JB/T 1308.18-1999 This standard is a revision of JB 1325-73 "Type, size and technical requirements of Pg (2500kgf/cm2) reducers". This standard specifies the type, size and technical requirements of reducers for ultra-high pressure valves. This standard is applicable to reducers for neutral media such as ethylene and polyethylene with a nominal pressure of 250MPa. This standard was first published on 2010-03-17. JB/T 1308.18-1999 PN250a reducer type, size and technical requirements JB/T1308.18-1999 standard download decompression password: www.bzxz.net

ICS23.060
Machinery Industry Standard of the People's Republic of China
JB/T1308.1~1308.21-1999
PN250MPa ultrahigh pressure valves and fittings
Technical conditions
Specifications for PN250MPa ultrahigh pressure valves and fittings
1999-07-12 Issued
State Bureau of Machinery Industry
Implementation on 2000-01-01
1 Scope
Machinery Industry Standard of the People's Republic of China
PN250MPa reduced joints
Type, dimensions and specifications of PN 250 MPa reduced joints This standard specifies the types, dimensions and technical requirements of reducing joints for ultrahigh pressure valves. JB/T1308.18—1999
Replaces JB1325—73
This standard applies to reducers for neutral media such as ethylene and polyethylene with a nominal pressure of PN250MPa. 2 Cited standards
The provisions contained in the following standards constitute the provisions of this standard through reference in this standard. When this standard is published, the versions shown are valid. All standards will be revised, and parties using this standard should explore the possibility of using the latest versions of the following standards. JB/1308.2—1999PN250MPa Technical conditions for valves, pipe fittings and fasteners JB/T1308.4—1999PN250MPa Neck joint types, dimensions and technical conditions Structural types and dimensions
3.1 The type of reducer shall be as specified in Figure 1. Its bearing capacity is 8 levels A, maintaining the angle of loss. Approved by the State Machinery Industry Bureau on 1999-07-12, 38, Baoshenyu, implemented on 2000-01-01. The dimensions of the reducer shall be as specified in Table 1.
Nominal diameter
10 ×3
15 ×10
Nominal diameter
10 ×3
10 ×6
15 ×10
Thread code
M24 × 22
M33 × 2-2
M48 × 22
4Technical requirements
Thread code
M20 ×1.52
M24 ×22
M33 ×22
Material of reducing joint 33CrNi3MoA.
JB/T1308.18-1999
The mechanical properties after heat treatment shall be as specified in Table 2. 4.2
Material grade
33CrNi3MoA
Tensile strength.
Service point. .
≥735
The end of the reducer shall comply with the provisions of JB/T1308.4. 4.3
Elongation 8,
Contraction rate medium
4.4The reducer shall be subjected to ultrasonic flaw detection and magnetic particle flaw detection in accordance with the provisions of JB/T1308.2. d,bZxz.net
Impact value A
269~321
4.5Each reducer shall be stamped with a steel stamp on the outer surface (at the mark in the figure), and the stamp content shall be: JB/T1308.18 specification/batch number. 5 Marking example
Reducing joint with nominal diameter 10×6mm:
5JB/T1308.18—1999
Reducing joint DN10×6
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