How to get high quality Gaskets?

What is a gasket?

gasket is a mechanical seal which fills the space between two or more mating surfaces, generally to prevent leakage from or into the joined objects while under compression.

Gaskets allow for “less-than-perfect” mating surfaces on machine parts where they can fill irregularities. Gaskets are commonly produced by cutting from sheet materials.
Gaskets for specific applications, such as high pressure steam systems, may contain asbestos. However, due to health hazards associated with asbestos exposure, non-asbestos gasket materials are used when practical.
It is usually desirable that the gasket be made from a material that is to some degree yielding such that it is able to deform and tightly fill the space it is designed for, including any slight irregularities. A few gaskets require an application of sealant directly to the gasket surface to function properly.
Some (piping) gaskets are made entirely of metal and rely on a seating surface to accomplish the seal; the metal’s own spring characteristics are utilized (up to but not passing σy, the material’s yield strength). This is typical of some “ring joints” (RTJ) or some other metal gasket systems. These joints are known as R-con and E-con compressive type joints.

Gaskets are normally made from a flat material, a sheet such as paper, rubber, silicone, metal, cork, felt, neoprene, nitrile rubber, fiberglass, polytetrafluoroethylene (otherwise known as PTFE or Teflon) or a plastic polymer (such as polychlorotrifluoroethylene).
One of the more desirable properties of an effective gasket in industrial applications for compressed fiber gasket material is the ability to withstand high compressive loads. Most industrial gasket applications involve bolts exerting compression well into the 14 MPa (2000 psi) range or higher. Generally speaking, there are several truisms that allow for better gasket performance. One of the more tried and tested is: “The more compressive load exerted on the gasket, the longer it will last”.
There are several ways to measure a gasket material’s ability to withstand compressive loading. The “hot compression test” is probably the most accepted of these tests. Most manufacturers of gasket materials will provide or publish the results of these tests.

Gasket, Flange gasket, Bolts for Flange Connections

Flange connection is to two pipes, pipe fittings or equipment before each fixed at a flange on the flange between the two, together with flange pad, fastened together with bolts to complete the connection.

Some of pipe fittings and equipment have been built-flange, also falls within the flange connection. Has flanged pipe and pipe fittings, also belongs to the flange. Flange connections are an important connection for pipeline construction. Flange connections easy to use, able to withstand greater pressure.

flange connection - How to get high quality Gaskets?

Sub-threaded flanges connection (wiretapping) flanges and welding flanges. Low-pressure small-diameter wire access flange, high pressure and low pressure are the use of large-diameter welded flange, different pressure, flange thickness and bolt diameter and the number of connections are different.

Within the family, pipe diameter, and are low-voltage, see flange connection. If produced in a boiler room or scene is full of flanged pipes and fittings.

As steel welded flange, a lot of customers have doubts is the quality is better than the forging of steel welded flange welding flange. Actually steel welded flange of quality and forged of welding flange of quality is as of, but steel welded flange what place cannot has guarantees does, is steel welded flange of material most no guarantees has, because General of process among,steel welded flange of density is no problem of, but in for production of process among, steel welded flange of rough rarely for detection, so for, by production out yahoo, not after detection of steel welded flange of material cannot guarantee.

The different grades based on the pressure, flange pad also has a variety of materials, from the low-pressure asbestos pad, high-pressure pads to the metal pads are asbestos.

Within the family, pipe diameter is small, but also ow-voltage, see flange connection. If a boiler room or a production site, full of flanged pipes and equipment. Flange connection is to two pipes, fittings or equipment before each fixed at a flange on the flange between the two, together with flange pad, fastened together with bolts to complete the connection. Some of pipe fittings and equipment have been built-flange, also falls within the flange connection.

flange gaskets banner - How to get high quality Gaskets?

Flange gaskets are used for improved joint performance.

They are considered much more superior than the conventional ring or full-face gaskets. Although pipe flange gaskets are usually used for all normal water and sewer service, they are especially useful in demanding services like in very large diameter flanged piping.

