Technical conditions for supercritical boiler plates of SA302GrC

1.       Scope

The technical conditions apply to plates of SA302GrC with thickness range 10mm-120mm use of Supercritical Boiler.

2.       Adopt standard:

ASME SA302/SA302M Standard Specification for Pressure Vessel Plates, Alloy Steel, Manganese-Molybdenum and Manganese-Molybdenum-Nickel

ASME SA20/SA20M Standard Specification for General Requirements for Steel Plates for Pressure Vessels

ASME SA370 Standard Test Methods and Definitions for Mechanical Testing of Steel Products

3.       Dimension, Shape, Weight and Permissible Deviation

The dimension, shape, weight and permissible deviation shall meet the requirements of ASME SA20/SA20M.

The thickness toleration: -0.25mm/+3.5mm

4.       Technical conditions

4.1   Chemical composition (Ladle analysis)

The chemical composition of plates shall be accordance with the following table 1.

Table 1 Chemical composition (Ladle analysis)

Note:

1)      Ladle analysis sampling per furnace and product analysis per each PC finished product.

2)      Thickness less than 25mm, the element C content less than 0.20%.

3)      Carbon equivalent (CEq)

Carbon equivalent shall be not more than 0.58% for plates of SA302C.

Carbon equivalent shall be calculated as follows:

CEq=C+Mn/6+(Cr+Mo+V)/5+(Ni+Cu)/15 (%)

4.2   Steel making process: EAF+LF/VD

4.3   Mechanical properties

The mechanical properties of SA302GrC shall meet the requirement as table 2&3.

Table 2 Tensile properties

4.4   Impact properties

Impact test in the longitudinal and transverse for plates of SA302GrC shall meet the requirements per table 3.

Table 3 Impact properties

4.5   Hardness: Max 240HV

4.6   SWHT: Simulated Post-Weld Heat Treatment of Mechanical Test Coupons shall be prepared in 600+/-10 C with min.5 minute per each mm of thickness.

4.7   Surface quality

The surface quality of plates shall be accordance with ASTM A20/A20M.

4.8   Ultrasonic inspection

Plates shall be ultrasonic inspected per ASTM A578/A578M level C.

4.9   Test method and inspection rules

Test items, sampling quantity, sampling method and test method shall conform to table 4.

Table 4 Test items for plates

5.       Package, marking and certificate

Package, marking and certificate shall conform to A20.

6.       The third party inspection

The chemical composition, tensile test and Charpy V impact test and HIC test for plates of SA302GrC shall be witnessed by surveyor of client.

7.       Delivery conditions

The delivery conditions for plates of SA302GrC shall be Normalized(accept ACC)+ Tempered(temperature not less than 700 C degree.)

8.       Other requirements

The other requirements for plates of SA302GrC shall be accordance with SA387/SA387M-2010.

MTC accordance with EN10204: 2004 3.1