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What is a Basis of Design or BOD? How to Write a Basis of Design for a Project?

Written by Anup Kumar Dey in Piping Design Basics,Process

The Basis of Design (BOD) is a very important document for every project. The basis of design or project design basis provides all the principles, business expectations, criteria, considerations, rationale, special requirements, and assumptions used for decisions and calculations required during the design stage. So, a basis of design is a project baseline and overview to kickstart the project activities.

The BOD is prepared by the Engineer or Designer with inputs from all departments. For oil and gas projects, the basis of design is usually prepared by process engineers. In this article, we will explore more about the Basis of Design, its purposes, writing methodology, responsibilities, etc.

What is a Basis of Design Document?

The Basis of Design document describes the technical approach planned for the project. Preliminary project technical details are incorporated in this essential document. The BOD is prepared during the pre-design stage and it serves as the basis for all the design calculations and other design decisions. Note that, BOD is not a substitute for code and standard guidelines or project design drawings. But a BOD simply includes the list of individual items to support the design work process based on the owner’s project requirements.

Even though the basis of design starts at the pre-design phase, the document is dynamic in nature. As the design work progresses, the basis of the design document is updated to include a specific description of the system and components, its function, how it relates to other systems, sequences of operation, and operating control parameters. However, BOD does not include detailed project information or calculations.

Purpose of Basis of Design Document

The basis of design for any project serves several important purposes like

  • It documents the major process and assumptions behind specific decisions.
  • A BOD concisely captures the owner’s requirements and vision into technical terms and design parameters.
  • For the commissioning team, BOD is a very important document to evaluate the ability of a design.
  • The BOD provides a listing of all major design decisions.
  • This is the document that provides a technical document providing the thought process of design professionals for developing the plant.
  • A project basis of design helps in calculating the life cycle cost analysis.

Responsibilities of the Basis of Design Document

As already stated earlier that the designers and engineers are responsible for creating and managing this document. They ensure that the document is complete in all respect. However, the client and commissioning manager review the document and approve it. Creating a quality Basis of Design for the project’s success by improving the communication and collaboration between the design consultant and client.

How to Write a Basis of Design (BOD)?

Writing a basis of design specification starts with the owner’s project requirement document. A lot of required data will be obtained from that document to start writing the BOD. In the following section, I will list the important parameters that are usually added to the basis of design for oil and gas projects. This will serve as a typical basis for design engineering examples.

Contents of a Basis of Design Oil and Gas Project:

Oil and gas projects typically include the following information on the basis of design documents.

  • Project background: This section includes a briefing of the project.
  • Document purpose: This section lists the requirement of this document.
  • Project Interface
  • Project Scope: This section includes the overall scope of the project in detail. A Separate scope of each discipline involved in that project is briefed. For example, a typical oil and gas basis of a design document may include the scopes or process team, piping team, pipeline teal, civil team, control and automation team, electrical team, etc.
  • Design basis: This section lists all the design information or assumptions for each discipline. Separate sub-modules of individual disciplines are prepared as process design basis, piping design basis, pipeline design basis, civil design basis, electrical design basis, C&A design basis, etc.
  • Design Philosophy: In this section, the following sub-modules (as applicable in that specific project) are included.
    • Operating, Control & Safeguarding Philosophy
    • Sparing & Maintenance Philosophy
    • Metering Philosophy
    • Sampling Philosophy
    • Design Philosophy Based on H2S content
  • Technical Assurance Review: This section ensures the safety and quality of the project by performing various quality reviews like Design review, HAZOP study, SIF, Alarm rationalization review, etc.
  • Design Criteria: In this section of the project design basis, various calculation basis is provided. For example,
  • Codes and Standards: In this section of the basis of the design document, all the relevant codes and standards are listed along with their editions.
  • Government Laws and regulations, if applicable
  • Process specification of Technology provider, if applicable
  • References and Appendices: This is the final section of the design basis. Here, all the references and appendices are attached to substantiate the above-mentioned decisions.

The above-mentioned points are the minimum required information to be produced in any basis of design document for oil and gas projects. The complete depth and information list will vary from project to project.

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Factory Acceptance Test– What Is FAT, and How Does It Work?

