New sealing washers:
A bonded seal is a type of washer used to provide a seal around a screw or bolt. Originally made by Dowty Group in the UK, they are also known as Dowty seals or Dowty washers. Now widely manufactured, they are available in a range of standard sizes and materials. Here in The States we typically call them Stat-O-Seal washers. This is the trademarked name given by the Parker Hannifin Corp USA. Derived from the English word stato or stasis meaning: a state of static balance or equilibrium.

Both washers consist of an outer annular ring of a hard material, typically steel, and an inner annular ring of an elastomeric material that acts as a gasket. It is the compression of the elastomeric part between the faces of the parts on either side of the bonded seal that provides the sealing action. The elastomeric material is bonded by heat and pressure to the outer ring, which holds it in place. This structure increases resistance to bursting, increasing the pressure rating of the seal. Because the bonded seal itself acts to retain the gasket material, there is no need for the parts to be sealed to be shaped to retain the gasket. This results in simplified machining and greater ease of use as compared to some other seals, such as O-rings.

Available sizes and just some of their (possible applications):


1/4 Inch ID – (Rocker box bolts, Drain plugs)


5/16 Inch ID – (Rocker box  bolts, Drain plugs)


3/8 Inch ID- (Rocker box bolts, Drain plugs, cylinder studs)


1/2 Inch ID – (Triumph 1/4 BSPP Fuel tap) – This one is not new


9/16 Inch ID (14mm) Amal Concentric drain plug


(16mm) BSA 3/8 BSPP Fuel tap

All have been tested for fuel and oil compatibility.