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Flange Insulation Gasket Sets

Q: Why do the retainer and sealing element have different temperature limits?

The retainer is the laminate body of the gasket and the sealing element is the facing. The two materials are chosen separately, and the joint is limited by whichever has the lower temperature ceiling. For example, a neoprene-faced phenolic gasket at 200°C is limited by the phenolic body (max +79°C), not by the neoprene. That is why both limits are published.

Kaxite flange insulation gasket sets ship as KXT-110 or KXT-120 for pipeline cathodic protection. Each set contains a gasket, sleeves, washers and backing washers, bagged by flange size and class. Five laminates — plain phenolic, neoprene-faced phenolic, silicone glass G-7, epoxy glass G-10, epoxy glass G-11 — with dielectric strength 350–550 V/mil and insulation resistance up to 200,000 Meg Ohms. Sealing elements Nitrile, Viton, Teflon, Neoprene or EPDM. Free samples from an ISO 9001 Ningbo factory.

Model:KXT-110

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Product Description

Flange Insulation Gasket Sets KXT-110 & KXT-120 – Five Laminates, Full Property Data for Cathodic Protection

Kaxite flange insulation gasket sets are complete isolation kits shipped bagged by flange size and pressure class, so a maintenance team can pull one set per joint without sourcing sleeves and washers separately. The set is available in two series — KXT-110 (standard kit with gasket, sleeves, washers and backing washers) and KXT-120 (gasket-only variant for projects that already hold the bolt hardware) — and in five laminate grades: plain phenolic, neoprene-faced phenolic, silicone glass G-7, epoxy glass G-10 and epoxy glass G-11. The performance differences between these grades are large enough to change the design, which is why the full property table is published below instead of a single headline number. For the pipeline joint itself, see the flange insulation gasket kit page; for the RTJ variant, see the Type D flange insulation gasket.

Two series: KXT-110 vs KXT-120

KXT-110 Full set — gasket + sleeves + washers + backing washers

One gasket, one insulating sleeve per bolt hole, two insulating washers and two steel backing washers per bolt, bagged by flange size and pressure class.

Best for: new isolation joints, turnarounds where the bolt hardware is replaced, cathodic protection retrofits.

KXT-120 Gasket-only variant for existing bolt hardware

The insulation gasket on its own, for sites that already stock sleeves, insulating washers and backing washers to the right bolt size.

Best for: repeat maintenance where the same bolt hardware is reused, mixed purchases across multiple flange sizes.

Both series share the same laminate selection and the same gasket geometry (Type E full-face, Type F raised-face or Type D RTJ). The only difference is whether the bolt hardware is included in the bag.

Five laminate grades side by side

Plain
Phenolic

Dielectric 500 V/mil General purpose, low cost

Neoprene-
Faced Phenolic

Dielectric 500 V/mil Softer sealing face

Silicone Glass
G-7

Dielectric 350–400 V/mil No hydrocarbon contact

Epoxy Glass
G-10

Dielectric 550 V/mil High mechanical strength

Epoxy Glass
G-11

Dielectric 550 V/mil Higher temperature

Full property values below — the difference between G-7 and G-11 spans 14× in water absorption and 80× in insulation resistance.

⚠ G-7 must not be used with hydrocarbons

Silicone glass G-7 has excellent high-temperature resistance, but the silicone resin is attacked by hydrocarbon solvents. Do not use G-7 where the media contains any hydrocarbon, even trace amounts. For hydrocarbon service, use epoxy glass G-10 or G-11, or the plain phenolic grade with an appropriate sealing element.

Physical properties of the five laminates

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Property	Plain Phenolic	Neo-Faced Phenolic	Silicone Glass G-7	Epoxy Glass G-10	Epoxy Glass G-11
Dielectric strength (V/mil)	500	500	350–400	550	550
Compressive strength (psi)	25,000	25,000	40,000	50,000	50,000+
Water absorption (%)	1.6	1.6	0.07	0.10	0.10
Insulation resistance (Meg Ohms)	40,000	40,000	2,500	200,000	200,000
Flexural strength (psi)	22,500	22,500	27,000	45,000	43,000
Operating temperature (°F)	-65 to +220	-65 to +175	-292 to +450	-292 to +280	-292 to +349
Operating temperature (°C)	-54 to +104	-54 to +79	-180 to +232	-180 to +138	-180 to +176

Plain phenolic and neoprene-faced phenolic are the standard grades for general isolation joints. G-10 and G-11 are chosen when the bolt load is high or the flange sees repeated torque cycling. G-7 is chosen for high-temperature dry gas only, never for hydrocarbons. The values are typical properties; a certificate of conformance is issued per production lot on request.