Written by Anup Kumar Dey in Construction,Inspection and Testing,Piping Interface

When a piece of new equipment is manufactured, it has the potential for countless errors. With an increase in the machine’s complexity, the error potential also increases. It is, therefore, required to test the equipment to find out if the equipment is working as needed without errors. This test is known as the factory acceptance test which is popular by its acronym “FAT”. In this article, we will explore more about FAT, its definition, purpose, steps, examples, checklist, and differences with the site acceptance tests (SAT).

What Is Factory Acceptance Testing or FAT?

Factory Acceptance Testing (FAT) is a test performed for newly manufactured and packaged equipment by the vendor prior to shipping to ensure the equipment meets its intended purpose. This optional test is performed once the design and fabrication of the equipment are complete following approved test plans as agreed with the client. The FAT ensures that the equipment meets all the client requirements as mentioned in the purchase order specifications.

Purpose of a Factory Acceptance Test

The factory Acceptance testing or FAT guarantees that the equipment is complying with all the requirements and are ready to be commissioned without any problem. This test is performed at the factory and is beneficial for both the end users and the manufacturer. Any functional issues are identified before the equipment leaves the factory premise and can easily be rectified by the manufacturer. Thus FAT helps in controlling the project timeline and cost.

Even though, FAT is optional, it must not be skipped. If any problem is found after the equipment is installed, it may result in costly shutdowns. So, a factory acceptance test provides a number of other benefits like:

  • Accessibility requirements for operation and maintenance are checked.
  • The location of tie-in connection points is ensured at the proper location.
  • Electrical connections are checked.
  • Equipment-related documentation is verified.
  • Equipment complying with the project-related drawings and specifications is ensured.
  • Hands-on training for the equipment operation can be taken from the manufacturer who knows all the nitty-gritty of the equipment.
  • Meeting the design, engineering, and fabrication team in person

Difference between a Factory Acceptance Test and a Site Acceptance Test

A Factory Acceptance Test is performed before the equipment is delivered. On the other hand, A Site Acceptance Test or SAT is conducted once the equipment is installed at the site. So, SAT is performed after FAT along with all interfaces and peripherals in the working environment of the equipment. The major differences between a Factory acceptance test and a Site acceptance test are provided in Table 1 below:

Factory Acceptance testSite Acceptance Test
The factory Acceptance test is performed at the factory workshop.The site acceptance test is performed at the construction site.
A factory Acceptance test is performed before the equipment is shipped from the manufacturer.A site acceptance test is performed once the equipment is installed at the site.
The duration of FAT is short.SAT is usually longer.
Testing in factory acceptance test is done only to check the equipment.The site acceptance test is done with all interfaces connected. So, it ensures the actual working in the site conditions.
As the factory acceptance test is performed inside the manufacturing facility, the environment is not extreme. The site environment during the test may be totally different from the FAT environment.
Detailed documentation is prepared for the factory acceptance test.The documentation is not much detailed in the case of the site acceptance test.
Table 1: Factory acceptance test vs Site acceptance test

Steps for Factory Acceptance Test

Factory acceptance testing is usually performed following the below-mentioned steps:

Planning for the FAT:

The first step is the proper planning for the FAT. All details mentioned in the customer’s order specification should be studied thoroughly. All applicable standards and drawings need to be checked to find out the FAT scope. All related reference documents must be kept ready. Some such documents are:

  • Customer scope and specifications.
  • Applicable Codes / References.
  • Relevant drawings like GA, P&ID, etc.
  • Equipment or component datasheets.
  • ITP (Inspection Test Plan).
  • FAT Checklists and Procedures.
  • Calibrations and Certifications as required by contract.

Testing:

During the factory acceptance testing, various parameters are inspected and ensured. Usually, the following things are addressed during a FAT:

  • Comprehensive inspection: In this stage, a range of conformity checking and verifications are performed. Any job-specific requirements as stated in the customer specifications are also ensured.
  • Contract Audit: To ascertain that all contractual obligations are taken care of.
  • Raw data is taken, recorded, and submitted to the customer to prove the functionality.
  • Along with the customer representative, various drawings like GA, P&ID, and electrical drawings are reviewed to verify their correctness.
  • NDE, Coating, Transportation, or Storage Procedures are reviewed.

