Metallic, semi-metallic and nonmetallic gasket materials interact with flange surfaces differently. Also, serrated flanges tend to … specifically to accommodate the surface finish requirements for each application. These figures are good general guidelines, but they do not tell the whole story. The picture shows a serrated finish on a Raised Face. A concentric or spiral serrated finish with 30 to 55 groves per inch and a surface roughness between 125 and 500 microinches. From the first Spiral Wound Gasket … to .0015?) The picture shows a serrated finish on a Raised Face. The ... the gasket seating surface should be considered acceptable. Sheet gasketing is designed to have a seating stress that allows the gasket material to “flow” into the serrations and irregularities of the flange face. Flange gasket contact surface finish shall be in accordance with ASME B16.5. The raised face or flat face shall be furnished with a serrated concentric or serrated spiral finish having a resultant surface roughness from 3.2μm to 6.3μm. To determine surface finish requirements, consult the OEM repair manual. CLA) is possible. MLS head gaskets are made of several layers of embossed stainless steel (most are 3 or 4 layers thick, but some have more). Most manufacturers will test with smooth surfaces as well as standard ASME serrated flange finishes. The cutting tool empolyed has an approximate 0.06 in. This allows different surface grades to be used with various types of gaskets to ensure a tight flange surface. Different gaskets require different surface finishes, so the surface finish must be matched to the type of gasket that is required for the application. Today, ElringKlinger is the leading supplier of cylinder-head gaskets. It is intended for applications for which ASME B16 Standards do not contain complete facing finish requirements. Cometic Gasket, Inc recommends a surface finish of 50RA or smoother for our head gaskets. Metallic gaskets require a smoother flange finish than either semi-metallic or nonmetallic. The flat gasket is the oldest and most popular way to seal a flange or joint. This can either be a contact type, where a stylus measures surface roughness with the results depending on the stylus and scan length, or a non-contact type that uses white-light interferometry to characterize the surface topography in 2D or 3D. Many variables are involved when considering the maximum stress or crush strength of a material, including surface finish, gasket width and thickness, material type and temperature. RTJ gasket Surface Finish Requirements With all metal to metal type seals, it is imperative that the gasket and groove sealing face are free from indentations, score marks, tool/chatter marks and other imperfections. Surface Finish Requirements. The ring type gaskets shall have a maximum Brinell hardness as specified below: The gasket is stamped, cut, or formed to size from suit-able materials which are often on hand. Flange surface finish is a critical aspect of gasket performance. The fastener size, spacing and retained fastener force produces applied flange pressure to compress and seal the gasket. A serrated finish, either concentric or spiral, is required with 30 to 55 grooves per inch and a resultant roughness between 125 and 500 micro inches. CLA) is possible for tongue and groove flange facings or for very thin gaskets (0.4mm or below). Use of asbestos in any form is strictly prohibited. To determine surface finish requirements, consult the OEM repair manual. Over 100 years of know-how. A thin coating (.001? Unless you are using the factories replacement gasket it is merely useless info. Most of the world’s major automobile manufacturers put their trust in our exceptional quality and reliability. `A serrated finish, either concentric or spiral, is required with 30 to 55 grooves per inch and a resultant roughness between 125 and 500 micro inches. Flat Ring Gaskets. It is squeezed between the mating surfaces as they are clamped or bolted together. The resultant surface finish has a 500 microinch (12.5 ㎛) approximate roughness. These are some of the common finishes used on raised faces and flat faces. Fel-Pro gaskets are designed specifically to accommodate the surface finish requirements for each application. The preferred range has traditionally been 80 to 100 RA. Proper surface finish is critical in assuring maximum seal performance and life within a given application. Surface Finish for Static O-Ring Seals. O-Ring Seats or Gasket Areas: Generally, extra steps in die design, die construction and casting production are required for the more exact­ing finishes, and additional cost may be involved. Temperature Seating Stress at Room Temp Min. Section 6.4.6 addresses acceptable flange facing surface finish imperfections. Though the surface finish requirements are not as severe, it is critical to ensure surface finish recommendations are met to maximise seal performance and life. No Asbestos. Different gaskets require different surface finishes, so the surface finish must be matched to the type of gasket that is required for the application. Surface roughness can be measured using a profilometer. b) Spiral Wound Gasketing. For tongue and groove flange facings or for very thin gaskets (0.4mm or below), a surface finish of 1.6mm to 6.3mm Ra (63 to 200 in. It is obvious that from a sealing perspective, a radial flaw extending half or quarter of the way across the gasket seating surface will be detrimental to the joint integrity. Most MLS gakets we came across when they first came out, called for a very fine finish. Fel-Pro gaskets are designed specifically to accommodate the surface finish requirements for each application. The design charts in the sections below indicate a surface roughness value not to exceed 32 micro-inches (32 rms) on the sealing surfaces for static seals with a maximum of 16 rms recommended for face-type gas seals. A surface finish of 1.6mm to 6.3mm Ra (63 to 200 in. Facing Material Max. EngineLabs: What are the drawbacks of reusing MLS head gaskets? Thicker gaskets are usually less resistant to over compression and crushing. The surface finish that’s required will depend on the type of head gasket. The surface finish of a gasket — which consists of grooves or channels pressed or machined onto the outer surface — governs the thickness and compressibility required by the gasket material to