In various industrial applications, flange connections are used to join piping systems. These connections require specialized fasteners that can withstand high loads and pressures while maintaining a leak-free seal. The stainless steel A193 B8M stud bolt and heavy hex nut A194 8M flange fastener is a commonly used solution for such connections.
The A193 specification covers high-temperature and high-pressure service bolting in various grades and classes, including the B8M material. The B8M grade is an austenitic stainless steel alloy that is highly resistant to corrosion in chloride environments, making it an ideal material for use in chemical, petroleum, and marine industries.
The A194 specification covers nuts made from various materials and grades, including the A194 8M material. The A194 8M heavy hex nut is made from the same B8M stainless steel alloy as the stud bolt. The heavy hex design of the nut provides a larger bearing surface area, which distributes the load evenly and reduces the risk of nut dislodgment due to vibration or shock.
The stud bolt is a threaded rod that is threaded from one end to the other. Full thread bolts provide greater strength and resistance to bending and shearing forces, making them ideal for high-stress applications. They are commonly used in flange connections where a precise bolt length is required to achieve the required bolt preload.
When selecting the right fastener for a flange connection, several factors must be considered, including the material compatibility, load capacity, and environmental conditions. Stainless steel materials are often preferred for their corrosion resistance and durability in harsh environments. The B8M and A194 8M materials are specifically designed for use in corrosive environments and high-pressure applications.
The A193 B8M stud bolt and A194 8M heavy hex nut provide several advantages over other types of fasteners. Firstly, the continuous threading of the stud bolt provides a consistent grip length, which helps to ensure that the bolt is properly torqued and that the flange connection is secure. Additionally, the use of heavy hex nuts provides a larger surface area for distributing the load, reducing the risk of nut dislodgment and loosening.
Another advantage of using B8M and A194 8M materials is their excellent resistance to corrosion. These materials are resistant to pitting, crevice corrosion, and general corrosion in chloride environments. They are also resistant to oxidation at high temperatures, making them suitable for high-temperature applications. This resistance to corrosion helps to ensure that the fasteners maintain their strength and integrity over time, reducing the risk of failure and downtime.
In addition to their corrosion resistance, the A193 B8M stud bolt and A194 8M heavy hex nut also offer high strength and durability. These fasteners are capable of withstanding high loads and pressures without degrading, ensuring a secure and reliable flange connection that can withstand the rigors of industrial applications.
In conclusion, the A193 B8M stud bolt and A194 8M heavy hex nut flange fastener made from stainless steel materials are an ideal solution for flange connections in high-pressure and corrosive environments. These fasteners provide high strength, consistent grip length, and excellent corrosion resistance, ensuring a secure and reliable flange connection that can withstand the rigors of industrial applications.
Stud Bolt Materials
The most common materials for stud bolts (for flanges) are ASTM A193 (grade B7, B8, B8M, B8T), ASTM A453 (grade 660), ASTM A320 (grade L7, L7M), and ASTM A182 (duplex and super duplex bolting). For aggressive fluids and environments, stud bolts can be coated with Xylan/PTFE, Zinc and other materials.
Physical Element | ASTM A193 grade B7 (AISI 4140) | ASTM A193 grade B8 (AISI 304) | ASTM A193 grade B8M (AISI 316) |
---|---|---|---|
Carbon | 0.38 - 0.48% | 0.08% max | 0.08% max |
Manganese | 0.75 - 1.00% | 2.00% max | 2.00% max |
Phosphorus, max | 0.035% | 0.045% | 0.045% |
Sulfur, max | 0.040% | 0.030% | 0.030% |
Silicon | 0.15 - 0.35% | 1.00% max | 1.00% max |
Chromium | 0.80 - 1.10% | 18.0 - 20.0% | 16.0 - 18.0% |
Nickel | absent | 8.0 - 11.0% | 10.0 - 14.0% |
Molybdenum | 0.15 - 0.25% | absent | 2.00 - 3.00% |
ASTM A193 | Size | Min Tensile Strength (KSI) | Min Yield Strength (KSI) | Min Elongation (%) | RA % min | Max HBW | Max HRC |
---|---|---|---|---|---|---|---|
ASTM A193 grade B7 | Up to 2-1/2 | 125 | 105 | 16 | 50 | 321 | 35 |
2-5/8 - 4 | 115 | 95 | 16 | 50 | |||
4-1/8 - 7 | 100 | 75 | 18 | 50 | |||
ASTM A193 grade B8 Class 1 | All | 75 | 30 | 30 | 50 | 223 | 35 |
ASTM A193 grade B8M Class 1 | All | 75 | 30 | 30 | 50 | 223 | 96 |
ASTM A193 grade B8 Class 2 | Up to 3/4 | 125 | 100 | 12 | 35 | 321 | 35 |
7/8 - 1 | 115 | 80 | 15 | 35 | |||
1-1/8 - 1-1/4 | 105 | 65 | 20 | 35 | |||
1-3/8 - 1-1/2 | 100 | 50 | 28 | 45 | |||
ASTM A193 grade B8M Class 2 | Up to 3/4 | 110 | 95 | 15 | 45 | 321 | 35 |
7/8 - 1 | 100 | 80 | 20 | 45 | |||
1-1/8 - 1-1/4 | 95 | 65 | 25 | 45 | |||
1-3/8 - 1-1/2 | 90 | 50 | 30 | 45 |
The material chosen for the threaded stud and the hex nuts should be compatible. Materials for bolting sets shall be selected based on the process's working temperatures, as shown in the table below:
TEMPERATURE °C ( °F ) | ||
STUD BOLTS MATERIALS | MIN. | MAX. |
CARBON STEEL | -29 (-20) | 300 (572) |
A193 B7, L7 | -73 (-100) | 400 (752) |
A193 B6 | 0 (32) | 500 (932) |
A193 B8 | -200 (-325) | 575 (1067) |
A193 B16 | 0 (32) | 520 (968) |
A193 B17B | -29 (-20) | 650 (1202) |
A913 Inconel 718 | 0 (32) | 750 (1382) |
A453 Gr. 660 | -29 (20) | 538 (1000) |
Stud bolts can be coated to increase the resistance to corrosion. The most common types of coatings for stud bolts are listed below:
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