DIN 50136 is a withdrawn DIN standard that describes a flattening (ring fold) test used on metallic tubes to assess tube integrity and formability under compressive flattening.
It is most often associated with tube and pipe quality checks where deformation behavior can indicate issues such as poor ductility or weld-related weaknesses. If you need help mapping a legacy DIN 50136 callout to a current test plan or successor standard, talk with our team.
DIN 50136:1979-06 — Testing of Metallic Materials; Flattening Test on Tubes
DIN 50136 is a short, legacy test standard (published 1979-06) for flattening test practice on tubes. While it is withdrawn, the designation is still encountered in older material specifications, drawings, and historical QA documentation.
When DIN 50136 is referenced, test setup and reporting expectations can depend heavily on the exact cited edition and any product standard that calls it up.
Quick Definition
Document type: Test method (tube flattening / ring fold test).
Purpose: Flatten a tube ring section between platens to evaluate deformation behavior and identify tube defects that show up during severe compressive deformation.
Status note: DIN 50136:1979-06 is withdrawn and is typically addressed today via successor standards when a current, controlled method is required.
What This Standard Covers
DIN 50136 covers a flattening-style compression test performed on a ring cut from a tube. The specimen is compressed between flat platens to a defined condition so the tube wall and (when present) weld region are stressed during deformation.
Because the method is specimen- and deformation-focused (not a chemical or dimensional specification), it is commonly used as a manufacturing-quality or incoming-inspection check rather than a design-property test.
Why This Standard Matters in Testing
Flattening a tube ring is a fast way to screen for problems that can remain hidden in simple dimensional checks—especially where deformation concentrates at imperfections or weak bonding lines.
In practice, this type of test is used to support decisions such as weld process validation, batch release, supplier qualification, or verification of tube/pipe lots for downstream forming operations.
Common Materials, Product Types, or Applications Covered
DIN 50136 is associated with metallic tubes and pipes where a ring specimen can be extracted and flattened in compression.
Common product context: Steel and other metal tubing, including welded tube where weld-zone performance is a specific concern.
Common Test or Verification Workflow
A typical workflow is to cut a ring from the tube, place it between compression platens, and compress it to a defined condition. The ring orientation may be controlled so the weld seam (if present) is positioned in a specified direction relative to the platens.
Common outputs: Pass/fail observations (e.g., appearance of cracking or other damage during/after flattening) and basic test details such as specimen identification and test conditions defined by the calling requirement.
Equipment Commonly Used for This Standard
DIN 50136 points to straightforward compression loading with flat, parallel platens. The most common approach is a universal testing machine (UTM) or compression testing system configured for controlled compression.
Common equipment: Compression-capable UTM or compression frame, flat compression platens, alignment aids/fixtures suitable for ring specimens, and guarding appropriate for brittle fracture risk.
Practical selection caution: Capacity, platen size/flatness, and alignment become more important as tube diameter and wall thickness increase, or when the test is used for weld-quality screening that is sensitive to uneven loading. If you are selecting a system for tube flattening work, you can request a detailed quote with capacity and platen options matched to your tube sizes.
How to Read This Designation or Revision
Designation format: DIN 50136:1979-06 indicates DIN standard number 50136 with the publication date (June 1979).
Status: DIN 50136:1979-06 is withdrawn. DIN lists it as replaced by DIN EN 10233:1994-01 and DIN EN ISO 8492:2004-10 (and later revisions of the ISO-based document may exist).
Revision sensitivity: When a drawing or purchase specification cites “DIN 50136” without a date, confirm the intended edition and whether a successor standard is acceptable before locking down acceptance criteria.
Related Standards, Methods, or Frameworks
DIN 50136 is commonly discussed alongside later European/ISO documents that cover tube flattening / ring fold testing and are used in place of the withdrawn DIN document.
- DIN EN 10233 — Metallic materials; tube; flattening test (withdrawn, but historically replaced DIN 50136).
- DIN EN ISO 8492 — Metallic materials; tube; flattening test (ISO-based successor lineage).
- ASTM A370 — Includes tube testing content (some users reference annex material for related flattening-style checks, depending on the product specification).
Get help selecting a tube-flattening test setup
If you are updating a legacy DIN 50136 requirement or equipping a lab for tube flattening / ring fold testing, we can help you scope machine capacity, platen size, alignment needs, and safety features for your tube dimensions—contact our team to discuss your application.