MIL-PRF-81733

Properties

The polysulfide sealing compounds specified in MIL-PRF-81733 have several essential properties.

Adhesion: Strong adhesion to various substrates, including metals and composites.

Flexibility: Remains flexible across a wide temperature range, crucial for maintaining seals in varying conditions.

Chemical Resistance: Resistant to fuels, oils, hydraulic fluids, and other chemicals commonly encountered in aerospace environments.

Curing: Cures at room temperature to form a durable and resilient seal.

Applications

Widely used in aerospace applications. Here are a few examples:

• Sealing fuel tanks and fuel lines
• Insulating pressurised cabins
• Sealing joints and seams in aircraft structures
• General-purpose sealing applications in harsh environments

Classes

Class 1:

• Effective from -65°F to +250°F (-54°C to +121°C)
• Used for sealing applications requiring fuel resistance and low-temperature flexibility.
  
  

Class 2:

• Effective from -80°F to +320°F (-62°C to +160°C)
• Designed for high-temperature applications and exposure to aircraft fluids.
  
  

Types

There are four main types of MIL-PRF-81733 sealant:

Type I: Typically used for integral fuel tanks and pressurized cabins.  
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Type II: Offers broader application due to its resistance to a wider range of chemicals.
Type III: Specifically designed for use with certain types of fuels.
Type IV: Used in specific applications requiring high temperature resistance.

Versions

The most recent version of the spec is MIL-PRF-81733D, where MIL = Military Specification, PRF = Performance Requirements, 81733 = Unique identification number, D = Revision version. This version was created in May 1998, Superseding MIL-S-81733C.

MIL-S-81733C was a previous version of the spec, where S = Sealant. MIL-S-81733C was established in March 1980, with a further amendment in February 1988.