Joint design

Gaskets come in many different designs based on industrial use, budget, chemical contact and physical parameters:

Sheet gaskets

Gaskets can be made by punching&action=edit&redlink=1 "Punch (metal working) (not yet drafted)") into the desired shape from a thin, flat sheet of material, resulting in a sheet gasket. Sheet gaskets are quick and cheap to produce, and can be made from a variety of materials, including fibrous materials and matte graphite (and in the past, compressed asbestos). These gaskets can meet different chemical requirements depending on the chemical inertness of the material used. Asbestos-free gasket sheets are durable, multi-material and thick. Examples of materials are mineral, carbon or synthetic rubbers such as EPDM, nitrile, neoprene, natural, SBR insert - each of which has unique properties suitable for different applications.[3]​ Applications using sheet gaskets involve acids, corrosive chemicals, steam or mild caustics. Flexibility and good recovery prevent breakage during installation of a sheet gasket.[4]​.

Solid material gaskets

The idea behind the solid material is to use metals that cannot be drilled into sheets but are still cheap to produce. These gaskets typically have a much higher level of quality control than sheet metal gaskets and can generally withstand much higher temperatures and pressures. The main drawback is that a solid metal must be highly compressed to sit flush with the flange head to prevent leaks. The choice of material is more difficult; Since primarily metals are used, process contamination and oxidation are risks. An additional drawback is that the metal used must be softer than the flange — in order to ensure that the flange does not deform and thus prevent sealing with future gaskets. Still, these boards have found a niche in the industry.

Spiral wound joints

Spiral wound gaskets comprise a mixture of metallic and filler material.[5] Generally, the gasket has a metal (usually high carbon or stainless steel) wound outward in a circular spiral (other shapes are possible) with the filler material (usually a flexible graphite) wound in the same way but starting from the opposite side. The result is an alternation of layers of filler and metal. The filling material in these joints acts as a sealing element, while the metal provides structural support.

These gaskets have proven to be reliable in most applications, allowing lower clamping forces than solid gaskets, although at a higher cost.

[1].

Constant Seat Tension Joints

The constant seating tension gasket consists of two components: a solid carrier ring of a suitable material, such as stainless steel, and two sealing elements of some compressible material installed within two opposing channels, one channel on each side of the carrier ring. Sealing elements are typically made of a material (expanded graphite, expanded polytetrafluoroethylene (PTFE), vermiculite, etc.) suitable for the process fluid and application.

Constant seat tension joints owe their name to the fact that the profile of the carrier ring takes into account the rotation of the flange (deflection under bolt preload). With all other conventional gaskets, when the flange bolts are tightened, the flange deflects radially under load, resulting in the greatest gasket compression, and greatest gasket tension, at the outer edge of the gasket.

Since the carrier ring used in constant seating tension gaskets takes this deviation into account when creating the carrier ring for a given flange size, pressure class, and material, the profile of the carrier ring can be adjusted to allow the seating stress of the gasket to be radially uniform across the sealing area. Furthermore, since the sealing elements are completely confined by the flange faces in opposing channels in the carrier ring, any in-service compressive force acting on the gasket is transmitted through the carrier ring and prevents any further compression of the sealing elements, thus maintaining a "constant" gasket seating stress while in service. In this way, the joint is immune to common joint failure modes, which include creep relaxation, high system vibrations or system thermal cycling.

The fundamental concept behind improving the sealing ability of constant seating tension gaskets is that (i) if the sealing surfaces of the flange are capable of achieving a seal, (ii) the sealing elements are compatible with the process fluid and application, and (iii) sufficient gasket seating tension is achieved in the installation necessary to achieve a seal, then the possibility of the gasket leaking in service is greatly reduced or eliminated entirely.

Double sleeve gaskets

Double jacket gaskets are another combination of filler material and metallic materials. In this application, a tube is made with ends that resemble a metal "C" with an additional piece made to fit inside the "C" making the tube thicker at the meeting points. Putty is pumped between the casing and the part. When used, the compressed gasket has a greater amount of metal at the two tips where contact occurs (due to the interaction between the shell and the part) and these two places carry the load of the sealing process. Since all that is needed is a shell and a part, these gaskets can be made from almost any material that can be made into sheet form and then a filler can be inserted.[6]​.

Kamm profile joints

Kammprofile gaskets (sometimes spelled Camprofile)[7]​ are used in many older gaskets as they have both a flexible nature and reliable performance. Kammprofiles work by having a solid corrugated core with a flexible covering layer. This arrangement allows for very high compression and an extremely tight seal along the ridges of the gasket. Since it is usually the graphite that fails rather than the metal core, Kammprofile can be repaired during subsequent downtime. Kammprofile has a high capital cost for most applications, but this is offset by long life and increased reliability.

