Dresser Gasket — Grade 42 BUNA-N | Nitrile Gasket for Dresser Style 38, 40, 138 Couplings

Grade 42 Nitrile (BUNA-N) | Oil & Hydrocarbon Resistant | Natural Gas Condensate | 212°F Maximum | Yellow Color Code

Overview

The Dresser Grade 42 BUNA-N Plain Gasket is the oil and hydrocarbon-resistant sealing element for Dresser Style 38, Style 40, Style 138, and related bolted couplings in pipeline service where the standard Grade 27 BUNA-S compound is chemically incompatible with the line content. Grade 42 is compounded from Nitrile Butadiene Rubber (NBR) — universally known as BUNA-N or Nitrile — which provides significantly superior resistance to petroleum hydrocarbons, aliphatic and aromatic solvents, oils, natural gas condensate, and fuel-related fluids compared to SBR-based compounds. It is the standard alternative to Grade 27 whenever the pipeline carries hydrocarbons rather than water or dry gas.

Grade 42 maintains the same wedge-section profile, Shore A durometer, and temperature rating as Grade 27 — it is a drop-in compound upgrade, not a dimensional change. The only field-identification difference is the Yellow color code vs. White for Grade 27. Grade 42 is available in both plain (this listing) and Armored versions (see Grade 42 Armored listing).

Applications — Grade 42 BUNA-N Is Recommended For

• Oil pipelines — crude oil, refined petroleum products, fuel oil, lubricating oil
• Natural gas distribution lines carrying wet gas or gas with condensate
• Natural gas fogging oil and condensate-bearing gas service lines
• Aromatic and aliphatic hydrocarbon lines — gasoline, kerosene, diesel, jet fuel
• Corn oil, cottonseed oil, linseed oil, soybean oil, and other vegetable oils
• Mineral oil and mineral spirits
• Freon refrigerant lines (chlorinated and fluorinated compounds)
• Blast-furnace gas and producer gas
• Carbon tetrachloride, castor oil, and glue service

Grade 42 is not the first choice for: water-based service, high-temperature steam, or aggressive oxidizing acids — Grade 27 (water/gas) or Grade 199 EPDM (steam/hot water) are more appropriate for those services.

Key Features

• BUNA-N (Nitrile) Compound — Superior Oil Resistance: Nitrile rubber is specifically formulated to resist swelling and degradation in the presence of petroleum oils, aliphatic hydrocarbons, and aromatic solvents — the failure mode of SBR-based Grade 27 when exposed to these fluids.
• Same Profile as Grade 27 — Drop-In Upgrade: Grade 42 uses the same wedge-section molded profile as Grade 27. When coupling sizing and pipe OD are correct for Grade 27, Grade 42 installs identically — no hardware changes required.
• Natural Gas Condensate Service: For natural gas distribution lines that carry significant condensate, Grade 42 provides the hydrocarbon resistance that Grade 27 lacks — preventing gasket swelling and seal degradation over time as condensate accumulates at the joint.
• Yellow Color Code for Field Identification: Grade 42 is color-coded Yellow at the mold — immediately distinguishable from White (Grade 27) in field storage and installation, reducing compound mix-up risk during maintenance.
• Armored Version Available: Grade 42 BUNA-N Armored (see separate listing) adds a brass coil to the gasket tip for applications requiring both oil resistance and electrical continuity through the joint.
• 212°F Maximum Temperature: Same temperature ceiling as Grade 27. For oil service above 212°F, consult Dresser engineering for Grade 224 Fluorocarbon options.

Specifications

Gasket Recommendations for Common Hydrocarbon Line Contents

Recommendations based on ambient temperature service. Consult Dresser engineering for elevated temperature, high-concentration chemical, or unusual service conditions.

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