Technical requirement
A) The Chemical & Mechanical Composition for 37Mn. should be as follow: (%)
| C | Si | Mn | P | S | P+S | ||
|---|---|---|---|---|---|---|---|
| 37 Mn | Min. | 0.30 | 0.10 | 1.35 | – | – | – |
| Max. | 0.38 | 0.35 | 1.70 | 0.020 | 0.02 | 0.03 |
(a) W.T. Tolerance: -0/+15%; O.D. Tolerance: ±1%
(b) NDT: Each pipe shall be inspected by UT.
(c) Mechanical properties guaranteed by tube manufacturer after Heat treatment in Lab of tube manufacturer
| Min. Value | |
|---|---|
| Tensile Strength | 735 N/mm2 |
| Yield Strength | 570 N/mm2 |
| Elongation | Not less than 15% |
| Hardness Test Value | 220 – 270 BHN and |
| Impact Test Individual | – 28 j/cm² minimum. Mean of 3–35 j/cm² min. |
| Test at | – 50 deg C as per ISO 11439 |
B) The Chemical & Mechanical Composition for 34CrMo4. should be as follow: (%)
| C | Si | Mn | P | S | Cr | Mo | P+S | ||
|---|---|---|---|---|---|---|---|---|---|
| 34CrMo4 | Min. | 0.30 | 0.10 | 1.50 | – | – | 0.90 | 0.15 | |
| Max. | 0.37 | 0.40 | 0.80 | 0.020 | 0.010 | 1.20 | 0.30 | 0.025 |
(a) W.T. Tolerance: -0/+15%; O.D. Tolerance: ±1%
(b) NDT: Each pipe shall be inspected by UT.
(c) Mechanical properties Minimum guaranteed required mechanical property to be achieved after Heat treatment in Lab of tube manufacturer is as below
| Min. Value | |
|---|---|
| Tensile Strength | 830 N/mm² (MPa), Maximum 950 N/mm² (MPa) |
| Yield Strength | 705 N/mm² |
| Elongation | Not less than 14%; |
| Hardness | Value range: 240 ~ 295 BNH |
| Impact: | Value-Individual –32 j/cm² min. Mean of 3–40 j/cm² min |
| Test at | – 50 deg C as per ISO 11439 |
C) The Chemical & Mechanical Composition for 34CrMo4. should be as follow: (%)
| C | Si | Mn | P | S | Cr | Mo | Ni | P+S | ||
|---|---|---|---|---|---|---|---|---|---|---|
| 34CrMo4 | Min. | 0.30 | 0.10 | 1.40 | – | – | 0.90 | 0.15 | 0 | |
| Max. | 0.37 | 0.40 | 1.00 | 0.020 | 0.010 | 1.20 | 0.30 | 0.15 | 0.025 |
(a) W.T. Tolerance: -0/+15%; O.D. Tolerance: ±1%
(b) NDT: Each pipe shall be inspected by UT.
(c) Mechanical properties Minimum guaranteed required mechanical property to be achieved after Heat treatment in Lab of tube manufacturer is as below
| Min. Value | |
|---|---|
| Tensile Strength | 928 N/mm² (MPa), Maximum 1100 N/mm² (MPa) |
| Yield Strength | 785 N/mm² |
| Elongation | Not less than 14%; |
| Hardness | Value range: 266 ~ 330 BNH |
| Impact: | Value – Individual –32 j/cm² min. Mean of 3 – 40 j/cm² min |
| Test at | – 50 deg C as per ISO 11439 |