Gasket Types: SWG, RTJ & Metal

Quick Reference

Five main gasket types: Non-asbestos (soft, low P/T), Spiral wound (SWG, high P/T), Ring joint (RTJ: R/RX/BX styles), Kammprofile, and Jacketed. Standards: ASME B16.20 (metallic), ASME B16.21 (non-metallic).

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Need bolt charts for your gasket installation? Download the ASME B16.5 Bolt Chart for stud bolt dimensions and torque values.

Pipe Gasket and Metal Gasket Types

What Is a Pipe Gasket?

A pipe gasket (also called flange gasket) is a sealing component designed to fit between two sections of pipe that are flanged together. Metal gaskets are used for high-pressure and high-temperature applications, while soft gaskets are suitable for lower service conditions.

Flanges are external or internal ridges that are used for strength or for the attachment of a component, like a pipe. The primary purpose of a flange gasket is to prevent leaks by providing a sealed interface between the two flange faces, ensuring no fluids or gases can escape from the flanged joint.

Gasket to Seal Flanges (Main & Companion)

Main Characteristics of Flange Gaskets

Characteristic	Description
Material Composition	Flange gaskets are made from rubber, non-asbestos synthetic fibers, metal, silicone, PTFE, and graphite. The choice of material depends on fluid type, operating temperature, pressure conditions, and chemical compatibility.
Shape and Size	Typically circular to match flange shape, with bolt holes aligned to the flange pattern. Available in various sizes and thicknesses per ASME B16.5 or EN 1092-1.
Gasket Types	Flat/sheet gaskets (low-pressure), spiral-wound gaskets (high P/T), ring-type joints (high-pressure), cam profile and metal-jacketed gaskets (wide range of temperatures and pressures). All types are reviewed in detail in this article.
Sealing Function	Creates a tight seal between two flange faces, preventing fluid escape and maintaining piping system integrity.
Versatility	Used across oil and gas, chemical processing, power generation, and water treatment in pipelines, tanks, and vessels.
Pressure and Temperature Resistance	Different gasket materials and designs withstand various pressure and temperature levels; correct gasket selection is required for safe operation.

Key Takeaway: Flange gaskets provide leak-free connections between flanged pipe sections. Proper gasket selection and installation maintain operational efficiency, safety, and environmental compliance.

Pro Tip

Store gaskets flat in their original packaging until installation - never hang them on hooks or store them bent. Spiral wound gaskets in particular can develop permanent set if deformed during storage, and that damaged gasket will leak no matter how carefully you torque the bolts.

Classification of flange gasket types

Why Are Gaskets Important in Piping Systems?

Flange gaskets maintain the integrity, safety, and efficiency of piping systems in oil and gas, chemical processing, power generation, and water treatment. They create tight, leak-proof seals between flange connections, enabling safe transport of fluids and gases.

Function	Description
Preventing Leaks	Gaskets prevent hazardous materials from leaking into the environment, protecting ecosystems and reducing accident risks. They maintain pressure and flow characteristics within the system, supporting process efficiency and reliability.
Withstanding Harsh Conditions	Gaskets are designed to withstand operational pressures and temperatures without degradation. Materials are selected for chemical compatibility, preventing breakdown and ensuring long-term sealing performance.
Maintenance and Flexibility	Flange gaskets allow disassembly and reassembly of pipe sections without damage, simplifying routine maintenance and inspections. They also enable the connection of dissimilar materials and easy system modifications.
Reducing Costs	By preventing leaks, gaskets save costs from lost products, environmental fines, and cleanup. The ability to reuse flanges and only replace gaskets during maintenance reduces component replacement expenses.
Improving Performance	Proper gasket selection ensures optimal pressure conditions, enhancing pump and system performance. Some gasket materials also dampen vibrations, reducing noise and wear on components.
Customization and Versatility	Gaskets are available in rubber, PTFE, graphite, and metals for application-specific customization. They can be designed and cut to fit any flange size and shape, supporting both standard and custom applications.

Specifications for Gaskets (ASME/API)

ASME (American Society of Mechanical Engineers) and API (American Petroleum Institute) publish specifications and standards for gaskets used in piping systems, pressure vessels, and related equipment, particularly in the oil, gas, and petrochemical industries. These standards define materials, dimensions, and performance requirements for gaskets under different operational conditions.

The main ASME and API specifications relevant to gaskets are:

ASME Specifications for Gaskets

• ASME B16.20: This standard covers metallic gaskets for pipe flanges in the raised face, flat face, and ring joint configurations. It includes spiral wound gaskets, metal-jacketed gaskets, and ring-type joint gaskets (RTJ). ASME B16.20 specifies dimensions, materials, and application guidelines.

• ASME B16.21: This specification details non-metallic flat gaskets for pipe flanges. It covers materials such as compressed fiber sheets, PTFE, and flexible graphite, providing dimensions and tolerances for various flange sizes and pressure classes.

API Specifications for Gaskets

• API 6A: This specification, titled “Specification for Wellhead and Christmas Tree Equipment,” includes requirements for ring-type joint gaskets used in high-pressure and high-temperature oil and gas production environments. It defines dimensions, materials, and performance criteria for RTJ gaskets.

• API 622: Titled “Type Testing of Process Valve Packing for Fugitive Emissions,” this standard, while focused on valve packing, indirectly affects gasket selection and usage in ensuring low emission levels in valves. It sets testing requirements to evaluate the performance of packing materials under various conditions.

• API 600: While primarily focused on steel gate valves for the petroleum and natural gas industries, API 600 also references gasket dimensions and materials compatible with the valve design standards, highlighting the importance of gasket selection in valve integrity and performance.

The sections below cover the different types of gaskets for flanges used in the oil & gas and processing industries.

Non-Asbestos Gaskets (“Soft”)

What Are Non-Asbestos Gaskets?

Non-asbestos gaskets are, in general terms, sealing devices used between two surfaces to prevent leaks of liquids or gases in various applications, especially in piping (in the context of flanged joints), machinery, and equipment.

The terms, “flat-cut gaskets”, “die-cut gaskets”, “compressed sheet gaskets”, “compressed-fiber gaskets” and “asbestos-free gaskets” are synonyms to define this first type of gaskets for flanges, and can be interchanged.

Asbestos-Free GasketsNon-asbestos gaskets are the simplest type of gasket for flanges and are produced by cutting graphite, organic, or inorganic non-asbestos sheets into a round-gasket shape (generally, with water jet cutting machines). The two main types of non-asbestos gaskets for flanges are the “full face” (FF) for FF flanges and the “flat ring” type for raised face flanges (RF). These two key sub-types are shown in the image below:

In piping systems, non-asbestos gaskets are used in low-pressure, low-temperature, and non-critical applications, i.e. they represent an entry-level alternative.

The ASME B16.21 specification covers non-asbestos sheet gaskets for flanges and flanged joints (types, sheet materials, dimensions, dimensional tolerances, and marking requirements).

Non-asbestos gaskets are designed to replace asbestos-containing gaskets, which were widely used in the past due to their durability, heat resistance, and sealing capabilities but have since been phased out (in the 70s) due to health risks associated with asbestos exposure, including respiratory issues and serious illnesses like asbestosis and mesothelioma.

Composition and Features:

Non-asbestos gaskets are made from a combination of synthetic fibers, such as Aramid (a strong and heat-resistant synthetic fiber), fiberglass, and elastomeric materials like nitrile rubber, EPDM, or Neoprene. These components are mixed and bound together to create a sheet material that can be cut and shaped into gaskets. The specific composition of a non-asbestos gasket can vary depending on the manufacturer and the intended application, allowing for customization to meet different sealing requirements.

Advantages:

• Health and Safety: The primary advantage of non-asbestos gaskets is their safety; they do not pose the health risks associated with asbestos fibers.
• Versatility: These gaskets can be engineered for specific applications, with resistance to different chemicals, temperatures, and pressures.
• Durability: Non-asbestos gaskets are designed to be durable and withstand harsh operational conditions, similar to their asbestos counterparts.
• Environmental Compliance: Using non-asbestos materials aligns with global regulations and standards aimed at reducing health risks and environmental impact.

Applications:

Non-asbestos gaskets are used in a variety of settings, including:

• Piping Systems: For sealing flanges in water, gas, and chemical pipelines.
• Automotive Industry: In engines, transmissions, and other systems requiring durable seals.
• Industrial Machinery: For sealing joints in pumps, valves, and other equipment.
• HVAC Systems: In heating, ventilation, and air conditioning units to prevent leaks.

Selection Criteria:

When selecting a non-asbestos gasket, consider:

• Operating Temperature and Pressure: Ensure the gasket material can withstand the specific conditions of the application.
• Chemical Compatibility: The gasket material should resist the chemicals it will be exposed to, preventing degradation and failure.
• Compliance and Certifications: Choose gaskets that meet relevant industry standards and certifications for quality and performance.

Common Materials for Soft Gaskets

Non-asbestos gaskets for flanges are made from synthetic materials that provide similar or superior performance to asbestos gaskets without health risks. These materials are selected for their ability to withstand different temperatures, pressures, and chemical exposures.

The most common materials used to manufacture compressed-fiber gaskets are Aramid fibers (Kevlar), Teflon (PTFE), graphite, glass fibers, elastomers, and Neoprene mixed with a multitude of binder materials (the most common binder is NBR, i.e. Buna-N):

Category	Materials
Aramid-based	Aramid + NBR binder, Aramid + SBR binder (premium)
Reinforced	Carbon graphite reinforced, Glass reinforced (steam service)
PTFE variants	PTFE bi-axially oriented (silica filler), PTFE (hollow glass microsphere), PTFE (pigment-free), Expanded PTFE, PTFE joint sealant
PTFE envelope	Slit type, Milled type, Formed type
Elastomers	SBR (styrene-butadiene), CR-chloroprene (Neoprene), EPDM, Fluorocarbon (Viton), BUNA-N (NBR), Hypalon
Graphite	Pure graphite, Graphite + SS316/316L insert
Specialty	MICA sheet, Ceramic fiber

Non-Asbestos Material Properties

The main features of each material class listed above are:

Material	Characteristics	Applications
Aramid Fiber	Known for strength, heat resistance, and durability. Often used as a replacement for asbestos.	Environments with high mechanical stress and where thermal stability is required.
PTFE	Highly resistant to chemicals with very low coefficient of friction. Stable across various temperatures.	Aggressive chemicals (strong acids/bases), food and pharmaceutical industries where cleanliness is critical.
Graphite	Excellent thermal stability, high compressibility, good resistance to most chemicals.	High-temperature applications: exhaust systems, steam services, and fire safety applications.
Fiberglass	Good thermal resistance and tensile strength. Less commonly used alone, often combined with other materials.	High-temperature applications, often in combination with PTFE or graphite.
Composite Materials	Combinations of synthetic fibers, fillers, and rubber binders tailored to specific requirements.	Versatile use across various conditions depending on composition.