Fishbone Joints

Fishbone gaskets are direct replacements for Kammprofile and Spiralwound gaskets. They are manufactured entirely on CNC machines from similar materials, but the design of the joints has eliminated the inherent deficiencies. Herringbone joints do not unroll in storage or in the plant. The rounded edges do not cause damage to the flanges. The added "stop step" prevents Fishbone joints from becoming excessively compressed or crushed, which is often caused by hot twisting techniques during plant start-up. The gasket bones remain ductile and adjust to the thermal cycles and pressure peaks of the system, resulting in a durable and reliable flange seal that significantly outperforms all other gaskets of this nature.

flange gasket

A flange joint is a type of joint made to fit between two sections of pipe&action=edit&redlink=1 "Pipe (material) (not yet drafted)") that are flared to provide greater surface area.

Flange gaskets come in a variety of sizes and are classified by their inner diameter and outer diameter.

There are many standards regarding gaskets for pipe flanges. Flange gaskets can be divided into four broad categories:

Sheet Gaskets are simple, cut to size with screw holes or without holes for standard sizes with various thicknesses and materials suitable for the medium pressure and pipe temperature.

Ring Joints are also known as RTJs. They are primarily used in offshore oil and gas pipelines and are designed to work at extremely high pressure. These are solid metal rings with different cross sections, such as oval, round, octagonal, etc. Sometimes they come with a hole in the center for pressure.

Spiral wound gaskets are also used in high pressure pipelines and are manufactured with stainless steel outer and inner rings and a center filled with spiral wound stainless steel tape together with graphite and PTFE, formed into a V shape. Internal pressure acts on the faces of the V, forcing the gasket to seal against the faces of the flange. Most spiral gasket applications use two standard gasket thicknesses: 1/8 inch and 3/16 inch. With 1/8 inch thick joints, it is recommended to compress to a thickness of 0.100 inch. For 3/16 inch, it should be compressed to a thickness of 0.13 inch.

Smooth cutting joint

Soft gasket is a term that refers to a gasket that is cut from a soft (flexible) sheet material and can easily conform to surface irregularities, even when the bolt load is low. Soft gaskets are used in applications such as heat exchanger, compressors, bonnet valves and pipe flanges.

Ring seal (RTJ seal)

The annular joint (RTJ joint) is a high-integrity, high-temperature, high-pressure gasket for applications in the petroleum industry, oilfield drilling, pressure vessel connections, pipelines, valves and more.

Annular packing (RTJ) movement can be described as uneven flow in the deformed sealing flange groove due to axial compression loading. Color gasket (RTJ) has a small loading area, which leads to large surface pressure between the sealing surface and the groove, the maintenance properties are poor and it is not suitable for reuse.

Joint design

Gaskets come in many different designs based on industrial use, budget, chemical contact and physical parameters:

Sheet gaskets

Gaskets can be made by punching&action=edit&redlink=1 "Punch (metal working) (not yet drafted)") into the desired shape from a thin, flat sheet of material, resulting in a sheet gasket. Sheet gaskets are quick and cheap to produce, and can be made from a variety of materials, including fibrous materials and matte graphite (and in the past, compressed asbestos). These gaskets can meet different chemical requirements depending on the chemical inertness of the material used. Asbestos-free gasket sheets are durable, multi-material and thick. Examples of materials are mineral, carbon or synthetic rubbers such as EPDM, nitrile, neoprene, natural, SBR insert - each of which has unique properties suitable for different applications.[3]​ Applications using sheet gaskets involve acids, corrosive chemicals, steam or mild caustics. Flexibility and good recovery prevent breakage during installation of a sheet gasket.[4]​.

Solid material gaskets

The idea behind the solid material is to use metals that cannot be drilled into sheets but are still cheap to produce. These gaskets typically have a much higher level of quality control than sheet metal gaskets and can generally withstand much higher temperatures and pressures. The main drawback is that a solid metal must be highly compressed to sit flush with the flange head to prevent leaks. The choice of material is more difficult; Since primarily metals are used, process contamination and oxidation are risks. An additional drawback is that the metal used must be softer than the flange — in order to ensure that the flange does not deform and thus prevent sealing with future gaskets. Still, these boards have found a niche in the industry.

Spiral wound joints

Spiral wound gaskets comprise a mixture of metallic and filler material.[5] Generally, the gasket has a metal (usually high carbon or stainless steel) wound outward in a circular spiral (other shapes are possible) with the filler material (usually a flexible graphite) wound in the same way but starting from the opposite side. The result is an alternation of layers of filler and metal. The filling material in these joints acts as a sealing element, while the metal provides structural support.

These gaskets have proven to be reliable in most applications, allowing lower clamping forces than solid gaskets, although at a higher cost.

[1].

Constant Seat Tension Joints

The constant seating tension gasket consists of two components: a solid carrier ring of a suitable material, such as stainless steel, and two sealing elements of some compressible material installed within two opposing channels, one channel on each side of the carrier ring. Sealing elements are typically made of a material (expanded graphite, expanded polytetrafluoroethylene (PTFE), vermiculite, etc.) suitable for the process fluid and application.