Factory Acceptance Test Result

All the findings from the test are documented. If there is any deviation found during the FAT from the expected working condition the same is studied and corrected. The reason for the deviation and what corrective actions are taken are also documented. If there is any deviation from the client’s requirements the same is also documented and informed to the client for their approval. Once all the modifications are corrected, the equipment is retested to find compliance with the requirements.

Who should participate in the FAT?

As the factory acceptance test is performed at the manufacturer’s workshop, all the key engineers should participate in the testing. Sometimes, the client is also invited for taking part in the test. There could be a requirement of 3rd party approval for the test. So, overall the following professionals should participate in the FAT:

  • Manufacturer engineers and managers.
  • Client representatives (Plant engineers, maintenance personnel, etc).
  • 3rd party inspectors.

Having more participants during testing increases efficiency. Also, in case of any problem, the same can be discussed mutually to arrive at a quick resolution.

Who is responsible for the Factory Acceptance Test?

Performing a factory acceptance test is the responsibility of the equipment manufacturer. However, the requirement of FAT shall be specified in the scope document. Once the factory acceptance test is included in the project scope, there is no extra cost for the test.

Factory Acceptance Test Checklist

A factory acceptance test checklist is an important tool to ensure that all important components are inspected during the FAT. A factory acceptance test checklist reduces costly project delays by ensuring all details are taken care of during the FAT. Even though the actual FAT checklist varies from equipment to equipment, in general, the following check-points are included:

  • Scope of the FAT indicating the specific tests required.
  • Applicable codes and standards: These ensure that the exact code and standard requirements are followed for the FAT.
  • Reference documents: It verifies if all the relevant documents are available and referred to.
  • Testing equipment: Additional instruments like gauges, speedometers, etc are available during the test.
  • P&ID and GAD: To verify the design and installation are as per the P&ID and GAD requirements. P&ID also ensures that the Tie-ins and interfaces are as per the requirement.
  • Equipment nameplate
  • Pressure test requirements
  • Drain connections, type, size, and location.
  • Material of Construction verified.
  • Vacuum test requirements if any
  • Component functional tests
  • Controls verified.
  • Welding verified.
  • Overall dimension verified.
  • Documentation
  • Deviations if any
  • Punch list if any
  • Corrective actions are performed.

Factory Acceptance Test Examples

All critical and complex equipment and components must be checked at the manufacturer’s premises and a factory acceptance test shall be performed. Factory acceptance tests are normally performed for equipment that will severely impact the schedule, installation, and handover in case there is any problem with the equipment. The requirement of FAT is dependent on the owner. Some examples of common equipment that undergo FAT are:

  • Compressors
  • Reactors
  • Pressure vessels
  • Pumps
  • Calibrated Pressure Gauges and Chart recorders
  • Turbines and Generators
  • Critical Valves
  • Hand tools
  • Voltmeter, Ohmmeter, etc

Duration of Factory Acceptance Test

The factory acceptance test duration varies based on the type of plant and equipment. In general, each FAT can range from a few hours to 3 days.

Common Factory Acceptance Test issues

The common issues that are found during a factory acceptance test are:

  • Poor quality of equipment or component parts.
  • Technical details are not followed 100%.
  • Changes in MOC.
  • Deviations from Standards or drawings.
  • Missing tag numbers for identification.

All such issues are usually discussed with the client and mutually resolved.

What is a Monorail Crane? Its Types, Components, Specifications, Advantages, and Applications

Written by Anup Kumar Dey in Construction,Maintenance,Mechanical

What is a Monorail Crane?

A monorail crane is a common type of overhead crane consisting of a single beam with a hoist. As a substitute for conventional cranes and conveyor belts, Monorail cranes are widely used in applications requiring repetitive material or product movement from one point to another within a restricted area. Running on a single stationary beam, monorail cranes are quite simple in design and highly cost-effective. Monorail cranes are popularly known as monorails.

Monorail cranes use a trolley that carries a hoist. The trolley is connected with a beam into the ceiling structure to run along a flat surface. Overhead Monorail cranes provide movements along two axes. Up and down movement via the hoist and forward and backward movement via the monorail beam. Monorail beams are mostly subjected to gravity loads and are used both indoors and outdoors.

