Seamless steel tube brand - manufacturing process
1. Seamless steel tube brand - blank control
The quality of billet directly affects the quality of boiler tube. The billet steel of the boiler tube shall be smelted by arc furnace or oxygen top blown converter, and shall be manufactured by external refining (LF+RH or LF) and vacuum degassing (VD). The quality and inspection of billet shall be controlled according to YB/T5137. When the user has special requirements on the composition, the boiler tube enterprise shall accurately transmit the requirements to the billet production enterprise.
The billet of boiler tube enterprises should be obtained from enterprises with good market performance. Tube billet enterprise should have issued by the state administration of quality supervision, inspection and quarantine of the People's Republic of China special equipment license (pipe), and the scope as stipulated in the permit and its attachments and the period of validity. It is better if the billet enterprise has passed PED certification of the eu. At present, many domestic power station boiler enterprises have put forward strict restrictions on the source of the billet used by the boiler tube enterprises.
Billet enterprises shall provide quality certificates in Chinese and English. The batch number, weight and length of each batch of billets should be detailed and traceable. For pipe billets with special requirements for foreign customers, acceptance shall be carried out according to the requirements, and special materials shall be used to avoid mixed steel.
2. Seamless steel tube brand - quality planning control points
Grease hot rolling control: special attention should be paid to the tracking management and marking management of the furnace number after hot rolling.
Cold drawing and cold rolling control: control the precision of outside diameter and wall thickness as well as the straight depth of inner and outer surfaces in accordance with the quality plan.
Holding heat treatment control: operate in strict accordance with heat treatment process, keep original records, so as to trace the problem and find the cause. Heat treatment records should be complete, including heat treatment methods, heat preservation temperature, heat preservation time and cooling methods. For continuous heat treatment furnace, special attention should be paid to the preservation of historical records in the computer system, such as heat treatment curve and heat treatment parameters, etc., and the data should be backup in time. Some internationally renowned boiler manufacturers pay great attention to the precision of thermocouple, so the boiler tube enterprises must have the towing test record of temperature check.
3. Seamless steel tube brand - inspection control
Physical and chemical performance control mainly includes chemical composition, mechanical properties, hardness testing and so on. Some users may add some additional inspection items. The boiler tube company should have the conditions to implement such inspection before the contract is signed, such as inspection equipment, inspection methods and judgment standards.
The finished product inspection items include the outer diameter, wall thickness, surface state, bending degree of steel pipe, etc., which should also be strictly controlled according to the quality plan.
Due to technical promotion in recent years, our country also more and more the number of the export of seamless steel pipe, due to the particularity of its purpose, quality control and inspection of more critical, boiler seamless steel pipe from the beginning of the tube billet quality, especially in hot rolling, cold drawing cold rolling, heat treatment, nondestructive testing process to strengthen control, in this paper, the export of boiler tube usually pay attention to the relevant requirements and discusses the control points, we hope that relevant views be helpful to the boiler tube export enterprises in China.
