①What is the delivery status?
It refers to the final plastic deformation or final heat treatment status of the delivered product. Generally, the product delivered without heat treatment is called hot-rolled or cold-drawn (rolled) status or manufacturing status; the product delivered after heat treatment is called heat-treated status, or normalizing (normalizing), tempering, solution, annealing status according to the type of heat treatment. When ordering, the delivery status must be indicated in the contract.
②What is delivery by actual weight or delivery by theoretical weight
Actual weight-at the time of delivery, the product weight is delivered according to the weighing (weighing) weight;
Theoretical weight-at the time of delivery, the product weight is the weight calculated according to the nominal size 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 (density of steel is 7.85kg/dm3) calculation formula:
W=0.0246615 (D-S) S
Where: W--theoretical weight of steel pipe per meter, kg/m;
D--nominal outer diameter of steel pipe, mm;
S--nominal wall thickness of steel pipe, mm.
③ Guarantee conditions
Inspection according to the specified items of the current standard and ensuring compliance with the provisions of the standard are called guarantee conditions. Guarantee conditions are divided into:
A. Basic guarantee conditions (also known as mandatory guarantee conditions). Regardless of whether the customer specifies it in the contract. The inspection must be carried out according to the standard regulations and the inspection results must be guaranteed to meet the standards.
Such as chemical composition, mechanical properties, dimensional deviation, surface quality, flaw detection, water pressure test or flattening or expansion and other process performance tests are all mandatory guarantee conditions.
B. Agreement guarantee conditions: In addition to the basic guarantee conditions, the standard also includes "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 stricter requirements for the basic guarantee conditions in the standard (such as composition, mechanical properties, dimensional deviation, etc.) or additional inspection items (such as steel pipe ovality, uneven wall thickness, etc.). When placing an order, the above terms and requirements are negotiated by the supply and demand parties, and the supply technical agreement is signed and noted in the contract. Therefore, these conditions are also called agreement guarantee conditions. Products with agreement guarantee conditions are generally subject to price increases.
④ Batch
The "batch" in the standard refers to an inspection unit, that is, an inspection batch. If the batch is grouped by delivery units, it is called a delivery batch. When the delivery batch is large, a delivery batch can include several inspection batches; when the delivery batch is small, an inspection batch can be divided into several delivery batches.
The composition of the "batch" is usually stipulated as follows (see the 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 mother furnace number, the same specification and the same heat treatment system (furnace).
B. For high-quality carbon steel structural pipes and fluid pipes, they can be composed of steel pipes of the same brand, the same specification and the same heat treatment system (furnace) from different furnaces (tanks).
C. Each batch of welded steel pipes should be composed of steel pipes of the same brand (steel grade) and the same specification.
⑤ High-quality steel and high-quality steel
In the GB/T699-1999 and GB/T3077-1999 standards, those with "A" after the brand are high-quality steels, and vice versa are general high-quality steels.
High-quality steel is superior to high-quality steel in some or all of the following aspects:
A. Narrowing the range of component content;
B. Reducing the content of harmful elements (such as sulfur, phosphorus, and copper);
C. Ensuring high purity (requiring less non-metallic inclusions);
D. Ensuring high mechanical properties and process performance.
⑥ Longitudinal and transverse
In the standard, longitudinal refers to the direction parallel to the processing direction (i.e., along the processing direction); transverse refers to the direction perpendicular to the processing direction (the processing direction is the axial direction of the steel pipe).
When doing the impact work test, the fracture of the longitudinal specimen is perpendicular to the processing direction. Therefore, it is called the transverse fracture; the fracture of the transverse specimen is parallel to the processing direction, so it is called the longitudinal fracture.