Applications of Overhead Monorail Cranes

Monorail overhead cranes are used in a variety of industries including:

  • Construction
  • Automotive
  • Oil and gas
  • Chemicals
  • Aircraft
  • Food and beverage
  • Metal processing
  • Machinery and equipment
  • Waste management
  • Injection molding
  • Pulp and paper
  • Wood and wood products
  • Ships and boats
  • Rubber and plastics
  • Warehouse loading docks

Types of Monorail Cranes

Monorail cranes can be classified depending on the various parameters provided below:

Based on the operating systems there are two types of monorail overhead cranes. They are:

  • Manually operated monorail cranes and
  • Electrically operated automated monorail cranes.

Depending on the travel path of the monorail cranes they are of two types:

  • Monorail cranes running on a straight path.
  • Monorail cranes running on a curved path.

Monorail System Components

A monorail system consists of the following parts:

  • Monorail beam
  • Hoist
  • Trolley and
  • Festoon

The hoist and trolley travel on the monorail beam, which is a single stationary beam supported by the ceiling or floor-mounted frame. Monorails are configured as underhung systems.

The trolley of the monorail system is usually a four-wheel type (eight-wheels for heavier loads) that travels on the bottom flange of the monorail beam. They can be equipped with pendant control electric lift and travel. Adjustable speed-type motor controller drive provides better flexibility.

Refer to Fig. 1 below which shows all the components.

Components of a Monorail System
Fig. 1: Components of a Monorail System

Characteristic Features of Monorail Systems

  • Monorail structures are usually made of Steel or Aluminum.
  • In constricted workflow areas, the use of monorails is ideal.
  • The capacity of monorails varies from manufacturer to manufacturer. For higher loads, steel structures are used. In general, they can carry a load of up to 4000 lbs.
  • Monorails are easy to install, move, and dismantle.
  • They have a long life.

Advantages of Monorail Cranes

Employing an overhead monorail crane in any facility provides a number of benefits. Some of the advantages of monorail cranes are:

  • Simple flexible operation.
  • Effortless load control in an efficient manner.
  • Monorail cranes being installed overhead, are above most obstacles during operation.
  • Safe and reliable functionality.
  • Low maintenance costs.
  • Monorail cranes can be easily customized as per the requirements of the product or material handling.
  • Easy control using automated systems from a single location.
  • Reduced labor expenses.

Specification of Monorail Hoists

Even though the actual specification of monorail hoists varies from organization to organization, in general, the following details should be mentioned:

  • Design code
  • Lifting capacity
  • Height of the lift
  • Travel length
  • Trolley type
  • Hoist type
  • Suspension type
  • Application description
  • Motion speed required
  • Wheels type
  • Motor details and types
  • Gear and Bearing details
  • Hook types and details
  • Power supply
  • Brake
  • Control panel
  • Document and Drawing requirements etc.

Codes and standards for Monorail crane systems

The following codes and standards provide guidelines for the design of monorail systems or components:

  • ASME B30.17
  • ASME B30.11
  • ASME B30.10
  • ASME B30.16
  • ASME HST-4
  • HMI
  • AS 1418.18

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What is a Pipe Sleeve? Its Functions, Materials, and Uses

Written by Anup Kumar Dey in Civil,Piping Design Basics

A pipe sleeve is a higher-size pipe section to protect the inner pipe from higher loads or to provide free movement in a certain direction. Through these pipe sleeves, the lower-size pipes or cables can easily run. In the process and power piping industry, there are many instances where pipe sleeves are used. In this article, we will learn the common applications of pipe sleeves in the piping and pipeline industry.

What is a Pipe Sleeve?

As already stated, a pipe sleeve is a protective cover to safeguard the original pipe. This protective shield for pipes ensures their longevity, integrity, and functionality. Depending on the purpose and application, A pipe sleeve can be made of various materials like Carbon steel, Cast Iron, Stainless steel, Copper, Nickel, Aluminum, PVC, Rubber, HDPE, Composites, etc. Carbon steel pipe sleeves are quite common. They create a barrier between the main pipe and its surroundings. Pipe sleeves do not restrict the thermal growth of piping and hence the thermal cycle remains unaffected. Refer to Fig. 1 for typical pipe sleeve applications.

