Table of Contents
What are Fasteners
A mechanical fastener is a device that is used to mechanically join (or fasten or affixes) two or more objects together.Â
In general, fasteners are used to create non-permanent joints; that is, joints that can be removed or dismantled without damaging the joining components.
Attempt Questions on Fasteners
1. What is a mechanical fastener used for?
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Explanation: A mechanical fastener is used to temporarily join two objects, allowing them to be removed or dismantled without damaging the joining components.
2. What components are used along with a bolt to fasten objects?
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Explanation: Bolts are used along with washers and nuts to fasten objects securely. The bolt holds the objects together, while the washer and nut fasten from the other end to hold it firmly.
3. What distinguishes a bolt from other types of fasteners?
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Explanation: A bolt is distinguished by having a head on one end and threads on the other end, allowing it to be fastened with a nut and washer.
What are Bolts
Bolts are mechanical fasteners used for the assembly of two non threaded components, with the aid of washer and nut.
A bolt has a head on one end and threads on the other end.
When the objects are fastened, the bolt holds the objects together, and washer and nut fasten from the other end that holds it firmly.
Attempt Questions on Fasterners Facts
1. What force does the nut apply in a bolted joint?
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Explanation: The nut applies an axial clamping force in a bolted joint.
2. What happens if the non-threaded grip length is too long?
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Explanation: An overly long non-threaded grip length prevents the nut from being tightened down correctly.
3. Why should the non-threaded grip length be around the same length as the thickness of the material?
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Explanation: The non-threaded grip length should be around the same length as the thickness of the material to ensure proper tightening and to prevent the threads from extending into the hole, which could cause wear and improper load distribution.
Interesting Facts about Fasteners
- Bolted joint is a combination of the nut applying an axial clamping force and the plain non threaded length (known as shrank) of the bolt pinning the joint against sideways shear forces.
- The non threaded grip length should be chosen carefully, to be around the same length as the thickness of the material and washers through which the bolt passes.
- An overly long non threaded length prevents the nut from being tightened down correctly.
- An insufficient non threaded length results in the threads extending into the hole, and places the shear load onto the threads, which may cause wear on the hole.
- No more than two turns of the thread should be within the hole.
FAQs on Fasterners
What are the common types of fasteners used in process piping?
- Common types include bolts, nuts, washers, and studs. Bolts can be hex head, socket head, or flange bolts, while nuts can be hex, lock, or flange nuts.
How do you select the appropriate material for bolts and fasteners in process piping?
- Material selection depends on factors such as the type of fluid, temperature, pressure, and environmental conditions. Common materials include carbon steel, stainless steel, and alloy steels.
What standards govern the use of fasteners and bolts in process piping?
- Standards such as ASTM, ASME, and ISO provide guidelines on dimensions, material properties, and testing procedures for fasteners and bolts.
What is the significance of bolt torque in process piping?
- Proper bolt torque ensures a leak-free connection by providing adequate clamping force. Over-tightening or under-tightening can lead to joint failure or leakage.
How do you determine the correct bolt length for flanged connections?
- Bolt length is determined by the flange thickness, gasket thickness, and the type of nuts and washers used. Generally, the bolt should extend through the nut by at least one to two threads.
What is the difference between a stud bolt and a machine bolt?
- A stud bolt is a threaded rod with no head, used with two nuts on either end, while a machine bolt has a head and is threaded on one end, used with a single nut.
Why are washers used in bolted connections in process piping?
- Washers distribute the load of the bolt, prevent damage to the flange surface, and reduce the risk of loosening due to vibration.
How do you ensure the integrity of bolted joints in high-temperature applications?
- Use high-temperature fasteners made from appropriate materials (e.g., Inconel, Hastelloy) and apply correct torque values. Periodic inspection and re-tightening may also be necessary.
What is the role of bolt tensioning in process piping?
- Bolt tensioning ensures uniform load distribution across the joint, minimizing the risk of leaks and joint failure. Hydraulic or mechanical tensioners are often used for this purpose.
How do you prevent galling in stainless steel bolts?
- To prevent galling, use anti-seize lubricants, select the correct grade of stainless steel, avoid over-tightening, and consider using coated or plated fasteners.
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