Bolting Material
Bolting materials used in Cast Steel Valves are carefully selected and controlled to assure reliability in service. The following describes the more usual bolting materials (studs and nuts) used in the bonnet and cover joints of valves.
Steel valves for all temperature services have alloy steel studs. For temperatures up to 875F, chromium-molybdenum steel conforming to ASTM A193-B7 is normally used, and for higher temperatures and/or corrosive services, other suitable ferritic (usually ASTM A193-B16) or austenitic grades are selected from ASTM A193. Nuts for ferritic alloy studs are normally carbon steel that meets the requirements of ASTM A194 Grade 2H. For low-temperature applications down to minus 150F, alloy steel studs conforming to ASTM 320-L7 are normally used in conjunction with alloy steel nuts meeting the requirements of ASTM A194 Grade 4.
Ferritic alloy steel bolting is heat treated to conform to the following minimum mechanical property requirements:
- Tensile strength (psi): 125,000 minimum
- Yield Point (psi): 105,000 minimum
- Elongation, percent in 2″: 16 minimum
- Reduction of Area, percent: 50 minimum
In cast iron valves, the bonnet, retainer, and cap joints have carbon steel bolting meeting the requirements of ASTM A307 Gr B. Carbon steel nuts are used.
In corrosion-resistant valves, the bonnet and gland bolts and nuts are made of austenitic stainless steel.
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Body Materials
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Temperature (degrees F) |
Material Specifications
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Bolts
|
Nuts
|
| Cast Iron |
-20 to 410 |
ASTM A307 Gr B | ASTM A307 Gr 7 |
| Ductile Iron |
-20 to 650 |
ASTM A193 Gr B7 | ASTM A194 Gr 2H |
| Carbon Steel (Grade WCB) |
-20 to 800 |
ASTM A193 Gr B7 | ASTM A194 Gr 2H |
| Carbon Steel (Grade LCB) |
-50 to 650 |
ASTM A193 Gr B7 | ASTM A194 Gr 2H |
| Carbon Moly (Grade WC1) |
-20 to 800 801 to 850 |
ASTM A193 Gr B7 ASTM A193 Gr B7 |
ASTM A194 Gr 2H ASTM A194 Gr 7 |
| 1¼Cr-½Mo (Grade WC6) |
-20 to 800 801 to 1000 |
ASTM A193 Gr B7 ASTM A193 Gr B7 |
ASTM A194 Gr 2H ASTM A194 Gr 7 |
| 2¼Cr-1Mo (Grade WC9) |
-20 to 800 801 to 1000 1001 to 1050 |
ASTM A193 Gr B7 ASTM A193 Gr B7 ASTM A193 Gr B16 |
ASTM A194 Gr 2H ASTM A194 Gr 7 ASTM A194 Gr 7 |
| 5Cr-½Mo (Grade C5) |
-20 to 800 801 to 1000 1001 to 1100 |
ASTM A193 Gr B7 ASTM A193 Gr B7 ASTM A193 Gr B16 |
ASTM A194 Gr 2H ASTM A194 Gr 7 ASTM A194 Gr 4 |
| 9Cr-1Mo (Grade C12) |
-20 to 800 801 to 1000 1001 to 1100 |
ASTM A193 Gr B7 ASTM A193 Gr B7 ASTM A193 Gr B16 |
ASTM A194 Gr 2H ASTM A194 Gr 7 ASTM A194 Gr 4 |
| Type 304 (Grade CF8) |
-425 to 100 100 to 1500 |
ASTM A320 Gr B8 *ASTM A193 Gr B8 |
ASTM A194 Gr 8 *ASTM A194 Gr 8 |
| Type 347 (Grade CF8C) |
-425 to 100 100 to 1500 |
ASTM A320 Gr B8 *ASTM A193 Gr B8 |
ASTM A194 Gr 8 *ASTM A194 Gr 8 |
| Type 316 (Grade CF8M) |
-325 to 100 100 to 1500 |
ASTM A320 Gr B8 *ASTM A193 Gr B8M |
ASTM A194 Gr 8 *ASTM A194 Gr 8M |
| 3½Ni (Grade LC3) |
-150 to –50 -50 to 650 |
ASTM A320 Gr L7 ASTM A193 Gr B7 |
ASTM A194 Gr 4 With Charpy Test or 8M ASTM A194 Gr 2H |
* Alloy steel bolting, A193 bolts and A194 Gr 2H nuts can be used at moderate temperatures depending on the permissible differential expansion.
Disclaimer: Performance data provided here has been developed from field testing, customer field reports and / or in-house testing. While the utmost care has been used in compiling this website, we assume no responsibility for errors. This edition cancels all previous issues. Subject to change without notice.