Elastomeric Compounds:

Elastomer	Key Properties	Typical Applications
Nitrile Rubber (NBR)	Resistant to oils, fuels, and some chemicals	Oil and hydrocarbon applications
EPDM	Excellent resistance to weathering, ozone, UV, and many chemicals	Water and steam services
Neoprene	Good resistance to oils, chemicals, and flame	Refrigerants and moderate acids

Non-asbestos gaskets can also be coated with graphite, for non-stick and steam resistance, mixed with PTFE for excellent chemical resistance, or with EPDM for potable water applications.

Dimensions

Soft Gaskets for ASME B16.5 Flanges

Non-asbestos gaskets dimensions (for ASME B16.5 FF flanges), in millimeters

NPS	d1 (ID)	Class 150	Class 300	Class 400	Class 600	Class 900
1/2	21	48	54	54	54	64
3/4	27	57	67	67	67	70
1	33	67	73	73	73	79
1 1/4	42	76	83	83	83	89
1 1/2	48	86	95	95	95	98
2	60	105	111	111	111	143
2 1/2	73	124	130	130	130.2	165
3	89	137	149	149	149	168
3 1/2	102	162	165	162	162	-
4	114	175	181	178	194	206
5	141	197	216	213	241	248
6	168	222	251	248	267	289
8	219	279	308	305	321	359
10	273	340	362	359	400	435
12	324	410	422	419	457	498
14	356	451	486	483	492	521
16	406	514	540	537	565	575
18	457	549	597	594	613	638
20	508	606	654	648	683	699
24	610	718	775	768	791	838

All values in millimeters

Soft Gaskets for ASME B16.47 - Series A Flanges

Non-asbestos gaskets dimensions (for ASME B16.47 series A flanges), in millimeters

NPS	d1 (ID)	Class 150	Class 300	Class 400	Class 600
26	660	775	835	832	867
28	711	832	899	892	914
30	762	883	953	946	972
32	813	940	1006	1003	1022
34	864	991	1057	1054	1073
36	914	1048	1118	1118	1130
38	965	1111	1054	1073	1105
40	1016	1162	1114	1127	1156
42	1067	1219	1165	1178	1219
44	1118	1276	1219	1232	1270
46	1168	1327	1273	1289	1327
48	1219	1384	1324	1346	1391
50	1270	1435	1378	1403	1448
52	1321	1492	1429	1454	1499
54	1372	1549	1492	1518	1556
56	1422	1607	1543	1568	1613
58	1473	1664	1594	1619	1664
60	1524	1715	1645	1683	1721

All values in millimeters

Soft Gaskets for ASME B16.47 - Series B Flanges

Non-asbestos gaskets dimensions (for ASME B16.47 series B flanges), in millimeters

NPS	d1 (ID)	Class 150	Class 300	Class 400	Class 600
26	660	725	772	746	765
28	711	776	826	800	819
30	762	827	886	857	879
32	813	881	940	911	933
34	864	935	994	962	997
36	914	987	1048	1022	1048
38	965	1045	1099	-	-
40	1016	1095	1149	-	-
42	1067	1146	1200	-	-
44	1118	1197	1251	-	-
46	1168	1256	1318	-	-
48	1219	1307	1368	-	-
50	1270	1357	1419	-	-
52	1321	1408	1470	-	-
54	1372	1464	1530	-	-
56	1422	1514	1594	-	-
58	1473	1580	1656	-	-
60	1524	1630	1705	-	-

All values in millimeters. Dimensional tolerances:

• For outside diameter NPS 12 and smaller: +0 / -1.5 mm.; NPS 14 and larger: +0 / -3.0 mm.
• For inside diameter NPS 12 and smaller: ± 1.5 mm; NPS 14 and larger: ± 3.0 mm

Spiral Wound Gasket (“SWG”)

What Are Spiral-Wound Gaskets?

A Spiral wound gasket for flanges features a core metal sealing element filled with graphite, PTFE, ceramic fibers, and, or non-asbestos fibers (fillers). For this reason, spiral wound gaskets are classified as “semi-metallic” gaskets.

The metal component of the spiral wound gasket provides strength to the seal, whereas the fillers enhance the gasket’s conformability and resilience. Inner and outer rings can be added to the core sealing element to simplify installation and increase the pressure rating. Spiral wound gaskets with graphite fillers are the most commonly used type.

Spiral wound gaskets withstand higher mechanical stress than soft gaskets in high temperature and high-pressure applications. They are widely used in oil and gas, chemical processing, power generation, and other sectors requiring reliable sealing under demanding conditions. They are particularly suited for:

• Fluctuating pressures and temperatures.
• High-pressure and high-temperature environments.
• Joints requiring high purity or where aggressive chemicals are present.

The structure of SWG gaskets consist of:

• Metallic Outer Ring: Often included as a centering ring, it provides radial strength and centers the gasket within the flange. It also is a compression stop and helps protect the gasket’s inner winding.
• Metallic Windings: Typically made from stainless steel or other alloys, these windings provide structural strength and ensure the gasket’s ability to withstand high pressures and temperatures.
• Filler Material: Sandwiched between the metal windings, common fillers include flexible graphite, PTFE (Polytetrafluoroethylene), or non-asbestos materials. The filler material is selected based on chemical compatibility with the media being sealed and the operational conditions.
• Inner Ring (optional): Used in some designs to prevent inward buckling of the gasket and protect the windings from corrosive or erosive media.

Flexitallic USA introduced spiral wound gaskets in the petrochemical industry back in 1912 to cope with an increasing demand for leak-proof seals in applications with higher and higher (and fluctuating) temperatures and pressures. Other reputable spiral wound gasket manufacturers are Garlock and Lamons. Since then, many manufacturers of SWG has emerged, also in developing countries as India and China.

The diameter of a spiral wound gasket may range between a few mm and up to 5.000 mm, and the typical thicknesses of spiral wound gaskets ranges from 3.2, 4.5, 6.4, to 7.2 mm.

A Spiral wound gasket may be ordered in different shapes, such as oblong, rectangular, oval, pear, and diamond.

ASME B16.20 is the spiral wound gasket specification.

The round type is, of course, the standard shape for the raised face (RF), male-and-female (M&F), and tongue-and-groove flanges (T&G) for petrochemical applications.

Common Mistake

Installing spiral wound gaskets without verifying the inner ring material matches the process fluid. The inner ring contacts the process - using carbon steel inner rings in chloride service will cause rapid corrosion and gasket failure. Always check the color coding or markings to confirm both winding and inner ring materials are correct for your service.

Types of SWG

A few different types of spiral wound gaskets exist, depending on two main construction parameters:

• the number of rings (center, outer and inner rings)
• the materials of the inner and the outer ring of the gasket
• the type of filler material used for the core-ring

A generally accepted taxonomy for SWG comprises the following base-types:

SWG Type	Description
Basic Type	The simplest form, consisting only of the metal spiral and filler material with no metal reinforcement on the inner and outer diameters. Suitable for tongue and groove flanges and some male-female flange arrangements.
With Inner Ring	Includes an inner metal ring that prevents inward buckling, is a heat and corrosion barrier, and ensures the filler material does not contact the process fluid. Used for raised face, male-female, and tongue-and-groove flanges in corrosive media applications.
With Outer Ring (Centering Ring)	Incorporates an outer metal ring as a centering device and compression stop, providing additional radial strength and preventing over-compression. Widely used with raised face flanges for alignment during installation.
With Inner and Outer Rings	Combines both rings: the inner ring protects against inward buckling and media erosion, while the outer ring centers the gasket and acts as a compression limit. Ideal for standard raised face and flat face flanges.
Windings With Metal Strip	Features a metal strip wound together with the filler material for enhanced strength. Less common, but used in extremely high-pressure applications requiring additional mechanical strength.
Specialty Gaskets	Custom-engineered for specific applications, with layers of different metals or fillers to address unique chemical resistance, temperature, or pressure requirements. Designed for particular operational conditions or regulatory compliance.

Based on this basic classification, it is therefore common to see in the catalogs of gaskets manufacturers nomenclatures like:

• Type 00: Spiral Wound Gasket without rings: they are used for tongue and groove, male and female flanges.
• Type 01: Spiral Wound Gasket with inner ring: they are used for male and female or special flange types.
• Type 10: Spiral Wound Gasket with outer ring: they are used for raised face flanges.
• Type 101: Spiral Wound Gasket with inner and outer rings: they are used for raised face flanges.
• Special Section: Spiral Wound Gasket with special rings: they are used for special flanges and special usage.

Each manufacturer, of course, uses specific codes to designate different types of spiral wound gasket in production, but the typical designs are recurring regardless of the producer.

The image shows how the different spiral wound gasket types are used for flanged joints in piping applications:

SWG Materials

Spiral Winding Materials

The sealing element of a spiral wound gasket is produced by interleaving plies of alternating metal winding strips combined with a filler material. The formed metal strip is the primary sealing element of this type of semi-metallic gasket.

The most common winding materials are:

• SS 304L
• SS 316L
• SS 321
• Titanium
• Nickel
• Nickel alloys
• Duplex

Filler Materials

Filler materials are used to enhance the conformability and resilience of a spiral wound gasket. The most used filler material is graphite, however, other filler materials may be used depending on the application:

• Graphite
• PTFE
• Ceramic fibers
• Non-asbestos

Inner and Outer Rings Materials

The inner and outer rings of a spiral wound gasket may be the same material as the winding core or a different one.

Solid inner rings are required by the ASME B16.20 specification for flanges with pressure rating 900# NPS 24 and larger, 1500# NPS 12 and larger, pressure class 2500#, NPS 4 and larger.

The inner ring improves the pressure rating of the spiral wound gasket, as it provides additional compression to the flanged joint and provides a heat and corrosion barrier protecting the gasket windings and the flanges from erosion.

