Instantly Website Visitors

<script async src="https://www.googletagmanager.com/gtag/js?id=AW-16512834322"></script>
<script>
 window.dataLayer = window.dataLayer || [];
 function gtag(){dataLayer.push(arguments);}
 gtag('js', new Date());
 
 gtag('config', 'AW-16512834322');
</script>

GTAG.js Script

<script>
(function(i,s,o,g,r,a,m){i['GoogleAnalyticsObject']=r;i[r]=i[r]||function(){
(i[r].q=i[r].q||[]).push(arguments)},i[r].l=1*new Date();a=s.createElement(o),
m=s.getElementsByTagName(o)[0];a.async=1;a.src=g;m.parentNode.insertBefore(a,m)
})(window,document,'script','https://www.google-analytics.com/analytics.js','ga');

ga('create', 'UA-YOUR_GA_ID', 'auto');
ga('send', 'pageview');
</script>

Google Analytics

Fasteners are an essential component in the construction industry. They are used to join two different components together, sometimes very heavy machinery, so knowing the proper fastener to use is necessary for safety and integrity of the project. The construction industry uses a wide variety of fasteners from corrosive resistant screws to structural bolts for heavy machinery.<h3>Common Types of Fasteners in Construction</h3><h4>Screws</h4>Screws are likely the most common fastener used in the construction industry. They are versatile for joining materials together, and the wide variety of points, thread, material, and coatings make them popular for a wide range of applications.&nbsp;<ul><li>Wood Screws: The coarse threads and tapered heads of wood screws make them ideal for use on hardwood surfaces.</li><li>Deck Screws: They feature self-tapping heads and are corrosive resistant; they mimic wood screws in appearance.</li><li>Sheet Metal Screws: Over a variety of drill points to cover a variety of applications. Used to fasten two pieces of metal.</li><li>Tek Screws: Self Drilling screws that do not require a pilot hole when fastening.</li></ul><h4>Bolts, Nuts, and Washers</h4>Bolts are also incredibly common in the construction industry. The variety of diameter, thread, material, strength, and finish cover every application. From low grade, Grade 2 (A307A), to structural grade ASTM A325, knowing the correct fastener for your application is critical.&nbsp;<figure class="table"><table><thead><tr><th>Grade and material</th><th>Min. Yield Strength(PSI)</th><th>Min. Tensile Strength(PSI)</th></tr></thead><tbody><tr><td>A307A</td><td>NA</td><td>60,000</td></tr><tr><td>Grade 2</td><td>57,000 (1/4"-3/4 DIA.) 36,000 (3/4" DIA.+)</td><td>74,000 (1/4"-3/4 DIA.) 60,000 (3/4" DIA.+)</td></tr><tr><td>Grade 5</td><td>92,000 (1/4"-3/4 DIA.) 81,000 (3/4" DIA.+)</td><td>120,000 (1/4"-3/4 DIA.) 105,000 (3/4" DIA.+)</td></tr><tr><td>Grade 8</td><td>130,000</td><td>150,000</td></tr><tr><td>ASTM A325</td><td>92,000</td><td>120,000</td></tr></tbody></table></figure><h4> Finish and Coating</h4>Finish is also necessary when choosing your fastener. Alloy steel, Zinc Plated, Hot Dipped Galvanized, and Stainless steel are the most common platings and coatings. Depending on your application, it may be necessary to choose a fastener with corrosion resistance to ensure the integrity of the application.<h3>Additional Fasteners</h3><h4>Anchors</h4>Anchors are used to attach materials to concrete, brick, or other masonry materials. They are available in a range of sizes and styles, including wedge anchors, sleeve anchors, and concrete anchors.<h4>Nails</h4>Nails are used to join wood together and are available in a variety of sizes and lengths. They lack threading but come in a variety of materials for your application.<h4>Rivets</h4>Rivets are used to join two metal pieces together and are typically used in aircraft and other applications where a strong, permanent joint is required. As a permanent fastening, rivets are used in many different forms of construction.<h2>Conclusion</h2>The construction industry is certainly one of the most common industries for fastener use. To ensure that even your most critical jobs and applications are safe, it is necessary to choose the correct fastener with strength, cycle of life, and finish in mind. Kenneth G. Lilly Fasteners sells a variety of fasteners for use in the construction industry. With our years of industry expertise and trust, contact us for a quote.

