Introduction to common terms in steel pipe standards

Introduction to common terms in steel pipe standards
①Delivery status
It refers to the final plastic deformation or final heat treatment state of the delivered product. Generally, those delivered without heat treatment are called hot-rolled or cold-drawn (rolled) state or manufacturing state; those delivered after heat treatment are called heat treatment state, or normalized (normalized), quenched and tempered, solid solution, and annealed according to the type of heat treatment. state. When ordering, the delivery status must be noted in the contract.
②Delivery according to actual weight or theoretical weight
Actual weight - at the time of delivery, the weight of the product is based on the weighing (weighing) weight;
Theoretical weight - at the time of delivery, the product weight is the weight calculated based on the nominal dimensions of the steel. The calculation formula is as follows (if delivery is required according to theoretical weight, it must be specified in the contract):
Theoretical weight of steel pipe per meter (the density of steel is 7.85kg/dm3) calculation formula: W=0.02466*(D-S)*S where: W--Theoretical weight of steel pipe per meter, kg/m; D--Nominal name of steel pipe Outer diameter, mm; S--nominal wall thickness of steel pipe, mm.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

③Guarantee conditions
Inspection according to the provisions of the current standards and ensuring compliance with the provisions of the standards are called guarantee conditions. Guarantee conditions are further divided into:
A. Basic guarantee conditions (also known as mandatory guarantee conditions). Regardless of whether the customer indicates this in the contract. This inspection must be carried out in accordance with the standards and ensure that the inspection results comply with the standards.
Such as chemical composition, mechanical properties, dimensional deviation, surface quality, flaw detection, hydraulic pressure test or process performance tests such as flattening or flaring, are all must-have conditions.
B. Agreement guarantee conditions: In addition to the basic guarantee conditions in the standard, there are also "according to the requirements of the demander, after negotiation between the supply and demand parties, and noted in the contract" or "when the demander requires..., it should be noted in the contract" "; some customers have put forward stricter requirements for the basic guarantee conditions in the standard (such as composition, mechanical properties, dimensional deviation, etc.) or added inspection items (such as steel pipe ovality, uneven wall thickness, etc.). The above terms and requirements, When ordering, the supplier and the buyer negotiate, sign a supply technical agreement and indicate it in the contract. Therefore, these conditions are also called agreement guarantee conditions. Products with agreement guarantee conditions generally require a price increase.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

④Batch
The "batch" in the standard refers to an inspection unit, that is, an inspection lot. If the batch is grouped by delivery unit, it is called a delivery batch. When the delivery batch is large, one delivery batch can include several inspection batches; when the delivery batch is small, one inspection batch can be divided into several delivery batches.
The composition of a "batch" usually has the following provisions (see relevant standards for details):
A. Each batch should be composed of steel pipes of the same brand (steel grade), the same furnace (tank) number or the same parent furnace number, the same specifications and the same heat treatment system (heats).
B. For high-quality carbon steel structural pipes and fluid pipes, they can be composed of steel pipes of the same brand, specification and heat treatment system (heats) from different furnaces (tanks).
C. Each batch of welded steel pipes should be composed of steel pipes of the same brand (steel grade) and specifications.
⑤High-quality steel and high-grade high-quality steel
In the GB/T699-1999 and GB/T3077-1999 standards, those with "A" at the end of their grades are high-grade high-quality steels, and vice versa are general high-quality steels.
High-grade high-quality steel is better than high-quality steel in some or all of the following:
A. Narrow the range of ingredient content;
B. Reduce the content of harmful elements (such as sulfur, phosphorus, copper);
C. Ensure high purity (requiring low content of non-metallic inclusions);
D. Ensure high mechanical properties and process performance
⑥Vertical and horizontal
According to the standard, longitudinal refers to the one parallel to the processing direction (that is, along the processing direction); transverse refers to perpendicular to the processing direction (the processing direction is the axial direction of the steel pipe).
When doing impact energy experiments, the fracture of the longitudinal specimen is perpendicular to the processing direction. Therefore, it is called the transverse fracture; because the fracture of the transverse specimen is parallel to the processing direction, it is called the longitudinal fracture.