For specially designed long-span installations, involving 2 or 3 or more lengths of pipe or with any underground flanges, flange gaskets are of great help because they could be subjected to undesirable beam loading.

These gaskets are available in numerous standard materials in various thickness and hardness options for various flange sizes. Flange gaskets are also available with adhesive on one or both sides or without adhesive. Most materials are available starting at 1/32” thick and can be supplied up to 1” thick. Some manufacturers supply flange gaskets in wide rolls from which you can cut your flange gaskets to size. Flange gaskets are also available to your exact requirements. Pipe flange gaskets are being very frequently used for flanged joints which are subjected to extreme chemical attacks.

Materials used:

A flange gasket is a type of gasket made to fit between two sections of pipe that are flared to provide higher surface area. Flange gaskets come in a variety of sizes and are categorized by their inside diameter and their outside diameter.

Flange gaskets are made of various materials like:

Ring Type Joint gaskets - How to get high quality Gaskets?

  • Rubber:Neoprene, EPDM, Nitrile, EVA, Silicone, Cork and Cork Rubber
  • Closed Cell Foam:Cross-linked Polyethylene, PVC
  • Plant Fiber
  • Cellulose Fiber
What Are the Different Types of Gaskets?

The most common types of gaskets are:

  • Gaskets used in piping (flange gaskets)
  • Gaskets used in vehicles (cars, boats, planes, trains)
  • Gaskets with certain material properties (cork, rubber paper etc.)
  • Gaskets used for a particular function (for pressure, temperature, or chemical resistance)
  • Bespoke or custom made gaskets
What is the difference between a RTJ, FF, and RF flange on seals and thermowells?

Pipe gaskets (otherwise known as flange gaskets) are made from wide range of materials such as rubber, non-asbestos and graphite. The gaskets can be bought as either Full Faced (with bolt holes) or Inner Bolt Circle (IBC, ring type or raised face).

There are many standards in gasket for flanges of pipes.

gaskets type rf - How to get high quality Gaskets?

Type RF

gaskets type ff - How to get high quality Gaskets?

Type FF

gaskets type rtj - How to get high quality Gaskets?

Type RTJ

The raised face, RF, is the standard process connection on our third party seals and thermowells. Both have options for a RTJ and FF type flange connections. The Raised Face (RF) is the most common type used in process plant applications.

The gasket surface of the flange is raised above the bolting circle face. A Ring-type Joint (RTJ) can also have a raised gasket face with the difference being the ring groove machined in this face. This groove will accommodate a steel ring gasket for flange mating. The Flat Face, FF, flange has a gasket surface that is in the same plane as the bolting circle face. None of these three flange types are interchangeable between types, i.e. RTJ flange cannot be mated to a RF flange.

How to select the gasket for Flange Connections?

One of the best all-around seals, the spiral wound gasket offers a low-cost solution that has the ability to handle temperature and pressure fluctuations. Multiple plies of metal and filler in the spiral create a barrier that reduces the possibility of leaks.

how to select the gasket - How to get high quality Gaskets?

Heat Exchanger Gaskets

Garlock manufactures a wide variety of double-jacketed, spiral-wound, metal-clad and solid metal gaskets for heat exchanger applications. GRAPHONIC and Kammprofile gaskets are also available in heat exchanger configurations.

Temperature and Chemical Considerations

Be certain that the gasket you order is as resistant as possible to the media and temperature involved. Check the chemical compatibility of the metal as well as the filler material for the media to be sealed. As a general rule, the metal used in either the spiral winding or double-jacketed gasket should be similar to the flange material.

The compressibility of flexible graphite makes it an excellent filler material for metallic gaskets. Flexible graphite may be used in services with temperatures up to 950ºF (485ºC), though it should not be used with strong oxidizers such as nitric or sulfuric acid.

PTFE filler material provides excellent chemical resistance at temperatures below 500ºF (260ºC). In accordance with ASME B16.20, an inner ring is required when using conventional PTFE filler materials, in order to protect the winding from radial buckling.