The Various Types, Materials, and Styles of Fasteners Used in Construction

Fasteners in Construction Industry

When it comes to industrial applications—from large-scale construction to high-pressure equipment assemblies—fasteners are the unsung heroes that literally hold everything together. With so many types to choose from, it’s easy to get overwhelmed by terms like threaded studs, rods, hex head cap screws, or socket head screws. In this post, we’ll walk you through the basics of these common fasteners, explaining what they are, how they’re used, and what makes them different.&nbsp;<h2>Threaded Studs</h2>&nbsp;What They Are A threaded stud is essentially a piece of metal rod that’s threaded on both ends (or sometimes along its full length). Unlike a conventional bolt, which has a head on one end, a stud is typically headless.&nbsp;Key Advantages<ul><li>Flexibility: You can adjust the clamping length by choosing nuts and washers as needed.</li><li>Strength: High-tension applications often call for studs rather than bolts.</li><li>Alignment: Because there’s no head, studs are frequently used where precise alignment of components is essential.</li></ul>&nbsp;Typical Uses<ul><li>Engine Blocks: Common in automotive and heavy-equipment applications for cylinder heads.</li><li>Pressure Vessels: High-pressure, high-temperature environments often employ studs to achieve a secure and uniform seal.</li><li>Flange Connections: Industrial piping and flange assemblies rely on studs to maintain robust connections over time.</li></ul>&nbsp;<h2>Threaded Rods</h2>&nbsp;What They Are Threaded rods look similar to studs but are fully threaded throughout their entire length. Also referred to as “all-thread,” these rods can be easily cut to a custom length, making them a versatile fastening solution.&nbsp;Key Advantages<ul><li>Adjustable Length: Cut to your exact specification, ideal for jobs that need custom lengths.</li><li>Versatility: Can be paired with standard nuts and washers for various load requirements.</li><li>Cost-Effective: Usually more affordable than specialized fasteners, especially for large-scale projects.</li></ul>Typical Uses<ul><li>Infrastructure Projects: Frequently utilized in construction for suspending ceilings, HVAC systems, or supporting structural components.</li><li>Electrical and Plumbing: Used to mount or support conduit, panels, and heavy fixtures.</li><li>DIY and Repair Work: Popular in home or workshop settings due to their versatility.</li></ul>&nbsp;<h2>Threaded Stud Assemblies (with Nuts)</h2>&nbsp;What They Are A threaded stud assembly is basically a stud provided with the appropriate nuts (and sometimes washers) as a complete set. This packaging ensures you have matching components—especially important where specific material grades or finishes are required.&nbsp;Key Advantages<ul><li>Convenience: Everything you need in one kit, reducing the risk of mismatch.</li><li>Quality Assurance: Guaranteed compatibility and meeting of specified standards.</li><li>Material Consistency: Helps maintain consistent performance across multiple connection points.</li></ul>Typical Uses<ul><li>High-Pressure or Temperature Applications: Where reliability is critical and parts must meet stringent specifications.</li><li>Maintenance and Repair: Great for quick fixes or replacements, especially when you need to minimize downtime.</li><li>OEM &amp; Equipment Assembly: Ensures uniform parts in manufacturing lines.</li></ul>&nbsp;<h2>Hex Head Cap Screws (Bolts)</h2>&nbsp;What They Are One of the most recognizable fasteners, hex head cap screws—often just referred to as “bolts”—feature a six-sided (hex) head and external threading. These are designed to be used with either a nut or a tapped (threaded) hole.&nbsp;Key Advantages<ul><li>Ease of Use: Standard hex heads allow for straightforward tightening with wrenches or sockets.</li><li>Variety: Available in a wide range of lengths, diameters, and materials (e.g., steel, stainless steel, alloy).</li><li>Versatility: Used everywhere from machinery and automobiles to construction and home improvements.</li></ul>Typical Uses<ul><li>Machine Assembly: Joining parts in industrial equipment, engines, and consumer products.</li><li>Structural Bolting: In construction beams or anywhere a secure, load-bearing connection is needed.</li><li>General Maintenance: The go-to fastener for nearly any repair task requiring robust clamping force.</li></ul>&nbsp;<h2>Socket Head Screws</h2>&nbsp;What They Are Socket head screws have a recessed socket drive (commonly a hex or Allen drive) rather than an external head. They can come in various head styles—such as button head, flat head, or standard socket head cap screws—making them popular for tighter spaces or flush installations.&nbsp;Key Advantages<ul><li>Compact Head: The recessed drive allows a cleaner, more streamlined profile.</li><li>Torque Control: A hex or Allen key offers excellent control for torque, reducing the risk of overtightening.</li><li>Aesthetic Appeal: Often seen in applications where a sleek, minimal protrusion is desired.</li></ul>Typical Uses<ul><li>Machine Tooling: Widely used in precision equipment, jigs, and fixtures due to their compact design.</li><li>Automotive and Motorcycle Mods: Enthusiasts often prefer socket head screws for aesthetic and practical reasons.</li><li>Electronics and Robotics: Great for tight spaces where a traditional wrench can’t fit.</li></ul>&nbsp;<h2>Material Considerations</h2>Regardless of which fastener type you choose, material selection is just as critical. Common materials include:&nbsp;<ul><li>Carbon Steel: Affordable and suitable for many general-purpose applications.</li><li>Alloy Steel: Provides higher strength and better heat resistance.</li><li>Stainless Steel: Excellent corrosion resistance, ideal for applications exposed to moisture or chemicals.</li><li>Exotic Alloys (Inconel, Monel, Titanium): Used in extreme conditions like high temperatures, high pressure, or corrosive environments.</li></ul>&nbsp;<h2>Picking the Right Fastener for Your Needs</h2><ol><li>Determine the Load Requirements: Understanding the forces (tensile, shear, vibration, etc.) involved is the first step.</li><li>Evaluate the Environment: Factors like temperature range, exposure to chemicals, and moisture levels will guide your material choice.</li><li>Review Standards and Specifications: Industries such as petrochemical, power generation, and construction often mandate compliance with standards like ASTM or ASME.</li><li>Consult an Expert: If you’re unsure, reach out to a specialty fastener distributor who can guide you to the correct product.</li></ol>&nbsp;Final ThoughtsFrom threaded studs and rods to hex head bolts and socket screws, each type of fastener has a specific purpose and set of advantages. Understanding the basics will help you select the right fastener for the job—keeping your projects safer, stronger, and compliant with industry requirements.Looking for a reliable source of industrial fasteners? We’re here to help guide you through choosing the perfect studs, rods, or bolts to meet your exact specifications. Contact us today to learn more about our full range of high-performance fasteners and how we can support your next project!

