Dresser 27 Buna 42 Buna N Viton Graphite Gaskets

The gasket is the only element in a Dresser coupling that actually contacts the fluid and the pipe OD simultaneously. Grade selection is not a cosmetic decision — it determines long-term seal integrity, chemical resistance, and service temperature limits. Eleven gasket grades cover potable water through high-temperature process steam.

11 products
Sort by:
Best selling
Sort by:
Best selling
Availability
Type
Price
$0
$1,593.28
Dresser Gasket | 27 Buna S
Dresser Gaskets

Dresser

Dresser Gasket | 27 Buna S

From $31.49
Dresser Gasket | 27 Buna S | Armored
Dresser Gaskets

Dresser

Dresser Gasket | 27 Buna S | Armored

From $34.26
Dresser Gasket | 42 Buna N
Dresser Gaskets

Dresser

Dresser Gasket | 42 Buna N

From $59.47
Dresser Gasket | Style 138
Dresser Gaskets

Dresser

Dresser Gasket | Style 138

From $76.67
Dresser Gasket | Style 4/41
Dresser Gaskets

Dresser

Dresser Gasket | Style 4/41

From $47.76
Dresser Gasket | Style 60/160
Dresser Gaskets

Dresser

Dresser Gasket | Style 60/160

From $169.75
Dresser Gasket | Style 65
Dresser Gaskets

Dresser

Dresser Gasket | Style 65

From $3.68
Dresser Gasket | Style 88
Dresser Gaskets

Dresser

Dresser Gasket | Style 88

From $3.77
Dresser Gasket | Style 90
Dresser Gaskets

Dresser

Dresser Gasket | Style 90

From $3.09
Dresser Gasket | 365 Graphite Fiber | High Temp
Dresser Gaskets

Dresser

Dresser Gasket | 365 Graphite Fiber | High Temp

From $194.88
Dresser Gasket | 42 Buna N | Armored
Dresser Gaskets

Dresser

Dresser Gasket | 42 Buna N | Armored

From $110.93
Dresser 27 Buna 42 Buna N Viton Graphite Gaskets
Description

Dresser Coupling Gaskets

The gasket is the only element in a Dresser coupling that actually contacts the fluid and the pipe OD simultaneously. Grade selection is not a cosmetic decision — it determines long-term seal integrity, chemical resistance, and service temperature limits. Eleven gasket grades cover potable water through high-temperature process steam.

11
Gasket Grades
–40°F to 1,200°F
Temperature Range
Plain + Armored
Construction Options
NSF 61
Potable Water Listed
Grade Reference
Gasket Grades by Style and Application
Dresser coupling gaskets are ordered by style (the coupling the gasket fits), pipe OD, and grade suffix. The suffix code tells the factory which elastomer compound to manufacture.
27Standard
Grade 27 — Buna-S (SBR)
Styrene-butadiene rubber. The default grade for potable water, natural gas, and general underground service. Factory default when no grade is specified on the order. Suffix -011 (plain) or -013 (armored).
WaterGas–40°F to 180°F
42Oil-Resistant
Grade 42 — Buna-N (NBR / Nitrile)
Nitrile rubber. Specified where Grade 27 would swell: petroleum-contaminated soils, hydrocarbon service, oil refineries, and any location where the pipe may carry or be exposed to aliphatic hydrocarbons.
Oil & PetroleumHydrocarbons–20°F to 275°F
365High Temp
Grade 365 — Graphite Fiber Composite
Non-elastomeric graphite fiber composite. The only Dresser gasket grade rated for steam and high-temperature process service. Requires RED-D Shopcoat housing — cannot be used with epoxy-coated couplings. Maximum 1,200°F.
SteamHigh Temp ProcessUp to 1,200°F
138CI/DI Style
Style 138 Gasket
Gasket manufactured specifically for Style 138 cast and ductile iron couplings. The wide ID tolerates the OD variation characteristic of older CI pipe. Available in standard and armored variants.
Style 138 OnlyCI/DI ODWide Tolerance
4/41Collar Clamp
Style 4/41 Gasket
Replacement gasket for Style 4 and Style 41 collar leak clamps. Ordered when a previously installed clamp requires resealing or when a gasket is damaged during clamp removal for pipe access.
Style 4 / 41Collar ClampReplacement
60/160Bell Joint
Style 60/160 Gasket
Gasket for Style 60 and Style 160 bell joint clamps. The gasket profile is shaped to conform to the stepped geometry at a bell-spigot joint. Not interchangeable with pipe body (Style 360) clamp gaskets.
Bell JointStyle 60 / 160Bell Profile
90Style 90
Style 90 Gasket
Replacement gasket for Style 90 compression fittings. Available for copper CTS and steel IPS OD. Required when a compression fitting is disassembled for pipe rework and the original gasket is not reusable.
Style 90CTS & IPSCompression Fitting
88Brass Fitting
Style 88 Gasket
Replacement gasket for Style 88 brass compression fittings. Brass fitting gaskets use the same elastomer compound as the standard compression fitting line but are sized for the brass follower geometry.
Style 88Brass FittingReplacement
65Comp. Fitting
Style 65 Gasket
Replacement gasket for Style 65 steel IPS compression fittings. Sized to fit 1/2" through 2" Style 65 regular and long body compression fittings. Specify pipe OD when ordering.
Style 65IPS Steel1/2"–2"
Material Science
What Each Elastomer Actually Resists
Elastomer compatibility is not intuitive. Buna-S swells in oil. Buna-N swells in ketones. Understanding the chemistry prevents field callbacks.
Chemical Exposure Grade 27 (Buna-S) Grade 42 (Buna-N) Grade 365
Potable Water Excellent Good Excellent
Natural Gas (dry) Excellent Excellent Excellent
Aliphatic Hydrocarbons Swells Excellent Good
Aromatic Hydrocarbons Swells Limited Good
Petroleum-Contaminated Soil Not Suitable Excellent Good
Steam / High Temperature Degrades Degrades Excellent
Dilute Acids / Bases Good Good Excellent
Ketones / Esters Limited Swells Good
Petroleum-Contaminated Soil

