NⅡ -type joint pipe for gas supply
MECHANICAL PROPERTIES:
The mechanical properties of NⅡ -type joint pipe for gas supply shall be as shown in the table:
Type of Cast | Minimum Tensile strength | Minimum Elongation Percent After fracture, A | Hardness Max.(HB) | |
DN80-2600 | DN80-1000 | DN1100-2600 | ||
Pipes centrifugally cast | 420 MPa | 10 % | 7 % | 230 |
Pipes not centrifugally cast, fittings and accessories | 420 MPa | 5 % | 5 % | 250 |
Note of NⅡ -type joint pipe for gas supply 1. By agreement between manufacturer and purchaser, the 0.2% proof stress may be measured. It shall be not less than 270 MPa when A ≥12% for DN60-1000 or 10% for DN > 1000. 2. For centrifugally cast pipes of DN60 to DN1000, the minimum elongation after fracture shall be 7% for thickness classes greater than K12 | ||||
HYDROSTATIC TEST PRESSURE AT WORKS:
All Pipes and fittings shall be subjected to a works hydrostatic test for a duration of at least 10 seconds at the minimum internal test pressure given in the table.
DN (mm) | Minimum work test pressure (Bar) | ||
Pipes centrifugally cast | Pipes not centrifugally cast and fittings 1) | ||
K<9 | K≥9 | All thickness classes | |
≤ DN300 | 0.5(k+1)2 | 50 | 25 2) |
350—600 | 0.5k2 | 40 | 16 |
700—1000 | 0.5(k-1)2 | 32 | 10 |
1200—2000 | 0.5(k-2)2 | 25 | 10 |
2200—2600 | 0.5(k-3)2 | 18 | 10 |
1).The works hydrostalic test pressure for fittings is less than that for pipes because the shape of fittings makes it difficult to provide sufficient restraint to high pressure during test. 2). 16 bar for pipes and fittings with PN10 flanges. | |||
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