Galvanized pipe clamps

[FS7]

When I use pipe clamps (Bessey H-style) I find that the clutch plates, when tightened onto galvanized pipe, cut into the zinc coating. Most of the problems with galvanized pipe seem to say that they slip. Mine have never slipped, but once tightened sufficiently it can be a pain to get them "unset". I usually have to use both hands to unseat the clutch plates, sometimes even needing a mallet. Every so often I'll just hit the pipes with a sander to take the sharp edges off.

Is this a common problem? Presumably this wouldn't happen with black pipe, but then you have to deal with the stains. What about EMT?

[Tony Z]

Can't answer your question, however I used some borg black iron pipe that shipped and wouldn't grab. The pipe had a very heavy coat of flat black paint on it, that presented problems like I've heard about galvinized pipe.

[R Clark]

Haven't seen a discussion of pipe lamps n here for a long time (maybe I haven't been paying attention.)  But way back when, it was pretty much a given that galvanized pipe had problems when used for pipe clamps.  I think the zinc coating is just too soft.

I've cleaned my black pipe with mineral spirits to cut the oily stuff.  I haven't really experienced big problems with staining from the black pipe.

What do you mean by "EMT"?

[Stwood_]

I have a few of galvanized pipes, mainly 3/4. A couple of 1/2 I think.
All from salvaged pipe. Yes, mine stick, and as you say, it takes a mallet sometimes to unstick them.

Someday I'll get around to taking a 80 grit ros to them.

[Roly]

When I use pipe clamps (Bessey H-style) I find that the clutch plates, when tightened onto galvanized pipe, cut into the zinc coating. Most of the problems with galvanized pipe seem to say that they slip. Mine have never slipped, but once tightened sufficiently it can be a pain to get them "unset". I usually have to use both hands to unseat the clutch plates, sometimes even needing a mallet. Every so often I'll just hit the pipes with a sander to take the sharp edges off.

Is this a common problem? Presumably this wouldn't happen with black pipe, but then you have to deal with the stains. What about EMT?

EMT is thin wall conduit, it would probably crush when tightening.  The problem with the galvanized coating is that it is zinc which is soft and digs in. Aluminum pipe has the same problem but worse.  Make some short sections of pvc pipe and slide them over the black iron pipe or cut a slot in the pvc pipe to snap over the iron pipe and the pvc will hold the black iron off of the wood.  Normally you only need two short sections of pvc on the pipe.   Roly

[toolmiser]

I've got a bunch that I've had for years, mine are mostly "recycled". I think over time they "wear in" a little and that along with a hammer will do the trick. Part of my exercise program Today the bulk of it was shoveling some snow at 0 degrees. I guess I prefer the galvanized since they don't rust like the black.

[Woodenfish]

Pipe clamps IME, were a major PITA and the day I sold them off was a very good day.

[rwe2156]

I used galvanized pipe for years, and I did have trouble with a couple slipping.  A tap with a hammer on the caul solved that problem.

Anyway I had the opportunity to get a bunch of black pipe for free, so I had them threaded and redid all my clamps. 

No question they clamp better and tighter.  Don't let the pipe touch a glue joint it will turn the wood black.

[FS7]

I think parallel clamps would be better, but they're considerably more expensive than pipe clamps. You can also shorten or lengthen them easily. I think I started using them because I read in a magazine or something that they had the best clamping pressure.

One thing you can only do with pipe clamps is make a 20 foot clamp. When I built my deck, I did almost all of it myself, and that included 100% of the decking. Some of the wood was warped enough that I couldn't just push it back tight before screwing it in, but a 22 foot clamp saved the day.

[Scoony]

I also use zinc pipes also and have never had them slip. They will stick as you describe, but I just give them a wack on the edge of the assembly table and they loosen right up