steel pipe
guys stop please, this is a serious thread. and please be logical a bit...150 psi for 2mm thick steel....man did you smoke or something? PVC which i plastic is rated 250 psi. i've taken a 1/2" pipe to 230 psi and no sign of stress nor leak. take a hamer, and smash pvc, your pipe is broken. smash a gal.steel pipe and it's your hammer that is hurt.
Real number please that results from wether formula or manufacturer.
Real number please that results from wether formula or manufacturer.
-
SpudStuff
- Sergeant 5
- Posts: 1410
- Joined: Sat Dec 10, 2005 3:55 pm
- Location: Cupertino, California
- Contact:
Read, Learn, and Get your Head out of your ass.
"From McMaster...
2" Sch 40 black steel pipe.
OD = 2.375"
ID = 2.067"
wt = .154"
Using standard thin wall pressure vessel theory....
Pressure = Stress * (2 * wt) / ID
CHEAP steel in this day and age yields at 35,000 psi but just to account for the "made in China" syndrome we'll assume 30,000. Further, steel fatigue strength is about 1/2 it's original strength so let's bump that down to 15,000.
Pressure = 15e3 * 2 * 0.154 / 2.067 = 2235 psi
Mind you, that's assuming no stress concentration factors or anything. It's also using thin walled assumptions which will give one a slightly high number. Still, I don't think it's too assinine to assume that *ACTUAL* failure pressure is on the order of 1500 psi.
Doesn't mean I want to USE that pipe at 1499 psi, mind you. There's something to be said for safety factors. At the office, 5:1 is what we use for designs involved in energetic scenarios... That takes you to 300 psi.
And heck, if somebody wanted 10:1 safety, you're right there at 150 psi. And that may not be ridiculous if you want to maintain 5:1 "real" safety factor in the face of water hammers and such.
The point to all of this: Even if steel pipe is only rated to 150 psi, I wouldn't think twice about putting a significantly higher pressure in it. Steel production techniques have improved greatly since those standards were written. We don't do anything that would even begin to fatigue steel. Yada yada yada. How high WOULD I go? Depends on what I *KNOW* about the pipe in question (ie, confirm assumptions previously made), but 300 psi sounds reasonable to me." -D_Hall
This guy knows what he is talking about.
"From McMaster...
2" Sch 40 black steel pipe.
OD = 2.375"
ID = 2.067"
wt = .154"
Using standard thin wall pressure vessel theory....
Pressure = Stress * (2 * wt) / ID
CHEAP steel in this day and age yields at 35,000 psi but just to account for the "made in China" syndrome we'll assume 30,000. Further, steel fatigue strength is about 1/2 it's original strength so let's bump that down to 15,000.
Pressure = 15e3 * 2 * 0.154 / 2.067 = 2235 psi
Mind you, that's assuming no stress concentration factors or anything. It's also using thin walled assumptions which will give one a slightly high number. Still, I don't think it's too assinine to assume that *ACTUAL* failure pressure is on the order of 1500 psi.
Doesn't mean I want to USE that pipe at 1499 psi, mind you. There's something to be said for safety factors. At the office, 5:1 is what we use for designs involved in energetic scenarios... That takes you to 300 psi.
And heck, if somebody wanted 10:1 safety, you're right there at 150 psi. And that may not be ridiculous if you want to maintain 5:1 "real" safety factor in the face of water hammers and such.
The point to all of this: Even if steel pipe is only rated to 150 psi, I wouldn't think twice about putting a significantly higher pressure in it. Steel production techniques have improved greatly since those standards were written. We don't do anything that would even begin to fatigue steel. Yada yada yada. How high WOULD I go? Depends on what I *KNOW* about the pipe in question (ie, confirm assumptions previously made), but 300 psi sounds reasonable to me." -D_Hall
This guy knows what he is talking about.
now this is a good answer, thanks spudstuff. and, i usualy hear people talking about 3:1 safety factor.
I've also read on web site explaining how to do really clean sldering job, that when testing the strength of a soldering, the pipe usualy breaks before the soldering, at 3000 psi.
I've also read on web site explaining how to do really clean sldering job, that when testing the strength of a soldering, the pipe usualy breaks before the soldering, at 3000 psi.
-
ProfessorAmadeus
- Sergeant
- Posts: 1046
- Joined: Fri Apr 28, 2006 5:39 pm
- Location: texas
Really there is no way to get to that pressure any ways. You would have to use unregulated co2 or oxygen. Plus there is no need to go that high. Also where would you get a valve for it.
SOO CUTE!! OMG!! I COULD JUST LICK YOU!!Insomniac wrote:Hey why am I a goose???? Why not somthing a little more awe inspireing, like an eagle or something? LOL
-
SpudStuff
- Sergeant 5
- Posts: 1410
- Joined: Sat Dec 10, 2005 3:55 pm
- Location: Cupertino, California
- Contact:
I knew that all along.
My point was, like PVC, it is not that safe to take the pipe and/or fittings above thier rated working pressure. Remember that what I posted does not take temp, fatigue, and rapid pressurization and depressurization into account.
