Check Valve Material
1 The valve body and valve cover
1.1 If no special request orders in the contract, the valve shell materials should be GB / T 12224 requirements, comply with GB / T 12228, GB / T 12229, GB / T 12230 requirements.
1.2 The valve has anti sulfur requirements, should select the appropriate materials. Parts and connecting stud pressure on sulfide stress corrosion cracking and other sensitive material heat treatment method should be adopted so that a favorable anti-sulfur performance improvement. Material heat treatment method should meet the criteria or process requirements.
5.1.3 welded valve body end connections shall comply with its carbon content:
a) carbon or carbon manganese steel, the maximum carbon content of 0.25%, the supplier shall provide the chemical composition, mechanical properties, heat treatment and quality of paper reports;
b) Cr5Mo the maximum carbon content of steel was 0.15%.
2 Seat
Split seat, the corrosion resistance of bulk material shall not be less than the body material, upon request, the sealing surface should be surfacing in other alloy materials.
3 Disc
Flap valve body with anti-corrosion performance of not less than the material body, upon request, the sealing surface should be surfacing in other alloy materials. Flexible seal materials used in sealing structure should at least use the working conditions meet the requirements of the fixing bolts or nuts should be used austenitic stainless steel material.
4 rocker, bracket, and pin
Rocker and support with the corrosion resistance of not less than the shell material, pin and fastening bracket with stainless steel fasteners, the corrosion resistance of not less than the shell material.
5 Connect the body and the valve cover stud
Valve temperature at -29 ℃ ~ 425 ℃ range, connecting the body and the valve cover stud material should be chrome molybdenum alloy steel, nut material should be high-quality carbon steel, stud of the hardness value is not greater than 321 HB; other temperature range stud material used to connect the requirements of the contract by order.
6 Plug
Plug body material with corrosion resistance with the same material.
7 Disc and seat sealing surface welding surface
Welding surface sealing surface should be used with the corrosion resistance of stainless steel or cemented carbide materials, can be used in table 5.
Table 5 surfacing material commonly used in sealing surface
Material type sealing surface hardness Remarks
Chromium stainless steel (13Cr series) minimum 250 HBa -
Cr - Ni stainless steel (304, CF3, Cr18-Ni-Mo, Cr25-Ni20, etc.) provided by the manufacturer -
Carbide (CoCrW) minimum 350 HBb -
Monel alloy (Cu-Ni) 175 HBc -
Hard 13Cr 750 HBc sclerosis
a valve seat and disc sealing surface sealing surface of the minimum hardness is 250 HB, the hardness difference between the minimum 50 HB.
b seat and disc sealing surface between the sealing surface hardness difference is not required.
c seat and disc sealing surface hardness of the sealing surface provided by the manufacturer difference.
8 Valve Cover Gasket
Valve cover gasket used with the corrosion resistance of the shell material should be not less than gasket, can be used in table 6.
Table 6 Valve Cover Gasket
Type using the pressure / MPa
≤ temperature / ℃
≤
Flexible graphite reinforced composite pad 425 5.0
Metal coated pad 425 5.0
Spiral Wound Pad 16.0 550
Corrugated metal pad 450 25.0
Metal ring pad 550 42.0