Truing Up Sealing Surfaces

[Traveler 45C]

Having done a forum search for Perfect Seal, I saw references made to truing up the sealing surfaces before putting the parts together. What exactly does that mean and what’s the proper way to do it? What should I be looking for and how should they look before assembly? Do they have to be completely smooth? At what point are they bad enough that I should use silicone?

When I RR’d some pipes on my eng’s HE, the surfaces were slightly pitted. Running my finger over the surfaces I could feel the roughness. I used 120 grit paper (don’t know if that was the right stuff but it hasn’t leaked…..yet. ) to clean and smooth them up, then I put on some oil.

I’m not a mechanic but love learning so if you guys don’t mind sharing your tricks and wisdom I could use the help.

 

[spartonboat1]

Just my 2cw, plus there are some very experience engine assemblers on this site. In my good'ole days in the skilled trades, mating surfaces were first scraped to removed all old gasket material, ensuring that gouges were not created on the surfaces. They were then cleaned up with "crocus cloth", which comes in rolls of cloth-like material that is coated with high grit material, about 600-1,000 grit.

I would not recommend oiling the mating surfaces, but rather ensure the surfaces are as dry as possible and all the gritty material from the high grit cloth was removed. The surfaces don't need to be absolutely smooth as a baby's backside. The very slight roughness from the 600 grit or so, provides a "key" for the gaskets to bite.

If you have the correct cork, rubber, or composite gaskets, then you should't need to use a silicone gasket. Some techs find a silicone type of gasketing material that works well, and stick to that, if no gaskets are avail.

I do use steam fitters anti-seize on some threaded pipes fittings, in the presence of corrosive elements. I used to use the teflon tape wrapped over pipe threads, but I have read of some corrosion issues with that tape and the teflon. So I have switched back to pipe thread compound for most pipe threads. Also note that some threads are NPT (National Pipe Thread) and tapered, vs. some are straight threads. Then there is the various copper line fittings, flared, etc. Rapid increase in ignorance now occurring.

Simple gasket kits are available for your seacocks, if they are Groco. I keep some around. Also for my impellers, which I pull each winter, so none of the wings takes a "set", I keep some extra gaskets around.

When torquing multiple fasteners on one fitting, try to use the star pattern, while tightening. If more than hand tightening is indicated, I use a torque, whenever possible, esp. where a pressurized system is involved. Always use two clamps on hoses, absolutely when below the waterline.

Again, my 2cw...