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 Steel Pipe |
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| Introduced the term commonly used in steel pipe standards | | |
(1) General terms
① delivery status
Refers to the delivery of the final product or final heat treatment of plastic deformation state. Generally not heat-treated hot-rolled or cold drawn, said delivery (rolled) state or manufactured state; after delivery of the said heat treatment state, or under the category called normalizing heat treatment (normalization), quenching, solution, annealing state. Order, the delivery status required in the contract.
② the actual weight of shipment or delivery according to theoretical weight
Actual weight - delivery, the weight of their products is based on weight (weighing) the weight of delivery;
Theoretical weight - delivery, the weight of their products is based on nominal size steel weight calculated. The formula is as follows (theoretical weight required by the delivery person is required in the contract):
Theoretical weight per meter of pipe (steel density 7.85kg/dm3) formula:
W = 0.02466 (D-S) S
The formula: W-tube theoretical weight per meter, kg / m;
D-pipe nominal diameter, mm;
S-pipe nominal wall thickness, mm.
③ guarantee conditions
The provisions of the current standard test items and to ensure compliance with the standard specification, called the guarantee conditions. Ensure that the terms be divided into:
A, the basic guarantee conditions (also known as a necessary condition). Regardless of whether the customers in the contract. Standards required by the provisions of the inspection, and to ensure test results meet the standard requirements.
Such as chemical composition, mechanical properties, size deviation, surface quality and inspection, pressure test or flattening or flaring process performance such experiments are a necessary condition.
B, the agreement guarantees conditions: standard conditions, in addition to the basic guarantees, there are "demand-side requirements based upon mutual agreement of supply and demand, and in the contract note? Quot; or" When the demand side requirements ... ... should be in the contract note out "; also customers, the basic guarantee of the standard conditions of tightening the requirements (such as composition, mechanical properties, size deviation, etc.) or by test items (such as pipe ovality, wall thickness of inequality). the above terms and requirements in order, by the supply and demand by the two sides signed the agreement and supply technology in the contract. Therefore, these conditions also known as the guarantee conditions of the agreement. there is an agreement to ensure the conditions of the products, generally have to follow suit.
④ approved
Standard in the "batch" refers to a test unit, the inspection lot. If approved delivery unit group, said the consignments. When a large volume delivery, a delivery batch can consist of several inspection lot; when the delivery volume is low, an inspection lot can be divided into several consignments.
"Batch" is usually composed of the following provisions (see the standard):
A, each batch should be the same grade (steel grade), the same furnace (pot) of the mother or the same heat number, the same specifications and the same heat treatment (furnace) of the steel composition.
B, for high quality carbon steel pipe, fluid pipe, can be different furnace (pot) of the same grade, same size and the same heat treatment (furnace) of the steel composition.
C, each consignment should be the same grade welded steel pipe (steel grade), composed of the same size of pipe.
⑤ high quality steel and high-quality steel
In GB/T699-1999 and GB/T3077-1999 standards, with the back of his trademark "A" character who, for the high quality steel, contrary to the general high quality steel.
High quality steel in the following part or all of superior quality steel:
A, narrowing the range of ingredients;
B, to reduce the harmful elements (such as sulfur, phosphorus, copper) content;
C, to ensure high purity (which requires less non-metallic inclusion content);
D, to ensure high mechanical properties and processing properties.
⑥ vertical and horizontal
Standard said longitudinal direction is parallel with the processing (ie processing along the direction of) persons; horizontal direction is perpendicular with the processing (processing the direction of the tube axis).
Impact work to do experiment, the longitudinal sample and processing due to the direction of vertical fracture. It is called horizontal fracture; transverse fracture of the sample parallel to the direction for and processing, so that vertical fracture.
(2) steel shape, size, terms
① nominal size and actual size
A, nominal size: the name specified in the standard size, is the users and manufacturers hope to achieve the ideal size is specified in the contract order size.
B, actual size: the production obtained during the actual size, the dimensions are greater than or less than the nominal size. This is greater than or less than the nominal size of the phenomenon is known as bias.
② bias and tolerance
A, deviation: in the production process, because the actual size is difficult to achieve nominal size requirements that are greater than or less than the nominal size, so the standard set forth in the actual size and nominal size to allow a difference between. Difference is called the positive bias is positive, the difference is called negative bias is negative.
B, Tolerance: standard requires positive and negative deviation of absolute value and is called tolerance, also called "tolerance zones."
Bias is directional, that is "positive" or "negative," said; tolerance is not directional, so the deviation is called "positive tolerance" or "negative tolerance", it is called is wrong.
③ delivery length
Delivery length or the length of the contract, also known as the length of user requirements. Standard delivery length on the following provisions:
A, usually the length (also known as non-cut-length): Where the length of the standard within the prescribed length and no fixed length request, are referred to as usual length. Standard requirements such as structural pipe: hot rolled (extrusion, expansion) tube 3000mm ~ 12000mm; cold drawn (rolled) steel 2000mmm ~ 10500mm.
B, Length Length: Length length should be within the usual length, is required by the contract size of a fixed length. However, the actual operation are cut out absolutely definite length is unlikely, therefore, the standard length of the cut-sets are allowed deviation.
Structural control standards:
Production cut-length tube become useful than the usual length of the tube decreased more, manufacturers fare increase is a reasonable request. Enterprises are not the same rate of increase is generally based on the increase for the base price about 10%.
C, fold-foot length: the length times the scale length should be typically within the contract should specify the length of a single double length and composition of the total length of a multiple (such as 3000mm × 3, or 3 multiples of 3000mm total length of 9000mm). Practice, should be based on the total length to allow positive deviation with 20mm, plus one times the foot length of each incision should be left margin. Structural tube, and the provisions of left incision margin: ≤ 159mm diameter was 5 ~ 10mm; diameter> 159mm for the 10 ~ 15mm.
If the standard deviation of no-fold-foot length and cut margin requirements should be negotiations between supply and demand in the contract. Times as long with the definite length scale, as producers will bring a significant reduction in finished product rate, so producers proposed fare increase is justified, the charge increases the rate of increase with the length of the same Length.
D, Scope Length: length range within the usual length, when the user requests a fixed range of length which is required in the contract.
For example: normally a length of 3000 ~ 12000mm, while the range of cut-length 6000 ~ 8000mm or 8000 ~ 10000mm.
Visible range longer than the length of fixed length and double length requirements relaxed, but a lot of tightening than the usual length, would become useful to the producers to bring the rate lower. So manufacturers proposed fee increases are justified, the tariff increases on the general increase in the base price of around 4%.
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