Alternative Skim Port

It appears that your HB Smith boiler does not have a dedicated Skim tapping according to the manual. The closest thing that manual shows is what appears tp be a 3/4" plug that has no access thru the boiler jacket in your photo.

That plug is not even labeled in the diagram on page 24. The skim tapping should be centered over the boiler’s widest top openings where the push nipples or gaskets connect the sections. This allows the water level during skimming to be positioned at the widest part of the top section connection. In the diagram you can see the location of the top opening gasket (17).

If your boiler repair technician is not referencing that opening, then you should not have them perform the skimming. They do not understand the purpose of the skimming process. Otherwise, you may end up paying someone to skim only the end section of the boiler rather than properly skimming all six boiler sections.

EDIT:

Your skim tapping is behind this knock out on the boiler jacket:

RED ARROW indicated skim tapping location. I might even consider getting a machinist in there to drill and tap a larger hole for 1" or -1/4" pipe and a cap for future use.

Hiring a machinist? I think I'd try a can of Squick first

These cleaning instructions are wild. They want you to blow the oil out the top via the PRV port along with water and steam until the water is clean.

i don't know that the firing is doing anything other than mixing up what is in the boiler and splashing the detergent on the sections above the water line. sounds like they are trying to emulsify the oil and drain it with the water.

I seem to recall someone, or, maybe a book? mentioning they didn't skim boilers years ago, but rather dry fired them and burned the oil out of it.

No idea how true it is etc, but it seemed true when I read / heard it.

By years ago, I mean 1930s and older.

Could you avoid machining by cutting a hole in sheet metal jacket to access the 3/4 plug Ed located? I’d use a 2” hole saw and go carefully . Once you get access it may still be a job breaking the plug loose.

cut it out.

Since the upper site glass port seems the highest tapping on the side (either side) of the boiler I would try the @ChrisJ method. It may be slower than normal skimming, but it may get the job done. The plug the plumber was attacking could have been drilled out enough to slice it as @mattmia2 suggests.

There was post not too long ago where the heat exchanger cracked just trying to remove the drain valve. Old boilers you really don't know how dilapidated they are. So brute force until something breaks may not be the best plan.

Homeowner here that would do his own work. I'd be afraid to remove the skim port and break something and I'd be a bit nervous about cutting out a wedge and screwing something up.

I'd remove the Tee where the pigtail is on the top of the site glass and install a cross. Install a nipple and a ball valve and route a short section of pipe to drain into a bucket or put a garden hose adapter on it to drain it from there.

My second option would be to use the PRV port. take the PRV off and install a Tee. Route some piping from there with a ball valve to a convenient drain location.

Neither would be ideal but would be better than nothing and I'd feel confident enough to do it on my own.

For a boiler that old, I think it is unlikely that oil is still floating on the surface requiring skimming.

Is your gauge glass indicated water level dropping dramatically at any time during a call for heat? You mention "surging I'm getting in the glass". Can you precisely describe or make a video of what you're seeing?

Yep.

I've done that on my WM boiler a few times to wash the glass out. I'd imagine it would work for skimming as well, just, slow. That's assuming the top of the glass is piped in as they show it on that diagram.

I'd drain 4 gallons and see what it looks like on the top of the bucket at the end. Oily / nasty is a good sign.