Specification: The specification requirements of spiral steel pipe should be stated in the import and export trade contract. Generally, it should include standard brand (model code), nominal diameter, nominal weight (mass), specified length and allowable values of the above indicators.
Its latest edition is applicable to this standard.
Allowable deviation between GB 222 steel chemical analysis pattern and finished product chemical composition;
Methods for chemical analysis of iron, steel and alloy-The diantipyrylmethane phosphomolybdic acid gravimetric method for the determination of phosphorus content
Methods for chemical analysis of iron, steel and alloy-The ammonium nitrate oxidation volumetric method for the determination of manganese content
Methods for chemical analysis of iron, steel and alloy-The reduced molybdosilicate photometric method for the determination of acid-soluble silicon content
GB/T 223. 10 Methods for chemical analysis of iron, steel and alloy The cupferron separation-chrome azurol S photometric method for the determination of aluminum content.
Methods for chemical analysis of iron, steel and alloy-The ammonium persulfate oxidation volumetric method for the determination of chromium content.
GB/T 223. 12 methods for chemical analysis of steel and alloy: sodium carbonate separation? The diphenylcarbazide photometric method for the determination of chromium content