Pipe Sleeves
Fig. 1: Pipe Sleeves

Purpose of Piping Sleeves

Piping sleeves serve several important purposes in piping systems:

  • Protecting Pipes: They shield pipes from damage where they pass through walls, floors, or other structural elements. This helps prevent external damage, abrasion, corrosion, leakage, or physical impact.
  • Allowing for Expansion and Contraction: Sleeves provide a space for pipes to expand and contract due to temperature changes without causing damage to the surrounding structure.
  • Facilitating Maintenance and Replacement: By providing a clear passage through walls or floors, pipe sleeves make it easier to remove or replace pipes without disturbing the surrounding material.
  • Preventing Leakage: Sleeves can help maintain the integrity of seals and prevent leaks between the pipe and the surrounding structure.
  • Reducing Vibration Transmission: For vibrating piping systems, piping sleeves can also help reduce the transmission of vibrations from the pipe to the building structure, minimizing noise and potential structural damage.

Overall, piping sleeves are essential for ensuring the durability, functionality, and maintainability of piping systems.

Materials for Pipe Sleeves

As mentioned earlier, various materials can be used for piping sleeves. Some common ones are explained below:

Carbon Steel

Carbon steel pipe sleeves are widely used for their robust construction and cost-effectiveness, making them ideal for providing long-lasting protection to pipes. Their durability ensures that they can handle substantial wear and tear while maintaining the integrity of the piping system. Carbon steel’s notable resistance to corrosion makes it suitable for environments where pipes are exposed to moisture and other degrading elements. Additionally, the material’s inherent strength enhances the overall structural integrity of the pipe, contributing to a prolonged lifespan. This combination of resilience and affordability makes carbon steel a popular choice across various industries.

Stainless Steel

Stainless steel pipe sleeves are renowned for their excellent corrosion resistance, which makes them ideal for harsh and corrosive environments. These sleeves effectively resist rust and staining, ensuring a long service life even under challenging conditions. Their superior durability helps maintain the integrity of the piping system over time. Additionally, stainless steel’s sleek and modern appearance adds an aesthetic appeal, making it suitable for applications where visual impact is important. The combination of functional benefits and visual attractiveness makes stainless steel pipe sleeves a preferred choice in many demanding industries.

PVC

PVC pipe sleeves are favored for their versatility, lightweight nature, and cost-effectiveness. They offer effective protection for pipes, cables, and wires while being easy to handle and install. PVC’s resistance to a wide range of chemicals makes it suitable for environments where exposure to corrosive substances is common. The lightweight quality of PVC simplifies the installation process, reducing both time and labor costs. Its durable and insulating properties further contribute to its popularity in various applications, providing a reliable and efficient solution for pipe protection across different industries.

Rubber

Rubber pipe sleeves are valued for their flexibility and durability, making them ideal for situations involving frequent movement or mechanical strain. Their pliability allows for easy installation and adjustment, ensuring a snug fit around pipes and accommodating varying geometries. Rubber’s impact resistance provides significant protection against physical damage, enhancing the pipe’s overall durability. Additionally, rubber sleeves offer effective sealing and insulation benefits, making them indispensable in applications requiring resilience and adaptability. These characteristics make rubber a practical choice for industries that need reliable performance under dynamic conditions.

Composites

Composite pipe sleeves, made from materials like fiberglass and carbon fiber, offer customized solutions to address specific challenges in industrial piping systems. They provide exceptional strength, chemical resistance, and thermal insulation, making them well-suited for demanding environments. The ability to tailor composite materials allows for a balance between strength, flexibility, and environmental resistance. Innovations in composite technology ensure that these sleeves meet evolving industry needs by combining the best attributes of various materials. This adaptability and advanced performance make composites a preferred choice for creating durable and efficient piping solutions.

Note that whatever material is used for the piping sleeve, when it is used for railroad crossings, proper design calculation has to be performed to ensure that the pipe sleeve thickness is sufficient to carry the loads. API 1102 provides certain guidelines for Rail-Road Crossing calculations.

Applications of Pipe Sleeves

Pipe sleeves find wide applications in the piping industry. Some of the common uses of pipe sleeves are:

  • While running through the dike-wall or bund walls in the tank farm area if a pipe is not required to be anchored, it is routed through pipe sleeves.
  • For buried pipes, while crossing rail or roads, or bridges and culverts, the original main pipe may be routed through pipe sleeves to protect the main pipe from heavy loads from vehicles and trains.
  • Pipe sleeves are also commonly used in piping insulation.
  • Plumbing pipe sleeves are used in industrial and residential buildings.

