JB/T 4703-2000 in English

1 Scope
This standard specifies the structural style and series dimension of steel pressure vessels welding neck flange
This standard is applicable to the steel pressure vessels welding neck flange which nominal pressure is 0.6〜 6.4 MPa, and working temperature is -70 ~450 ℃.
This standard is applicable to corrosion allowance ≤three min

2 Normative References
The involved provisions in the following standard will become the provisions quoted by this standard. When published, all the shown versions are valid. All the standards will be modified, and all parties using this standard shall discuss the possibility of using the latest version.
JB/T 4700—2000Classification and technical conditions for pressure vessel flanges
JB/T 4704—2000Nonmetallic Gaskets
JB/T 4705—2000Spiral Wound Gaskets
JB/T 4706—2000metallic-jacketed Gaskets
JB/T 4707—2000Stud Bolts

3 Structural style and dimension
The Structural style and dimension of welding neck flange of every kind of sealing surface shall be in accordance with the provisions of figure1 to Figure 6 and Table 2;the quality of flange and lined-ring is listed in Table 2

4 Selection provisions
4.1 The materials of flange and assorted gasket, stud, and screw nut, maximum allowable working pressure, technical conditions and its label shall be in accordance with the provisions of JB/T 4700
4.2 Flange-used nonmetallic gaskets, spiral wound gasket, and metallic-jacketed gaskets shall be in accordance with the provisions of JB/T 4704、JB/T 4705、JB/T 4706 respectively.
4.3 Flange-used equilong double-end screw bolt shall be in accordance the provisions of JB/T 4707
4.4 When the thickness of the butt joint cylinder which is connected with flange, is less than the minimum thickness δ0 of butt cylinder in table 1, it shall meet the requirements of Table 3, and adjust the total height H of flange, and mark it out together with flange's height in flange's label.