Constant seat tension joints owe their name to the fact that the profile of the carrier ring takes into account the rotation of the flange (deflection under bolt preload). With all other conventional gaskets, when the flange bolts are tightened, the flange deflects radially under load, resulting in the greatest gasket compression, and greatest gasket tension, at the outer edge of the gasket.

Since the carrier ring used in constant seating tension gaskets takes this deviation into account when creating the carrier ring for a given flange size, pressure class, and material, the profile of the carrier ring can be adjusted to allow the seating stress of the gasket to be radially uniform across the sealing area. Furthermore, since the sealing elements are completely confined by the flange faces in opposing channels in the carrier ring, any in-service compressive force acting on the gasket is transmitted through the carrier ring and prevents any further compression of the sealing elements, thus maintaining a "constant" gasket seating stress while in service. In this way, the joint is immune to common joint failure modes, which include creep relaxation, high system vibrations or system thermal cycling.

The fundamental concept behind improving the sealing ability of constant seating tension gaskets is that (i) if the sealing surfaces of the flange are capable of achieving a seal, (ii) the sealing elements are compatible with the process fluid and application, and (iii) sufficient gasket seating tension is achieved in the installation necessary to achieve a seal, then the possibility of the gasket leaking in service is greatly reduced or eliminated entirely.

Double sleeve gaskets

Double jacket gaskets are another combination of filler material and metallic materials. In this application, a tube is made with ends that resemble a metal "C" with an additional piece made to fit inside the "C" making the tube thicker at the meeting points. Putty is pumped between the casing and the part. When used, the compressed gasket has a greater amount of metal at the two tips where contact occurs (due to the interaction between the shell and the part) and these two places carry the load of the sealing process. Since all that is needed is a shell and a part, these gaskets can be made from almost any material that can be made into sheet form and then a filler can be inserted.[6]​.

Kamm profile joints

Kammprofile gaskets (sometimes spelled Camprofile)[7]​ are used in many older gaskets as they have both a flexible nature and reliable performance. Kammprofiles work by having a solid corrugated core with a flexible covering layer. This arrangement allows for very high compression and an extremely tight seal along the ridges of the gasket. Since it is usually the graphite that fails rather than the metal core, Kammprofile can be repaired during subsequent downtime. Kammprofile has a high capital cost for most applications, but this is offset by long life and increased reliability.

Fishbone Joints

Fishbone gaskets are direct replacements for Kammprofile and Spiralwound gaskets. They are manufactured entirely on CNC machines from similar materials, but the design of the joints has eliminated the inherent deficiencies. Herringbone joints do not unroll in storage or in the plant. The rounded edges do not cause damage to the flanges. The added "stop step" prevents Fishbone joints from becoming excessively compressed or crushed, which is often caused by hot twisting techniques during plant start-up. The gasket bones remain ductile and adjust to the thermal cycles and pressure peaks of the system, resulting in a durable and reliable flange seal that significantly outperforms all other gaskets of this nature.

flange gasket

A flange joint is a type of joint made to fit between two sections of pipe&action=edit&redlink=1 "Pipe (material) (not yet drafted)") that are flared to provide greater surface area.

Flange gaskets come in a variety of sizes and are classified by their inner diameter and outer diameter.

There are many standards regarding gaskets for pipe flanges. Flange gaskets can be divided into four broad categories:

Sheet Gaskets are simple, cut to size with screw holes or without holes for standard sizes with various thicknesses and materials suitable for the medium pressure and pipe temperature.

Ring Joints are also known as RTJs. They are primarily used in offshore oil and gas pipelines and are designed to work at extremely high pressure. These are solid metal rings with different cross sections, such as oval, round, octagonal, etc. Sometimes they come with a hole in the center for pressure.

Spiral wound gaskets are also used in high pressure pipelines and are manufactured with stainless steel outer and inner rings and a center filled with spiral wound stainless steel tape together with graphite and PTFE, formed into a V shape. Internal pressure acts on the faces of the V, forcing the gasket to seal against the faces of the flange. Most spiral gasket applications use two standard gasket thicknesses: 1/8 inch and 3/16 inch. With 1/8 inch thick joints, it is recommended to compress to a thickness of 0.100 inch. For 3/16 inch, it should be compressed to a thickness of 0.13 inch.

Smooth cutting joint

Soft gasket is a term that refers to a gasket that is cut from a soft (flexible) sheet material and can easily conform to surface irregularities, even when the bolt load is low. Soft gaskets are used in applications such as heat exchanger, compressors, bonnet valves and pipe flanges.

Ring seal (RTJ seal)

The annular joint (RTJ joint) is a high-integrity, high-temperature, high-pressure gasket for applications in the petroleum industry, oilfield drilling, pressure vessel connections, pipelines, valves and more.

Annular packing (RTJ) movement can be described as uneven flow in the deformed sealing flange groove due to axial compression loading. Color gasket (RTJ) has a small loading area, which leads to large surface pressure between the sealing surface and the groove, the maintenance properties are poor and it is not suitable for reuse.