custom flange gasket

Custom Flange Gaskets: Materials, Dimensions and Ordering Guide

Quick Answer: A custom flange gasket is cut or fabricated for a non-standard flange profile, a special material requirement, or a specific pressure and temperature condition. CORASEALS supplies custom flange gaskets in rubber sheet, PTFE, graphite, non-asbestos, spiral wound, kammprofile, RTJ and sanitary profiles. Send the flange type, gasket standard, ID × OD × thickness, pressure class, temperature, medium and required quantity, and we will prepare a quotation.

Custom flange gaskets solve sealing problems that standard catalog parts cannot cover. A flange may have an unusual outside diameter, a resurfaced face, an enlarged bore, a heat exchanger partition, or a chemical condition that requires a specific material. In these cases, the correct gasket is specified by dimensions, material and flange face type, not by a part number alone.

What is a custom flange gasket?

A custom flange gasket is made from customer dimensions, a drawing, a sample, or a measured flange face. The gasket may be cut from a sheet, machined from PTFE or graphite, formed as a spiral wound component, or produced as a metal RTJ ring. The purpose of the custom gasket is to match the actual flange geometry and service conditions.

Common custom gasket requests include large diameter flanges, non-standard bolt circles, heat exchanger pass bars, manway covers, sanitary connections and flanges that have been resurfaced or repaired. A dimension check is required before production when only a standard flange designation is provided.

Custom flange gasket materials

Material selection must match the medium, temperature, pressure and flange load. The table below lists common material groups and their typical flange service conditions.

Material group	Common flange service	Selection notes
NBR rubber sheet	Oil, fuel, water and general industrial	Good oil resistance. Confirm temperature and chemical limits for the specific sheet grade.
EPDM rubber sheet	Water, steam, weather and diluted acids	Not suitable for mineral oil, most fuels and many solvents.
FKM rubber sheet	Oils, fuels, acids and high temperature service	Check the specific FKM grade against the chemical exposure.
PTFE and filled PTFE	Aggressive chemicals, food, pharmaceutical and high purity	Use filled PTFE when creep resistance and dimensional stability are required.
Graphite and flexible graphite	Steam, high temperature and heat transfer	Check flange load, oxygen exposure and grade limits for the operating condition.
Non-asbestos fiber sheet	Oil, water, steam and mild chemicals	Confirm pressure class, temperature and bolt load for the selected grade.
Spiral wound and kammprofile	Piping flanges, heat exchangers and thermal cycling	Specify metal winding, filler, inner ring and outer ring when required.
RTJ metal	High pressure and high temperature ASME and API flanges	Specify ring number, material and hardness.

Actual temperature and pressure limits depend on the specific material grade, sheet construction and flange design. Do not select a gasket material from a general list without checking the chemical compatibility chart for the operating fluid and concentration.

Dimensions, flange face types and standards

For a custom flange gasket quote, provide these dimensions and specifications:

Gasket ID and OD, or a drawing with the sealing shape
Gasket thickness
Flange face type: flat face, raised face, RTJ, tongue and groove, male and female
Bolt circle, number of bolts and bolt hole diameter when the gasket has bolt holes
Flange standard and pressure class: ASME B16.5 Class 150, Class 300, Class 600, Class 900, Class 1500, Class 2500, ASME B16.47, EN 1092-1, JIS B2220, API 6A or API 6B
Medium or chemical, operating temperature and pressure

Custom flange gasket types

CORASEALS can supply several custom gasket construction types.

Custom cut rubber gaskets in NBR, HNBR, FKM, EPDM, silicone, neoprene, CR, Aflas and FEPM
Custom cut PTFE and filled PTFE gaskets for chemical, food and pharmaceutical service
Flexible graphite and reinforced graphite gaskets for high temperature flanges
Non-asbestos fiber sheet gaskets for general industrial piping
Spiral wound gaskets with graphite or PTFE filler and optional inner and outer rings
Kammprofile gaskets for heat exchangers, piping flanges and thermal cycling conditions
RTJ gaskets machined to ASME B16.20 ring numbers in soft iron, stainless steel and other alloys
Sanitary gaskets for tri-clamp, DIN 11851 and DIN 11864 connections
Heat exchanger gaskets with pass bars, partition ribs and custom outer shapes

Common applications for custom flange gaskets

Custom flange gaskets are used in pipe flanges with oversized bores, heat exchanger flanges with partition plates, manway and tank flanges, pump and valve covers, sanitary process piping, and high pressure RTJ flanges. The sealing solution must match both the flange design and the process fluid.

Selection checks before ordering a custom flange gasket

These checks reduce the risk of gasket failure caused by material or dimensional mismatch.

Confirm medium compatibility with the gasket material at operating temperature and concentration.
Confirm the flange face type and gasket seating area. A raised face gasket does not always fit a flat face flange.
Confirm ID and OD after flange resurfacing or bore modification.
Confirm bolt circle, bolt hole diameter, number of bolts and gasket outer shape before cutting.
For spiral wound and kammprofile gaskets, confirm the filler material, ring type and pressure class.
For RTJ gaskets, confirm the ring number and groove condition. The ring number must match the flange groove.

How to order custom flange gaskets from CORASEALS

Send the following information with the inquiry:

Flange standard, pipe size and pressure class, or a drawing of the flange face
Gasket construction and material grade
Gasket ID × OD × thickness
Bolt circle, number of bolts and bolt hole diameter if bolt holes are required
Flange face type and any groove or partition details
Operating temperature, pressure and medium
Required quantity and delivery location

For a non-standard gasket, a sketch, sample photo, existing gasket image or CAD file helps reduce dimensional errors. CORASEALS will confirm the production dimensions before manufacturing custom sizes.

Request a quote: Send the flange type, gasket standard, ID × OD × thickness, material, pressure class, temperature, medium and required quantity. We will quote the custom flange gasket based on the dimensions and service conditions you provide.

Frequently Asked Questions

Can you cut a custom flange gasket from a drawing or sample? Yes. CORASEALS can use a customer drawing, a scanned flange sketch, a sample gasket, or measured flange dimensions to produce a custom gasket.

Which materials are available for custom flange gaskets? Common materials include NBR, HNBR, FKM, EPDM, silicone, neoprene, CR, PTFE, filled PTFE, flexible graphite, non-asbestos fiber sheet, stainless steel and alloy materials for spiral wound, kammprofile and RTJ gaskets.

Do you make heat exchanger gaskets with pass bars? Yes. Heat exchanger gaskets can be produced with pass bars, partition ribs and custom outer shapes. Provide a drawing or the heat exchanger make and model for confirmation.

What dimensions do you need for a custom flange gasket quote? We need ID, OD, thickness, flange face type, bolt circle, number of bolts, bolt hole diameter, pressure class, medium and operating temperature and pressure.

Can you match a standard ASME or EN flange gasket? Yes. Standard flange dimensions help identify the likely gasket size, but the actual sealing face must still be checked. Some flanges are damaged, resurfaced or non-standard despite using ASME or EN designations.