Mechanical Properties by Material

Material	DIN Specification	DIN Material Nr.	AISI/UNS	BS/ASTM	Hardness HV 10	Min Temp (°C)	Max Temp (°C)	Density (g/cm³)
Soft Iron (Armco)	-	1.1003	-	-	90-100	-60	500	7.85
Steel (LCS)	RSt.37.2	1.0038	-	-	100-130	-40	500	7.85
Stainless Steel 304	X5CrNi 18	1.4301	304	304S15/16/31	130-180	-250	550	7.9
Stainless Steel 304L	X2CrNi 189	1.4306	304L	304S11	130-190	-250	550	7.9
Stainless Steel 309	X15CrNiMo 2012	1.4828	309	309S24	130-190	-100	1000	7.9
Stainless Steel 316	X5CrNiMo 1810	1.4401	316	316S31/33	130-180	-100	550	7.9
Stainless Steel 316L	X2CrNiMo 1810	1.4404	316L	316S11/13	130-190	-100	550	7.9
Stainless Steel 316Ti	X10CrNiMoTi 1810	1.4571	316Ti	320S31	130-190	-100	550	7.8
Stainless Steel 321	X10CrNiTi 189	1.4541	321	321S12/49/87	130-190	-250	550	7.9
Stainless Steel 347	X10CrNiNb 189	1.4550	347	347S31	130-190	-250	550	7.9
Nickel 200	Ni 99.2	2.4066	N02200	3072-76 NA11	90-120	-250	600	8.9
Monel 400	NiCu 30 Fe	2.4360	N04400	3072-76 NA13	110-150	-125	600	8.8
Inconel 600	NiCr 15 Fe	2.4816	N06600	3072-76 NA14	120-180	-100	950	8.4
Incoloy 800	X10NiCrAITi 3220	1.4876	N08800	3072-76 NA15	140-220	-100	850	8.4
Incoloy 825	NiCR 21 Mo	2.4858	N08825	3072-76 NA16	120-180	-100	450	8.14
Hastelloy B2	NMo 28	2.4617	N10665	-	170-230	-200	450	9.2
Hastelloy C276	NiMo 16Cr15W	2.4819	N10276	-	170-230	-200	450	8.9
Titanium	Ti 99.8	3.7025	-	-	110-140	-250	500	4.5

Color Coding for SWG

Spiral wound gaskets featuring various combinations of winding and filler materials can be readily identified through standardized color codes. Each material combination is marked with distinct colors: the primary color represents the winding material, while stripes signal the type of filler used.

• Metallic winding materials: the metallic winding material is designated by a solid color identification around the outside edge of the centering, as shown in the image below
• Non-metallic filler color coding: the gasket filler materials are designated by several stripes placed at equal distances around the edge of the centering ring

Color Codes for Winding Materials

Metallic Winding Material for Spiral Wound Gasket	Abbreviated WindingMaterial Name	Color Code
Carbon steel	CRS	Silver
304 SS	304	Yellow
304 L SS	304 L	No color
309 SS	309	No color
316 L SS	316 L	Green
347 SS	347	Blue
321 SS	321	Turquoise
Monel 400	MON	Orange
Nickel 200	NI	Red
Titanium	TI	Purple
Hastelloy B	HAST B	Brown
Hastelloy C	HAST C	Beige

Color Codes for Filler Materials

Polytetrafluoroethylene	PTFE	White stripe
Mica-graphite	Manufacturer’s designation	Pink stripe
Flexible graphite	F.G.	Gray stripe
Ceramic	CER	Light green stripe

Inconel 600	Inconel 600	Gold
Inconel 625	Inconel 625	Gold
Incoloy 800	Incoloy 800 H / HT	White
Incoloy 825	Incoloy 825	White

ASME Marking Requirements for SWG

ASME B16.20 defines specific marking requirements for spiral wound gaskets to ensure proper identification and application. These markings enable correct gasket selection and use in piping systems.

According to ASME B16.20, the following information must be marked directly on the spiral wound gasket or on a tag attached to the gasket:

Required Marking	Purpose
Manufacturer’s Name or Trademark	Identifies the manufacturer, ensuring traceability and accountability.
Gasket Type	Indicates the specific SWG construction and design features.
Nominal Pipe Size and Pressure Class	Confirms the size and pressure rating of the compatible flanges, ensuring system compatibility.
Material Identification	Winding material (e.g., SS, Monel), filler material (e.g., flexible graphite, PTFE), and inner/outer ring material (if applicable) must all be identified.
ASME B16.20 Designation	Confirms the gasket has been manufactured under the ASME B16.20 standard.

Optional or additional markings may include special features or modifications to the standard design, and heat code or lot number for traceability back to the manufacturing batch.

The illustration shows the typical marking of spiral wound gaskets:

Dimensions of SWG

Size of SWG Class 150

Dimensions of class 150 spiral wound gaskets for ASME B16.5 (in mm.)

Spiral wound gasket dimensions

NPS	Inner Ring	Sealing Element	Outer Ring
Inside Diameter (d1)	Inside Diameter (d2)	Outside Diameter(d3)	Outside Diameter (d4)
1/2	14.2	19.1	31.8
3/4	20.6	25.4	39.6
1	26.9	31.8	47.8
1¼	38.1	47.8	60.5
1½	44.5	54.1	69.9
2	55.6	69.9	85.9
2½	66.5	82.6	98.6
3	81	101.6	120.7
4	106.4	127	149.4
5	131.8	155.7	177.8
6	157.2	182.6	209.6
8	215.9	233.4	263.7
10	268.2	287.3	317.5
12	317.5	339.9	374.7
14	349.3	371.6	406.4
16	400.1	422.4	463.6
18	449.3	474.7	527.1
20	500.1	525.5	577.9
24	603.3	628.7	685.8
NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner - and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring
The thickness of the inner and outer ring: 2.97 mm - 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm - 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger.

Size of SWG Class 300

Dimensions of class 300 spiral wound gaskets for ASME B16.5 (in mm.)

Dimensions of spiral wound gaskets

NPS	Inner Ring	Sealing Element	Outer Ring
Inside Diameter (d1)	Inside Diameter (d2)	Outside Diameter (d3)	Outside Diameter (d4)
1/2	14.2	19.1	31.8
3/4	20.6	25.4	39.6
1	26.9	31.8	47.8
1¼	38.1	47.8	60.5
1½	44.5	54.1	69.9
2	55.6	69.9	85.9
2½	66.5	82.6	98.6
3	81	101.6	120.7
4	106.4	127	149.4
5	131.8	155.7	177.8
6	157.2	182.6	209.6
8	215.9	233.4	263.7
10	268.2	287.3	317.5
12	317.5	339.9	374.7
14	349.3	371.6	406.4
16	400.1	422.4	463.6
18	449.3	474.7	527.1
20	500.1	525.6	577.9
24	603.3	628.7	685.8
NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner - and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring
The thickness of the inner and outer ring: 2.97 mm - 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm - 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger.

Size of SWG Class 400

Dimensions of class 400 spiral wound gaskets for ASME B16.5 (in mm.)

Dimensions of spiral wound gasket

NPS	Inner Ring	Sealing Element	Outer Ring
Inside Diameter (d1)	Inside Diameter (d2)	Outside Diameter (d3)	Outside Diameter (d4)
1/2	14.2	19.1	31.8
3/4	20.6	25.4	39.6
1	26.9	31.8	47.8
1¼	38.1	47.8	60.5
1½	44.5	54.1	69.9
2	55.6	69.9	85.9
2½	66.5	82.6	98.6
3	81	101.6	120.7
4	102.6	120.7	149.4
5	128.3	147.6	177.8
6	154.9	174.8	209.6
8	205.7	225.6	263.7
10	255.3	274.6	317.5
12	307.3	327.2	374.7
14	342.9	362	406.4
16	389.9	412.8	463.6
18	438.2	469.9	527.1
20	489	520.7	577.9
24	590.6	628.7	685.8
NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner - and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring
_The thickness of the inner and outer ring: 2.97 mm - 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm - 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger. _

Size of SWG Class 600

Dimensions of class 600 spiral wound gaskets for ASME B16.5 (in mm.)

Dimensions of spiral wound gaskets

| NPS | Inner Ring | Sealing Element | Outer Ring | | -------------------- | -------------------- | --------------------- | --------------------- | ----- | | Inside Diameter (d1) | Inside Diameter (d2) | Outside Diameter (d3) | Outside Diameter (d4) | | 1/2 | 14.2 | 19.1 | 31.8 | 54.1 | | 3/4 | 20.6 | 25.4 | 39.6 | 66.8 | | 1 | 26.9 | 31.8 | 47.8 | 73.2 | | 1¼ | 38.1 | 47.8 | 60.5 | 82.6 | | 1½ | 44.5 | 54.1 | 69.9 | 95.3 | | 2 | 55.6 | 69.9 | 85.9 | 111.3 | | 2½ | 66.5 | 82.6 | 98.6 | 130.3 | | 3 | 78.7 | 101.6 | 120.7 | 149.4 | | 4 | 102.6 | 120.7 | 149.4 | 193.8 | | 5 | 128.3 | 147.6 | 177.8 | 241.3 | | 6 | 154.9 | 174.8 | 209.6 | 266.7 | | 8 | 205.7 | 225.6 | 263.7 | 320.8 | | 10 | 255.3 | 274.6 | 317.5 | 400.1 | | 12 | 307.3 | 327.2 | 374.7 | 457.2 | | 14 | 342.9 | 362 | 406.4 | 492.3 | | 16 | 389.9 | 412.8 | 463.6 | 565.2 | | 18 | 438.2 | 469.9 | 527.1 | 612.9 | | 20 | 489 | 520.7 | 577.9 | 682.8 | | 24 | 590.6 | 628.7 | 685.8 | 790.7 |

NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner - and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring The thickness of the inner and outer ring: 2.97 mm - 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm - 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger.

Size of SWG Class 900

Dimensions of class 900 spiral wound gaskets for ASME B16.5 (in mm.)

Dimensions of spiral wound gaskets

NPS	Inner Ring	Sealing Element	Outer Ring
Inside Diameter (d1)	Inside Diameter (d2)	Outside Diameter(d3)	Outside Diameter (d4)
1/2	14.2	19.1	31.8
3/4	20.6	25.4	39.6
1	26.9	31.8	47.8
1¼	33.3	39.6	60.5
1½	41.4	47.8	69.9
2	52.3	58.7	85.9
2½	63.5	69.9	98.6
3	78.7	95.3	120.7
4	102.6	120.7	149.4
5	128.3	147.6	177.8
6	154.9	174.8	209.6
8	196.9	222.3	257.3
10	246.1	276.4	311.2
12	292.1	323.9	368.3
14	320.8	355.6	400.1
16	374.7	412.8	457.2
18	425.5	463.6	520.7
20	482.6	520.7	571.5
24	590.6	628.7	679.5
NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner - and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring
The thickness of the inner and outer ring: 2.97 mm - 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm - 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger.

Size of SWG Class 1500

Dimensions of class 1500 spiral wound gaskets for ASME B16.5 (in mm.)

