A time- and money-saving idea from Loctite’s Pre-Applied Coating Centre
dispenses with sealing washers or the need for special machining. Instead
of pre-coating the threads of bolts with Dri-Seal, the company now
applies the sealant under the bolt head. When such treated bolts are
tightened, the Dri-Seal is crushed, filling the space between the bolt
heads and end-cap to provide an instant seal.
A manufacturer of hydraulic steering units used to machine special flat
head bolts and counter-bore the end-caps to ensure a ‘no-leak’ assembly.
Now it uses normal Grade-8 high-tensile steel bolts with an under-head
ring of Dri-Seal and plain end-caps. Every assembled unit is tested to
its rated pressure, which is typically 172bar.