Understanding the Basics of Fasteners: Threaded Studs, Rods, Screws, Bolts, and More

Leveraging our network of external service providers, vetted through decades of business relationship building, we have access to a variety of trusted customization capabilities:&nbsp;Fasteners Cut-to-Length to Meet Your Specific Application RequirementsThis includes cutting threaded studs, threaded rod, and bolts to your specific length requirements. Commonly, our customers have specific length requirements for threaded stud assemblies that are not readily available as off-the-shelf products. Let us know your specific needs, and we'll work with you to ensure you have a rapidly deployed solution.&nbsp;GrindingGrinding removes excess material from fasteners after they've been cut-to-length. Additionally, this process creates a smooth finish and can shape parts to precise size and tolerances. During grinding, small pieces are shaved off until the right thickness or angle is reached. The grinding process removes rough spots or edges to ensure there are no issues when your team is in the field installing our fasteners. Different types of grinding exist, such as surface grinding or cylindrical grinding, each designed for a certain shape or purpose. Although it can be slower than other methods, grinding delivers high accuracy and a polished look.&nbsp;ChamferingChamfering is the process of cutting or filing off a sharp corner to make a slanted edge. This prevents cuts or scrapes and helps parts fit together more smoothly. Many industries use chamfering on metal, plastic, or wood. For example, machines may bevel bolt ends or trim corners on metal plates. The size of the chamfer depends on the product’s needs. A small chamfer just takes off the edge, while a larger bevel might be used for a tight fit in assembly. Chamfering improves safety, makes parts easier to handle, and helps them line up during installation.&nbsp;PlatingPlating adds a thin layer of metal on top of another metal surface. A common way is dipping the part in a liquid bath with metal particles. Then an electric current helps those particles stick to the part. Plating can protect the part from rust, make it stronger, or give it a shiny look. Different metals, like zinc or nickel, are used based on the job. For example, zinc plating fights corrosion, while nickel plating adds hardness.&nbsp;&nbsp;CoatingCoating covers a material (often metal) with paint, powder, or another protective layer. This shields the surface from moisture, chemicals, and wear. Many coatings also add color or a smooth finish. Factories might spray the coating on, dip the parts, or use special equipment that heats powder onto the surface. Good surface prep is important so the coating sticks well. Coatings can be as simple as paint or as complex as PTFE.

