Pier tube materials

[charlesd]

I have access to 300mm x 1.6mm spiral wound mild steel duct (4 ply lock seam), and am wondering what ICE members think of it as a suitable material. the lock seam tube is not welded but folded to make a mechanical seam.

I am thinking of embedding one end in a concrete block sunk below ground and on the other end have a steel flange welded to which i can attach the usual plates and adjustment bolts to make the scope level. I am not going to fill the tube with concrete as the 1.6mm material should be strong enough to support the load.

My C8 scope, wedge and assorted fittings is less than 20kg. The part of the tube that pokes out of the block will be about 1.2m in length. I don't see the 1.6mm thick tube material crumpling under the load at that length (I am going to verify this)

here is the manufacturers web site: http://www.roladuct.com.au/round_tubing.html

[Russ59]

Hi Charles,

I would be concerned about what happens when any moisture in the concrete works its way into the sheetmetal-type base material and rusts it out - inside or at the base of the slab!

Just my thoughts.

Russ

[charlesd]

good point.

do you think a tube with flange at either end with one end bolted to the concrete block would be any better ? you could put a spacer, between the pier and concrete to keep the pier off the concrete

you cold paint the galvanised steel tube with rust inhibitor

[Russ59]

Hi Charles,

With a thick enough base flange (I am using 10mm thick steel plate 300x300mm square) I don't believe you will require any spacing between the base flange and the slab.

I'm sure other members will provide some advice on this.

I came across this website: http://obs.nineplanets.org/obs/obslist.html

There is a small section at the bottom of the page for piers. One thing I did notice that Sonotube is more popular in the USA than here.

Russ

[Stardrifter_WA]

I got three pieces of 20mm thick steel plate from a scrap metal yard along with some large diameter hydraulic cylinder tube (nice thick wall), all for nicks...will make a sweet permanent pier! All I need now is the use of a lathe! But, if I have to pay for machining, that will not be too bad, since material was free. But it will annoy me though since I am a retired machinist :)

[Waxing_Gibbous]

A good dose of Zinc-Chromate primer followed by a coat of tar-based waterproofing should do the trick.
Another option woud be to use shrink-wrap plastic to cover the end of the pier.
This is available from commercial suppliers and shrinks to fit when heated with a hair-dryer or heat-gun.
Both should provide enough moisture protection for years.

[jenchris]

1.6mm is not very thick.
I'm wondering if the spiral seams are not locked or welded, will they expand and rotate the pier as they go?
I'm presuming that this is non stressed ventilation ducting?

Procuring a solid piece of tube from a steel fabricator might be a better solution. (I used 12mm wall sch40 water mains - free from a building site near you)

[2stroke]

Lol i wouldn't waste my time with 1.6mm, just head to any metal supplier and ask for some 200 nb heavy/extra black pipe or 100 nominal bore at a min. If you can afford a c8 i can't see why you would skimp on $30-$90 worth of metal pending the nominal bore.

[charlesd]

Thanks for the suggestions. I was trying to think outside the square re the pier material. I have come full circle now, and it will be black steel pipe with plates and gussets.

[bojan]

OK, provided it's filled with concrete ;)

[DaveGee]

Hmmm, 300mm dia concrete.:bowdown:

Even heavy steel will ring like a bell unless it's heavily braced = $$$ :sadeyes:

[2stroke]

Sand is the answer :)

[baileys2611]

I "found" a parking bollard that does the trick nicely. It's 200mm, comes pre-filled with concrete and has a 20mm thick 300mm x 300mm base plate.

What I am going to do is mount this on to the top of my in-ground water tank (300mm thick "slab") by drilling holes for marine grade stainless steel dyna-bolts 40mm into the slab. The holes will be filled with construction grade adhesive to prevent any moisture leaking onto the concrete. I'll then use flexible tile glue (from any hardware store) and a 6mm piece of landscaping rubber matt, followed by more tile glue and finally plonk the pier onto that mass of rubber and glue.

The pier has to be prepared though, got to sand off the rust, treat what is left on the metal (using rust-converter) and prime then paint it gloss black.

I was planning on getting a local company to weld a 300mm x 18mm thick steel plate to the top of the mount, then use some stainless steel threaded rod to attach an 18mm aluminium plate, upon which I need to find and place a "puck" to mount my IEQ45 on.

I'm facing some difficulties getting the measurements for those plates, not to mention the puck. Looking like I may have to find someone to machine those for me.

Does anyone see any major hassles with this?