Dimensions of spiral wound gaskets

| NPS | Inner Ring | Sealing Element | Outer Ring | | -------------------- | -------------------- | -------------------- | --------------------- | ----- | | Inside Diameter (d1) | Inside Diameter (d2) | Outside Diameter(d3) | Outside Diameter (d4) | | 1/2 | 14.2 | 19.1 | 31.8 | 63.5 | | 3/4 | 20.6 | 25.4 | 39.6 | 69.9 | | 1 | 26.9 | 31.8 | 47.8 | 79.5 | | 1¼ | 33.3 | 39.6 | 60.5 | 88.9 | | 1½ | 41.4 | 47.8 | 69.9 | 98.6 | | 2 | 52.3 | 58.7 | 85.9 | 143 | | 2½ | 63.5 | 69.9 | 98.6 | 165.1 | | 3 | 78.7 | 92.2 | 120.7 | 174.8 | | 4 | 97.8 | 117.6 | 149.4 | 209.6 | | 5 | 124.5 | 143 | 177.8 | 254 | | 6 | 147.3 | 171.5 | 209.6 | 282.7 | | 8 | 196.9 | 215.9 | 257.3 | 352.6 | | 10 | 246.1 | 266.7 | 311.2 | 435.1 | | 12 | 292.1 | 323.9 | 368.3 | 520.7 | | 14 | 320.8 | 362 | 400.1 | 577.9 | | 16 | 374.7 | 406.4 | 457.2 | 641.4 | | 18 | 425.5 | 463.6 | 520.7 | 704.9 | | 20 | 476.3 | 514.4 | 571.5 | 755.7 | | 24 | 577.9 | 616 | 679.5 | 901.7 |

NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner - and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring

The thickness of the inner and outer ring: 2.97 mm - 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm - 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger.

Size of SWG Class 2500

Dimensions of class 2500 spiral wound gaskets for ASME B16.5 (in mm.)

Dimensions of spiral wound gaskets

| NPS | Inner Ring | Sealing Element | Outer Ring | | -------------------- | -------------------- | -------------------- | --------------------- | ----- | | Inside Diameter (d1) | Inside Diameter (d2) | Outside Diameter(d3) | Outside Diameter (d4) | | 1/2 | 14.2 | 19.1 | 31.8 | 69.9 | | 3/4 | 20.6 | 25.4 | 39.6 | 76.2 | | 1 | 26.9 | 31.8 | 47.8 | 85.9 | | 1¼ | 33.3 | 39.6 | 60.5 | 104.9 | | 1½ | 41.4 | 47.8 | 69.9 | 117.6 | | 2 | 52.3 | 58.7 | 85.9 | 146 | | 2½ | 63.5 | 69.9 | 98.6 | 168.4 | | 3 | 78.7 | 92.2 | 120.7 | 196.9 | | 4 | 97.8 | 117.6 | 149.4 | 235 | | 5 | 124.5 | 143 | 177.8 | 279.4 | | 6 | 147.3 | 171.5 | 209.6 | 317.5 | | 8 | 196.9 | 215.9 | 257.3 | 387.4 | | 10 | 246.1 | 270 | 311.2 | 476.3 | | 12 | 292.1 | 317.5 | 368.3 | 549.4 |

NOTES: • All dimensions are in millimeters • Spiral Wound gasket with Inner - and Outer ring • d1 = Inside diameter Inner ring. • d2 = Inside diameter sealing element when no Inner ring is used. • d3 = Outside diameter of sealing element. • d4 = Outside diameter of an Outer ring The thickness of the inner and outer ring: 2.97 mm - 3.33 mm. • Thickness sealing element: 4.45 mm. • Tolerance Outside diameter for NPS 1/2 through NPS 8 is ± 0.8 mm; for NPS 10 through NPS 24 tolerance is + 1.5 mm - 0.8 mm. • There is no class 400 flanges NPS 1/2 thru NPS 3 (use Class 600), class 900 flanges NPS 1/2 thru NPS 2½ (use Class 1500), or class 2500 flanges NPS 14 or larger.

Ring Joint Gaskets Style R, RX, BX (“RTJ”)

What Is a Ring Joint Gasket?

A ring joint gasket (RTJ) is a metal gasket designed for high-pressure and high-temperature applications in the oil, gas, petrochemical, and offshore industries. RTJ gaskets seal flanged connections subjected to extreme conditions where conventional gaskets would fail. They are used with ring-type joint (RTJ) flanges, which have grooves cut into their faces to accommodate the gasket.

Ring joint gaskets come in oval and octagonal cross-sections (the most common shapes), plus BX and RX styles designed for specific RTJ flanges and pressures. They are made from soft iron, stainless steel, Hastelloy, Inconel, and Monel, selected based on temperature, pressure, and chemical compatibility.

A Ring Joint Gasket provides a strong metal-to-metal seal between two mating RTJ flanges. As the flanges are bolted, the softer material of the ring joint gasket is “squeezed” into the flange grooves (made of a harder material) and seals the connection tightly. RTJ gaskets are available in three styles: R (oval, octagonal), RX, and BX.

RTJ gaskets provide a durable seal for flanges, valves, piping spools, and vessels at high pressures and temperatures typical of petrochemical processes. They offer a high-integrity metal-to-metal seal that withstands significant pressure variations and vibrations, excellent temperature and pressure resistance, and potential reusability provided the gasket is undamaged and correctly reinstalled.

RTJ gaskets are available in different designs (called “styles”) and dimensions, as illustrated in the picture below (BX, R, and BX).

RTJ Gaskets Types

R Type Ring Joint Gasket (Oval and Octagonal)

“Style R” is the most common RTJ gasket type. R-type ring joint gaskets are available in oval or octagonal cross-sections and manufactured according to API 6A and ASME B16.20 to suit API 6B and ASME/ANSI B16.5 flanges.

This type of RTJ gasket is machined to tight manufacturing tolerances to ensure correct installation with standard ASME B16.5 and API 6B ring joint faced flanges. “R style” oval and octagonal RTJ gaskets can seal pressures up to 6.250 psi by ASME B16.20 and up to 5.000 psi according to the API 6A pressure ratings.

Type R RTJ gaskets are frequently used for valve covers.

Style RX RTJ Gasket

The RX-type RTJ gasket is manufactured according to API 6A and ASME B16.20 to suit API 6B and ASME/ANSI B16.5 flanges.

The RX is a pressure-energized version of the R octagonal gasket and fits the R-type flat-bottomed groove.

The RX has an increased height and utilizes the internal system pressure to energize and improve the seal as internal pressure increases.

Some RX sizes have a pressure relief hole to equalize pressure on both sides of the sealing faces.

Style BX RTJ Gasket

The BX-type RTJ gaskets are manufactured according to API 6A and are suitable for use in high-pressure API 6BX flanges.

The gaskets form a metal-to-metal seal on assembly and the efficiency improves as internal pressure increases.

All BX sizes have a pressure relief hole to equalize pressure across sealing faces.

RTJ Gasket Materials

The material of RTJ gaskets shall match the material of the flange but must have a lower hardness: this is to ensure that the gasket, and not the flange, gets plastically deformed within the groove of the flange as the two mating flanges are bolted together.

In case a harder material for the ring-type joint is used, the groove of the flange would be damaged as the flanges are tightened (the hardness values for ring joint gaskets are given below).

Field Note

Always inspect RTJ flange grooves before installing a new gasket - even minor nicks, corrosion pits, or scratches in the groove will cause leaks regardless of how much you torque the bolts. Run your fingernail across the sealing surface; if you can feel any defect, the groove needs machining or the flange needs replacement. And never reuse an RTJ gasket - they’re designed to deform once.

Types of Materials for Ring Joint Gaskets

RTJ GASKET MATERIAL	RING ID	ASTM GRADE	DIN GRADE	WKSTOFF NUMBER	AISIGRADE	BSGRADE	OTHER SPECS
Soft Iron	D			1.1003 / 1.0335			Aramco / StW24
LCS	S			1.1003 / 1.0335			Aramco / StW24
CS360 LT	CS360LT	A516 Gr70
4140	4140	UNS G41400	42CrMo4	1.7225	4140
F5	F5	UNS K42544	12CrMo195	1.7362			5Cr 1/2Mo
SS304	S304	S30400	X5CrNi 18 9	1.4301	304	304S15
SS304L	S304L	S30403	X2CrNi 18 9	1.4306	304L	304SS12
SS309	S309	S30900	X15CrNiSi2012	1.4828	309	309S24
SS310	S310	S31008	XX15CrNiSi2520	1.4841	310	310S24
SS316	S316	S31600	X5CrNiMo18 10	1.4401	316	316S16
SS316L	S316L	S31603	X2CrNiMo18 10	1.4404	316L	316S11/316S12
SS316L UREA	S316UG	S31603	X2CrNiMo 18 14 3	1.4435
SS316Ti	S316Ti	S31635	X10CrNiMoTi1810	1.4571	316Ti	320S31/320S17
SS321	S321	S32100	X10CrNiTi18 9	1.4541	321	321S12
SS347	S347	S34700	X10CrNiNb 18 9	1.455	347	347S51
SS410	S410	S41000	X10Cr13	1.4006	410	410S21
Monel 400	Monel400	N04400	NiCu30Fe	2.436
Inconel 600	INC600	N06600	NiCr15Fe	2.4816
Inconel 625	INC625	N06625	NiCr22Mo9Nb	2.4856
Inconel 718	INC718	N07718
Incoloy 800	INC800	N08800	X5NiCrAlTi31-20	1.4958
Incoloy 800H	INC800H	N08810		1.4958
Incoloy 825	INC825	N08825	NiCr21Mo	2.4858
904L	904L	N08904	X1NiCrMoCu25-20-5	1.4539
F51	F51	S31803	X2CrNiMoN22-5-3	1.4462			2205 /Duplex
F53	F53	S32750	X2CrNiMoN25-7-4	1.441
F55	F55	S32760	X2CrNiMoCuWN 25 7 4	1.4501			Zeron 100
F60	F60	S32205					Duplex
Titanium	Ti	R 50400		3.7035
17-4PH	17-4PH	S17400		1.4542			630
S254	S254	S31254	X1CrNiMoCuN20-18-7	1.4547			F44 / 6Mo
C276	C276	N10276	NiMo16Cr15W	2.4819			Hastelloy
Alloy 28	Alloy28	N08028	X1 NiCrMoCuN 31 27 4	1.4563			SANICRO 28

Mechanical Properties Ring Joint Gaskets Materials

| | Maximum Hardness of RTJ Gaskets | | | ---------------------- | ------------------------------- | --- | ---- | | RTJ Gasket Material | Brinell | HRB | ID | | Soft Iron-S | 90 | 56 | D | | Low Carbon Steel | 120 | 68 | S | | 4 - 6% Chrome1/2% Moly | 130 | 72 | F5 | | SS 304 Stainless Steel | 160 | 83 | S304 | | SS 316 Stainless Steel | 160 | 83 | S316 | | SS 347 Stainless Steel | 160 | 83 | S347 | | SS 410 Stainless Steel | 170 | 96 | S410 |

