Type Of Gasket For Piping and Flanges

What is Gasket :

A gasket is a type of mechanical seal that fills the gap between two or more surfaces that are joined together. Its primary function is to prevent fluids or gases from leaking out of or into the connected objects when they are under pressure. 

Where to use gaskets :

Gaskets are widely used in various industries, such as the automotive, aerospace, plumbing, and  Manufacturing and Industrial Equipment, Electronics and Electrical Equipment, Oil and Gas Industry, Food and Beverage Industry.

Automotive : Engine, transmission, and brake systems.

Aerospace : Fuel systems, hydraulic systems, and engine components.

Chemical processing : Pipelines, tanks, and reactors.

Oil and gas : Pipelines, valves, and pumps.

Power generation : Boilers, turbines, and generators.

HVAC : Heating, ventilation, and air conditioning systems.

Industrial equipment : Pumps, compressors, and gearboxes.

Marine : Propulsion systems, fuel systems, and piping.

What is the use of gasket :

A gasket seal is a critical component used to create a tight seal between two or more mating parts, such as flanges, pipes, or covers, to prevent leakage of fluids, gases, or other substances. 

Leak prevention : To prevent the escape of fluids, gases, or other substances from a system, such as oil, water, air, or chemicals.

Pressure containment : To withstand internal pressure and maintain the integrity of a system, such as in high-pressure pipes or vessels.

Temperature resistance : To resist extreme temperatures, such as in engines, boilers, or heat exchangers.

Chemical resistance : To resist corrosion or degradation from exposure to chemicals, such as in chemical processing or storage systems.

Vibration and shock absorption : To absorb vibrations and shocks, reducing the risk of leakage or damage to the system.

Electrical insulation : To provide electrical insulation between two conductive surfaces, such as in electrical enclosures or switchgear.

Noise reduction : To reduce noise and vibration in systems, such as in exhaust systems or pumps.

Type Of Gasket Selection Criteria :

• Temperature

• Vibration and Oscillation

• Fluid contamination risk

• Corrosion resistance

• Robustness

• Availability

• Cost

• Expected service life

How Many Types Of Gasket :

Basically there are three types of gasket  : 01. Non-metallic  02. Metallic  03. Composite or semi-metallic.

01. Non-metallic Gasket :

Non-metallic gasket or soft gasket are fabricated from material such as rubber, fiber, polytetrafluoroethylene (PTFE)and graphite.

Non-metallic gaskets are used in a large range of application such as pipe flanges, heat exchanger, compressor and bonnet valves.

There are generally used for low pressure applications and low temperature.

Non-metallic gasket are used with low-pressure class flanges such as 150 and 300 class and also in low-temperature however, graphite gasket can be used up to 500 degree centigrade.

Non-metallic gasket are not suitable for high temperature and high pressure.

Non-metallic gasket are not suitable hydrocarbon services.

Non-metallic gasket are usually the most cost-effective.

Type of Non-Metallic gasket :

• Rubber Gaskets : EPDM, nitrile (NBR), silicone, Fluor silicone (FSi), Natural Rubber (NR), Hydrogenated Nitrile (HNBR), Neoprene / Chloroprene (CR), Styrene butadiene (SBR), Poly Acrylate (ACM), Ethylene Acrylic (AEM), and Viton (FKM)

• Compressed Non-Asbestos Fiber (CNAF) Gaskets

• PTFE (Teflon) Gaskets

• Graphite Gaskets

• Cork Gaskets

• Felt Gaskets

• Foam Gaskets

• Paper Gaskets

02. Metallic Gasket :

• Metallic gaskets are designed for high-pressure, high-temperature, and corrosive environments.

• Made from metals such as steel, copper, or aluminum, metallic gaskets are used in high-pressure and high-temperature environments. Common types include spiral wound gaskets, ring-type joint (RTJ) gaskets, and corrugated metal gaskets.

• Metallic gasket is used in high-pressure class flanges, normally above 900 class.

• Metallic gasket is used in high pressure and temperature services.

• Metallic gasket are very costly compere to non-metallic gasket.

• Metallic gasket material are stainless steel, low carbon steel, soft iron monel and inconel.

• Metallic gasket are very robust & most costly.

