When identifying a pipe by its size, is it standard practice to identify a pipe by its inside diameter? I argued that you can have two pipes with exactly the same outside diameters, but different inside diameters due to pipe wall thickness.
Inside for drainage for sure.
For monuments some do inside, outside or neither.
I just label OD or ID and put spell it out in my legend along with Below Grade and Above Grade: Found Pipe 1inch OD BG 0.4feet.?ÿ?ÿ
NC requires that we state whether a monument is found or set but doesn't require additional detail so all the old folks still get to label all corners as, "FND IRON", and can roll their collective eyes at my verbose descriptions.
Engineers all work with flow volumes. So, proper historical nomenclature is id. Inside diameter.?ÿ
However, it can be difficult to measure this. Like if it??s been beat on, and mushroomed out. So, if you label it, such as ??found 3/4? pipe? is probably the same as ??found 1? od pipe?.
either way, it??s descriptive. And that??s what we need. Some industrial applications use very thick or thin wall pipe. Or, conduit.?ÿ
I??ve even found and labeled rebar that were standard 5/8? rebar, or 1/2?. But, due to rust erosion they were smaller than before. So, I called it ??found 9/16? rebar?. We, that was what I FOUND!???
?ÿ
I was under the impression all pipe sizes were measured by inside diameter.?ÿ Maybe I should start specifying ID if that's not the case.
Fortunately, this doesn't come up very often for me as pipes are not commonly found.?ÿ There are some, of course.?ÿ The main thing is to label it a pipe as opposed to FD IRON.?ÿ Iron what??ÿ Some label a rebar as an iron rod and others as an iron bar.?ÿ I, too, have found what was labeled as 9/16" rod to be just that.?ÿ A smooth rod of that dimension.?ÿ It's more fun to find a leaf spring, cultivator spike, horseshoe over broken stone, etc.
Assume inside diameter, unless specified. And it isn't really a specific measurement, it is a nominal size. A product name rather than an exact dimension. For instance 1/2" iron pipe that you buy today is actually closer to 5/8" inside measure. Who ever heard of a 5/8" pipe on a survey??ÿ
Think of it this way. IF you go into Home depot and ask for 1/2" pipe what are you going to get??ÿ If you show a found pipe to a plumber and ask him to identify it he is going to say 1/2" of 3/4", etc., at a glance. If you survey a plumbers property and tell him you found 5/8" I.D. (or 1" O.D.) pipe at his corners he will snicker and then tell his buddies stories about that idiot surveyor for the rest of his life.?ÿ ?ÿ?ÿ
Iron pipes where originally a specific inside measure with the wall thickness dictated by the metallurgy of the day. As time went by and manufacturing processes improved the walls could be made thinner. But the outside diameter had to be maintained so that new pipe could be readily married to existing systems. So the inside diameters became progressively larger.?ÿ ?ÿ?ÿ
I actually had a related discussion at work once.?ÿ Sometimes field crews would shoot the top of a pipe instead of the invert and then measure the diameter horizontally.?ÿ I asked if the wall thickness of the pipe was a concern when it came to calculating the true invert elevation.?ÿ It seemed like it should to me but the responses I got were mixed.?ÿ For PVC or corrugated metal and the like there's probably not much difference but some concrete pipes can be pretty thick...?ÿ Do any of you guys have a particular stance on this?
Pipes are fairly common hereabouts. They were the go-to monument up to about the 1960's, when rods became more common. I agree that the important thing is to identify a pipe as a pipe, the diameter is less critical. The County Surveyors insist on labelling monuments one way or the other but I won't hold you to it.
A common trick was to divide up section of pipe by bending then over double, then back and forth until they broke off - rather than cutting them. This results in what we call a "pinch-top" pipe. Really tough to measure the diameter of such a pipe, inside or out.
Driving of a pipe in solid ground results in mushroomed tops. Really tough to measure the diameter of such a pipe, inside or out. ?ÿ
If you are comfortable with building a ~0.2' bias into your invert measurements then go for it.?ÿ That's not me.?ÿ Too easy to account for. Just do it.
Technically specific nomenclature escapes the majority of the population.?ÿ And we surveyors are lumped in there too.?ÿ I've even seen a referenced corner that called for a 1/2" machine gear.?ÿ ?ÿMost of us would recognize it as a gin spike.
