NII-type joint pipe

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:

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

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.