There are two type metallic gasket here,

• Octagonal type cross-section

• Ellipse (oval) type of cross-section

Type of metallic gasket :

• Spiral Wound Gaskets

• Ring-Type Joint (RTJ) Gaskets

• Kammprofile Gaskets

• Corrugated Metal Gaskets

• Metal Jacketed Gaskets

• Compressed asbestos fiber (CAF)

03. Composite OR Semi-Metallic Gasket : 

• These type of gasket can be used to a large variation of pressure and temperature.

• These type of gasket can be used to a medium pressure and temperature.

Type of composite or non-metallic gasket :

• Spiral wound gasket

• Metal jacketed gasket

• Cam profile gasket 

• Envelope gasket 

What kind of gasket is used in piping 

» In piping systems, the type of gasket used typically depends on the pressure, temperature, and the type of fluid or gas being transported.

ASME And ANSI Codes Related To Gaskets :

1. ASME B16.20 – Metallic Gaskets for Pipe Flanges

This standard covers the design, materials, dimensions, and marking requirements for metallic gaskets, including spiral wound, ring-joint, and metal-jacketed gaskets. These gaskets are commonly used in high-pressure and high-temperature piping systems in industries like oil and gas, chemical processing, and power generation.

 

2. ASME B16.21 – Non-Metallic Flat Gaskets for Pipe Flanges

This standard pertains to non-metallic flat gaskets, including those made from rubber, PTFE, and compressed fibers. It covers materials, dimensions, tolerances, and marking requirements for these gaskets, which are often used in lower-pressure systems like water treatment, HVAC, and general industrial piping.

 

3. ANSI B16.5 – Pipe Flanges and Flanged Fittings

While primarily focused on flanges and flanged fittings, this standard also includes information on the use of gaskets with these components. It specifies dimensions and pressure ratings for flanges, which are directly related to the size and type of gaskets used. This standard is applicable in a wide range of industries, including petrochemical, oil and gas, and manufacturing.

 

4. ASME PCC-1 – Guidelines for Pressure Boundary Bolted Flange Joint Assembly

This document provides guidelines for the assembly of bolted flange joints, including the selection and installation of gaskets. It covers procedures to ensure proper gasket performance, including tightening sequences and torque values. This standard is used in critical applications where maintaining a leak-free seal is essential, such as in pressure vessels, piping systems, and heat exchangers.

 

5. ANSI/ASME B16.47 – Large Diameter Steel Flanges (NPS 26 Through NPS 60)

This standard specifies dimensions, tolerances, and pressure ratings for large-diameter steel flanges, which often require specific gasket types, particularly in large-scale industrial applications. This standard is used in large-diameter piping systems, such as those found in oil and gas pipelines and power plants.

 

 ASME And ANSI Standards For Gaskets :

Safety : Ensures that gaskets are manufactured to withstand specific pressures, temperatures, and chemical exposures, reducing the risk of leaks or failures.

 

Interchangeability : Standardization allows for the interchangeability of gaskets across different manufacturers and systems, facilitating easier maintenance and replacement.

 

Compliance : Meeting these standards is often a regulatory requirement, particularly in industries such as oil and gas, chemical processing, and power generation.

 

Quality Assurance : Adherence to these standards ensures consistent quality in gasket performance, contributing to the overall reliability and efficiency of the piping systems.

Q&A :

01. What are the three types of gaskets ?

Ans. There are three types of gasket  : 01. Non-metallic  02. Metallic  03. Composite or semi-metallic

02. What is the full form of PTFE gasket ?

Ans. Polytetrafluoroethylene

03. What is the minimum gap between flanges ?

Ans. 0.8 mm to 1.5 mm  

04.  What are the two functions of a gasket ?

Ans. Its primary function is to prevent fluids or gases from leaking out of or into the connected objects when they are under pressure. 

05. Which gasket use in the plant ?

Ans. Spiral Will Metallic Gasket, Sheet Gasket, Rubber Gasket, Teflon Gasket, Graphite Gasket, Ring Gasket

06. What is A full form of ASME & ANSI ?

Ans.  ASME (American Society of Mechanical Engineers) and ANSI (American National Standards Institute)