TU 48-19-251-85

TU 48-19-251-85

Seamless thin-walled tubes made of molybdenum, its alloys and niobium. Technical conditions*

These specifications apply to thin-walled seamless tubes made of molybdenum and its alloys obtained by vacuum arc melting and vacuum-melted niobium, intended for special purposes.

Example of conventional designation: Molybdenum pipes of the МЧВП brand with a diameter of 10.0 mm and a wall thickness of 1.0 mm:

MChVP (10.0x1.0) TU 48-19-251-85 MChVSHO (10x1.0) TU 48-19-251-85

1. Technical requirements

1.1. Pipes made of niobium, molybdenum and alloys based on them must comply with the requirements of these technical conditions.

1.2. Niobium and molybdenum pipes are divided depending on the method of obtaining the original blank:

• Niobium pipes are made from vacuum-melted niobium ingots;
• molybdenum pipes of the МЧ brand are made from powder blanks of molybdenum of the МЧ brand (pure molybdenum without additives);
• Molybdenum pipes of the МЧВП brand are made from vacuum-melted ingots obtained by melting powder blanks of molybdenum of the МЧ brand using carbon as a deoxidizer;
• Molybdenum pipes of the MBVP brand are made from vacuum-melted ingots obtained by melting powder blanks of molybdenum of the MShV brand using boron as a deoxidizer and alloying element.

1.4. The length of the pipes must correspond to that indicated in Table 1.

Table 1

1.5. Depending on the established maximum deviations for the outer diameter, pipes of precision class I and II are produced.

1.5.1. The maximum deviations of the outer diameter of pipes must not be greater than those specified in Table 2.

Table 2

1.5.2. The maximum deviations of the pipe wall thickness must not exceed those specified in Table 3.

Table 3

1.6. The chemical composition of niobium and molybdenum pipes must correspond to that indicated in Table 4.

Table 4

1.7. Pipes must be straight. Deviations from straightness must not exceed 0.1% of the length for pipes of the 1st accuracy class and 0.5% of the length for pipes of the 2nd accuracy class.

1.8. The ends of the pipes must be cut evenly and have no burrs.

1.9. The outer and inner surfaces of the pipes must be free of cracks, oxidation and traces of grease.

Traces of cleaning, films, dents, cavities, burrs that do not take the dimensions of the pipes beyond the permissible deviations are not a rejection sign.

1.10. The wall thickness and ovality of pipes must not exceed the established permissible deviations in wall thickness and diameter.

1.11. The mechanical properties of molybdenum pipes of the МЧ and МЧВП grades must comply with the requirements given in Table 5.

Table 5

Notes:

• For other sizes of molybdenum pipes of the МЧ and МЧВП grades, not indicated in Table 5, mechanical properties are not determined.
• The mechanical properties of niobium pipes and molybdenum pipes of the MBVP brand are not determined.

1.12. The roughness parameter _Ra of the outer surface of pipes with a diameter of up to 14 mm inclusive must be no more than 1.25 µm; of the inner surface - no more than 2.50 µm according to GOST 2789-73.

1.13. At the customer's request, niobium and molybdenum pipes can be subjected to hydraulic pressure testing (for leak tightness).

* The page contains an excerpt from TU 48-19-251-85 "Seamless thin-walled pipes made of molybdenum, its alloys and niobium".