MIL-R-6855 (MIL-PRF-6855): Classes, Grades and Status

Status: active as MIL-PRF-6855

The document older prints call MIL-R-6855 carries the Document ID MIL-PRF-6855 on DLA ASSIST, the Defense Department's standardization database, with the status Active and the next review due in July 2027. Its current text is revision F of June 2009, a performance specification, with Amendment 1 of February 2012 folded in, and validation notices of June 2017 and August 2022 confirmed it for use in acquisition. The route there was not straight: the last MIL-R revision, MIL-R-6855E of July 1992, was cancelled in December 1998 in favor of SAE AMS-R-6855, then reinstated in June 2001. SAE's own record lists AMS-R-6855B as cancelled in December 2010, so the government document is the one in force.

The specification sheets that turn it into part numbers are active for sheet (/1), strip or tape (/2), tubing (/4) and extruded channel (/5). The sheets for rods (/3) and special extruded shapes (/6) were cancelled in June 2000 with no superseding sheet. MIL-PRF-6855 is a rubber goods document, not an O-ring specification; the mil-spec O-ring pages cover the O-ring documents and their part numbers.

Classes, types and grades

Source for the classes: MIL-PRF-6855F with Amendment 1, paragraphs 1.2 and 6.1, read 2026-09-27.

Types apply to Classes 2 and 4 only: Type A is for high ozone concentrations, Type B for general use, and Type A material may be supplied where Type B is called for. Grades run 30, 40, 50, 60, 70 and 80, and the number is the Shore A durometer hardness measured to ASTM D2240. Every class must pass a cold-bend test, and polyurethane is excluded from the specification altogether.

Reading a MIL-R-6855 callout

A drawing callout names the specification, the class, the grade and, for Classes 2 and 4, the type. MIL-R-6855, Class 2, Grade 50, Type B asks for rubber that resists petroleum oil, weather and ozone, at 50 Shore A, in the general-use ozone type; the specification lists neoprene as meeting Class 2. The material is marked the same way, with the class number, the grade in parentheses and the type letter, so that sheet reads 2 (50) B, beside the maker's compound number and the cure date and use-by date by quarter. An older print that says MIL-R-6855 with no revision letter is read against the revision the contract names, and the drawing owner settles it when neither says.

A part number that starts M6855/ is the specification-sheet form. The number after the slash picks the sheet, /1 for sheet or /2 for strip, and the six digits after the dash encode the part. On the /1 sheet those six digits are a two-digit class, type and grade code, a two-digit thickness code, and one digit each for length and width.

Verification, QPL status and paperwork

MIL-PRF-6855 is verified lot by lot, not through a qualified products list: its DLA ASSIST record carries no qualification link, and the document sets out first article inspection and conformance inspection instead. First article inspection applies when the contract calls for it, such as a first offering or a change of compound, process or plant, and conformance tests run on every lot, where one failed sample rejects the lot. When no first article is required, the specification's notes allow the contractor to certify in writing that the material meets every requirement. The evidence for MIL-R-6855 material is therefore the maker's certification and lot test results, not a listing; the QPL guide explains how a qualified products list works where a specification has one.

A certificate of conformance ships with every order and names the part number, the specification, the manufacturer, the lot, the quantity and the manufacturer's cure date. The manufacturer's own certificate ships with specification parts, and Conquest can also supply the manufacturer's certification on the raw material or from the maker of the finished part. A first article test report goes on the purchase order, because the specification treats first article inspection as a contract option. For shelf life the specification defers to the contract, with the Defense Department's shelf-life handbook as guidance, and the shelf-life guide gives that handbook's figures for the MIL-R-6855 classes.

How to quote MIL-R-6855 parts

• The drawing for a cut gasket, as a DXF, DWG or PDF, with the thickness the print states.
• The callout as printed: MIL-R-6855 or MIL-PRF-6855, the revision if given, the class, the grade and, for Classes 2 and 4, the type.
• The form: sheet, strip, extrusion or molded shape, and the M6855 part number if the print has one.
• Dimensions and quantity, with any tolerance, surface finish or color the print adds.
• Paperwork: first article inspection or its report if the contract requires one, marking, and any shelf-life limit counted from the cure date.

Send the drawing and the specification together, with the callout as the print states it, through the quote form, and a person replies within one business day. The custom gasket page covers what to send for a gasket cut to a drawing, and the gasket hub lists each sheet material with its own page.

Sources

1. DLA ASSIST-QuickSearch record for MIL-PRF-6855 and its specification sheets /1 to /6 (status, document category, revision history), read 2026-09-27
2. MIL-PRF-6855F with Amendment 1, 27 February 2012, Rubber, Synthetic, Sheets, Strips, Molded or Extruded Shapes, General Specification for (scope, classification, marking, verification, intended use), read 2026-09-27
3. MIL-PRF-6855/1A, Rubber, Synthetic, Sheets, 15 June 2009 (part number structure), read 2026-09-27
4. MIL-R-6855E Notice 1 (cancellation, 18 December 1998) and Notice 2 (reinstatement, 15 June 2001), and MIL-PRF-6855F Notice 2 (validation, 1 August 2022), read 2026-09-27
5. SAE Mobilus record for AMS-R-6855B (cancelled December 2010), read 2026-09-27
6. ASTM D2240 (title only)
7. Conquest Seal's certificate of conformance, as the certificate of conformance guide sets it out: it ships with every order (company statement of 2026-09-22) and prints the manufacturer's cure date (company statement of 2026-09-24); the manufacturer's certification on the raw material or from the maker of the finished part (company statement of 2026-09-24)

Reviewed by Grant Midstokke, Conquest Seal Corporation. Last updated September 28, 2026. Spec values in this guide are drawn from the sources listed above; the compound datasheet and your application conditions govern the final choice.