form a physical barrier in the clearance gap between the flanges. • If the surface is too smooth, the gasket will have less “grip” and may leak. You need to use the finish recommended by the maker of the gasket you are using. • Surface finish can be checked using a surface finish comparator or a profilometer. Surface Finish in Gasket Sealability Testing • Specifies test platens for sheet gasket sealability (leak rate at load) testing in Section 5.2.4 • Roughness values in units of "uin RMS" • Suggested that this be revised to more common parameter Ra, since use of RMS values has been discontinued and is … Though Ra (Roughness Average) has traditionally been used to describe surface finish, most gasket engineers today say a more accurate perimeter is Rz, which is the average difference between the peak height and valley depth. • If the surface is too rough, the gasket will have a difficult time conforming to surface imperfections and may also leak. Asbestos shall not be used for non-metallic gaskets or part of metallic gaskets. or larger radius. A finish that is too fine or shallow is undesirable, especially on hard gasket materials, because the … The flange surface area determines the flange pressure distributed across the gasket surface. For many years, most aftermarket gasket manufacturers have recommended a head gasket surface finish of 55 to 110 micro-inches RA (roughness average), or 60 to 125 RMS (root mean square). Flange gasket contact surface finish shall be in accordance with ASME B16.5. In respect to surface finish, You can read and follow all the factory published BS you want about resurfaceing heads to a specific finsh. of nitrile rubber or Viton is used on the external surfaces as well as between the layers to provide maximum sealing. This allows for various grades of surface finish to be made available by flange manufactures for the gasket contact surface of metal flanges. And if an engine builders chooses to reuse an MLS gasket, what are warning signs of overuse or damage? Gasket Surface Finish. Flange Facing Types. marks are practically impossible to seal regardless of the type of gasket used. Depend - ing on the joint requirements, the gasket mate - Flexitallic® Safe Over the last century, our aggressive R&D efforts have helped customers become Flexitallic® Safe. ElringKlinger cylinder-head gaskets. Surface Finish Requirements Cross-Section Through C#SC Assembly SPIRAL WOUND GASKET Gasket Description Gasket Cross Section Flange Surface Finish Microinch Ra Flange Surface Finish Micrometer Ra Spiral Wound Gasket 125 - 250 3.2 - 6.3 Kammprofile Gasket 125 - 250 3.2 -6.3 Metal Jacketed Gaskets 100 … The flange facings are machine finished toANSI/ASME B16.5 requirements. MSS SP-6-2017 covers the types of contact faces, such as flat face or ring joint, as well as the contact face materials, including steel, ductile iron, gray iron, and bronze, of pipe flanges. This allows for various grades of surface finish to be made available by flange manufactures for the gasket contact surface of metal flanges. The goal of the designer is to specify surface finishes that are as coarse as possible but will still function within the part’s desired operating parameters. Rescue Gasket, which ensure we are able to continually meet the ever more stringent requirements of our customers. Surface finishes below 1.6mm are not recommended due to their negative effect on creep resistance of the gasket. The finish or the condition of the gasket seating surface has a definite effect on the ability of the gasket to create a seal. Optical and especially components used with X-Rays have some of the finest surface finish requirements achievable. Surface for Spiral Wound Gasket. * Recommended surface roughness of flange sealing surfaces Characteristics and Details In order to avoid damage to the flanges with the metal core of grooved gaskets, they are generally used with layers of graphite, PTFE, aluminium or silver, providing total protection to the flanges and a secure seal even at low minimum surface pressures. The latter two limits correspond, respectively, to defects that are the serration depth and approximately one half of the gasket width for a spiral wound gasket and significantly deeper than the serrations and one quarter of the gasket width for a spiral wound. … Surface Finish. Any flange surface irregularity and flexibility produce flange contact pressure … The static sealing and housing surface also has a significant influence on the operation and service life of a seal. A serrated finish, either concentric or spiral, is required with 30 to 55 grooves per inch and a resultant roughness between 125 and 500 micro inches. The picture shows a serrated finish on a Raised Face. This “bite” aids the gasket in resisting the effects of internal pressure, creep and cold flow. FLANGE SURFACE FINISH REQUIREMENTS The ideal flanges surface finish for use with Flexitallic FLEXPRO® gaskets is 125 - 250 m-inch Ra. The company’s story began in 1879, when it started trading in gaskets and other technical products. psi (Mpa) Max. A serrated finish, either concentric or spiral, is required with 30 to 55 grooves per inch and a resultant roughness between 125 and 500 micro inches. Each of these gasket types require specific ranges of surface finish for optimum gasket performance with lowest leakage. It also allows a defect in the flange surface finish of between 0.06 and 0.25 inches deep, with the same radial width. Kistner: Cometic does not recommend the reuse of any head gasket as there is an issue with trying to define what a use is. This allows for various grades of surface finish to be made available by flange manufactures for the gasket contact surface of metal flanges. Surface finishes below 1.6mm are not recommended due to their negative effect on creep resistance of the gasket. Either a serrated-concentric or serrated-spiral finish having from 30 to 55 grooves per inch is used. The cutting tool employed should have an approximate 1.5 mm or larger radius, and there should be from 1.8 grooves/ mm through 2.2 grooves/ mm. Where gaskets components made from austenitic stainless steel to ASTM A240 Gr 316L are specified, the product shall be in a solution annealed condition, before assembly. The amount of load required to seal is affected by the surface finish of the joint system. 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