Temperature Limits for Common Metals

Row color indicates guide ring color. Due to browser color display differences, you may wish to consult our

Material Minimum Maximum Abbr.
ºF  ºC ºF  ºC
304 Stainless Steel -320 -195 1400 760 304
316L Stainless Steel -150 -100 1400 760 316L
317L Stainless Steel -150 -100 1400 760 317L
321 Stainless Steel -320 -195 1400 760 321
347 Stainless Steel -320 -195 1700 925 347
Carbon Steel -40 -40 1000 540 CRS
20Cb-3 (Alloy 20) -300 -185 1400 760 A-20
HASTELLOY® B 2 -300 -185 2000 1090 HAST B
HASTELLOY® C 276 -300 -185 2000 1090 HAST C
INCOLOY® 800 -150 -100 1600 870 IN 800
INCONEL® 600 -150 -100 2000 1090 INC 600
INCONEL® X750 -150 -100 2000 1090 INX
MONEL® 400 -200 -130 1500 820 MON
Nickel 200 -320 -195 1400 760 NI
Titanium -320 -195 2000 1090 TI
Spiral Wound Gasket Metallic Windings - How to get high quality Gaskets?

ASME B16.20 Color Code Chart
Spiral Wound Gasket Metallic Windings
and Non-Metallic Fillers

Operating Pressure

Changes in spiral winding construction affects gasket density. Higher pressure applications require windings with more wraps of thinner filler material. This construction withstands higher bolt loads, and provides a better seal against high pressures. A lower pressure gasket has fewer wraps of metal and filler, allowing the gasket to seat under lower bolt loads.

Gasket Selection by Flange Type

Flange face EDGE™ CD™/RW RWI SW MC MCR HH RW-RJ LMF LTG STG
Flat Face * * * * * *
Raised Face * * * *
Ring Joint *
Male-Female * * * * *
Tongue-&-Groove * * * *
Groove-to-Flat * *
Flange gasket

A flange gasket is a type of gasket made to fit between two sections of pipe that are flared to provide higher surface area.

Types of flange gaskets - How to get high quality Gaskets?

Flange gaskets come in a variety of sizes and are categorized by their inside diameter and their outside diameter.
There are many standards in gasket for flanges of pipes. The gaskets for flanges can be divided in major 4 different categories:

Sheet gaskets are simple, they are cut to size either with bolt holes or without holes for standard sizes with various thickness and material suitable to media and temperature pressure of pipeline.
Ring gaskets also known as RTJ. They are mostly used in offshore oil- and gas pipelines and are designed to work under extremely high pressure. They are solid rings of metal in different cross sections like oval, round, octagonal etc. Sometimes they come with hole in center for pressure equalization.
Spiral wound gaskets are also used in high pressure pipelines and are made with stainless steel outer and inner rings and a center filled with spirally wound stainless steel tape wound together with graphite and PTFE, formed in V shape. Internal pressure acts upon the faces of the V, forcing the gasket to seal against the flange faces.

Octagonal Ring Joint Gaskets

> Ring Joint Gaskets are for oilfield and process industry duties.

> Octagonal shape gasket is belong to API 6A R series 

> These gaskets are used in pressures up to 10,000 PSI, more than Oval ring joint.

> The oval type is the only gasket that will fit a bottom radiused groove.

> Gaskets and not re-used after torque.

Octagonal Ring Joint Gasket was initially developed for high pressure and temperature applications found in the petroleum industry and is primarily used in the oil field on drilling and completion equipments. However, today this product range can also be found on valves and pipework assemblies, along with some high integrity pressure vessel joints.

> Ring Joint Gaskets are for oilfield and process industry duties.
> Oval shape gasket is belong to API 6A R series 
> These gaskets are used in pressures up to 10,000 PSI.
> The oval type is the only gasket that will fit a bottom radiused groove.

> Gaskets and not re-used after torque.