RTJ Gasket Dimensions (ASME B16.20)

Style R Ring Joint Gaskets Dimensions (for ASME B16.5 flanges)

| RTJ GASKET RING NUMBER | Diameter P | Width A | Height | Oct C | Oct R1 | NPS / CLASS | | ---------------------- | ---------- | ------- | ------ | ----- | ------ | ----------- | ------------------- | | Oval B | Oct H | | R 11 | 34.14 | 6.35 | 11.2 | 9.7 | 4.32 | 1.5 | 1/2300 / 600 | | R 12 | 39.7 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 1/2900 / 1500 | | R 13 | 42.88 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 3/4300 / 6001/22500 | | R 14 | 44.45 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 3/4900 / 1500 | | R 15 | 47.63 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 1150 | | R 16 | 50.8 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 1300 / 15003/42500 | | R 17 | 57.15 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 1¼150 | | R 18 | 60.33 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 1¼300 / 150012500 | | R 19 | 65.1 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 1½150 | | R 20 | 68.28 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 1½300 / 1500 | | R 21 | 72.24 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 1¼2500 | | R 22 | 82.55 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 2150 | | R 23 | 82.55 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 2300 6001½2500 | | R 24 | 95.25 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 2900 / 1500 | | R 25 | 101.6 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 2½150 | | R 26 | 101.6 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 2½300/ 60022500 | | R 27 | 107.95 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 2½900 / 1500 | | R 28 | 111.13 | 12.7 | 19.1 | 17.5 | 8.66 | 1.5 | 2½2500 | | R 29 | 114.3 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 3150 | | R 30* | 117.48 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 3300 / 600 | | R 31 | 123.83 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 3300 / 900 | | R 32 | 127 | 12.7 | 19.1 | 17.5 | 8.66 | 1.5 | 32500 | | R 33 | 131.78 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 3½150 | | R 34 | 131.78 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 3½300 / 600 | | R 35 | 136.53 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 31500 | | R 36 | 149.23 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 4150 | | R 37 | 149.23 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 4300 / 900 | | R 38 | 157.18 | 15.88 | 22.4 | 20.6 | 10.49 | 1.5 | 42500 | | R 39 | 161.93 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 41500 | | R 40 | 171.45 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 5150 | | R 41 | 180.98 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 5300 / 900 | | R 42 | 190.5 | 19.05 | 25.4 | 23.9 | 12.32 | 1.5 | 52500 | | R 43 | 193.68 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 6150 | | R 44 | 193.68 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 51500 | | R 45 | 211.15 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 6300 / 900 | | R 46 | 211.15 | 12.7 | 19.1 | 17.5 | 8.66 | 1.5 | 61500 | | R 47 | 228.6 | 19.05 | 25.4 | 23.9 | 12.32 | 1.5 | 62500 | | R 48 | 247.65 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 8150 | | R 49 | 269.88 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 8300 / 900 | | R 50 | 269.88 | 15.88 | 22.4 | 20.6 | 10.49 | 1.5 | 81500 | | R 51 | 279.4 | 22.23 | 28.7 | 26.9 | 14.81 | 1.5 | 82500 | | R 52 | 304.8 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 10150 | | R 53 | 323.85 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 10300 900 | | R 54 | 323.85 | 15.88 | 22.4 | 20.6 | 10.49 | 1.5 | 101500 | | R 55 | 342.9 | 28.58 | 36.6 | 35.1 | 19.81 | 2.3 | 102500 | | R 56 | 381 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 12150 | | R 57 | 381 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 12300 900 | | R 58 | 381 | 22.23 | 28.7 | 26.9 | 14.81 | 1.5 | 121500 | | R 59 | 396.88 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 14150 | | R 60 | 406.4 | 31.75 | 39.6 | 38.1 | 22.33 | 2.3 | 122500 | | R 61 | 419.1 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 14300 600 | | R 62 | 419.1 | 15.88 | 22.4 | 20.6 | 10.49 | 1.5 | 14900 | | R 63 | 419.1 | 25.4 | 33.3 | 31.8 | 17.3 | 2.3 | 141500 | | R 64 | 454.03 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 16150 | | R 65 | 469.9 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 16300 600 | | R 66 | 469.9 | 15.88 | 22.4 | 20.6 | 10.49 | 1.5 | 16900 | | R 67 | 469.9 | 28.58 | 36.6 | 35.1 | 19.81 | 2.3 | 161500 | | R 68 | 517.53 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 18150 | | R 69 | 533.4 | 11.13 | 17.5 | 16 | 7.75 | 1.5 | 18300 600 | | R 70 | 533.4 | 19.05 | 25.4 | 23.9 | 12.32 | 1.5 | 18900 | | R 71 | 533.4 | 28.58 | 36.6 | 35.1 | 19.81 | 2.3 | 181500 | | R 72 | 558.8 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 20150 | | R 73 | 584.2 | 12.7 | 19.1 | 17.5 | 8.66 | 1.5 | 20300 600 | | R 74 | 584.2 | 19.05 | 25.4 | 23.9 | 12.32 | 1.5 | 20900 | | R 75 | 584.2 | 31.75 | 39.6 | 38.1 | 22.33 | 2.3 | 201500 | | R 76 | 673.1 | 7.95 | 14.2 | 12.7 | 5.23 | 1.5 | 24150 | | R 77 | 692.15 | 15.88 | 22.4 | 20.6 | 10.49 | 1.5 | 24300 600 | | R 78 | 692.15 | 25.4 | 33.3 | 31.8 | 17.3 | 2.3 | 24900 | | R 79 | 692.15 | 34.93 | 44.5 | 41.4 | 24.82 | 2.3 | 241500 |

Style R Ring Joint Gaskets Dimensions (for ASME B16.47 Series A flanges)

| RTJ GASKET RING NUMBER | DiaP | WidthA | Height | OctC | OctR1 | NPSCLASS | | ---------------------- | ------- | ------ | ------ | ---- | ----- | -------- | --------- | | OvalB | OctH | | R 93 | 749.3 | 19.05 | … | 23.9 | 12.32 | 1.5 | 26300 600 | | R 94 | 800.1 | 19.05 | … | 23.9 | 12.32 | 1.5 | 28300 600 | | R 95 | 857.25 | 19.05 | … | 23.9 | 12.32 | 1.5 | 30300 600 | | R 96 | 914.4 | 22.23 | … | 26.9 | 14.81 | 1.5 | 32300 600 | | R 97 | 965.2 | 22.23 | … | 26.9 | 14.81 | 1.5 | 34300 600 | | R 98 | 1022.35 | 22.23 | … | 26.9 | 14.81 | 1.5 | 36300 600 | | R 100 | 749.3 | 28.58 | … | 35.1 | 19.81 | 2.3 | 26900 | | R 101 | 800.1 | 31.75 | … | 38.1 | 22.33 | 2.3 | 28900 | | R 102 | 857.25 | 31.75 | … | 38.1 | 22.33 | 2.3 | 30900 | | R 103 | 914.4 | 31.75 | … | 38.1 | 22.33 | 2.3 | 32900 | | R 104 | 965.2 | 34.93 | … | 41.4 | 24.82 | 2.3 | 34900 | | R 105 | 1022.35 | 34.93 | … | 41.4 | 24.82 | 2.3 | 36900 |

Style RX Ring Joint Gaskets Dimensions

RTJ GASKET RING NUMBER	720-960	2900#	3000#	5000#	OD	HEIGHT	WIDTH	GASKET Wt. ( kg )
RX20	1 ½	-	1 ½	1 ½	76.2	19.05	8.74	0.24
RX23	2, 2 1/16	-	93.27	25.4	11.91	0.52
RX24	-	-	2, 2 1/16	2, 2 1/16	105.97	25.4	11.91	0.6
RX25	-	-	-	3 1/8	109.55	19.05	8.74	0.5
RX26	2 ½ , 2 9/16	-	-	-	111.91	25.4	11.91	0.64
RX27	-	-	2 ½, 2 9/16	2 ½, 2 9/16	118.26	25.4	11.91	0.68
RX31	3 , 3 1/8	-	3, 3 1/8	134.54	25.4	11.91	0.78
RX35	-	-	-	3, 3 1/8	147.24	25.4	11.91	0.86
RX37	4 , 4 1/16	-	4, 4 1/16	-	159.94	25.4	11.91	0.95
RX39	-	-	-	4, 4 1/16	172.64	25.4	11.91	1.03
RX41	5, 5 1/8	-	5, 5 1/8	-	191.69	25.4	11.91	1.15
RX44	-	-	-	5, 5 1/8	204.39	25.4	11.91	1.23
RX45	6, 7 1/16	-	6, 7 1/16	-	221.84	25.4	11.91	1.34
RX46	-	-	-	6, 7 1/16	222.25	28.58	13.49	1.66
RX47	-	-	-	8	245.26	41.28	19.84	3.88
RX49	8, 9	-	8, 9	280.59	25.4	11.91	1.72
RX50	-	-	-	8, 9	283.36	31.75	16.66	2.43
RX53	10, 11	-	10, 11	334.57	25.4	11.91	2.06
RX54	-	-	-	10, 11	337.34	31.75	16.66	2.92
RX57	12, 13 5/8	-	12, 13 5/8	391.72	25.4	11.91	2.42
RX63	-	-	14	441.73	50.8	27	11.96
RX65	16, 16 3/4	-	-	-	480.62	25.4	11.91	3
RX66	-	-	16, 16 3/4	-	457.99	31.75	16.66	4.25
RX69	18	-	544.12	25.4	11.91	3.41
RX70	-	-	18	-	550.06	41.28	19.84	9.12
RX73	20, 21 1/4	-	-	-	596.11	31.75	13.49	5.27
RX74	-	-	20, 20 3/4	-	600.86	41.28	19.84	10.01
RX82	-	1	-	-	67.87	25.4	11.91	0.36
RX84	-	1 ½	-	-	74.22	25.4	11.91	0.4
RX85	-	2	-	-	90.09	25.4	13.49	0.4
RX86	-	2 ½	-	-	103.58	28.58	15.09	0.81
RX87	-	3	-	-	113.11	28.58	15.09	0.9
RX88	-	4	-	-	139.29	31.75	17.48	1.46
RX89	-	3 ½	-	-	129.77	31.75	18.26	3.09
RX90	-	5	-	-	174.63	44.45	19.84	7.75
RX91	-	10	-	-	286.94	45.24	30.18	1.5
RX99	8	-	8	-	245.67	25.4	11.91	2.2
RX201	-	-	-	1 3/8	51.46	11.3	5.74	0.1
RX205	-	-	-	1 13/16	62.31	11.1	5.56	0.13
RX210	-	-	-	2 9/16	97.64	19.05	9.53	0.35
RX215	-	-	-	4 1/16	140.89	25.4	11.91	0.8

