2507 duplex stainless steel valve uses JB/T7746 “Compactsteel valve” industry standard introduction
Our company specializes in the production of seawater 2205 duplex stainless steel ball valve 2507 duplex stainless steel ball valve 2205 duplex stainless steel globe valve 2507 duplex stainless steel globe valve 2205 duplex stainless steel gate valve 2507 duplex stainless steel gate valve 2205 duplex stainless steel Y-type filter 2507 duplex stainless steel filter 2205 check valve 2507 check valve and other products
Seawater 2205 duplex steel valve molybdenum duplex stainless steel has good resistance to chloride stress corrosion under low stress. Generally, 18-8 type austenitic stainless steel is prone to stress corrosion fracture in neutral chloride solution above 60C. Heat exchangers, evaporators and other equipment made of this kind of stainless steel in the industrial medium of trace chloride and hydrogen sulfide have a tendency to produce stress corrosion fracture, while duplex stainless steel has a good resistance.
(2) Seawater 2205 duplex steel valve molybdenum duplex stainless steel has good corrosion resistance. The critical pitting potential of duplex stainless steel is similar to that of austenitic stainless steel with the same pitting resistance (PRE=Cr%+3.3Mo%+16N%). The corrosion resistance of duplex stainless steel and austenitic stainless steel is similar to that of AI 316L. The corrosion resistance of high chromium duplex stainless steel containing 25%Cr, especially nitrogen, is higher than that of AI 316L.
(3) With good corrosion resistance to fatigue and wear corrosion performance. In some corrosive medium conditions, suitable for the production of pumps, valves and other power equipment.
(4) Good comprehensive mechanical properties. High strength and fatigue strength, yield strength is 18-8 type austenitic stainless steel 2 times. In the solid solution state, the elongation reaches 25%, and the toughness value AK (V-notch) is above 100J.
(5) Good weldability, small hot crack tendency, generally before welding without preheating, welding without heat treatment, can be welded with 18-8 type austenitic stainless steel or carbon steel and other dissimilar.
(6) The thermal working temperature range of duplex stainless steel containing low chromium (18%Cr) is wider than that of 18-8 austenitic stainless steel, and the resistance is small. It can be rolled directly to produce steel plate without forging. Duplex stainless steel containing high chromium (25%Cr) is slightly more difficult than austenitic stainless steel thermal processing, can be produced plate, tube and wire products.
(7) cold working than 18-8 type austenitic stainless steel work hardening effect is large, in the tube, plate deformation at the initial stage, need to apply greater stress to deformation.
(8) Compared with austenitic stainless steel, high thermal conductivity, low linear expansion coefficient, suitable for equipment lining and production of composite plate. It is also suitable for making the tube core of heat exchanger, and the heat transfer efficiency is higher than that of austenitic stainless steel.
(9) There is still a variety of brittleness tendency of high chromium ferrite stainless steel, should not be used in higher than 300C working conditions. The lower the chromium content of duplex stainless steel, the less the harm of the equal brittle phase.
JB/T7746 “Compact Steel Valve” Industry standard introduces the present design and manufacture standard for forging steel small diameter valve in our country is JB/T 7746-2006 “Compact Steel Valve”, the standard is approved and released on September 14, 2006, the implementation date is March 1, 2007. Instead of JB/T 7746-1995 “Reduced diameter forged steel Valve”.
I. Overview
At present, the design and manufacture standard of forged steel small diameter valve in our country is JB/T 7746-2006 “Compact Steel Valve”, this standard is approved and issued on September 14, 2006, the implementation date is March 1, 2007, in place of JB/T 7746-1995 “Reduced diameter Forged Steel Valve”.
This revision references the American Petroleum Institute API 602-1998 “Compact Steel Gate Valves for Flanged, Threaded, Welded and Extended Body Connections” and is consistent with API 602 in major technical requirements.
This standard specifies the structural type, technical requirements, test methods, inspection rules, marking and supply requirements of reduced diameter steel valves.
