GOST 11068-81 Electrically Welded Stainless Steel Tubes – Corrosion-Resistant Steel Pipes

TORICH supplies GOST 11068-81 electrically welded stainless steel tubes manufactured from corrosion-resistant austenitic and ferritic steel grades. These tubes are produced with a longitudinal welded seam, controlled dimensional tolerances, and specified mechanical properties to support reliable fabrication and assembly.

GOST 11068-81 covers nominal outside diameters from 8 to 102 mm and wall thicknesses from 0.8 to 4.0 mm, subject to the permitted size combinations. Available grades include 08Kh18N10T, 10Kh18N10T, 12Kh18N10T, 08Kh18T1, and 04Kh17T. TORICH can provide customized cutting, heat treatment, surface finishing, and inspection according to the applicable standard and agreed purchasing specifications.

Product Specifications

Dimensional note: GOST 11068-81 specifies particular combinations of outside diameter and wall thickness rather than permitting every combination within the overall ranges. Tubes made from 08Kh18T1 and 04Kh17T are limited to wall thicknesses of 2.0 mm or less.

Main Characteristics

1. Controlled Dimensional Accuracy

GOST 11068-81 defines normal and improved precision classes to support accurate tube fitting and fabrication.

For example, a tube with an outside diameter of 20 mm can be specified with an improved diameter tolerance of ±0.20 mm. For a wall thickness of 1.5 mm, the improved tolerance is ±0.15 mm.

The maximum straightness deviation of 1.5 mm/m helps reduce alignment problems during cutting, tube forming, and component assembly.

2. Defined Mechanical Strength and Ductility

The mechanical properties depend on steel grade and delivery condition.

Heat-treated 08Kh18N10T tubing requires a minimum tensile strength of 530 MPa and minimum elongation of 37%.

Heat-treated 10Kh18N10T and 12Kh18N10T tubing require a minimum tensile strength of 550 MPa and minimum elongation of 35%.

These properties provide measurable acceptance criteria for material selection and subsequent forming operations.

3. Controlled Internal Weld Bead

The internal weld bead is an important consideration for applications requiring a consistent internal passage.

GOST 11068-81 specifies the following maximum internal weld-bead heights:

• General-purpose welded tubes: 0.7 mm.

• General-purpose tubes with nominal internal diameters above 20 mm, when requested: 0.3 mm.

• Tubes intended for tubular electric heating elements: 0.1 mm.

The transition between the internal bead and the tube wall must be smooth. This requirement helps reduce interference during downstream manufacturing.

4. Defined Pressure and Corrosion Testing

GOST 11068-81 requires tubes to withstand a hydraulic test pressure of 6 MPa or undergo nondestructive examination of the welded seam.

Higher hydraulic test pressures may be specified by the purchaser under GOST 3845, up to a maximum of 20 MPa, subject to the applicable strength calculation.

Intergranular corrosion testing is required for certain heat-treated corrosion-resistant grades used in chemical engineering and chemical processing, and may also be requested for other applications.

Our Advantages

1. How Can Buyers Reduce Weld-Seam Defects During Production?

A welded tube may meet its dimensional requirements while still containing defects in the longitudinal seam.

TORICH addresses this concern through defined weld inspection requirements and documented acceptance criteria.

Under GOST 11068-81, each tube is subject to dimensional and surface inspection, together with hydraulic testing or nondestructive weld examination.

For projects requiring additional verification, hydraulic pressure testing can be specified alongside nondestructive weld examination.

The inspection method, test coverage, and acceptance criteria are confirmed before production to avoid uncertainty during incoming material inspection.

2. How Can Buyers Avoid Problems Caused by Internal Weld Beads?

An excessive internal weld bead can interfere with component insertion, internal forming, or the assembly of heating elements.

For tubular electric heating element applications, TORICH can manufacture welded tubes to the GOST 11068-81 maximum internal bead height of 0.1 mm.

The required internal seam condition is established during order review, with inspection arrangements defined according to the tube diameter and final application.

This allows purchasers to specify a measurable internal weld condition rather than relying on a general description such as "smooth inside surface."

3. How Can Buyers Verify Material Grade and Corrosion Resistance?

Stainless steel grades with similar chromium content do not necessarily provide identical corrosion resistance or forming behavior.

TORICH supports material selection through verification of chemical composition, heat-treatment condition, and the required mechanical properties.

For example, 08Kh18N10T and 12Kh18N10T are titanium-stabilized austenitic grades, while 08Kh18T1 and 04Kh17T are ferritic grades with different nickel content and mechanical characteristics.

Material identification and applicable inspection results can be documented for each production batch. Intergranular corrosion testing can also be specified where required by GOST 11068-81 or the purchasing agreement.

Applicable Standards

Standard compliance note: GOST 11068-81 is the governing standard for this product. ASTM, EN, JIS, and GB standards are included as related international purchasing references, not as direct equivalents. Compliance with any additional standard requires separate verification of material grades, dimensions, mechanical properties, and testing.

Application: Tubular Heating Element Sheaths for Industrial Immersion Heaters

<text strong>Specific Product: Stainless Steel Outer Sheath for Tubular Electric Heating Elements</text>

Electrically welded stainless steel tubing manufactured according to GOST 11068-81 can be used as the outer protective sheath of tubular electric heating elements.

In this application, the stainless steel tube encloses the heating resistance wire and electrically insulating material, commonly compacted magnesium oxide.

The tube must maintain appropriate dimensional consistency during component insertion, filling, compaction, and subsequent forming operations.

A critical requirement is the internal weld-bead height. GOST 11068-81 specifies a maximum height of 0.1 mm for tubes used in the manufacture of tubular heating elements.

A controlled internal seam helps minimize interference during filling and compaction, while the appropriate stainless steel grade provides resistance to the intended operating environment.

Material selection must also consider operating temperature, heating medium, corrosion exposure, and the finished heater design.

Chemical Composition

The following chemical compositions are based on GOST 11068-81, Table 3, and the GOST 5632-72 chemical composition requirements referenced by the product standard.

All values are expressed as mass percentages (%).

Notes:

1. The titanium expressions describe the minimum titanium content calculated from the carbon concentration through the stated maximum titanium content.

2. A dash in the nickel column indicates that nickel is not specified as an intentional alloying element. Residual nickel is subject to the applicable material standard.

3. The chemical composition of 10Kh18N10T and 04Kh17T is specified directly in GOST 11068-81, Table 3.

4. The other three grades follow the referenced GOST 5632-72 composition requirements.

5. Permissible deviations and any separately agreed chemical restrictions must be checked against the applicable standard and purchase specification.

Mechanical Properties

The following values are the minimum mechanical-property requirements for heat-treated tubes according to GOST 11068-81, Table 4.

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