Dresser Gasket — Style 138 | Replacement Gasket for Style 138 Couplings

Cast Iron & Ductile Iron Pipe | Grade 27 BUNA-S | Sizes 4 in – 12 in | Up to 212°F | Flexible Pipeline Sealing

Overview

The Dresser Style 138 Gasket is the factory-specified replacement gasket for Dresser Style 138 bolted couplings used on cast iron and ductile iron pipe. The Style 138 coupling system was engineered to solve a persistent problem in municipal water distribution and gas distribution maintenance: the OD variation that exists between older cast iron pipe — some cast as far back as the late 1800s — and modern ductile iron pipe of the same nominal size. A single Style 138 middle ring can accept up to four different gasket and follower combinations, allowing field crews to stock one coupling size and seal pipes across a wide historical OD range without custom hardware.

The Style 138 gasket is molded to a specific wedge-section profile that matches the Style 138 middle ring's conical flare geometry — it is not interchangeable with Style 38 gaskets despite sharing the same nominal pipe sizes. Compounded from Grade 27 BUNA-S (SBR) rubber as standard, the Style 138 gasket absorbs vibration, thermal expansion and contraction, and angular deflection at the pipe joint, maintaining a leak-proof seal even as the line moves in service.

What Is the Dresser Style 138 Coupling?

The Dresser Style 138 Coupling is a multi-range bolted pipe coupling designed exclusively for cast iron and ductile iron pipe in nominal sizes 4 in through 12 in. Its defining feature — one middle ring compatible with multiple gasket and follower combinations — makes it the preferred stocking choice for utilities, contractors, and municipalities that maintain aging infrastructure with mixed pipe vintages. Whether connecting Class 150 grey cast iron to modern AWWA C151 ductile iron, or joining two cast iron pipes of slightly different OD classes, the Style 138 system accommodates the variation without the need for custom-sized couplings.

Key Features

• Purpose-Built for Style 138 Couplings: Molded to the exact profile and OD range of the Style 138 middle ring. Do not substitute Style 38 gaskets — the flare angle and gasket geometry differ.
• Multi-Range Compatibility: Works across the full OD variation range built into the Style 138 coupling system, accommodating historical cast iron and current ductile iron pipe of the same nominal size in one joint.
• Grade 27 BUNA-S (SBR) Compound Standard: The most widely used Dresser gasket compound for water, gas, and general utility pipeline service. Potable water safe, flexible, and chemically compatible with the broadest range of pipeline fluids.
• Absorbs Pipe Movement: Resilient rubber construction accommodates expansion, contraction, vibration, and angular deflection at the joint — the fundamental requirement of any flexible coupling system.
• Available in Multiple Compounds: Grade 42 BUNA-N (Nitrile) available for oil and hydrocarbon service. Grade 169 Butyl, Grade 199 EPDM, and Grade 224 Fluorocarbon available for special service conditions. Consult factory.
• Drop-In Replacement: Exact fit for all Dresser and Dresser-pattern Style 138 couplings in nominal sizes 4 in through 12 in. Direct field replacement — no tooling required beyond standard coupling installation wrenches.

Gasket Specifications

Available Gasket Grades for Style 138

Temperature ratings are reference values. Consult factory for specific recommendations based on line content, operating pressure, and temperature cycling conditions.

? STYLE 138 GASKETS ARE NOT STYLE 38 GASKETS: Style 138 and Style 38 gaskets have different wedge-section profiles and are not interchangeable. Confirm your coupling style number before ordering replacement gaskets. Installing an incorrect gasket profile will result in an improper seal.

Questions? Contact us at sales@watermainsupply.com or call 281.664.8000.