Fastener Customization Capabilities via Trusted External Service Providers

Our Fastener Customization Capabilities

<a target="_blank" rel="noopener noreferrer" href="https://www.kglilly.com/category/fasteners/threaded-studs-rods/astm-a193-threaded-studs-rods/astm-a193-grade-b7-threaded-studs">ASTM A193 B7</a> alloy steel is commonly used in high pressure, high temperature environments because it undergoes heat treatment during manufacturing. It can withstand service temperatures up to 750 degrees F. It maintains a minimum tensile strength of 125 ksi and a minimum yield strength of 105 ksi.Where <a target="_blank" rel="noopener noreferrer" href="https://www.kglilly.com/category/fasteners/threaded-studs-rods/astm-a193-threaded-studs-rods/astm-a193-grade-b7-threaded-studs">A193 B7</a> is a chromium-molybdenum alloy, <a target="_blank" rel="noopener noreferrer" href="https://www.kglilly.com/category/fasteners/threaded-studs-rods/astm-a193-threaded-studs-rods/astm-a193-grade-b16-threaded-studs">A193 B16</a> adds an element: chromium-molybdenum-vanadium.<a target="_blank" rel="noopener noreferrer" href="https://www.kglilly.com/category/fasteners/threaded-studs-rods/astm-a193-threaded-studs-rods/astm-a193-grade-b16-threaded-studs">A193 B16</a> has similar mechanical properties to its little brother A193 B7 (minimum tensile strength of 125 ksi and a minimum yield strength of 105 ksi). However, the addition of vanadium enables A193 B16 to withstand higher service temperatures: up to 1000 degrees F.Both grades are available in <a target="_blank" rel="noopener noreferrer" href="https://www.kglilly.com/category/fasteners/threaded-studs-rods/astm-a193-threaded-studs-rods">stud bolts</a> and hex bolts. They are marked “B7” or “B16” respectively, but B16 studs are also painted fluorescent green at the tips.Both grades are most often used uncoated. These grades are meant for use in high pressure and high temperature environments, but not in corrosive environments. Upon request, they can be zinc plated to add some corrosion resistance, but it is important to consider Appendix X2 of the ASTM A193 specification. Zinc has a melting point of 780 degrees F. At any field temperatures more than approximately half of that melting point – so at 390 degrees F – there is an increased risk of embrittlement. That is to say, because the coating will begin to behave differently at 390 degrees F, the entire assembly is at higher risk of embrittlement significantly before the maximum temperature of 750 degrees F when used plain, without a coating.These stud bolts and hex bolts can be coated with PTFE, but are not for use at high temperatures, so while you will frequently see PTFE coated B7, it is generally not used on B16 since B16 is used in higher temperature environments.

A193 B7 vs A193 B16

ASTM A193 B7 vs ASTM A193 B16

Grade 8 screws are equivalent to metric grade 10.9. Alloy steel socket head screws (ASTM A574) are stronger than grade 8 screws and are equivalent to metric grade 12.9.Alloy steel is the most common grade in socket head cap screws. These socket heads are also commonly manufactured with a 3A thread fit – tighter and more precise than the 2A fit on most grade 5 or grade 8 fasteners. They are often used in blind holes in precisely machined equipment. Where grade 8’s might be removed as part of regular maintenance, socket heads are meant to resist loosening and hold strength for a longer maintenance cycle – often the entire lifecycle of the equipment.

Grade 8 Fasteners vs Alloy Steel - Is there a difference?