I'm pretty forgiving of bad judgement calls by other surveyors when it comes to monument descriptions...as long as they're within reason.?ÿ I myself find it hard to tell a #4 rebar from a #5 just by looking at the top.?ÿ The one that usually trips up most of us is the difference between a 40d and a 60d nail.?ÿ The heads are almost exactly the same diameter.?ÿ The shafts differ in size by only two hundredth of an inch.?ÿ The visibly identifying difference is the length of the shaft.?ÿ So when someone notes they found a 40d or a 60d nail driven in a corner post it makes me wonder how the hell they knew how long it was...or did they break out a micrometer and measure the shaft in-situ??ÿ Noting a "found spike" or even a "large nail" might be more descriptively correct.?ÿ But we surveyors are all guilty of trying to be specific in our notes, to the point our pencil outruns our knowledge.
And then there's "power poles" and "telephone poles".?ÿ Most folks can't tell the difference.?ÿ And if you're thinking that power poles have power lines on them and telephone poles have telephone lines: that in itself is misleading.?ÿ ?ÿPoles have owners.?ÿ The only way to tell is if the pole is tagged or branded.?ÿ Each utility company keeps track of their poles on a CPR (continuing property record).?ÿ And yes there are plenty of telephone poles that might only have power hanging on them..and visa versa.?ÿ The conductors that hang on them can change over the years.?ÿ I just call them utility poles.
Once I was unfortunate enough to fall down a rabbit hole by trying to discuss this topic seriously with our buddy Kent.?ÿ ?ÿI'm recalling his sentiment was that a called for 1" pipe on a survey that was actually 3/4" ID should be discounted because...well because.?ÿ This was around Christmas.?ÿ I sent him a Christmas present of fairly inexpensive pipe-mic measuring device so he would be sure to be correct when he denigrated a previous surveyor's notes.
I bet he still has it.?ÿ 😉
?ÿ
We used to do a lot of surveys for gas line location/extension.?ÿ Steel gas lines are another critter altogether, the insulation on the pipes can vary according to size and manufacturer.?ÿ We used to carry "diameter tapes" to measure the outside diameters of all lines.?ÿ Wrap the tape around the pipe and measure directly, each "inch" of tape is pi inches long.?ÿ If you have any questions just record what you measure.
Andy
I've always used a "rule-of-thumb" when shooting the top of RCP and then calculating the invert with the wall thickness:
Take the nominal size in feet, call it inches and add another inch.?ÿ Example:?ÿ 24" RCP = 2'.?ÿ Call that inches (2") and then add 1".?ÿ So a 24" RCP usually has a 3" wall thickness.
Please note this is just a rule-of-thumb.?ÿ Pipe is manufactured with different loading factors and wall thickness can vary, but this simple rule has been a good friend of mine for a long time.
I??d like a pipe micrometer. But, I just use a box tape, with inches and fractions on one side, and tenths on the other.?ÿ
I dream of the day we can use 4 d ground penetrating radar, with some additional color for magnetism. Sort of like maternity??s wards have. And, can determine pipe size and shape without digging.?ÿ
N
I agree.?ÿ Drives me nuts around here, people labeling a capped iron pipe as a pin
If a 1" pipe is called out, and I find what I'd call a 3/4" pipe, based on the inside diameter, I'm going to assume that it's the monument.
This results in what we call a "pinch-top" pipe
nit picking here but not entirely correct. A shear press creates the pinchtop, I know as that is what I used in the junk yard
For monuments OD
For other reasons usually ID.
Sounds like a convenient formula.?ÿ I was googling pipe manufacturers at the time and looking up the specs that way.?ÿ It seemed to be largely standardized so I was comfortable with my calculations but your way sounds quicker and probably just as accurate.
It depends on the project and the overall experience of the crew.?ÿ If inexperienced, I'll default to telling them offsets to inverts are okay if the measure the offset not calculate it as you suggest.?ÿ Someone with experience will know the minimum vertical and horizontal separation between sewer, water, and other utilities and should be able to approximate the required precision.?ÿ?ÿ
It also depends on who will be designing off the data.?ÿ I work with one lady who has it dialed and needs virtually no notes outside of my F2F linework.?ÿ I frequently discuss this stuff with designers (I don't dare call them CAD techs) and it helps me and them.
