GB/T 3091 “Welded steel pipe for low pressure fluid transportation” (2015 version of the standard version) has been approved by the National Standardization Committee and officially released, since June 01, 2016 formal implementation; At the same time, the original GB/T 3091-2008 standard version is officially invalid!
Interpretation of the important provisions of the new National Standard:
1. Galvanized weight — “Bottom line”
In the new national standard, on the zinc layer weight index of galvanized steel pipe for the first time put forward the “bottom line requirements”! Namely: in the old version of the standard only “negotiated terms” on the basis of increased “steel pipe internal and external surface galvanized layer unit area total weight should not be less than 300g/m²” mandatory standard requirements.
As a result, the average life of steel pipe is extended by at least 30%!!
2. Pipe end
Steel pipes with an external diameter of no more than 114.3mm(4 inches or less) should be mechanically flat (without burrs at the end).
3. Repair welding of defects
After the revision of the new standard, the repair of defects is changed to: straight seam electric welded steel pipe with outer diameter less than 219.1mm is not allowed to repair welding.
Comparison: GB/T3091-2008 stipulates that “steel pipe with outer diameter not greater than 114.3mm is not allowed to repair welding, steel pipe with outer diameter not less than 114.3mm, can repair the defects at the base metal and weld.”
4. Wall thickness
The new standard stipulates the minimum value of nominal wall thickness of steel pipe, that is, Table 1 “Nominal diameter, outer diameter, Nominal Wall thickness and uncircularity of Steel pipe with outer diameter not greater than 219.1mm” is added, which provides a direct basis for the design and selection of materials of engineering design units.
Ø Steel pipe with nominal wall thickness less than ** small is not allowed to make GB/T3091-2015 standard!!
5. Steel pipe mark
The new standard states: “The marking of steel pipes shall include at least the following: manufacturer’s name or trademark, product standard number, steel brand number, product specification and traceability identification number.”
The steel pipe mark consists of the product label and the pipe body code. If any of the above information is missing, it is illegal.
Post time: Jul-09-2022