DIN1629 St37 NBK Cold Drawn Seamless Tube

1. Descripition of DIN1629 St37 NBK Cold Drawn Seamless Tube

the steel billets is from Baosteel, Xingcheng Special Steel or Huaisteel, we do 100% visual inspection and chemical inspection randomly, then bars were cut into short pcs as per requirement of final tube length requirement to do hot piercing, the whole processing flow chart of seamless pipe as below:

2. Specification of DIN1629 St37 NBK Cold Drawn Seamless Tube

2.1 Dimensions

Tubes shall be ordered:

2.1.1. by outside diameter and inside diameter.

2.1.2. by outside diameter and wall thickness.

2.2 Tolerances

2.2.1. Values according to standards

• out of roundness is included in the tolerances of diameter

• tolerances of the wall thickness is ±10%

• eccentricity is included in the tolerances of wall thickness

2.2.2. Tolerances by agreement

2.2.3. Dimensions and tolerances according to standard ASTM A450

2.3 Steel grades

Steel is produced in electric arc furnace and is fully killed. Steel grades are shown in the survey table of standards and in the table of chemical composition and mechanical properties (values are informativeonly).

2.4 Delivery conditions and heat treatment

BK (+C) Cold finished/hard (cold finished as drawn). No heat treatment after the last cold forming process

BKW (+LC) Cold finished/soft (lightly cold worked). After the last heat treatment there is a light finishing pass (cold drawing).

BKS (+SR) Cold finished/stress relieve annealed. After the final cold forming process the tubes are stress relieve annealed.

GBK (+A) Annealed. After the final cold forming process the tubes are annealed in a controlled atmosphere.

NBK (+N) Normalized. After the final cold forming process the tubes are annealed above the upper transformation point in a controlled atmosphere

2.5 Surface condition

Tube surface corresponds to the standards and depends on the method of tube manufacturing and method of heat treatment. Value of roughness Ra <1 µm.

2.6 Tube ends

The tubes are delivered with plain ends without burrs at the ends of the tube.

Upon request ends could be plugged with plastic caps

3.Testing of Carbon Steel Cold Drawn Precision Seamless Pipe

Testing is performed in accordance with corresponding standards or by agreement

• flattening test , drift expanding test, flaring test, bending test

•mechanical properties test

• roughness measurement

• NDT for detection of transverse imperfections and wall imperfections

4. Packing and Protective coating

4.1 Tubes are supplied either uncoated or with the manufacturers standard mill coating at the option of the customer (subject of agreement between customer and manufacturer).

4.2 Packaging

Tubes are packed in round or hexagonal bundles with weight max.2000 kg. Other possibilities by agreement.

5. Mill Test Certificate

Types of inspection documents according to EN 10204 3.1.B Inspection certificate (inspector representing the manufacturer)

6. Quality System(ISO9001&TS16949)

7. Quality Control