Style BX Ring Joint Gaskets Dimensions

RTJ GASKET RING NUMBER	2000#	3000#	5000#	10000#	15000#	20000#	OUTSIDE DIA	HEIGHT OF THE RING	WIDTH OF THE RING	RTJ GASKET WEIGHT KG
BX 150	-	-	-	1 11/16	1 11/16	-	72.19	9.3	9.3	0.13
BX 151	-	-	-	1 13/16	1 13/16	1 13/16	76.4	9.63	9.63	0.15
BX 152	-	-	-	2 1/16	2 1/16	2 1/16	84.68	10.24	10.24	0.19
BX 153	-	-	-	2 9/16	2 9/16	2 9/16	100.94	11.38	11.38	0.29
BX 154	-	-	-	3 1/16	3 1/16	3 1/16	116.84	12.4	12.4	0.4
BX 155	-	-	-	4 1/16	4 1/16	4 1/16	147.96	14.22	14.22	0.55
BX 156	-	-	-	7 1/16	7 1/16	7 1/16	237.92	18.62	18.62	1.87
BX 157	-	-	-	9	9	9	294.46	20.98	20.98	2.97
BX 158	-	-	-	11	11	11	352.04	23.14	23.14	4.35
BX 159	-	-	-	13 5/8	-	-	426.72	25.7	25.7	6.53
BX 160	-	-	13 5/8	-	-	-	402.59	23.83	13.74	3.06
BX 161	-	-	16 ¾	-	-	-	491.41	28.07	16.21	5.35
BX 162	-	-	16 3/4	16 3/4	16 3/4	-	475.49	14.22	14.22	1.94
BX 163	-	-	18 3/4	-	-	-	556.16	30.1	17.37	6.9
BX 164	-	-	-	18 3/4	18 3/4	-	570.56	30.1	24.59	5.86
BX 165	-	-	21 ¼	-	-	-	624.71	32.03	18.49	8.76
BX 166	-	-	-	21 ¼	-	-	640.03	32.03	26.14	12.82
BX 167	26 3/4	-	-	-	-	-	759.36	35.86	13.11	8.53
BX 168	-	26 3/4	-	-	-	-	765.25	35.86	16.05	10.54
BX 169	-	-	-	5 1/8	-	-	173.51	15.85	12.93	0.73
BX 170	-	-	-	6 5/8	6 5/8	-	218.03	14.22	14.22	1.03
BX 171	-	-	-	8 9/16	8 9/16	-	267.44	14.22	14.22	1.24
BX 172	-	-	-	11 5/32	11 5/32	-	333.07	14.22	14.22	1.56
BX 303	30	30	-	-	-	-	852.75	37.95	16.97	-

How to Order Ring Joint Gasket

The following tables show how to select the correct ring joint gasket depending on the flange size (NPS), manufacturing norm (ASME or API), and flange rating:

Style R Ring Joint Gaskets

| NOMINAL PIPE SIZE | PRESSURE CLASSES | | ----------------- | ---------------- | -------------------- | ----- | ----- | --------------- | ----- | ----- | ----- | ------ | ---- | ----------- | ---- | ----- | | ASME B16.5 | API 6B | ASME B16.47 Series A | | 150# | 300# - 600# | 900# | 1500# | 2500# | 720# - 960# (1) | 2000# | 3000# | 5000# | 10000# | 150# | 300# - 600# | 900# | | 1/2” | - | R-11 | R-12 | R-12 | R-13 | - | - | - | - | - | - | - | - | | 3/4” | - | R-13 | R-14 | R-14 | R-16 | - | - | - | - | - | - | - | - | | 1” | R-15 | R-16 | R-16 | R-16 | R-18 | R-16 | R-16 | R-16 | R-16 | R-82 | - | - | - | | 1 1/4” | R-17 | R-18 | R-18 | R-18 | R-21 | R-18 | R-18 | R-18 | R-18 | - | - | - | - | | 1 1/2” | R-19 | R-20 | R-20 | R-20 | R-23 | R-20 | R-20 | R-20 | R-20 | R-84 | - | - | - | | 2” | R-22 | R-23 | R-24 | R-24 | R-26 | R-23 | R-23 | R-23 | R-24 | R-85 | - | - | - | | 2 1/2” | R-25 | R-26 | R-27 | R-27 | R-28 | R-26 | R-26 | R-26 | R-27 | R-86 | - | - | - | | 3” | R-29 | R-31 | R-31 | R-35 | R-32 | R-31 | R-31 | R-31 | R-35 | R-87 | - | - | - | | 3 1/2” | R-33 | R-34 | - | - | - | - | - | - | R-37 | R-89 | - | - | - | | 4” | R-36 | R-37 | R-37 | R-39 | R-38 | R-37 | R-37 | R-37 | R-39 | R-88 | - | - | - | | 5” | R-40 | R-41 | R-41 | R-44 | R-42 | R-41 | R-41 | R-41 | R-44 | R-90 | - | - | - | | 6” | R-43 | R-45 | R-45 | R-46 | R-47 | R-45 | R-45 | R-45 | R-46 | - | - | - | - | | 8” | R-48 | R-49 | R-49 | R-50 | R-51 | R-49 | R-49 | R-49 | R-50 | - | - | - | - | | 10” | R-52 | R-53 | R-53 | R-54 | R-55 | R-53 | R-53 | R-53 | R-54 | R-91 | - | - | - | | 12” | R-56 | R-57 | R-57 | R-58 | R-60 | R-57 | R-57 | R-57 | - | - | - | R-57 | R-57 | | 14” | R-59 | R-61 | R-62 | R-63 | - | R-61 | R-61 | R-61 | - | - | - | R-61 | R-62 | | 16” | R-64 | R-65 | R-66 | R-67 | - | R-65 | R-65 | R-65 | - | - | - | R-65 | R-66 | | 18” | R-68 | R-69 | R-70 | R-71 | - | R-69 | R-69 | R-69 | - | - | - | R-69 | R-70 | | 20” | R-72 | R-73 | R-74 | R-75 | - | R-73 | R-73 | R-73 | - | - | - | R-73 | R-74 | | 22” | - | - | - | - | - | - | - | - | - | - | R-80 | R-81 | - | | 24” | R-76 | R-77 | R-78 | R-79 | - | - | - | - | - | - | - | R-77 | R-78 | | 26” | - | - | - | - | - | - | - | - | - | - | - | R-93 | R-100 | | 28” | - | - | - | - | - | - | - | - | - | - | - | R-94 | R-101 | | 30” | - | - | - | - | - | - | - | - | - | - | - | R-95 | R-102 | | 32” | - | - | - | - | - | - | - | - | - | - | - | R-96 | R-103 | | 34” | - | - | - | - | - | - | - | - | - | - | - | R-97 | R-104 | | 36” | - | - | - | - | - | - | - | - | - | - | - | R-98 | R-105 |

Style RX Ring Joint Gaskets

| NPS | PRESSURE RATING | | -------- | --------------- | ----- | ----- | ----- | -------------- | ------ | | API 6B | | 720# | 960# | 2000# | 2900# | 3000# | 5000# | | 1” | - | - | - | RX-82 | - | - | | 1 3/8” | - | - | - | - | - | RX-201 | | 1 1/2” | RX-20 | RX-20 | RX-20 | RX-84 | RX-20 | RX-20 | | 1 13/16″ | - | - | - | - | - | RX205 | | 2” | RX-23 | RX-23 | RX-23 | RX-85 | RX-24 | RX-24 | | 2 1/2” | RX-26 | RX-26 | RX-26 | RX-86 | RX-27 | RX-27 | | 2 9/16” | - | - | - | - | - | RX210 | | 3” | RX-31 | RX-31 | RX-31 | RX-87 | RX-31 | RX35 | | 3 1/2” | - | - | - | RX-89 | - | - | | 4” | RX-37 | RX-37 | RX-37 | RX-88 | RX-37 | RX-39 | | 4 1/16″ | - | - | - | - | - | RX-215 | | 5” | RX-41 | RX-41 | RX-41 | RX-90 | RX-41 | RX-44 | | 6” | RX-45 | RX-45 | RX-45 | - | RX-45 | RX-46 | | 8” | RX-49RX-99 (2) | RX-49 | RX-49 | - | RX-49RX-99 (2) | RX-50 | | 10” | RX-53 | RX-53 | RX-53 | RX-91 | RX-53 | RX-54 | | 12” | RX-57 | RX-57 | RX-57 | - | RX-57 | - | | 14” | - | - | - | - | - | RX-63 | | 16” | RX-65 | RX-65 | RX-65 | - | RX-69 | - | | 18” | RX-69 | RX-69 | RX-69 | - | RX-73 | - | | 20” | RX-73 | RX-73 | RX-73 | - | RX82 | - |

Style BX Ring Joint Gaskets

| NPS | PRESSURE RATING | | -------- | --------------- | ------ | ------------- | ------ | ------ | ------ | | API 6BX | | 2000# | 3000# | 5000# | 10000# | 15000# | 20000# | | 1 11/16″ | - | - | - | BX-150 | BX-150 | - | | 1 13/16″ | - | - | - | BX-151 | BX-151 | BX-151 | | 2 1/16″ | - | - | - | BX-152 | BX-152 | BX-152 | | 2 9/16″ | - | - | - | BX-153 | BX-153 | BX-153 | | 3 1/16″ | - | - | - | BX-154 | BX-154 | BX-154 | | 4 1/16″ | - | - | - | BX-155 | BX-155 | BX-155 | | 5 1/8″ | - | - | - | BX-169 | - | - | | 6 5/8″ | - | - | - | BX-170 | BX-170 | - | | 7 1/16″ | - | - | - | BX-156 | BX-156 | BX-156 | | 8 9/16″ | - | - | - | BX-171 | BX-171 | - | | 9″ | - | - | - | BX-157 | BX-157 | BX-157 | | 11″ | - | - | - | BX-158 | BX-158 | BX-158 | | 11 5/32″ | - | - | - | BX-172 | BX-172 | - | | 13 5/8″ | - | - | BX-160 | BX-159 | BX-159 | BX-159 | | 16 3/4″ | - | - | BX-161 BX-162 | BX-162 | BX-162 | - | | 18 3/4″ | - | - | BX-163 | BX-164 | BX-164 | - | | 21 1/4″ | - | - | BX-165 | BX-166 | - | - | | 26 3/4″ | BX-167 | BX-168 | - | - | - | - | | 30″ | BX-303 | BX-303 | - | - | - | - |

Kammprofile Gasket

What Are Kammprofile Gaskets?

A Kammprofile gasket, also known as a serrated or grooved gasket, is a high-performance seal used in industrial applications that require tight sealing under varying pressures and temperatures. It combines the benefits of soft gasket materials with the strength of metal, providing a reliable sealing option for flanges and other joint types.