Sealing element temperature limits

Nitrile-65 to +250 °F · -54 to +121 °C

Viton-20 to +350 °F · -29 to +177 °C

Teflon (PTFE)-292 to +450 °F · -180 to +232 °C

Neoprene-40 to +248 °F · -40 to +120 °C

EPDM-65 to +248 °F · -54 to +120 °C

On KXT-110 and KXT-120, the retainer (laminate) and the sealing element have different temperature ceilings. Use whichever is lower. For example, a neoprene-faced phenolic gasket at 200 °C is limited by the laminate (max +79 °C), not by the neoprene element. If the two numbers differ, the retainer limits the joint.

Gasket geometries covered by both series

Type E — full-face gasket, bolt holes cut to match the flange, maximum surface protection

Type F — raised-face only, no bolt holes, centres on the flange raised face

Type D — RTJ ring groove, for API and ASME ring type joint flanges

G-10 / G-11 body — high bolt load, repeated torque cycles, larger flange sizes

Neoprene-faced phenolic — softer sealing face for rougher flange surfaces

Teflon element — chemical resistance on aggressive media

The neoprene-faced phenolic construction that combines a phenolic body with a neoprene sealing face is also available as a standalone product; compare the neoprene faced phenolic gaskets page if you are sourcing the gasket separately from the bolt hardware.

Choosing between KXT-110, KXT-120 and the standalone kit

Pick KXT-110 when the joint needs a complete bagged set and the bolt hardware will be replaced at the same time. Pick KXT-120 when the bolt hardware is already on site and only the gasket needs to be renewed. Pick the standalone flange insulation gasket kit when you want a single bespoke joint sized to a non-standard flange rather than a bagged set off the shelf. All three share the same laminate selection and the same Type E / F / D geometries, so the isolation result is the same — the difference is packaging and where the bolt hardware is sourced.

Bulk supply and documentation

Kaxite Sealing produces flange insulation gasket sets in Ningbo, Zhejiang, on the same line as the insulation gasket kits, so the laminate, sealing element and bolt hardware are matched before the set is bagged. Standard sizes follow ASME B16.5 Class 150 to 2500; larger and non-standard flanges are quoted from drawings. Free samples are available for qualified projects with the material certificate attached, and the full property table above is issued with every shipment. Factory visits and video audits are welcome by appointment; ISO 9001 certificate details are available on request. For the complete product family, see the flange insulation gasket kits parent page.

Frequently asked questions

What is the difference between KXT-110 and KXT-120?

KXT-110 is a full set — it ships with the gasket, one insulating sleeve per bolt hole, two insulating washers and two steel backing washers per bolt, bagged by flange size and pressure class. KXT-120 is the gasket-only variant, for sites that already stock the correct sleeves and washers. The gasket geometry and the laminate choice are identical between the two, so the isolation result is the same — the difference is packaging and whether the bolt hardware is replaced.

Why does the page say G-7 must not be used with hydrocarbons?

G-7 is a silicone glass laminate, and the silicone resin is attacked by hydrocarbon solvents. Even a trace amount of hydrocarbon in the process fluid can degrade the laminate and destroy the electrical isolation. G-7 is chosen for high-temperature dry gas only. For any hydrocarbon service, use epoxy glass G-10 or G-11, or plain phenolic with an appropriate sealing element — the physical property table on this page shows the trade-off.

Which laminate should I choose for a standard cathodic protection joint?

Plain phenolic or neoprene-faced phenolic are the standard grades for general isolation joints on water, oil, gas and refinery service. G-10 or G-11 are chosen when the bolt load is high or the flange sees repeated torque cycling. G-7 is only for high-temperature dry gas. Send the media, temperature and torque spec and Kaxite will confirm the grade.

Why do the retainer and sealing element have different temperature limits?

The retainer is the laminate body of the gasket (phenolic, G-7, G-10, G-11) and the sealing element is the facing (Nitrile, Viton, Teflon, Neoprene, EPDM). The two materials are chosen separately, and the joint is limited by whichever has the lower temperature ceiling. For example, a neoprene-faced phenolic gasket at 200 °C is limited by the phenolic body (+79 °C max), not by the neoprene. That is why the page publishes both limits.

What documentation ships with each set?

Each set ships with a material certificate for the laminate and the sealing element, the full physical property table for the selected grade, a bolt-count packing list, and a dimensional record against the referenced ASME B16.5 flange size and class. Factory visits and video audits are welcome by appointment; ISO 9001 certificate details are available on request.

Request a flange insulation gasket set quote

Tell us series (KXT-110 / KXT-120), flange size, ASME B16.5 class, gasket type (E / F / D), laminate grade, sealing element and working media. Full property table and free samples available for qualified projects.

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