Both standards are standard specifications for ferritic-ausic stainless steel tubing used in corrosive environments. ASTM A790 specifies the elements and requirements for the manufacture of seamless and welded pipes, while ASTM A928 covers only electric fusion welded pipes. ASTM A790 requires that duplex and super duplex steel pipes be welded without the addition of any filler metal. ASTM A928 requires that the weld be welded with the addition of filler metal.
ASTM A928 duplex steel pipes ASTM A790 duplex steel pipes
2. Manufacturing process
The manufacturing processes listed in the ASTM A790 and ASTM A928 duplex steel pipes standards also provide manufacturers with some freedom of choice. For example, under the specific conditions that the raw material (coil or plate) has been solution annealed, both standards allow the finished pipe not to anneal, and the steel pipe in this case will be marked with HT-0. However, the ASTM A790 standard has restrictions on this situation: when using UNS S31803, S32205, S32750, S32760 and S32520 materials to produce steel pipes, corrosion tests must be supplemented. The buyer and the manufacturer must agree on specific differences between the two standards.Grade 5: All weld passes of the steel pipe shall be double-sided welded by adding filler metal, and X-ray sampling inspection shall be carried out (every 15m weld shall be inspected not less than 300mm)
In order to make the product meet the steel pipe tolerances stipulated by the two standards, the pressure of the production plant is very high (see Table 1).
Within BUTTING, for the destructive tests specified in the ASTM A790 and ASTM A928 standards, from sample preparation to recording documents, it must be carried out in accordance with DIN ENISO 17025:2000 certified by the material testing laboratory. Required tests include tensile, hoop tensile, and bending tests and hardness measurements. Table 2 is a comparison of the destructive test requirements in ASTM A928 and ASTM A790.
Table 3 shows the different non-destructive testing requirements of the two standards.
6. The importance of practice
This article compares the standards based on the current general standards, and only reflects some of the most important features in the steel pipe production, and the details are inevitable. anyway,
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