The defining feature of a Kammprofile gasket is its metal core, typically made from stainless steel or other corrosion-resistant alloys. The core is machined to have a concentrically serrated profile on both sealing surfaces. These grooves improve sealing efficiency by concentrating the compressive forces applied upon them.

The serrated metal core is covered on one or both sides with a layer of soft sealing material, such as flexible graphite, PTFE (polytetrafluoroethylene), or non-asbestos-compressed fiber. This soft layer helps to create an effective seal by conforming to the flange surfaces and filling any minor irregularities.

A Kammprofile gasket (or “Camprofile”) is manufactured by applying a sealing layer in non-metallic materials (such as graphite, PTFE-Teflon, ceramic fibers, non-asbestos, Mica, etc) or metallic materials (such as aluminum or silver) on both sides of a metal core featuring concentric grooves of 1 mm Cam-Pitch. This sealing product, called also a “grooved metal gasket” or “corrugated metal gasket”, is used for high-pressure and temperature oil & gas applications.

Kammprofile gaskets are used in many industrial, petrochemical, power generation, and nuclear installations (to seal flanges, heat exchangers, superheaters, and, other pressure equipment) and are preferred to Spiral Wound Gaskets for processes with constant high pressure/temperatures requiring strong bolt-loads and remarkable flanged joints’ resistance.

Kammprofile gaskets fit smooth and stock flange surface finish (3.2 to 6.3 μm Ra, i.e. 125-250 RMS).

The common thickness of a Kammprofile gasket is between 2 and 4 mm (3 mm is the most common specification in petrochemical applications).

A Kammprofile gasket offers several benefits, due to its wide sealing area and construction:

• May resist temperatures up to approx. 1000°C (the Kammprofile temperature rating depends on the materials of the metal core and the sealing layer)
• May rate up to 250 bars, which is a considerable pressure rating
• The gasket does not damage the flange surface, due to the protection offered by the sealing layer
• The gasket can absorb fluctuations in temperature and pressure
• It is more tolerant than Spiral Wound Gaskets to improper bolting torques
• Suits both light and heavyweight flanges, even of large sizes
• After assembly, the thickness of the sealing material is extremely low (0.1 - 0.2 mm), thus reducing leaks and failure rates
• The core of a Kammprofile gasket can be re-used after cleaning and fitting the gasket with new layering material. This is critical for expensive applications, such as heat exchanger gaskets that are made of exotic, expensive, materials (Inconel, Monel, Hastelloy, and Cupronickel).

An outer metallic (integral or floating) ring may be added to the gasket to center it during installation on a flange. The sealing layers protect the flange surface and reinforce the seal.

Kammprofile Gasket Types

Overall Design

Kammprofile gaskets come in several types to suit different applications and flange configurations. The variations primarily concern the presence and type of guide rings and the choice of facing material.

Kammprofile Type	Description	Applications
Basic	Simplest form: serrated metal core without additional layers or coatings. Core grooves engage directly with flange surfaces.	Smooth, clean flanges with no need for additional compression limiting or flange protection.
With Integral Outer Ring	Includes an integral outer guide ring (same material as core) that centers the gasket and acts as a compression stop, preventing over-tightening.	Standard raised-face flanges requiring additional alignment and protection.
With Loose Outer Ring	Similar to integral type but with a loose outer ring for easier alignment and installation. The loose ring also is a compression stop.	Raised face and flat face flanges where alignment under bolt tightening is a concern.
With Inner Ring	Features an inner ring within the gasket’s serrations providing additional radial strength, preventing inward buckling of the soft sealing layer.	Protection against corrosive or erosive media and applications involving turbulent flow.
With Both Inner and Outer Rings	Combines both rings, offering centering, protection from over-compression, and enhanced sealing against erosion and corrosion.	Raised face, flat face, and male-female flanges in more demanding operational conditions.

Parallel vs. Convex Core

Kammprofile gaskets can be designed with different core profiles to improve their sealing under specific conditions. The two main variations are parallel root cores and convex root cores, each affecting the gasket’s compressibility, recovery, and sealing performance.

Feature	Parallel Root Core	Convex Root Core
Design	Serrations are straight and parallel, creating a uniform profile with consistent groove depth and width.	Serrations have a convex curve at the root of each groove, increasing contact pressure at the peaks.
Advantages	Even compressive force distribution, good recovery and resilience under fluctuating loads and temperatures.	Higher sealing efficiency under lower bolt loads, improved resilience and stress distribution, reduced leakage risk.
Applications	Standard flange connections with relatively consistent pressures and temperatures; sealing liquids and gases.	Restricted bolt loading, lightweight flanges, lower compressive forces, irregular or damaged flange surfaces.

Kammprofile Gasket Materials

Metal Core Materials

The core material of a Kammprofile gasket shall match the material of the piping system

| Kammprofile Core Materials | DINDesignation | DIN Material Number | AISI ASTM UNSDesignation | British StandardDesignation | HardnessHB/HV | Temperature in C°Min. Max. | Density in gr/cm3 | | -------------------------- | ---------------- | ------------------- | ------------------------ | --------------------------- | ------------- | -------------------------- | ----------------- | ---- | | Soft Iron | - | - | - | - | 90 - 100 | - 60 | 500 | 7.85 | | Steel (LCS) | RSt. 37.2 | 1.0038 | - | - | 100 - 130 | - 40 | 500 | 7.85 | | Stainless Steel 304 | X5 CrNi 1810 | 1.4301 | 304 | 304S15/16/31 | 130 - 180 | -250 | 550 | 7.9 | | Stainless Steel 304 L | X2CrNi 1911 | 1.4306 | 304L | 304S11 | 130 - 190 | -250 | 550 | 7.9 | | Stainless Steel 309 | X15CrNiSi 2012 | 1.4828 | 309 | 309S24 | 130 - 190 | -100 | 1000 | 7.9 | | Stainless Steel 316 L(1) | X2CrNiMo 1713 | 1.4404 | 316L | 316S11/13 | 130 - 190 | -100 | 550 | 7.9 | | Stainless Steel 316 Ti | X6CrNiMoTi 1712 | 1.4571 | 316Ti | 320S31 | 130 - 190 | -100 | 550 | 7.8 | | Stainless Steel 321 | X6CrNiTi 1810 | 1.4541 | 321 | 321S12/49/87 | 130 - 190 | -250 | 550 | 7.9 | | Stainless Steel 347 | X6CrNiNb 1810 | 1.4550 | 347 | 347S31 | 130 - 190 | -250 | 550 | 7.9 | | Aluminium | Al 99,5 | 3.0255 | - | - | 20 - 23 | -250 | 300 | 2.73 | | Silver | - | - | - | - | 28* | -250 | 750 | 10.5 | | Copper | - | 2.0090 | - | - | 50 - 80 | -250 | 400 | 8.9 | | Nickel 200 | Ni 99,2 | 2.4066 | N02200 | 3072-76 NA11 | 90 - 120 | -250 | 600 | 8.9 | | Monel 400 ® | NiCu 30 Fe | 2.4360 | N04400 | 3072-76 NA13 | 110 - 150 | -125 | 600 | 8.8 | | Inconel 600 ® | NiCr 15 Fe | 2.4816 | N06600 | 3072-76 NA14 | 120 - 180 | -100 | 950 | 8.4 | | Incoloy 800 ® | X10NiCrAITi 3220 | 1.4876 | N08800 | 3072-76 NA15 | 140 - 220 | -100 | 850 | 8.0 | | Incoloy 825 ® | NiCr 21 Mo | 2.4858 | N08825 | 3072-76 NA16 | 120 - 180 | -100 | 450 | 8.14 | | Hastelloy B2 ® | NiMo 28 | 2.4617 | N10665 | - | 170 - 230 | -200 | 450 | 9.2 | | Hastelloy C276 ® | NiMo16Cr15W | 2.4819 | N10276 | - | 170 - 230 | -200 | 450 | 8.9 | | Titanium | Ti 99,8 | 3.7025 | - | - | 110 - 140 | -250 | 350 | 4.5 |

Sealing Layer

The most common layer materials for Kammprofile gaskets are graphite and PTFE (Teflon). The advantages of a graphite layering material are:

• Excellent gas tightness qualities
• Non-aging properties
• Very good chemical resistance
• Resistance to high (fluctuating) temperatures and pressures

PTFE is also used due to its excellent chemical resistance, resistance to temperatures up to 250°C, and excellent sealing properties for gas applications.

| Sealing Layer Material for Kammprofile | Temperature in C°Min. Max. | Max. operating pressure in Bars | Gas tightness | Recommended Application | | -------------------------------------- | -------------------------- | ------------------------------- | ------------- | ----------------------- | ---------------- | | Graphite | -200 | 550 | 250 | Good | Aggressive media | | PTFE (Teflon ® ) | -200 | 250 | 100 | Good | Aggressive media | | Non-asbestos | -100 | 250 | 100 | Good | Gas and liquids | | Silver | -200 | 750 | 250 | Good | Aggressive media |

Kammprofile Gasket Dimensions

Kammprofile Gasket Class 150-400

Kammprofile gasket dimensions for AMSE B16.5 flanges

| NPS | d1 | d2 | d3 | | --- | ----- | ----- | ----- | ----- | ----- | | 150 | 300 | 400 | | 1/2 | 23 | 33.3 | 44.4 | 50.8 | 50.8 | | 3/4 | 28.6 | 39.7 | 53.9 | 63.5 | 63.5 | | 1 | 36.5 | 47.6 | 63.5 | 69.8 | 69.8 | | 1¼ | 44.4 | 60.3 | 73 | 79.4 | 79.4 | | 1½ | 52.4 | 69.8 | 82.5 | 92.1 | 92.1 | | 2 | 69.8 | 88.9 | 101.6 | 108 | 108 | | 2½ | 82.5 | 101.6 | 120.6 | 127 | 127 | | 3 | 98.4 | 123.8 | 133.4 | 146.1 | 146.1 | | 3½ | 111.1 | 136.5 | 158.8 | 161.9 | 158.7 | | 4 | 123.8 | 154 | 171.5 | 177.8 | 174.6 | | 5 | 150.8 | 182.6 | 193.7 | 212.7 | 209.5 | | 6 | 177.8 | 212.7 | 219.1 | 247.7 | 244.5 | | 8 | 228.6 | 266.7 | 276.2 | 304.8 | 301.6 | | 10 | 282.6 | 320.7 | 336.5 | 358.8 | 355.6 | | 12 | 339.7 | 377.8 | 406.4 | 419.1 | 415.9 | | 14 | 371.5 | 409.6 | 447.7 | 482.6 | 479.4 | | 16 | 422.3 | 466.7 | 511.2 | 536.6 | 533.4 | | 18 | 479.4 | 530.2 | 546.1 | 593.7 | 590.5 | | 20 | 530.2 | 581 | 603.2 | 650.9 | 644.5 | | 24 | 631.8 | 682.6 | 714.4 | 771.5 | 765.2 |

