To determine surface finish requirements, consult the OEM repair manual. 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. The ring type gaskets shall have a maximum Brinell hardness as specified below: 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. Over 100 years of know-how. 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 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. 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). The fastener size, spacing and retained fastener force produces applied flange pressure to compress and seal the gasket. Either a serrated-concentric or serrated-spiral finish having from 30 to 55 grooves per inch is used. Asbestos shall not be used for non-metallic gaskets or part of metallic gaskets. 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. Flange gasket contact surface finish shall be in accordance with ASME B16.5. or larger radius. Proper surface finish is critical in assuring maximum seal performance and life within a given application. 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. 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. Cometic Gasket, Inc recommends a surface finish of 50RA or smoother for our head gaskets. A surface finish of 1.6mm to 6.3mm Ra (63 to 200 in. It is squeezed between the mating surfaces as they are clamped or bolted together. • If the surface is too smooth, the gasket will have less “grip” and may leak. The flat gasket is the oldest and most popular way to seal a flange or joint. The surface finish that’s required will depend on the type of head gasket. This allows for various grades of surface finish to be made available by flange manufactures for the gasket contact surface of metal flanges. * 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. • If the surface is too rough, the gasket will have a difficult time conforming to surface imperfections and may also leak. Thicker gaskets are usually less resistant to over compression and crushing. Section 6.4.6 addresses acceptable flange facing surface finish imperfections. Surface Finish Requirements. Most of the world’s major automobile manufacturers put their trust in our exceptional quality and reliability. The preferred range has traditionally been 80 to 100 RA. Each of these gasket types require specific ranges of surface finish for optimum gasket performance with lowest leakage. Surface Finish for Static O-Ring Seals. Metallic gaskets require a smoother flange finish than either semi-metallic or nonmetallic. The flange surface area determines the flange pressure distributed across the gasket surface. Facing Material Max. Surface Finish. Any flange surface irregularity and flexibility produce flange contact pressure … FLANGE SURFACE FINISH REQUIREMENTS The ideal flanges surface finish for use with Flexitallic FLEXPRO® gaskets is 125 - 250 m-inch Ra. The picture shows a serrated finish on a Raised Face. Surface roughness can be measured using a profilometer. Kistner: Cometic does not recommend the reuse of any head gasket as there is an issue with trying to define what a use is. 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. Most manufacturers will test with smooth surfaces as well as standard ASME serrated flange finishes. From the first Spiral Wound Gasket … Temperature Seating Stress at Room Temp Min. Most MLS gakets we came across when they first came out, called for a very fine finish. ElringKlinger cylinder-head gaskets. The gasket is stamped, cut, or formed to size from suit-able materials which are often on hand. Flat Ring Gaskets. 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 static sealing and housing surface also has a significant influence on the operation and service life of a seal. The picture shows a serrated finish on a Raised Face. This allows different surface grades to be used with various types of gaskets to ensure a tight flange surface. These figures are good general guidelines, but they do not tell the whole story. The ... the gasket seating surface should be considered acceptable. Flange Facing Types. It is intended for applications for which ASME B16 Standards do not contain complete facing finish requirements. The finish or the condition of the gasket seating surface has a definite effect on the ability of the gasket to create a seal. Surface finishes below 1.6mm are not recommended due to their negative effect on creep resistance of the gasket. • Surface finish can be checked using a surface finish comparator or a profilometer. The company’s story began in 1879, when it started trading in gaskets and other technical products. Depend - ing on the joint requirements, the gasket mate - The picture shows a serrated finish on a Raised Face. of nitrile rubber or Viton is used on the external surfaces as well as between the layers to provide maximum sealing. It also allows a defect in the flange surface finish of between 0.06 and 0.25 inches deep, with the same radial width. 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 … Flange gasket contact surface finish shall be in accordance with ASME B16.5. A thin coating (.001? 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. 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. EngineLabs: What are the drawbacks of reusing MLS head gaskets? psi (Mpa) Max. Unless you are using the factories replacement gasket it is merely useless info. specifically to accommodate the surface finish requirements for each application. This allows for various grades of surface finish to be made available by flange manufactures for the gasket contact surface of metal flanges. 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. 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 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. 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. MLS head gaskets are made of several layers of embossed stainless steel (most are 3 or 4 layers thick, but some have more). 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. This allows for various grades of surface finish to be made available by flange manufactures for the gasket contact surface of metal flanges. 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. This “bite” aids the gasket in resisting the effects of internal pressure, creep and cold flow. Gasket Surface Finish. Different gaskets require different surface finishes, so the surface finish must be matched to the type of gasket that is required for the application. … Also, serrated flanges tend to … Surface for Spiral Wound Gasket. A finish that is too fine or shallow is undesirable, especially on hard gasket materials, because the … Use of asbestos in any form is strictly prohibited. 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. These are some of the common finishes used on raised faces and flat faces. The amount of load required to seal is affected by the surface finish of the joint system. Rescue Gasket, which ensure we are able to continually meet the ever more stringent requirements of our customers. Serrated finish with 30 to 55 groves per inch is used on Raised faces and flat faces a! Tend to … Cometic gasket, Inc recommends a surface finish has a definite effect on the surfaces. 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