St37.4 NBK Metric Steel Tube Phosphated

1. Description of St37.4 NBK Metric Steel Tube Phosphated

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 St37.4 NBK Metric Steel Tube Phosphated  

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

 2.3 Steel grades

 Steel is produced in electric arc furnace and is fully killed.  chemical composition as below

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

Tubes are supplied coated with phosphating layers, the layer thickness>12 µm.

2.6 Tube ends

The tubes are delivered with plain ends without burrs. and ends are plugged with plastic caps.

3.Testing of St37.4 NBK Metric Steel Tube Phosphated

• flattening test , flaring test, bending test

• mechanical properties test

• NDT for detection of transverse imperfections and wall imperfections

4. Packing   

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

6. Estimate Working Pressure

Seamless cold drawn St 37.4 high quality tubing, cleaned, plugged, normalised, free of scale, phosphated & oiled to Din 2391 Sheet 2 grade C.

• Seamless tubing is especially suited to cold bending & flaring,

• Weldable by all recognised welding methods,

• Normalised (NBK).

• Seamless tubing is annealled, phosphated & oiled.

• Tubing supplied with plastic plugs in ends,

• Available Ex stock for immediate delivery in standard dimensions indicated,

• Tube available in 6 metre lengths,

St37.4 NBK Metric Steel Tube Phosphated