Oval Ring Joint Gasket was initially developed for high pressure and temperature applications found in the petroleum industry and is primarily used in the oil field on drilling and completion equipments. However, today this product range can also be found on valves and pipework assemblies, along with some high integrity pressure vessel joints.

Spiral Wound Gasket can be made from a large selection of alloys and filler materials in a variety of shapes and sizes.

Yaang also provide non-round spiral wound gaskets, manhole and handhole spiral wound, and just inner & outer rings for SWG.

The Spiral Wound Gaskets is suitable for flange, valve, pump, heat exchange etc.

Corrugated/Serrated Gaskets, for ASME standard corrugated gasket.
The CMG gaskets is punched by moulds, the tolerance is strictly control.
Corrugated Metal Gasket are known as Graphonic Gaskets.
Corrugated metal gasket is widely used for pipe flange, pump, valve joint.
We supply the complete corrugated gaskets, and metal core only.
PTFE Gaskets
> 100% PTFE resistant to all corrosive media
> Soft, twistable and bendable, used continue their service and keep its best performance
> Excellent anti-wriggle variation ability and cold current resistance
> Even in case of cross change of temperature and pressure, good sealing can be assured
It has 100% PTFE structure. It can be bear the most bitter chemical medium, and has good anti-creeping performance.

Expanded Graphite Gaskets are known as Flexible Graphite Gasket. According to different operating conditions,

gaskets can be covered with single or double eyelets, or without eyelet. We also provide nuclear grade graphite

gasket, sulphur content less than 600ppm. Superior performance.

Graphite gaskets is widely used for pipe flange, pump, valve joint.
Types of flange gaskets

Materials for gaskets can be divided into three main categories:

  • Non-Metallic types
  • Semi-Metallic types
  • Metallic types

Non-Metallic types

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Non metallic gaskets are usually the most cost-effective option for flange gasketapplications.

Non-Metallic gaskets are usually composite sheet materials are used with flat-face and raised-face flanges in low Pressure Class applications. Non-metallic gaskets are manufactured from arimid fiber, glass fiber, elastomer, Teflon® (PTFE), graphite etc.. Full-face gasket types are suitable for use with flat-face flanges. Flat-ring gasket types are suitable for use with raised face flanges.
ASME B16.21 covers types, sizes, materials, dimensions, dimensional tolerances, and markings for non-metallic flat gaskets.

Semi-Metallic types

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Semi-metallic gaskets can generally be used in pressures ranging from vacuum to those seen in ASME B16.5 standard 2500 pressure class flange ratings.

Semi-Metallic gaskets are composites of metal and non-metallic materials. The metal is intended to offer strength and resiliency, while the non-metallic portion provides conformability and sealability. Often used semi-metallic gaskets are spiral wound and camprofile, and a variety of metal-reinforced graphite gaskets. Semi-metallic are designed for almost all operating conditions and high-temperature and pressure applications, and are used on raised face, male-and-female, and tongue-and-groove flanges.
ASME B16.20 covers materials, dimensions, dimensional tolerances, and markings for metallic and semi-metallic gaskets.

Metallic types

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Two types of RTJ gaskets

Metallic gaskets are fabricated from one or a combination of metals to the desired shape and size. Often used metallic gaskets are ring-type-joint gaskets (RTJ). They are always applied to special, accompanying flanges which ensure good, reliable sealing with the correct choice of profiles and material.
Ring Type Joint gaskets are designed to seal by “initial line contact” or wedging action between the mating flange and the gasket. By applying pressure on the seal interface through bolt force, the “softer” metal of the gasket flows into the microfine structure of the harder flange material, and creating a very tight and efficient seal.
ASME B16.20 covers materials, dimensions, dimensional tolerances, and markings for metallic and semi-metallic gaskets.

