Pipe Fittings Significance in Piping Field Part - 4

II JAY SHRI KRISHNA II

Hello Friends, whether it is simple household plumbing system or a complex industrial networks. Pipe Fittings are the critical components that make it all work. The joint or connection of two flanges, valves and eqpt. nozzles cannot be done without Bolts and Gaskets. 

Pipe Fittings Significance in Piping Field Part - 4

In this blog, we will see detail of Types, Material of Construction, Dimensional Standard & Uses of Gasket and Bolting.

Types of Pipe Fittings:

The another most common types of Pipe Fittings including:

Gasket:

Gasket used For Flange Joint

The primary purpose of a Gasket is to prevent leakage of fluids such as gases or liquids from the joint between two flanges, as shown in the figure.

The first preference of any flanged assembly is to connect Piping System in such a manner as to produce a leak-free environment. Because creating a leak-free seal between two connecting metal surfaces in industrial setting is almost impossible. Therefore, Gaskets perform a main function in plant safety.

The choice of Gasket material depends on the specific conditions and requirements of the flange connection.

Gaskets can be made of materials like asbestos, rubber, neoprene, Teflon and lead or copper. When bolts are tightened & flange faces are drawn together, the gasket material will confirm to any imperfections in the flange faces to create a uniform seal.

Gaskets

A typical Gasket has a thickness of 3.175mm. At every occurrence of a flange bolting to a nozzle, two flanges joining together, two valves joining together or flange connecting to valve, a Gasket thickness is then added to the length of the pipe components.

The Selection of Gasket depends upon the following factors.

1. Compatibility of the Gasket material with the process fluid.

2. Ability to withstand to the pressure & temp. of the system.

Uses of Gaskets:

Use of Gaskets

They come in various materials and design, each suited for particular temperature & pressure ranges. Soft Gasket i.e. cork, rubber, vegetables fiber, graphite, asbestos is commonly used. For very corrosive fluid PTFE or PTFE enveloped Gasket are used.

For high temp. pressure service spiral wound metallic Gaskets are used. The most commonly used spiral wound Gaskets are the Austenitic SS304, 316, 321 with asbestos or graphite filler. The spiral wound Gasket are also provided with carbon steel external ring known as centering ring to position the Gasket sometime the inner ring is also provided.

ANSI/ASME B16.20 standard covers metallic and non-metallic Gaskets.

Some common types of Gasket include:

1. Non-Metallic Gaskets:

Rubber Gasket - Used for low pressure applications & water systems

Cork Gasket - Suitable for sealing liquids & gases at low pressure

2. Metallic Gaskets:

Spiral Wound Gaskets – Effective in high temp. & high pressure applications

Ring Joint Gaskets – Common in high pressure & high temp. pipelines.

3. Semi –Metallic Gaskets:

Graphite Gaskets – resistance to extreme temp. & chemical corrosion.

4. RTJ (Ring Type Joint) Gaskets:

Used in high pressure & high temp. applications, often in oil & gas industries.

5. Metal Jacketed Gaskets:

Combine the strength of metal with the sealing capability of non –metallic materials.

6. Double Jacked Gaskets:

Employed in applications requiring high temp. and pressure resistance.

The choice of Gasket depends on factors like pressure, temperature, fluid nature and the specific needs of the Piping Systems.

Bolting:

To Complete any Flange assembly, two additional items are required which are Bolts & Gaskets. Bolts are hold mating flanges, nozzles or valves together.

It is critical to drawings the exact orientation of flanges to the fabricator. Otherwise, bolt holes may not fit to align properly. To confirm that bolt holes on flanges, nozzles or valves align or fit properly, bolt holes are equally spaced around the flange.

Bolts are available in two types

1. Machine Bolts &

2. Stud Bolts.

Machine Bolts (Hex, Bolts & Nut) and Stud Bolts & Nut

• Machine Bolts have a Head on one end & threads on the other.

• Stud Bolts have threads throughout their entire length & require the use of two nuts. Stud Bolts type are the most common used and are available in two grades, which are A-193-B7 and A-193-B16.

• In general, B7 grade bolts are suitable for most applications. However, for high-temperature environments above 1000°F, B16 grade bolts offer superior performance.

• Depending upon the service, pressure / temp. & the type of flange, gasket, type of bolting is decided.

• The length of bolts and studs for the flanges of all pressure classes are specified in ANSI/ASME B16.5.

Material of Construction for Bolting:

ASTM A307      Low Carbon Steel Bolting material

ASTM A320      Alloy Steel Bolting Material for low Temp.

ASTM A193      Alloy Steel Bolting Material for High Temp.

ASTM A194      Alloy Steel Nut for High Temp. Services

Dimensional Standard for Bolts:

ANSI/ASME     B18.2.1 Square and hex. Head Bolts & Studs

ANSI/ASME     B18.2.2 Square and hex. Nuts

Conclusion:

So Friends, have you observe that the Gaskets and Bolts are small in size but how important they are…!! I understand that any object or person, no matter how small it is… never make the mistake of underestimating them… God has given some strength and quality to everyone to make his identity own way so that they can keep their existence value for self as well as use for other also. God values all people equally.

For more about earlier blogs Part series follow the links which are

Pipe Significance in Piping Field

Pipe Fittings Significance in Piping Field Part – 1, Part-2, Part -3 and Part -5, O' let Fittings, 

A Deeper Look at Pipe Fitting Selection Criteria

Selection of Gasket Material Guide,

Valves Significance in Piping Field

For further Pipe Fittings details kindly follow my next blog series….

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To be continue……