Dresser Gasket | 27 Buna S | Pinned Armored

Dresser Gasket — Grade 27 BUNA-S Pinned Armored | Heavy-Duty Armored Gasket for Dresser Style 711 Coupling

Grade 27 SBR Compound | Pinned Brass Coil Armor | Maximum Extrusion Resistance | Electrical Continuity | High-Pressure & Restraint Service | Up to 212°F

Overview

The Dresser Grade 27 BUNA-S Pinned Armored Gasket is the heaviest-duty armored gasket in the Grade 27 family. It uses the same BUNA-S (SBR) rubber compound and the same integral brass coil armor as the standard armored gasket, with one additional feature: the armor coil is mechanically pinned to the gasket body, locking the helix in position under high compressive and hydrostatic load. This pinning prevents the armor from shifting or the rubber from extruding past the coil when the joint sees elevated pressure, thermal cycling, or thrust load — conditions where a standard armored gasket can begin to extrude or lose its electrical contact path over time.

Pinned armored gaskets are specified where the joint must do two jobs at once: maintain a reliable electrical continuity path for cathodic protection or natural gas service, and withstand higher working pressure or restraint loads than a standard armored gasket is rated for. Because the pinned construction holds the seal geometry stable under load, it is the correct selection for high-pressure mains, deep-bury installations, and joints subject to thrust where a standard armored gasket would be marginal.

How Pinned Armored Differs from Standard Armored

A standard armored gasket carries a continuous elastic brass coil molded into the gasket tip — the coil bites the pipe at both ends to provide electrical continuity, and the rubber on either side seals the joint. A pinned armored gasket adds mechanical pins that anchor that coil to the gasket body. Under high compression, the pins keep the armor seated and prevent the rubber sealing lip from extruding past the coil. The result is a gasket that retains both its seal integrity and its low-resistance electrical path at pressures and loads beyond the standard armored gasket's comfortable range. For ordinary distribution-pressure joints where electrical continuity is the only special requirement, standard armored is sufficient and more economical; reserve pinned armored for the high-pressure and restraint-critical applications where it is specified.

When You Need Pinned Armored

Specify pinned armored Grade 27 whenever: (1) the joint requires electrical continuity (cathodic protection or natural gas conductive joint) and operates above the working pressure range where a standard armored gasket is rated; (2) the installation is subject to thrust or restraint loads that would tend to extrude a standard gasket; (3) the engineer, utility standard, or coupling manufacturer's submittal calls for pinned armored construction specifically; or (4) you are replacing gaskets in a coupling that originally shipped with pinned armored gaskets. For continuity-only requirements at normal distribution pressure, use standard Grade 27 Armored; for joints with no continuity requirement, use plain Grade 27.

Key Features

• Pinned Brass Coil Armor: The integral brass helix is mechanically pinned to the gasket body, locking the armor in position under high compressive and hydrostatic load. Resists shifting and rubber extrusion that can compromise a standard armored gasket at elevated pressure.
• Maximum Extrusion Resistance: The pinned construction holds the sealing-lip geometry stable under load — the highest extrusion resistance in the Grade 27 gasket line. Correct for high-pressure mains, deep bury, and thrust-restrained joints.
• Metal-to-Metal Electrical Continuity: Like the standard armored gasket, the coil bites into the pipe surface at both ends as the coupling is tightened, providing a cathodic-protection current path through the coupled joint — retained reliably under high load thanks to the pinned armor.
• Grade 27 BUNA-S Base Compound: Same SBR rubber as plain and standard armored Grade 27 — same 212°F temperature rating, same chemical compatibility, same durometer, same White color code. The pinned armor is the only difference from standard armored.
• Direct Replacement Geometry: Same nominal sizes, outside diameters, and gasket sections as the corresponding plain and standard armored Grade 27 gaskets — drops into the same Dresser coupling bodies.
• Specified Construction: Where a submittal or utility standard calls for pinned armored specifically, this is the code-compliant gasket. Do not substitute standard armored where pinned is specified.

Specifications

PINNED vs. STANDARD ARMORED vs. PLAIN — COLOR CODE IS IDENTICAL: All three Grade 27 gaskets (plain, armored, and pinned armored) share a White mold color code. Always confirm the exact grade from the part number or product label before installing — not from color alone. Do not substitute standard armored where pinned armored is specified, or vice versa.

NEED STANDARD ARMORED OR PLAIN INSTEAD? For continuity-only joints at normal distribution pressure, see our Grade 27 Armored gaskets. For joints with no electrical continuity requirement, see our plain Grade 27 gaskets.

Several sizes in this line are quoted per order. Questions or need a price on a call-for-quote size? Contact us at sales@watermainsupply.com or call 281.664.8000.

Grade 27 Buna-S Gasket Product Submittal

Gasket Shelf Life Technical Bulletin

Dresser Gaskets Overview