6.2 Eddy current testing
A method of detecting flaws in the surface and near surface of steel pipes using the principle of electromagnetic induction, denoted by the symbol ET.
6.3 Magnetic flux leakage testing
Magnetizing the surface of the steel pipe, picking up the leakage magnetic field of the defect, forming a defect electrical signal, and achieving a non-destructive test method for finding the defect, represented by the symbol LT.
6.4 Magnetic particle testing
A non-destructive testing method for magnetic flux leakage detection using a phenomenon in which a magnetic field is adsorbed by a leakage magnetic field generated by a surface defect of a ferromagnetic material in a strong magnetic field, and is represented by a symbol MT.
6.5 radiographic testing
A flaw detection method that uses a ray to penetrate an object to find an internal defect of the object, and is represented by a symbol RT.
6.6 color flaw detection
A test method for penetrant inspection (PT), in which a penetrating agent in which a color dye (such as a red dye) is dissolved is infiltrated into a microcrack on the surface of the workpiece, and after washing, an adsorbent is applied to cause the colored oil in the defect to permeate to the surface, according to The method of finding and judging defects with colored spots and stripes.
7, common defects
7.1 Out-of-roundness out-of-roundness
The difference between the largest and smallest diameters in a cross section of a circular steel tube, also called ellipticity.
7.2 Uneven wall thickness
Refers to the phenomenon that the wall thickness of different parts of the steel pipe is inconsistent.
7.3 linear defect
These include, but are not limited to, cracks, laps, plug scores, straights, and inner and outer spirals. The crack refers to a gap formed on the surface or inside of the metal. The folding refers to a layer of metal skin on the inner and outer surfaces of the steel tube. The indentation refers to the straight trace left by the hard object on the inner and outer surfaces of the steel tube. It refers to a straight line with a convex or concave surface and a certain width on the inner and outer surfaces of the steel pipe. The inner and outer spirals generally refer to a spiral pattern with a convex surface along the axial direction of the steel pipe surface. These defects are completely removed by the dressing method, the wall thickness of the dressing is not allowed to exceed the negative deviation of the nominal wall thickness, and a smooth transition is maintained.
7.4 Nonlinear defects non-linear defect
Including but not limited to pits, scabs, laminations. The pit refers to a pit-like defect formed on the surface of the steel pipe, the skin refers to a small piece of metal skin in a part of the inner and outer surfaces of the steel pipe, and the layering refers to a defect of a layered structure formed by separating the inside of the steel pipe. Surface defects such as pits and bumps can be removed by grinding, but delamination defects occur inside the metal, and portions with such defects must be removed.
8, other common terms
8.1 Furnace No. heat no.
Also known as the furnace number, refers to the number of steelmaking furnace.
8.2 Production lot number lot no.
In the production process of steel pipes, the production unit shall express the steel pipe products of the same specification and the same material produced by the same feeding and the same production process with a batch number. The batch number indicates the date and batch of production, which facilitates the sampling inspection of steel pipe products and also represents the quality of the batch.
8.3 smelting analysis
Chemical composition analysis of different furnace numbers reported by steel mills.
8.4 Product analysis product analysis
Chemical composition analysis of finished steel pipes of different furnace numbers reported by the steel pipe manufacturer.
8.5 Microstructure micro-structure
The ground surface of the metal sample treated by a suitable method (e.g., etching) is placed under an optical microscope or an electron microscope to observe the obtained structure.
8.6 grain size grain size
The level used to indicate the grain size inside the metal material. The finer the grain, the higher the grain size level.
8.7 Inspection lot inspection lot
A limited number of steel pipe products to be produced under conditions of uniformity.
8.8 Theoretical weight
The weight calculated from the nominal size and density of the steel tube is called the theoretical weight.
8.9 actual weight
Refers to the weight of the steel pipe actually weighed (overweight).