Functions and Uses of a Pipe Sleeve

Pipe sleeves can also be used to repair a pipe temporarily to avoid costly shutdowns. By properly deciding the sleeve pipe thickness they can be welded directly over the main pipe and can serve the purpose of the main pipe. Pipeline sleeves are used for the temporary repair of pipeline leakages.

Full encirclement pipe sleeves are used in the weaker sections of the pipe to provide reinforcement on the parent pipe. They are also widely used during hot tapping operations where branch connection is taken from operating lines.

PVC pipe sleeves are widely used for cable and wiring solutions, mostly for building applications.

In some situations, spacers are provided to support the pipe or pipeline inside the pipe sleeve. This type of arrangement with equidistant spacer supports is quite common for buried composite piping systems (FRP and GRP piping systems) where running through rail or road crossings.

What is a Wing Nut? Its Working, Types, Materials, Applications, Advantages

Written by Anup Kumar Dey in Construction,Engineering Materials,Mechanical

Nuts are one of the most widely used common types of fasteners. Wing-nut is a type of nut having two large metal wings to tighten or loosen using the hands. Wingnuts are also popularly known as butterfly nuts. Wing-nuts consists of a metal piece with a threaded hole. To hold two or more objects together, they are used with a wing bolt or wing screw. To assemble, the wing bolt is inserted through the objects, after which a wingnut is inserted on the end of the bolt and tightened by turning it. ASME B18.17 or DIN 315 provides the specifications relating to wing nuts (Fig. 1).

Characteristics of Wing Nuts

  • The metal wings characterize this special type of not. They got their name from the presence of the tabs or wings.
  • Usually, they are hexagonal in shape.
  • Wingnuts have internal threads to engage with a bolt.
Typical Wing Nuts
Fig. 1: Typical Wing Nuts

Working of Wing Nuts

The working of wingnuts is similar to other nuts. The basic function of holding two or more objects together is achieved when assembling the nut and bolt together. The main advantage of wing nuts lies in their easy installation and removal procedure. The presence of wings in wingnuts, help operators to grip and tighten easily. Wing nuts protrude from an integral round base with a flat bearing surface and are placed 180 degrees apart.

Types of Wing Nuts

Wingnuts are classified based on style and manufacturing method. ASME B18.6.9 classifies wing nuts into the following four types.

Wing Nut TypesManufacturing MethodRemarks
Type ACold-forged or cold-formedType A wing nuts are produced in regular, light, and heavy dimensional series
Type BHot forgedType B wingnuts are available in three different wing styles.
Type CDie-castType C wing nuts are produced in regular, and heavy dimensional series
Type DSheet metal stampedType D wingnuts are available in three different wing styles.
Table 1: Types of Wing Nuts

Stamped wing nuts have hollow wings that are open at the top while cold-forged wing nuts are solid parts.

Materials of Wing Nuts

Wing nuts can be manufactured from various materials. Some of the common materials are stainless steel, copper, brass, aluminum, plastic, steel, and other ferrous alloys. They may be zinc plated to increase corrosion resistance.

Size of Wing Nuts

The nominal thread diameter decides the size of a wing nut. Common sizes range from about #6 to 3/4″. Sizes less than 1/4″ are listed as a number size while sizes that are 1/4″ and larger are specified in inches, usually fractional rather than decimal. Not all types are available in all sizes. With the size of the wing nut, their dimensions vary. The following table in Fig. 2 provides typical dimensions of wing nuts.

Wing nut dimensions
Fig. 2: Wing nut dimensions

Application of Wing Nuts

Wing nuts are suitable for parts requiring frequent assembly and disassembly. They are mostly used for applications requiring less torque as wing nuts are hand-turned without using any tool. Depending on the application requirement, wing nuts can have a standard or metric thread. Common applications of wing nuts include:

  • Car batteries
  • Furniture
  • Bicycle wheels
  • Drum kits
  • Boat accessories, etc

Advantages of Wing Nuts

Wing nuts provide a number of benefits like:

  • Easy engagement and removal.
  • Lower torque requirement for tightening.
  • Easy tightening by hand without the need for a tool.
  • Usually does not require heat treatment.
  • Wingnuts can be used with or without washers.

