Analysis of commonly used terms for seamless pipes:
- Delivery status
Refers to the final plastic deformation or heat treatment state of seamless steel pipe products. Divided into hot rolling, cold drawing (rolling) state or manufacturing state, and heat treatment state, such as normalizing, quenching and tempering, solid solution, annealing state. The delivery status must be stated in the contract.
2. Delivery of actual weight or theoretical weight of seamless steel pipe
The actual weight delivery is calculated according to the weighed (weighed) weight, and the theoretical weight delivery is based on the weight calculated from the nominal size.
Carry out inspections according to the items specified in the standards and ensure compliance with the standards. Divided into basic guarantee conditions and agreement guarantee conditions. The basic guarantee conditions are chemical composition, mechanical properties, dimensional deviation, surface quality, flaw detection, hydraulic test or process performance tests such as flattening or flaring. The guarantee conditions of the agreement are the terms and requirements indicated in the contract according to the requirements of the buyer.
An inspection unit, the inspection lot. 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. Each batch shall consist of steel pipes of the same designation (steel grade), same furnace (tank) number or the same parent furnace number, same specification and same heat treatment system (heating number). 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 (heat) in different furnaces (tanks). Each batch of welded steel pipes shall be composed of steel pipes with the same welding process, the same welding materials, the same operator, the same specification and the same heat treatment system (heat).
How many delivery states are there for seamless steel pipes?
Seamless steel pipes can be divided into four categories according to the delivery status: hot-rolled, thermally expanded seamless steel pipes, cold-drawn seamless steel pipes, and cold-rolled seamless steel pipes.
The hot-rolled seamless steel pipe is that the round steel is pierced into a tube blank by a piercer, and then the tube blank is set to a specified outer diameter by a hot rolling mill to form a hot-rolled seamless steel pipe product. The process is simple and the price is relatively low, but the dimensional precision is not high. According to domestic production technology, seamless steel pipes with an outer diameter of 60mm to 600mm can be hot-rolled.
The heat-expanded seamless steel pipe is formed by using the seamless steel pipe billet or the finished seamless steel pipe to be fired in an electric furnace to above 1050 degrees, and then expanded to a certain outer diameter with an alloy core head inside. After expanding into a heat-expanded seamless steel pipe, the wall thickness is thinner than the raw material, the length becomes shorter, and the outer diameter becomes larger.
Cold-drawn seamless steel pipe is a seamless steel pipe formed by drawing the seamless steel pipe blank or the finished seamless steel pipe through the abrasive tool of the cold drawing machine. It happens to be opposite to the thermal expansion process, and the drawn finished pipe is longer than the raw material , the wall thickness is thinner, and the outer diameter is smaller. The drawing process does not require heating, forming at room temperature, and can also be annealed, sometimes it is not necessary to anneal.
The cold rolling process is also produced at room temperature like the cold drawing process, but the cold rolling machine is different from the cold drawing machine. Production is slower than cold drawing process production.
The so-called carbon steel seamless steel pipe delivery status refers to these four production processes. Carbon steel pipe is made of steel ingots or solid round steel through perforation into capillary, and then made by hot rolling, cold rolling or cold drawing. Carbon steel pipe is the most common type of steel pipe. It is a steel pipe produced from carbon steel. Carbon steel pipes can be divided into seamless steel pipes, straight seam steel pipes and spiral steel pipes. Rolled seamless carbon steel pipe is made of steel ingot or solid round steel through perforation to make capillary, and then hot rolled, cold rolled or cold drawn.