Maxiprofile Gasket

From www.gasketwiki.com

A Maxiprofile or Kammprofile is a semi-metallic gasket that can be used for most applications from low to very high pressure. 

Contents 1 How they Work 2 History 3 Design 3.1 Serrated Metal Core 3.2 Compressible Facing Material 4 Materials 4.1 Serrated Metal Core 4.2 Compressible Facing Material 5 Features & Benefits 6 Manufacturing 7 Failure

How they Work

Maxiprofile style gaskets utilize compressible facing material that is secured to a serrated metal core. When the gasket is placed inside an application and loaded, the soft facing material is forced into the serrated grooves of the metal core. The load densifies the facing material within the groove profile and multiple concentric high pressure seals are created across the gasket face.

Unlike spiral wound gaskets, that rely on essentially a single continuous seal from the gasket's inner to outer diameter,  the parallel concentric machined grooves act as separate, independent seals across the gasket sealing face, greatly increasing the joint's reliability. 

History

The Kammprofile gasket was developed within the German market as an alternative to both traditional metal jacketed and spiral wound gaskets. DIN 2697 was developed to standardize the groove cross-section of kammprofile gaskets in 1972, and this original style has been modifed by respective manufacturers to maximize the gasket's performance.The kamprofile gasket offered the advantage of being capable of providing a seal at a relatively low seating stress as well as maintaining a seal under extremely high flange clamping forces. Within the european market, kammprofiles were increasingly used to replace jacketed/clad gaskets is pressuer vessel applications, and are being used to replace spiral wound gaskets in pipeline service.

Design

This type of gasket is comprised of two main components: the serrated metal core and the compressible facing material.

Serrated Metal Core

This component provides the mechanical strength and excellent sealability of the gasket by its many concentric grooves that run along both faces of the core. It is critical that the grooves be of the correct profile depth or it could result in gasket failure or flange damage.

• If the groove profile is too shallow, the facing material would compress inside the grooves with excess material sitting outside. This excess material would be at risk of a blow out since it have no real mechanical strength to hold it in place.
• If the groove profile is too deep, the facing material will fill the groove cavity, but not densify entirely, resulting in the groove peaks coming into direct contact with the flange face, causing flange damage and potential seal failure.

Two fundamental core designs exist for the Maxiprofile: the lateral profile and the convex profile: 

• The lateral profile has a flat profile for the grooved sides of the gasket. It has spreads the stress on the gasket in a uniform manner and is the best choice for most applications.
• The convex profile has a slightly curved profile for the grooved sides of the gasket. This design feature increases the seating stress as the center of the core. This style of Maxiprofile was designed for under-bolted flanges and excessive flange rotation, and is used only for very difficult sealing applications due to its high cost.

The Maxiprofile gasket is available in three common cross-sections, depending on the joint to be sealed:

• The LA1 has the profiled core and a guide ring machined from one piece of metal to form one solid component. This is the common style to seal Raised Face (RF) or Full Face (FF) flanged connections, where the outer ring provides axial alignment to the pipe bore.
• The LA2 is a stand-alone sealing element, one whose axial alignment is provided by a tongue & groove, groove, or male / female flanged connection.  Not recommended for RF or FF flange types due to misalignment issues.
• The LA3 is a profiled-core with a floating guide ring that is conected onto the outside diameter of the core. This style is used in RF and FF flanged connections where the core material is very expensive / hard to machine, and a separate more cost-effective outer ring of a simple structural metal is preferred.  This style is also utilized when differential expansion causes stress across the surface of large diameter gaskets, and allowing fora gap between the thicker sealing element and the thinner outer ring relieves this stress.
  

Compressible Facing Material

The compressive facing material is what provides the sealing action of the Maxiprofile gasket. It is compressed into the concentric grooves of the serrated metal core and forms many regions of high pressure that provide an excellent seal.

Materials

Serrated Metal Core

304 SS
316 SS
347 SS

Compressible Facing Material

Flexible Graphite
Mica
PTFE

Features & Benefits

The Maxiprofile gasket has many features and benefits that make it an excellent option for sealing applications. It has the best seating stress range of any gasket currently available and has the lowest Y Factor of any semi-metallic gasket. Maxiprofile Y = 2,500psi compared to a standard spiral wound gasket Y = 10,000psi and jacketed gaskets Y = 5,500 to 9,000 psi. The upper limit of the seating stress is determined by the compressive strength of the metal core as the graphite material will only compress to a certain amount before it does not further compress. In many cases the fasteners will strip before the gasket is damaged. This type of gasket also has the ability to seal at lower bolt loads than other types of gaskets and will maintain a seal as bolt loads relax after bolt-up or hydrostatic end thrust effect.
The thermal stability of the Maxiprofile is also another important benefit. Once the gasket is compressed, the facing material is entraped within the concentric profiles. This prevents direct access for oxidizing meda to deteriorate the facing material. Compared to a spiral wound gasket, the Maxiprofile loses less graphite volume at high temperature and will maintain thickness and bolt load which extends the maintenance cycle and increases reliability.
An important feature of the Maxiprofile is that the serrated metal core can usually be refurbished if it has not been damanged. The lowered cost of refurbishing the core and replacing the facing material offsets the initial high cost of the gasket with its long term cost savings.

Manufacturing

A blank ring is made from sheet material by using a punch press, water-jet or laser cutting. The ring is then loaded onto a special groove profiler machine that will form the serrations on the core. The compressible filler material is then cut to the exact gasket dimensions and fixed to either side of the serrated metal core.

Failure

Unless if the compressible facing material or steel type of the core was not suitable for the application, these gaskets are not commonly prone to failure.