Grade 8 Fasteners vs Alloy Steel

There are various stainless steel alloys used in fasteners, but the most common are 304 and 316.&nbsp;The main alloying element in stainless steel is chromium. In fact, to be considered a true stainless steel, an alloy must contain a minimum of 10.5% chromium as it is the primary factor in what makes stainless “stain less.”&nbsp;304 stainless steel has approximately 18% chromium. It is often called “18-8” because it contains 18% chromium and 8% nickel (approximately).316 stainless steel has about the same amount of chromium as 304 but adds more nickel and more molybdenum, increasing its overall corrosion resistance.&nbsp;Both 304 and 316 are in the category of stainless known as Austenitic which refers to the molecular structure. Stainlesses in this series (300 series) are high in chromium and nickel. Contrast that with 400 series stainless steels which are known as Martensitic and have a higher proportion of carbon. With their higher carbon content, 400 series stainless steels tend to be stronger, harder, and less ductile than 300 series stainless steels.&nbsp;

304 Stainless vs 316 Stainless Bolts, Screw, and Nuts - How Do They Differ?

304 Stainless vs 316 Stainless (A2 vs A4)

304 Stainless vs 316 Stainless (A2 vs A4) - How Do They Differ?

Both coatings are zinc, an element that corrodes much slower than plain steel. The primary difference is that zinc plating is a thin coat (under 1 mil) and galvanizing is a thicker coat (over 1 mil). Zinc is also shinier, as it is often paired with a chromate additive.&nbsp;Zinc plating is applied most often via an electrical bath. Galvanizing on the other hand is done most often by dipping it in a bath of zinc.This bath is what gives galvanized material a thicker coating, and it is because of this extra thickness that galvanized parts must be used with one another – the threads are cut to accommodate extra layers of coating. Without that accommodation in thread size, the coating would make the part unable to mate with other, non coated parts.Galvanized fasteners are more corrosion resistant than zinc plated fasteners. The galvanized coating is thicker and is considered “self healing.” When it is damaged or scratched it is able to fill itself in, protecting the underlying steel. This is not the case for zinc plating. Once a zinc plating is scratched the steel beneath is exposed.

Zinc Plated Fasteners vs Hot Dipped Galvanized Fasteners

Zinc Plated vs Hot Dipped Galvanized Fasteners

SAE grades 5 and 8 are equivalent to metric classes 8.8 and 10.9, respectively. Grade 5 and metric class 8.8 have approximately equivalent tensile strengths, and the same is true between Grade 8 and class 10.9.<figure class="table"><table><tbody><tr><td>Strength</td><td>Grade&nbsp;</td><td>Tensile strength minimum</td><td>Head marking</td></tr><tr><td>Medium</td><td>Metric Class 8.8</td><td>800 MPa (116 ksi)</td><td>8.8</td></tr><tr><td>Medium</td><td>SAE Grade 5</td><td>120 ksi</td><td>3 radial lines</td></tr><tr><td>High</td><td>Metric Class 10.9</td><td>1040 MPa (150 ksi)</td><td>10.9</td></tr><tr><td>High</td><td>SAE Grade 8</td><td>150 ksi</td><td>6 radial lines</td></tr></tbody></table></figure>&nbsp;It may be tempting to think of metric class 8.8 as the equivalent to the SAE grade 8. That is not the case! The metric naming system is derived from the performance of the bolts. The naming system of SAE grades is arbitrary, counting up from 1. Higher means stronger in both systems, but the similarities end there. A fun (and useful) fact about the metric convention is in what follows the decimal in the class. That is, the .8 in class 8.8 and the .9 in class 10.9. The number before the decimal corresponds to the tensile strength, and the decimal value after corresponds to the yield strength, expressed as a percentage of tensile strength. To illustrate:<figure class="table"><table><tbody><tr><td>Strength</td><td>Grade&nbsp;</td><td>Tensile strength min (MPa)</td><td>Yield strength (% of tensile)</td><td>Yield strength (MPa)</td></tr><tr><td>Medium</td><td>Metric Class 8.8</td><td>800 MPa</td><td>80% (or 0.8)&nbsp;à</td><td>640 MPa</td></tr><tr><td>High</td><td>Metric Class 10.9</td><td>1040 MPa</td><td>90% (or 0.9)&nbsp;à</td><td>940 MPa</td></tr></tbody></table></figure>&nbsp;Tensile strength is the point at which a bolt breaks. It’s yield comes before that. The yield is the point at which the bolt is deformed past the point that it can return to shape. Keep in mind that bolts will “stretch” while in service, but they will “bounce” back to size after each stretch, like a spring. However, at a certain point, they will get stretched too far. They will get deformed past the point of return. That is the yield point. Between the yield point and the tensile point, the bolt with elongate. It will behave like taffy or mozzarella cheese until it breaks away from its other half. Higher grades are typically harder and more brittle than lower grades. They will not experience very much “stretch” before breaking. We might think of lower grades as being weaker but also “stretchier” – after beginning to yield, they experience greater elongation than the higher strength grades before breaking.&nbsp;Is there any benefit to getting a weaker grade bolt for its “stretchiness”? After all, the ability of a bolt to stretch and reform is part of what makes it an effective fastener. In general, no. A properly manufactured high strength bolt maybe be more brittle than its weaker counterpart but the weaker bolt (at least in the case of grade 5 and 8) will both yield AND break before the stronger bolt has begun to yield.Both grade 5 and grade 8 are available in plain steel and zinc plated steel. The zinc plating for grade 5 is almost always clear and the plating for grade 8 is almost always yellow. They are not functionally different – the color just helps distinguish them from each other. They can also be distinguished by the head markings (three radial lines for grade 5 and six radial dashes for grade 8).&nbsp;