All values in millimeters

Kammprofile Gasket Class 600-2500

Kammprofile gasket dimensions for AMSE B16.5 flanges

| NPS | d1 | d2 | d3 | | --- | ----- | ----- | ----- | ----- | ----- | ----- | | 600 | 900 | 1500 | 2500 | | 1/2 | 23 | 33.3 | 50.8 | 60.3 | 60.3 | 66.7 | | 3/4 | 28.6 | 39.7 | 63.5 | 66.7 | 66.7 | 73 | | 1 | 36.5 | 47.6 | 69.8 | 76.2 | 76.2 | 82.5 | | 1¼ | 44.4 | 60.3 | 79.4 | 85.7 | 85.7 | 101.6 | | 1½ | 52.4 | 69.8 | 92.1 | 95.2 | 95.2 | 114.3 | | 2 | 69.8 | 88.9 | 108 | 139.7 | 139.7 | 142.8 | | 2½ | 82.5 | 101.6 | 127 | 161.9 | 161.9 | 165.1 | | 3 | 98.4 | 123.8 | 146.1 | 165.1 | 171.5 | 193.7 | | 3½ | 111.1 | 136.5 | 158.7 | … | … | … | | 4 | 123.8 | 154 | 190.5 | 203.2 | 206.4 | 231.7 | | 5 | 150.8 | 182.6 | 238.1 | 244.5 | 250.8 | 276.2 | | 6 | 177.8 | 212.7 | 263.5 | 285.8 | 279.4 | 314.3 | | 8 | 228.6 | 266.7 | 317.5 | 355.6 | 349.3 | 384.1 | | 10 | 282.6 | 320.7 | 369.9 | 431.8 | 431.8 | 473 | | 12 | 339.7 | 377.8 | 454 | 495.3 | 517.5 | 546.1 | | 14 | 371.5 | 409.6 | 488.9 | 517.5 | 574.7 | … | | 16 | 422.3 | 466.7 | 561.9 | 571.5 | 638.1 | … | | 18 | 479.4 | 530.2 | 609.6 | 635 | 701.7 | … | | 20 | 530.2 | 581 | 679.5 | 695.3 | 752.4 | … | | 24 | 631.8 | 682.6 | 787.4 | 835 | 898.5 | … |

All values in millimeters

Jacketed Gasket

What Is a Jacketed Gasket?

A jacketed gasket is a composite gasket used in industrial piping, vessels, and heat exchangers, designed for a range of temperatures, pressures, and chemical conditions. It consists of a soft, compressible filler material enclosed in a metal jacket. The metal jacket provides mechanical strength, chemical resistance, and thermal stability, while the filler material conforms to the flange surfaces and provides an effective seal.

Jacketed gaskets can be fully jacketed, partially jacketed, or single-jacketed, depending on the application requirements:

• Fully Jacketed Gaskets: The filler material is completely enclosed in the metal jacket, offering maximum protection and strength. This type is typically used in applications involving high pressures and temperatures.
• Partially Jacketed Gaskets: Only certain sections of the filler material are covered by the metal jacket. This design is chosen based on specific sealing and operational needs, providing a balance between the compressibility of the filler and the strength of the metal jacket.
• Single-Jacketed Gaskets: The metal jacket covers only one face and the inside edge of the gasket. This type is suitable for applications where the gasket needs extra strength on one side, such as in narrow flanges.

A metal jacket gasket requires flat face flanges with a smooth face finish to seal effectively.

The size range and thickness tolerances for this type of gasket are covered by ASME B16.21 specification:

• OD: Less than 5,000mm
• Thickness: 2~8mm with tolerance +0.03 inch. to -0.000 inch (+0.8mm, -0.0mm)

Jacketed Gasket Materials

Jacketed gaskets use the following materials:

• Metal Jacket: Common materials for the jacket include stainless steel, aluminum, copper, Monel, and Inconel. The choice of metal is based on the required thermal, chemical, and mechanical properties.
• Filler Material: Typical fillers include flexible graphite, PTFE (Polytetrafluoroethylene), non-asbestos compressed fiber, and ceramic. The filler selection depends on the sealing requirements, including chemical compatibility and temperature resilience.

The table shows the recommended temperature range for common metal jacket materials:

Jacket Materials	Hardness HB	Temp.℃
Carbon Steel	90	-60~+450
304 (L)	130	-270~+550
316 (L)	130	-270~+550
321	130	-270~+550
Monel	110	-60~+500
Inconel	90	-60~+600
AL	30	-250~+300
CU	80	-250~+400

Jacketed Gasket Types

The two main types of metal jacketed gaskets are the single and the double jacket designs. Besides these two basic types, other designs are available on the market as illustrated below:

	Double Jacketed Corrugated- soft fillerReduced contact area, enhances compression characteristics, suitable for uneven flanges.
	Double Jacketed Corrugated- metal fillerUsually stainless outer casing with soft iron filler ring.Core material available St. St. -304.316L.321Soft iron, Monel, Inconel
	Single Corrugated- asbestos rope fillerTypically used on very poor or pitted flanges, low bolt loading requirement.
	Metal Jacket Laminates- soft fillerCombines flexible graphite with stainless steel core material
	Solid metal ring machined on each contact face to provide a serrated surface finish covered with Graphite.PTFE Nonas or Asbestos.

	Double Jacketed - soft fillerUsed on high-temperature pressure applications or where corrosion problems may exist
	Single Jacketed - metal filler- partly enclosedVery seldom used, old design. Used in applications where poor or pitted flanges exist on one face.
	Single Jacketed - Soft filler- partly enclosedUsed on narrow flanges
	Single Jacketed - Soft filler- open outside edgeUsed in narrow flanges, protection of filler cleared for by casing
	Single Corrugated - no fillerUsed mainly in valve applications, small recess gap. Sometimes referred to as the Taylor ring.

Jacketed Gasket Dimensions

Jacket Gasket Class 150-400

Jacketed gasket dimension

NPS	d1	d2
150	300	400
1/2	23.8	44.5
3/4	31.8	54
1	36.5	63.5
1¼	46	73
1½	52.4	82.6
2	73.2	101.6
2½	85.9	120.6
3	107.8	133.4
4	131.8	171.5
5	152.4	193.8
6	190.5	219.1
8	238.3	276.3
10	285.8	336.6
12	342.9	406.4
14	374.7	447.7
16	425.5	511.2
18	489	546.1
20	533.4	603.3
24	641.4	714.4
NPS	d1	150

Jacket Gasket Class 600-2500

Jacketed gasket dimensions for AMSE B16.5 flanges

| NPS | d1 | d2 | | --- | ----- | ----- | ----- | ----- | ----- | | 600 | 900 | 1500 | 2500 | | 1/2 | 23.8 | 50.8 | 60.4 | 60.4 | 66.8 | | 3/4 | 31.8 | 63.5 | 66.7 | 66.7 | 73.1 | | 1 | 36.5 | 69.9 | 76.2 | 76.2 | 82.5 | | 1¼ | 46 | 79.4 | 85.8 | 85.8 | 101.6 | | 1½ | 52.4 | 92.1 | 95.3 | 95.3 | 114.3 | | 2 | 73.2 | 108 | 139.7 | 139.7 | 143 | | 2½ | 85.9 | 127 | 161.9 | 161.9 | 165.1 | | 3 | 107.8 | 146.1 | 165.1 | 171.5 | 193.8 | | 4 | 131.8 | 190.5 | 203.2 | 206.5 | 231.9 | | 5 | 152.4 | 238.2 | 244.6 | 250.9 | 276.3 | | 6 | 190.5 | 263.6 | 285.8 | 279.4 | 314.5 | | 8 | 238.3 | 317.5 | 355.6 | 349.3 | 384.3 | | 10 | 285.8 | 396.9 | 431.8 | 431.8 | 473.2 | | 12 | 342.9 | 454.1 | 495.3 | 517.6 | 546.1 | | 14 | 374.7 | 489 | 517.6 | 574.7 | … | | 16 | 425.5 | 562 | 571.5 | 638.2 | … | | 18 | 489 | 609.6 | 635 | 701.8 | … | | 20 | 533.4 | 679.5 | 695.5 | 752.5 | … | | 24 | 641.4 | 787.4 | 835.1 | 898.6 | … |

How to Order a Metal Jacketed Gasket

The following information should be provided to the gasket supplier to order a jacket gasket properly:

• Outside diameter
• Inside diameter (NPS)
• Shape per standard index
• Type Number
• Thickness
• Materials (metal or metal filler)
• Bar size
• Radii
• Distance from the centerline of the gasket to the centerline of the bars

Frequently Asked Questions

What is the maximum temperature for a spiral wound gasket?

Spiral wound gaskets with flexible graphite filler can operate up to approximately 500°C (930°F) in oxidizing atmospheres and up to 650°C (1200°F) in non-oxidizing/reducing environments. With PTFE filler, the limit drops to about 260°C (500°F). For temperatures above 650°C, metal ring joint (RTJ) gaskets or Kammprofile gaskets with metal-only contact are recommended.

What determines the correct gasket thickness for a flanged joint?

For spiral wound gaskets, the standard thickness is 4.5 mm (with inner/outer rings) per ASME B16.20. For sheet gaskets (ASME B16.21), common thicknesses are 1.5 mm, 2.0 mm, and 3.0 mm. Thinner gaskets (1.5 mm) provide better blowout resistance and lower creep, while thicker gaskets (3.0 mm) compensate for flange surface irregularities. As a rule: use the thinnest gasket that will seal properly given the flange face condition.

What is the difference between a metallic and a non-metallic gasket?

Non-metallic gaskets (rubber, PTFE, compressed fiber) are used for low-pressure, low-temperature applications and flat-face (FF) flanges. Semi-metallic gaskets (spiral wound, Kammprofile) combine a metal structure with soft filler material for medium-to-high pressure with raised-face (RF) flanges. Metallic gaskets (ring joint, solid metal) are pure metal, used for the highest pressures and temperatures with RTJ flanges (Class 600+).

When is a ring type joint (RTJ) gasket required instead of a spiral wound?

RTJ gaskets are required for Class 900 and above (per most project specifications), and for any application requiring metal-to-metal sealing: high-pressure/high-temperature service, subsea, sour (H2S) service, and critical applications where zero-leakage is mandatory. RTJ gaskets seat into machined grooves on the flange face and provide the highest sealing reliability, but require better flange alignment and higher bolt loads than spiral wound gaskets.