My point was, like PVC, it is not that safe to take the pipe and/or fittings above thier rated working pressure. Remember that what I posted does not take temp, fatigue, and rapid pressurization and depressurization into account.
-
judgment_arms
- Sergeant 3
- Posts: 1272
- Joined: Tue Oct 17, 2006 8:49 pm
- Location: Not so beautiful North Carolina, but at least it’s the U.S.A.!
roughboy, I’m going to barrow your thread for a second.
Quick question: is black pipe forged or cast? Because if it’s cast I can’t work it.
Quick question: is black pipe forged or cast? Because if it’s cast I can’t work it.
-
The Haymaker
- Private 4
- Posts: 74
- Joined: Thu Sep 22, 2005 4:52 am
- Location: Cowtipping, Maine
- Contact:
I see one problem with all this presure stuff......... He never said what his pipe is!
For all we know it could be metal stove pipe, and he is currently trying to figure out why something went boom in the shop and wondering why his ears are ringing.......... There's lots of pipes, metals, thickness, etc, need I go on?
For instance, I just finished making one of two air tanks for the TaterHater out of 4" EMT. This stuff is made to run wires through, not compressed air, so how can someone use a generic formula to decide what pressure is safe for me to use?
I look at it this way, it HAS to be safer than the pair of 3" sched40 PVC tanks that, as of last weekend, are scattered across my back yard looking like the Discovery.......
E
For all we know it could be metal stove pipe, and he is currently trying to figure out why something went boom in the shop and wondering why his ears are ringing.......... There's lots of pipes, metals, thickness, etc, need I go on?
For instance, I just finished making one of two air tanks for the TaterHater out of 4" EMT. This stuff is made to run wires through, not compressed air, so how can someone use a generic formula to decide what pressure is safe for me to use?
I look at it this way, it HAS to be safer than the pair of 3" sched40 PVC tanks that, as of last weekend, are scattered across my back yard looking like the Discovery.......
E
-
ProfessorAmadeus
- Sergeant
- Posts: 1046
- Joined: Fri Apr 28, 2006 5:39 pm
- Location: texas
You see stuff that isnt made for pressure isnt made for pressure. After 1 psi it could blow or it could be at 250 before it blows (pulling #'s out of my ass) The thing is its more important to be safe then to save a coulpe dollars. Nice welding by the way. Im terrible 
SOO CUTE!! OMG!! I COULD JUST LICK YOU!!Insomniac wrote:Hey why am I a goose???? Why not somthing a little more awe inspireing, like an eagle or something? LOL
-
The Haymaker
- Private 4
- Posts: 74
- Joined: Thu Sep 22, 2005 4:52 am
- Location: Cowtipping, Maine
- Contact:
I knew that answer, I just hated to see anyone get hurt. This stuff is 1/8" galvanized, I can't see it being too weak, but........
Anyway, I welded in 1/8" end caps made with the trusty 4.25 hole saw. It was a pain, as the blanks are slightly smaller than the hole, requiring quite a bit of fill. I'm doing this with a stick welder, not exactly the weapon of choice. The trick to welding? Practice, practice a lot. Learn to focus your heat on the larger piece of metal (whichever will take more heat), and in the case of this thinwall stuff, weld only a little at a time to keep from blasting holes. I'm no pro, the tanks have a little too much bubblegum, but it'll work.
Hopefully this thing will work. The plan is to be all metal, I'm tired of replacng PVC, so far I've been lucky and not hit by any shrapnel. I'm hoping fr a working piston valve and breech load. 17' of barrel is too far to run every time you reload!
E
Anyway, I welded in 1/8" end caps made with the trusty 4.25 hole saw. It was a pain, as the blanks are slightly smaller than the hole, requiring quite a bit of fill. I'm doing this with a stick welder, not exactly the weapon of choice. The trick to welding? Practice, practice a lot. Learn to focus your heat on the larger piece of metal (whichever will take more heat), and in the case of this thinwall stuff, weld only a little at a time to keep from blasting holes. I'm no pro, the tanks have a little too much bubblegum, but it'll work.
Hopefully this thing will work. The plan is to be all metal, I'm tired of replacng PVC, so far I've been lucky and not hit by any shrapnel. I'm hoping fr a working piston valve and breech load. 17' of barrel is too far to run every time you reload!
E
-
boilingleadbath
- Staff Sergeant 2
- Posts: 1635
- Joined: Sat Mar 12, 2005 10:35 pm
- Location: Pennsylvania, USA
From my experience machining steel pipe, I believe that steel pipe is not cast - although I honestly don't know enough about the machining qualities of cast iron to say for sure.
I will say, however, that when machining aluminum pipe on a lathe, you really have to plug the end with some wadded paper (or better yet, clay)... because otherwise it resonates like some sort of 90 decibell tuning fork.
I will say, however, that when machining aluminum pipe on a lathe, you really have to plug the end with some wadded paper (or better yet, clay)... because otherwise it resonates like some sort of 90 decibell tuning fork.