Fastener Grades 5 vs 8 vs 8.8 vs 10.9

Grade 5 vs Grade 8 vs Class 8.8 vs Class 10.9

The Purchaser's Definitive Guide to ASTM A193 Grade B7 Threaded Studs and Rods

Guide to ASTM A193 Grade B7 Threaded Studs and Rods

Choosing the correct stud bolts for industrial applications, especially those involving extreme temperatures, is paramount for operational integrity and safety. ASTM A193 Grade B7 and ASTM A320 Grade L7 are two common, yet critically different, fastener specifications. This guide from KG Lilly Fasteners, leveraging over 60 years of expertise, delves into the nuances of B7 and L7 stud bolts, clarifying their properties, applications, and the vital testing that differentiates them, empowering purchasers and installers to make informed decisions and prevent costly failures.<h2>Introduction: The Critical Choice in Extreme Temperature Fastening</h2>In the demanding environments of petrochemical plants, power generation facilities, and cryogenic processing units, the reliability of every component is crucial. Fasteners, though small, play a meaningful role in maintaining structural integrity and preventing catastrophic failures. ASTM A193 Grade B7 and ASTM A320 Grade L7 stud bolts are frequently encountered in these environments. While both are high-strength alloy steel fasteners, their suitability for varying temperature extremes is distinctly different. Misapplication can lead to compromised safety, and regulatory non-compliance.&nbsp;This comprehensive guide, brought to you by KG Lilly Fasteners, a trusted name in fastener solutions since 1964, aims to highlight differences between B7 and L7 stud bolts. We will explore their material properties, intended service conditions, and crucial testing requirements, providing the clarity needed for confident selection in your critical industrial applications.<h2>Understanding ASTM A193 Grade B7: The High-Temperature Workhorse</h2>ASTM A193 Grade B7 stud bolts are a mainstay in various industrial settings, selected for their high tensile strength and reliable performance in elevated temperature and high-pressure services.&nbsp;<ul><li>Material Composition: B7 studs are typically manufactured from AISI 4140 or 4142 medium carbon chromium-molybdenum (often called "chrome-moly") alloy steel. This material is quenched and tempered to achieve its desired mechanical properties.</li><li>Typical Applications: You'll find A193 B7 bolts in pressure vessels, valves, flanges, and fittings intended for high-temperature service. Industries such as oil and gas refining, petrochemical processing, and power generation extensively utilize B7 fasteners.</li><li>Key Mechanical Properties:<ul><li>Tensile Strength: For diameters up to 2.5 inches, B7 studs have a minimum tensile strength of 125 ksi (860 MPa).</li><li>Yield Strength: Minimum yield strength is 105 ksi (720 MPa) for sizes up to 2.5 inches.</li><li>Hardness: Typically ranges between 21 HRC to 35 HRC (Rockwell C).</li></ul></li><li>Temperature Range: A193 B7 bolts are primarily designed for applications ranging from ambient up to approximately 800°F (427°C). Their strength can decrease at higher temperatures, so specific application limits must be considered based on design codes like ASME. They are not suitable for sub-zero temperature applications where impact toughness is a primary concern.</li><li>Testing: Standard testing for B7 fasteners includes dimensional checks, chemical analysis, and mechanical property verification (tensile, yield, hardness). Importantly, Charpy impact testing is not a standard requirement for ASTM A193 B7.</li></ul><h2>Delving into ASTM A320 Grade L7: Engineered for Low-Temperature Resilience</h2>When applications involve sub-zero temperatures, the risk of brittle fracture in standard alloy steels increases significantly. ASTM A320 Grade L7 stud bolts are specifically engineered and tested to maintain their integrity in these challenging low-temperature and cryogenic environments.&nbsp;<ul><li>Material Composition: Like B7, L7 studs are also commonly made from AISI 4140/4142 chromium-molybdenum alloy steel. However, they undergo specific heat treatment processes to optimize their low-temperature toughness.</li><li>Critical Applications: A320 L7 fasteners are essential for cryogenic storage and transport, LNG (liquefied natural gas) facilities, refrigeration systems, and any industrial process operating at significantly low temperatures where impact strength is critical.