Disadvantages of Wing Nuts

However, there are a few drawbacks of wing nuts. Some of the disadvantages are:

  • Not suitable for vibrating applications.
  • Not suitable for heavy load applications.

What is Buffing? | Differences between Buffing and Polishing: Buffing vs Polishing

Written by Anup Kumar Dey in Mechanical

What is Buffing?

Buffing is a surface finishing process to shine metal, wood, or composites. It levels out the residues or excess products to provide a smooth surface and look. The buffing process usually uses a cloth wheel impregnated with loose abrasives as cutting compounds. The cloth buff carries the abrasive compound which removes the superficial material and imperfections to create a glossy uniform surface.

Buffing Process

The buffing operation is usually performed in two steps; an initial cut buff and then a finish buff.

Cut Buffing:

Cut buffing is the coarsest buffing operation. This is the preliminary buffing operation to remove major discontinuities and surface roughnesses. Surface preparation is required before the buffing operation to get better surfaces. With a very good surface preparation, the cutting buff will remove pits, course abrasive lines, deep scratches, etc.

Finish Buffing:

It is the final buffing operation after cut-buffing is performed. This step produces a very good luster on the surface and removes the fine lines generated during cut buffing. Finish buffing is usually quicker, easier, and less pressure process as compared to cut buffing.

Buffing Wheels

Buffing wheels that carry the required abrasive compounds are the transferring agent between the workpiece and the abrasive compound. To get the desired surface smoothness, the construction of the buff should match the workpiece. A harder buff is more aggressive and not flexible and so, usually used for flat surfaces. Whereas a softer buff is ideal for complex shapes as it is less aggressive.

As mentioned earlier there are two types of buffing operations; cut buffing and finish buffing. Both of these operations use different kinds of buffs. Cut buffing operation uses spiral sewn, set up wheels, sisals, and treated airways type of buffs. On the other hand, finish buffs use loose buffs, concentric sewn, airway, and Flannel types of buffs.

Buffing Compound

Buffing compound which is made of binders and abrasives comes in a solid bar or liquid form. Animal fats, grease-less waxes (glue and water), and petroleum-based products are normally used as binders. Proper use of a binder is very important for appropriate buffing operation as the binder decides the cutting ability, hardness, adhesion ability, and lubrication of the buff.

Common abrasive compounds for buffing operation are Aluminum Oxide, Tripoli, Iron Oxide, Silicon Carbide, Calcined Alumina, and Chrome Oxide. The following table in Fig. 1 provides some typical specifications of abrasives used in the buffing process:

Abrasive Specifications for Buffing
Fig. 1: Abrasive Specifications for Buffing

In general, Greaseless Compound, Stainless Compound, and Tripoli are used for cut buffing; while Green Rouge, White Rouge, Reg Rouge, and Calcined Alumina are used for finish buffing.

Surface Speed for Buffing

The surface speed is one of the important parameters for the buffing process as it decides the work rate speed, the pressure required, heat build-up, and the actual finish that will be produced. Depending on the material of the buffing operation, the surface speed for the buffing operation is decided. Buffing speed is usually measured in feet per minute or SFM unit. The following table in Fig. 2 provides some typical speed recommendations for various material types.

Surface Speed of Buffing with respect to materials
Fig. 2: Surface Speed of Buffing with respect to materials

What is Polishing?

Polishing is also a surface finishing process performed using abrasives that are secured with glue or other adhesives to the wheel. Polishing is believed to be a more aggressive finishing process as compared to buffing. It has the ability to remove more superficial material from the workpiece surface which in turn allows for a brighter and more polished finish.

Differences between Buffing and Polishing | Buffing vs Polishing

The main differences between buffing and polishing are:

  1. Both buffing and polishing are surface finishing processes. Buffing uses loose abrasives on the wheel whereas polishing uses abrasives that are secured to the wheel.
  2. Polishing is usually performed using a high-grit abrasive whereas buffing is normally performed using a low or medium-grit abrasive.

Applications of Buffing and Polishing Process

The buffing and polishing process is widely used for removing scratches, coatings, oxides, imperfections, pits, etc from the surface of the workpiece. Major applications of the buffing and polishing process are found in:

  • Tools, fixtures, and sports industries
  • Household utensils and appliances sector
  • Automobile, bicycle, motorcycle parts.

References and Further Studies