The charecteristics of Good Gasket
It will seal the fluid system.
A good gasket should be chemically inert to resists the system fluid to avoid chemical reaction with fluid system.
Should deform enough to flow into the imperfections on the gasket seating surfaces to provide intimate contact between the gasket and the seating surfaces.
Withstands system temperatures without serious damaging the fluid system properties.
Should be resilient and resists creep enough to maintain an adequate portion of the applied load.
A good gaskets has sufficient strength to resist crushing under the applied load, and maintain its integrity when being handled and installed.
Should not corrode the gasket seating surfaces.
There are limits on the degree of flange surface imperfection that can be sealed successfully with a gasket. Large nicks, dents, or gouges must be avoided, since a gasket cannot properly seal against them. 
The surface finish of a flange is described as follows:
1. Roughness : Roughness is read in millionths of an inch (or meter) as the average of the peaks and valleys measured from a midline of the flange surface.
2. Lay – Lay : is the direction of the predominant surface-roughness pattern. Example: multidirectional, phonographic spiral serrations, etc.
3. Waviness : Waviness is measured in thousandths or fractions of an inch. Basically, it is the departure from overall flatness.
Typical roughness readings can be from 125 to 500 micro-inches for serrated flanges and 125-250 micro-inches for non-serrated flanges. Fine finishes, such as polished surfaces, should be avoided. Adequate “bite” in the surface is required to develop enough friction to prevent the gasket from being blown out or from extruding or creeping excessively.
The lay of the finish should follow the midline of the gasket. For example, concentric circles on a round flange, or a phonographic spiral. Every effort should be made to avoid lines across the face, such as linear surface grinding, which at 180º points will cross the seal area at right angles to the gasket, allowing a direct leak path.
Waviness is seldom a problem under normal conditions. There are two areas that must be watched, however, since excessive waviness is very difficult to handle.
The first area is glass-lined equipment where the natural flow of the fused glass creates extreme waviness. Often the answer here is to use thick and highly compressible gasketing.
The second area of concern is warped flanges. If warpage is caused by heat or internal stresses, re-machining is generally sufficient. However, warpage due to excessive bolt loads or insufficient flange thickness results in what is generally called bowing. 
The solution is to redesign for greater flange rigidity. Sometimes backer plates can be added to strengthen the design without replacing the parts. Another step would be to add more bolts. When this is done, usually smaller bolt diameters are possible, thus adding more bolt stretch and better joint performance.

Source: China Gaskets Manufacturer – Yaang Pipe Industry (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@steeljrv.com

Please notice that you might be interested in the other technical articles we’ve published:

  • What are reducing flanges

  • When to use slip on flanges
  • HOW TO GET HIGH QUALITY BLIND FLANGES
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  • How to test pipe fitting
  • HOW TO GET HIGH QUALITY STAINLESS STEEL PIPES
  • Development trend of high pressure pipe fittings
  • How to get high quality flanges
  • How to get high quality pipe fittings
  • What are Specialty Flanges
  • How to get high quality alloy steel pipes
  • HOW TO GET HIGH QUALITY STEEL PIPES
  • What are socket weld flanges
  • When to use slip on flanges
  • What are slip on flanges
  • WHEN TO USE A SPECTACLE BLIND FLANGE

  • HOW TO GET HIGH QUALITY BOILER TUBES
  • When to use lap joint flange
  • How to get high quality plate flanges
  • The difference between pipe nipple and pipe coupling
  • How to get high quality lap joint flanges
  • The Differences between socket welding flanges and butt welding flanges
  • HOW TO GET HIGH QUALITY SPACER RINGS AND SPADE FLANGES

  • HOW TO GET HIGH QUALITY ORIFICE FLANGES

  • HOW TO GET HIGH QUALITY SOCKET WELDING FLANGES

  • How to get high quality Spectacle Blind Flanges

  • HOW TO GET HIGH QUALITY THREADED FLANGES

  • HOW TO GET HIGH QUALITY WELDING NECK FLANGES

  • How to install gaskets correctly

  • A Simple Introduction to Graphite Gaskets

  • What Are A, B, C, D , R, RIR, CG and CGI Types for Spiral Wound Gaskets

  • Applications of Eight Different Gaskets

  • What are gaskets

References:

  • https://en.wikipedia.org/wiki/Gasket
  • https://www.yaang.com

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