</li><li>Key Mechanical Properties: At ambient temperatures, the tensile and yield strength requirements for L7 studs are similar to B7 (e.g., 125 ksi minimum tensile strength for diameters up to 2.5 inches). The defining characteristic is their proven toughness at low temperatures.</li><li>Temperature Range: ASTM A320 L7 bolts are designed for service at low temperatures, typically down to -150°F (-101°C). For even lower temperatures, other L-grade materials within the A320 specification (like L7M) might be considered.</li><li>Mandatory Charpy V-Notch Impact Testing: This is the crucial differentiator. ASTM A320 L7 mandates Charpy V-Notch impact testing at -150°F (-101°C) to ensure the material's ability to absorb energy and resist fracture in cold conditions. This test is vital for preventing brittle fracture, a catastrophic failure mode where the material breaks without significant prior plastic deformation. Each bar and, in some cases, each finished L7 stud must meet minimum impact energy absorption values.</li></ul><h2>Head-to-Head: Critical Differences Between B7 and L7 Fasteners</h2>Understanding the direct comparison points is key to selecting the correct stud bolt for your application.<figure class="table"><table><thead><tr><th>Feature</th><th>ASTM A193 Grade B7</th><th>ASTM A320 Grade L7</th></tr></thead><tbody><tr><td>Primary Application</td><td>High-temperature, high-pressure service</td><td>Low-temperature, cryogenic service</td></tr><tr><td>Governing Standard</td><td>ASTM A193/A193M</td><td>ASTM A320/A320M</td></tr><tr><td>Material (Typical)</td><td>AISI 4140/4142 Cr-Mo Steel</td><td>AISI 4140/4142 Cr-Mo Steel (with specific heat treatment/tempering requirements)</td></tr><tr><td>Temperature Range</td><td>Ambient up to ~800°F (427°C)</td><td>Down to -150°F (-101°C)</td></tr><tr><td>Impact Testing</td><td>Not required by standard</td><td>Mandatory Charpy V-Notch impact testing at -150°F (-101°C)</td></tr><tr><td>Key Differentiator</td><td>High-temperature strength</td><td>Low-temperature toughness &amp; impact resistance</td></tr><tr><td>Common Misconception</td><td>Suitable for all temperatures due to high strength</td><td>Interchangeable with B7 if strength seems similar at ambient</td></tr></tbody></table></figure>Why is Charpy Impact Testing so important for L7? Metals can behave differently at various temperatures. While a steel might be ductile and tough at room temperature, it can become brittle and fracture easily when exposed to cold conditions. The Charpy V-Notch test simulates this by striking a notched specimen with a weighted pendulum. The amount of energy absorbed by the specimen before it fractures is a measure of its toughness. For A320 L7, this test provides essential assurance against brittle fracture in its intended low-temperature service environments.<h2>Procurement and Compliance Essentials: Making the Right Choice with KG Lilly Fasteners</h2>Navigating fastener specifications involves more than just understanding technical properties; procurement and compliance are equally vital.&nbsp;<ul><li>Cost Considerations: Generally, ASTM A193 B7 stud bolts are more cost-effective than A320 L7. The additional heat treatment and mandatory Charpy impact testing for L7 contribute to its higher price point. Using L7 where B7 would suffice incurs unnecessary costs, while using B7 in low-temp applications is a severe safety risk.</li><li>Availability: B7 studs are widely available due to their broad range of applications. A320 L7 studs, being more specialized, might have longer lead times or require sourcing from specialized suppliers like KG Lilly Fasteners who understand the critical nature of these components.</li><li>Compatible Nuts and Washers:<ul><li>For A193 B7 studs, common compatible nuts are ASTM A194 Grade 2H.</li><li>For A320 L7 studs, compatible nuts like ASTM A194 Grade Grade 7/7L are typically specified. Crucially, these nuts must also be Charpy impact tested at the same temperature as the L7 studs to ensure the entire bolted joint assembly maintains its low-temperature toughness.</li></ul></li><li>Mill Test Reports (MTRs): The Cornerstone of Verification: An MTR (also known as a Material Test Certificate or Mill Cert) is a quality assurance document that certifies a material's chemical and physical properties. For both B7 and L7, the MTR may be essential for your procurement requirements.