If the installation site has any history of petroleum storage, pipeline leakage, or industrial waste, specify Grade 42 regardless of the fluid being carried inside the pipe. It is the soil chemistry — not the pipe contents — that degrades Grade 27 in contaminated ground.

When in Doubt

Grade 42 (Buna-N) is the safe upgrade from Grade 27 for most water and gas utility applications. The cost premium over Grade 27 is modest, and the chemical resistance profile is broader. Many utilities specify Grade 42 as their standard on all new installations.

Service Reference
Temperature and Pressure Limits by Grade
Both temperature and pressure limits apply simultaneously. A Grade 27 gasket at 170°F and 250 PSI is operating at both its temperature limit and its pressure limit — reduce one or upgrade the grade.
Grade Elastomer Min Temp Max Temp Max Pressure Primary Use
27 / Plain Buna-S (SBR) –40°F 180°F Per coupling WP Water, gas, general underground
27 / Armored Buna-S + SS Ring –40°F 180°F Per coupling WP Rocky soil, vibratory service
42 / Plain Buna-N (NBR) –20°F 275°F Per coupling WP Petroleum, hydrocarbons
42 / Armored Buna-N + SS Ring –20°F 275°F Per coupling WP Rocky soil + petroleum exposure
365 Graphite Fiber –100°F 1,200°F Per coupling WP Steam, high-temperature process
Armored Gasket Series
When to Specify Armored Over Plain
The armor ring is a stainless steel insert embedded in the gasket heel. It prevents gasket extrusion under cyclic loading and protects against physical displacement in aggressive soil conditions.
🪨
Rocky / Fractured Soil
Stone or fractured rock in the trench can migrate against the gasket during backfill settlement. The armor ring prevents a rock point from puncturing or displacing the elastomer.
Specify Armored
🔊
Vibratory Service
Pump discharge lines, compressor headers, and mains subject to water hammer experience cyclic gasket compression. Armored gaskets resist extrusion under repeated pressure cycles.
Specify Armored
💰
Plain Gasket — Most Installs
For standard underground distribution in good soil with stable operating pressure, plain gaskets provide equivalent service life at lower cost. Reserve armored for the specific conditions above.
Plain — Standard Service
Selection Guide
Grade Selection in Four Questions
Answer these four questions in order. Stop as soon as one gives you a definitive grade.
1
Is the service temperature above 275°F?
If yes — Grade 365 Graphite Fiber. No elastomeric grade is suitable above 275°F. Also confirm you have ordered a RED-D Shopcoat coupling housing — epoxy coatings are not compatible with Grade 365 service.
2
Is the pipe in or near petroleum-contaminated soil?
If yes — Grade 42 Buna-N. Petroleum contamination is a soil condition, not a fluid condition. It affects the gasket regardless of what is flowing inside the pipe.
3
Is there physical stress on the gasket — rocky soil, water hammer, vibration?
If yes — add armored suffix to whatever grade you have selected (Grade 27 → suffix -013; Grade 42 → suffix -134). Armor rings do not change chemical compatibility.

Ready to Order or Need Technical Help?

Contact our team for availability, custom sizing, and volume pricing on Dresser Utility Solutions products.

Email sales@watermainsupply.com Call 281.664.8000