This standard applies to gate, globe, lift and swing check valves. For internal thread and socket welding valves with nominal pressure PN18~PN250 and nominal size DN8~DN65; Also applicable to nominal pressure PN18~PN250, nominal size DN8~DN100 flange connection and butt welding connection valve. Applicable medium for water, petroleum and petroleum related products, natural gas, steam, etc.
This standard also applies to valves with bellows sealed connection, nominal pressure PN16~PN250, nominal size DN8~DN50.
Two, JB/T 7746 “compact steel valve” the main difference between the old and new standards
1, the name change, the original JB/T7746-95 standard named “Reduced diameter forged steel valve”, the new standard JB/T 7746-2006 standard named “compact steel valve”;
2. Increased the order requirements;
3. Add “Bellows Sealing Valve Structure”, “Nominal Pressure PN250 Valve pressure-temperature Grade in Appendix B” and “Butt welding end Size in Appendix C”;
4, the scope of application increases the scope of pressure grade caliber and the structure of the valve cover is bellows sealed valve, the pressure grade of the valve increases PN16, PN63, internal thread, to undertake welding valve diameter increases DN8 and DN65, flange and butt welding valve diameter increases DN8, DN65, DN80,DN100;
5. The typical structure of the bellows sealing valve is added to the legend;
6. The pressure-temperature rating of PN250 valve specified in Section 5.1 shall be in accordance with Appendix B;
7. In Section 5.2 “Valve body connecting end”, the section is divided into four parts according to the connection form, and the structural length size of the valve with socket welding and internal thread connection is revised, and the size of the socket welding and butt welding end is specified;
8. In Section 5.4, provisions are added for bolts and nuts used in valve bodies of different materials;
9. In Section 5.5, the narrative order of parts was changed, and the provisions of internal materials corresponding to different body materials were added, as well as the definition of the small inner diameter of the valve stem and the provisions of the thread of the valve stem were added;
10. Contents of ex-factory inspection and form test are added in 7.1 and 7.2.
3. Major differences between JB/T 7746-2006 and API 602 standards
JB/T 7746-2006 standard corresponds to API 602-1998 “Flanged, threaded, welded and Body elongated connection of the compact steel gate valve”, this standard and API 602-1998 the degree of consistency is not equivalent, the main differences are as follows:
1. Compared with API 602-1998, this standard adds globe valves and check valves to the valve network types;
2. Compared with the API 602-1998 standard, the units in this standard adopt the metric system;
3. Compared with API 602-1998, this standard adds requirements for the size of socket and butt welding ends;
4. Relative to API 602-1998, this standard adds structural length requirements for socket welding and internal threaded valves;
5. This standard cancellations the content of lengthening valve body connection part in API 602-1998 standard;
6. This standard cancellations the content marked in API 602-1998 standard and instead directly refers to GB/T 12220 “Valve Marks”;
7. The content of Table 3 Pressure-temperature Ratings for gate Valves for 800 lb class in API 602-1998 has been streamlined;
8. This standard cancels the material specification in Table 8 of API 602-1998 standard and the content of corresponding ASTM standard;
9. The stem material content in Table 10 of API 602-1998 is appropriately simplified in this standard;
10, this standard cancels the content of seal number and substitute seal number in Table 11 of API602-1998 standard;
11. This standard cancelates the content of Article 6 shipment in API602-1998 standard and instead references JB/T 7928 “Valve Supply Requirements” standard;
12. This standard has been appropriately condensed from Appendix A of API602-1998, “Additional Requirements for Compact Bellows Sealed Gate Valves”, and incorporated into the body of the standard.
13. Compared with API 602-1998, the static pressure life of valves is specified in this standard;
14. Relative to the API 602-1998 standard, this standard adds requirements for inspection and testing of bellows valves;
15 Compared with API 602-1998, this standard adds requirements for static pressure life test, factory inspection and type inspection of valves;
Iv. Problems that should be paid attention to when using this standard
Table 6 in this standard specifies the small diameter of the stem, where stem diameter refers to the diameter of the cross-sectional area of the stem through the packing.
Post time: Nov-25-2022