<ul><li>For B7: The MTR will confirm chemical composition and mechanical properties like tensile and yield strength.</li><li>For L7: The MTR is even more critical as it must explicitly state the results of the Charpy V-Notch impact tests, including the test temperature and absorbed energy values.</li></ul></li></ul>&nbsp;KG Lilly Fasteners can ensure that your B7 and L7 fastener purchase orders are accompanied by fully traceable MTRs when requested at the time of your order. Our Certified Fastener Specialists (CFS) can help you interpret these reports, as needed.<h2>Ensuring Integrity: The KG Lilly Advantage</h2>KG Lilly Fasteners has decades of experience supplying B7 and L7 studs to customers within various industries and applications, such as:&nbsp;<ul><li>Low Temp Environments in the Petrochemical Industry</li><li>Cryogenic Applications within LNG Terminals</li><li>High Pressure Steam Lines within Power Generation Plants</li><li>Refinery Maintenance Turnarounds</li></ul><h2>Key Takeaways: B7 vs. L7 at a Glance</h2><ul><li>ASTM A193 B7: For high-temperature, high-pressure service. Not impact tested for low temperatures.</li><li>ASTM A320 L7: For low-temperature service (down to -150°F / -101°C). Mandatory Charpy V-Notch impact testing is the defining feature, ensuring toughness and preventing brittle fracture.</li><li>Selection Criteria: Always base selection on the minimum design temperature of your application.</li><li>Compliance: For L7, verify Charpy impact test results. Ensure nuts are also rated for the service temperature.</li></ul><h2>Frequently Asked Questions (FAQ)</h2>Q1: What is the primary difference between ASTM A320 L7 and A193 B7 stud bolts?A1: The primary difference is their intended service temperature and impact testing requirements; A193 B7 bolts are for high-temperature applications and are not typically impact tested, while A320 L7 bolts are for low-temperature applications (down to -150°F) and require mandatory Charpy V-Notch impact testing to ensure toughness.Q2: What is the temperature range for ASTM A320 L7 bolts?A2: ASTM A320 L7 bolts are designed for low-temperature service, typically specified for use down to -150°F (-101°C).Q3: What are ASTM A193 B7 studs used for?A3: ASTM A193 B7 studs are commonly used in high-temperature and high-pressure applications such as pressure vessels, flanges, valves, and piping systems in industries like oil and gas, petrochemical, and power generation.Q4: Is ASTM A320 L7 more expensive than A193 B7?A4: Yes, ASTM A320 L7 stud bolts are generally more expensive than A193 B7 due to the additional specialized heat treatment and the mandatory Charpy V-Notch impact testing required to meet the L7 specification.Q5: What is the Charpy V-Notch test for L7 bolts?A5: The Charpy V-Notch test is a standardized high strain-rate test that determines the amount of energy absorbed by a material during fracture. For A320 L7 bolts, this test is performed at -150°F (-101°C) on notched specimens to ensure the material retains sufficient toughness to prevent brittle fracture at low service temperatures.Q6: How do the mechanical properties of B7 and L7 compare at ambient temperature?A6: At ambient temperatures, the minimum tensile and yield strength requirements for ASTM A193 B7 and ASTM A320 L7 are very similar for comparable sizes. The critical distinction in mechanical properties arises at their respective intended service temperatures, particularly L7's proven impact toughness at low temperatures.<h2>Conclusion: Partnering for Fastener Excellence</h2>The choice between ASTM A193 B7 and A320 L7 stud bolts is critical for the safety, compliance, and efficiency of your industrial operations. Understanding their distinct properties, particularly the low-temperature toughness and mandatory impact testing of L7, is non-negotiable.&nbsp;At KG Lilly Fasteners, we are more than just suppliers; we are your partners in fastener excellence. Our deep expertise, commitment to quality (our quality management system is certified by Intertek to meet the requirements of ISO9001:2015), and experienced Certified Fastener Specialists are at your disposal to help you in your procurement journey.

learn about fasteners

Recent Blogs