What are the processing methods for steel pipes

First, steel pipe loading into the furnace:

1. Steel pipes prone to deformation during heat treatment should be heated using a special fixture.

2. The steel pipe should be placed within the effective heating zone.

Second, steel pipe preheating:

1. For steel pipes with complex shapes, abrupt changes in cross-section, or large effective thickness, preheating should be stopped.

2. Preheating methods include: primary preheating at 800℃, secondary preheating at 500℃~550℃, and 850℃. The rate of temperature increase during primary preheating should be limited.

Third, steel pipe heating:

1. Steel pipes with grooves and no through holes, castings, welded parts, and formed stainless steel pipes are generally not suitable for heating in a salt bath furnace.

2. Sufficient holding time should be provided during steel pipe heating, depending on the effective thickness and required thickness of the steel pipe. (Practical thickness multiplied by the pipe shape coefficient)

Fourth, Cooling of Steel Pipes:

1. When air-cooling martensitic stainless steel and heat-resistant steel, they should be stored in a dry place.

2. Martensitic stainless steel pipes and heat-resistant steel should be cleaned, cryogenically treated, or tempered before cooling to room temperature after quenching.

3. Steel pipes should be tempered promptly after quenching. The time interval should generally not exceed 4 hours. For steel pipes with low carbon content and simple shapes, it should not exceed 16 hours.

4. For welded assemblies composed of martensitic stainless steel and heat-resistant steel, the time interval between welding and subsequent heat treatment should not exceed 4 hours.

Fifth, Cleaning of Steel Pipes:

1. Cleaning should be carried out according to the requirements and surface condition of the steel pipe using alkaline washing, water-soluble cleaning agents, chlorine solvent, sandblasting, shot blasting, etc.

2. Acid pickling is not used for cleaning ordinary steel pipes.