NB/T 47008-2017Carbon and alloy steel forgings for pressure equipment (English PDF)

3.1 Hollow forging Axisymmetric

hollow forging with an axial length L greater than its outer diameter D, as shown in Figure 1 a). t is the nominal thickness.

Axisymmetric hollow forging with an axial length L less than or equal to its outer diameter D, as shown in Figure 1 b). The smaller one of L and t is the nominal thickness.

3.2 Ring forging

3.3 Disk forging

Axisymmetric solid forging with an axial length L less than or equal to its outer diameter D, as shown in Figure 1 c). L is the nominal thickness.

3.4 Bowl forging

Axisymmetric forging with a concave cross-section and an axial length H less than or equal to its outer diameter D, as shown in Figure 1 d). The larger one of t1 and t2 is the nominal thickness.

5.1 Smelting method

Forging steel shall be killed steel smelted using electric furnace or oxygen converter and subjected to secondary refining. Agreed upon between the supply and demand parties, electroslag remelting and other smelting methods can be used.

5.2 Chemical composition

5.2.1 Smelting analysis

5.2.2 Finished product analysis

5.2.2.1 The demand party may carry out the finished product analysis, and the analysis result and the allowable deviation of the specified value in Table 1 shall comply with the provisions of GB/T 222.

5.3 Forging

5.3.1 Steel ingots, steel billets or rolling materials for forging shall have a quality certificate of the smelting organization.

5.4 Forging grade

5.4.1 Forgings are divided into 4 grades, i.e. I, II, III and IV. The inspection items and inspection quantity of each grade shall comply with the provisions of Table 2.

5.6 Mechanical properties

5.6.1 The mechanical properties of finished forgings shall comply with the provisions of Table 3. The mechanical properties of other forgings for supporting valves and special components are shown in Annex A.

5.6.2 The three measured values of hardness test shall not exceed the limits specified in Table 3.

5.12 Repair by welding

5.12.1 Steel forgings are not allowed to be repaired by welding without the consent of the demand party.

5.12.2 As agreed by the demand party, the repair by welding of steel forgings shall comply with the provisions of relevant regulations and standards. The position, depth, area of repair by welding, welding material, welding technology, welder qualification requirements, nondestructive testing methods and qualification grades before and after repair by welding shall be agreed upon between the supply and demand parties.

6.1 Chemical analysis

The chemical analysis shall comply with the provisions of GB/T 223, GB/T 4336, GB/T 20123, GB/T 20124. The arbitration test shall comply with the provisions of GB/T 223.

6.2 Tensile test

The room temperature tensile test shall comply with the provisions of GB/T 228.1, and the high temperature tensile test shall comply with the provisions of GB/T 228.2.

6.7 Ultrasonic testing

The ultrasonic testing shall comply with the provisions of NB/T 47013.3.

6.8 Appearance inspection

The appearance inspection of forgings shall be visual inspection under full lighting conditions.

7.1 Inspection

The inspection of forgings is carried out by the supply party's inspection department.

7.2 Sample requirements

7.3 Sampling quantity

7.3.1 Chemical analysis

TAKE 1 sample form each smelting furnace for chemical analysis.

7.3.2 Tensile and impact

7.3.2.1 For heat treated forgings with a mass less than or equal to 3 500 kg, take 1 set of samples (1 for room temperature tensile, 3 for impact).

7.3.2.2 For heat treated forgings with a mass greater than 3 500 kg, take 2 sets of samples (in each set, 1 for room temperature tensile, 3 for impact), and 2 sets of samples are at an interval of 180 °. If the length of the forging is greater than 1.5 times the diameter, each take a set of samples at two ends of the forging and at an interval of 180 °.