Aerospace Material Standards: MIL Standards | Trelleborg

There are a large number of standards that apply to the aerospace industry. Listed in this section are the key ones.

Standard authorities
All standards prefixed with either AS (Aerospace Standard) or ARP (Aerospace Recommended Practice) are issued by SAE International (Society of Automotive Engineers) in the US. Trelleborg Sealing Solutions is an active contributor to the SAE work. Copies of SAE standards may be obtained from the Society of Automotive Engineers.

This is a standards development organization for the engineering of powered vehicles of all kinds including aerospace. In addition, MIL standards cover military aircraft and are issued by the US Department of Defense.

Aerospace Standards

ARP1234, Revision B
Gland Design, Elastomeric O-Ring Seals, Static Axial, Without Back-Up Rings
Provides standardized dimensional criteria for static axial elastomeric O-Ring seal glands, without Back-up Rings. This standard supplements ARP 1231, “Gland Design, Elastomeric O-Ring Seals, General Considerations.“ The criteria are similar, but not identical, to those in MIL-G-5514.

Storage of Elastomer Seals and Seal Assemblies Which Include an Elastomer Element Prior to Hardware Assembly
Addresses the general requirements for data recording procedures, packaging and storing of elastomeric seals and seal assemblies which include an elastomeric element prior to the seal being assembled into hardware components.

The requirement for packaging is an integral part of the controlled storage procedure and provides a means of positive product identity from the time of manufacturing to the time of assembly into a component.

Aerospace Rod Scraper Gland Design Standard
Defines gland dimensions for rod scrapers. Gives specifications for rod diameters from ¼ to 15 ½ inches/ six to 394 mm, inclusive corresponding to AS568 O-Ring Dash No. sizes -108/-111, -206/-222, -325/-349 and -425/-460. The gland details provide more space than MS33765 and are sufficient to fit more efficient and reliable exclusion devices.

Gland Design: Scraper, Landing Gear, Installation
Covers an alternate gland design for the installation of scraper/ wiper rings in the lower end of landing gear shock struts for the purpose of contaminant exclusion.

Piston rod diameters, gland internal diameters, groove sidewall angles and the surface finish are all defined by AS4716, but the gland outer retaining wall diameter is changed. The gland has a reduced atmospheric gland lip and profiled lead in geometry to allow for a PTFE jacket metal spring-energized scraper to be installed.

Gland Design, O-Ring and Other Elastomeric Seals
Provides standardized gland design criteria and dimensions for elastomeric seal glands for static and dynamic applications.

The glands have been specifically designed for applications using SAE AS 568 size O-Rings, with related class 2 tolerances, at pressures exceeding 1,500psi/ 10.3 MPa utilizing one or two anti-extrusion Back-up Rings and applications at pressures under 1,500psi/ 10.3 MPa without Back-up Rings. While this specification covers the basic design criteria and recommendations for use with standard size O-Rings, these glands are also for use with other elastomeric and PTFE based seals and packings.

Gland Design: Nominal 3/8 Inch Cross Section for Custom Compression Type Seals
Offers gland details for a nominal 3/8 inch/ 0.364 mm cross section gland with proposed gland lengths for compression-type seals with two Back-up Rings over a range of eight to 20 inches/ 203 to 508 mm in diameter.

A dash number system is proposed similar to AS568A. Seal configurations and design are not a part of this document. This gland is for use with custom compression-type seals including, but not limited to O-Rings, T-Rings, D-Rings, etc.

To select the optimum material for your application use our online tools:

  • Material search allows you to identify compounds that meet specific property requirements and those that comply to specific approvals or standards.
  • Chemical compatibility check allows you to find the level of resistance of material groups to a broad range of media, both fluids or gases including those used within semiconductor manufacturing.