Re: Air Compressor tank welding question

On Sun, 13 Aug 2006 22:05:53 -0500, KIMO wrote:


OK guys,

I have been reading this thread and have a question that you may think
is nuts but I will ask it anyway because the stupid question is the
one not asked, right?

This is just for my information, I have no tank or plans to weld on
one.

Gunner stated the tank is just shy of 1/4" thick. It is made of steel,
right?

Now, my little brother has piped his entire shop with 1/2" PVC and
runs it at his compressor's max of 125 (so he says).

If PVC can hold that much pressure being plastic and glued together,
why is there such concern for nearly 1/4" steel not being able to
handle it? Is there stress that steel can't handle but PVC can?

I am simply looking at a comparison that does not make sense to me.


Kimo

White or gray PVC is a linear hand grenade waiting to go off. And sooner
or later..It will. With luck, no one will be in the room as the razor
sharp shards fly in all directions.

Ive seen dozens of machine shops plumbed with it..some of which is 10
yrs old. And Ive also ran new black pipe or copper plumbing to replace
all that PVC when it ultimately exploded off the walls, or off the top
of florescent light runs (which generally blows out the bulbs, spraying
floresent tube glass in all directions of the fixture above which the
main break occured.

PVC ages poorly for high pressure use. Plus the oil that inevitably
comes out of the compressor tends to form a film inside the PVC and
degrades the pipe to the point its as brittle as a grahm cracker. A
knock, a dirty look and it blows out..and as its brittle now..it blows
shards everwhere. Heat, compressor oil, natural aging..and the fact that
as an air pipe..its expanding and contracting all the time. Far more so
than if it simply carries water at the normal house pressure. And if
its poorly supported..that first shock will break the pipe in many other
places at the same time.

Now lots of folks get away with it, and for many years. I repair machine
tools and do facilities maint..and am one cheap ***. And my home has
black pipe or air hose running from point to point..NO PVC will ever be
used in my shop(s)

One of my clients in Orange California had a blow out of their 10 yr old
PVC pipe. All of which was run overhead on the long florescent light
runs. When she let go..it took out 8, 8' tubes, broke in 11 places in
the 1500 or so linear feet of run, in 5 differnet rooms of the shop.

I made some decent money replacing fixtures, tubes and running all new
3/4" black pipe, putting in the proper slopes, water traps and so forth
over 2 full days.

The question is not if the steel can hold the pressure..but if the PVC
can hold it. <G>

Your brother may luck out and it may last for years, particularly if he
doesnt keep pressure on the lines 24/7. But it WILL blow sooner or
later.

Gunner







On Fri, 11 Aug 2006 09:03:51 GMT, Gunner <gunnerNOSPAM@xxxxxxxxxxxxxx>
wrote:

I picked up a Kellog two stage compressor the owner claimed had been
freshly rebuilt..and after firing it up..I believe him. Quiet, good
compression and fast build up.

The issue I have..is the tank. Cosmetically..it looks very good.
However..as best as I can figure..it was made in 1948. There is NO
bottom drain plug..draining is accomplished by a pipe stinger coming
out of the end bell and hanging down the inside of the tank to within
a half inch or so of the bottom of the tank. I found this out by
pulling one of the 3" plugs on the side of the tank..big! pipe
wrench..6' snipe and some grunting.

Bottom of the tank has about 3/4" of sediment on it. A bit of poking
with a stick moved enough stuff around to get a glimps of the inside
of the bottom..and no big pits were noted. Ill get out the pressure
washer this weekend and clean it out.

My question is...Im spooky about not having a drain plug on the bottom
of the tank, and really think I should put one in. What I want to
do..is drill a proper hole in the bottom of the tank, thread in a 1"
fitting, then weld it in place. Tank data plate says tank walls are
.235 thick..which is a smidge less than 1/4"..and if I cut into the
tank..and find the bottom to be significantly less than that..Ill junk
the tank, which the data plate says is rated 200lbs.

Does anyone have any caviats or hints and kinks to doing this? I plan
on tapping the tank simply to hold the flange..threading it in..then
MIG a bead around the fitting.. Or I could Tig..Ive got the
capabilities of both.

Should I hydro the tank when Im done? Ill never run it above
100lbs..so I figure I can fill it with water, then pump up 150-175 and
see if it springs a leak.

Any discussion on this would be apprciated

Gunner



"If I'm going to reach out to the the Democrats then I need a third
hand.There's no way I'm letting go of my wallet or my gun while they're
around."

"Democrat. In the dictionary it's right after demobilize and right
before demode` (out of fashion).
-Buddy Jordan 2001

"I think this is because of your belief in biological Marxism.
As a genetic communist you feel that noticing behavioural
patterns relating to race would cause a conflict with your belief
in biological Marxism." Big Pete, famous Usenet Racist
.

Loading