Scope of application
1. This standard applies to the thinnest-walled seamless steel pipes used in tubular heat exchangers, condensers and similar heat transfer devices;
2. This standard applies to steel pipes of 3.2~76.2mm. to
General requirements Except as otherwise provided in this standard, all applicable provisions of ASTM A450/A450M should also be complied with. to
3. Surface quality: No iron oxide scale, other surface quality is in accordance with ASTM A450/A450M.
4. Heat treatment: After the last cold drawing, heat treatment is carried out at a temperature of not less than 650°C. 6 Hardness test HRB≤72, the sampling requirement is to take two samples of steel pipes from each batch of steel pipes for Rockwell hardness test. (The so-called batch refers to all unsegmented steel pipes of the same nominal diameter and wall thickness produced with the same furnace steel. If it is a batch furnace, the batch only refers to the same furnace number, the same size, and the same furnace heat treatment steel pipes; if it is a continuous furnace, the batch should include all steel pipes of the same heat number, the same size and heat treated in the same heat treatment furnace at the same temperature, the same heating time and the same furnace speed.
5. Flattening test method is in accordance with ASTM A450/A450M. Sampling is to take two steel pipes from each batch of steel pipes or their remaining parts and cut out samples for testing. (One batch of tubes is 250 tubes).
6. Expansion performance method: According to ASTM A450/A450M, two steel pipes from each batch of steel pipes or their remaining parts are sampled for testing. (One batch of tubes is 250 tubes).
7. Hemming performance: For steel pipes with S/D <10% (S is the actual average wall thickness), if specified, hemming will be used instead of expansion. Method: Sampling according to ASTM A450: Take two steel pipes from each batch of steel pipes or their remaining parts and cut out samples for testing. Steel pipes that do not fall within the above requirements do not need to undergo hemming testing. (One batch of tubes is 250 tubes.
8. Hydraulic pressure test: Water pressure is tested one by one. If the buyer agrees, non-destructive test can be used instead of water pressure. Non-destructive testing is in accordance with ASTM A450/A450M. to
9. In addition to complying with ASTM A450/A450M, the finished product mark should also include the name of the purchaser and the order number.
