# How much weight will a 1" black pipe hold over a 4' span before it begins to deflect?



## JLawrence08648 (Mar 1, 2019)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*

Hundreds of pounds, 1" is strong, but there is the extra weight of bouncing, however 4' center is strong


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## HotRodx10 (Aug 24, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*

What weight of pipe, Standard, X-strong, or XX-Strong?

Also, what grade?

Btw, it will "begin to deflect" under any load, so you'll need specify how much deflection can be tolerated.


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## That Guy (Aug 19, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*

I dunno... say 3-6 aluminum/fiberglass extension ladders, ranging from 16'-44'?

Possibly a 16' step ladder (that thing weighs an unbelievable amount lol

Figured Id go to Homedepot and put this together in the parking lot to make sure I have all the parts lol


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## HotRodx10 (Aug 24, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*

If you get standard (Schedule 40) black steel pipe from Home Depot, it's A53, Grade A (30,000 psi yield strength), according to their website. At a 4' span, just over 300 lbs in the middle is what it would take to yield it (permanent deflection). It'll deflect about a 1/4" under 300 lbs. At about 350 lbs, it will bend, and just keep on bending.


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## That Guy (Aug 19, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



HotRodx10 said:


> If you get standard (Schedule 40) black steel pipe from Home Depot, it's A53, Grade A (30,000 psi yield strength), according to their website. At a 4' span, just over 300 lbs in the middle is what it would take to yield it (permanent deflection). It'll deflect about a 1/4" under 300 lbs. At about 350 lbs, it will bend, and just keep on bending.


So would sched80 be 600lbs?


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## HotRodx10 (Aug 24, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



That Guy said:


> So would sched80 be 600lbs?


No; only about a 20% increase in strength, so around 360 lbs.

1 1/4" Schedule 40 will get you to a little over 500 lbs, though.

If you want to get over 600 lbs of capacity, without danger of it failing, you'd have to go to 1 1/2".

The theoretical point load at midspan sufficient to yield a 1 1/2" Schedule 40 steel pipe (A53, Grade A), is 815 lbs, assuming it yields at 30,000 psi, which at least 95% of the pieces should exceed, per the ASTM standards.


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## That Guy (Aug 19, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



HotRodx10 said:


> No; only about a 20% increase in strength, so around 360 lbs.
> 
> 1 1/4" Schedule 40 will get you to a little over 500 lbs, though.
> 
> ...


Well... hmm... so 1" is prob gonna be my best bet, and itll be 3 rails... 4' apart so each rail will hold only 1/2 the weight of the ladder as the 3rd (middle rail) is more to reduce ladder bounce, keep the ladders straight...

Then 3 pts of connection on each rail one on each end then one in the middle... I was thinking of tying the rails together on the ends, not sure if I should though


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## SeniorSitizen (Sep 10, 2012)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*

Before getting too carried away with the claim of ( 30,000 psi yield strength ) that sounds more like tensile strength.


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## HotRodx10 (Aug 24, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



SeniorSitizen said:


> Before getting too carried away with the claim of ( 30,000 psi yield strength ) that sounds more like tensile strength.


The tensile strength of A53, Grade A (which is what Home Depot shows for their black pipe), has a min tensile strength of 48,000psi, and yield strength of 30,000psi.


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## Colbyt (Jan 27, 2014)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*

Just keep in mind that a ladder is not concentrating all the weight at the exact center point of the pipe. The load is spread over 16-18". I know that factors in I just don't know the math.


I use a 1" pipe for the safety rail on my old scaffold set. Over a 10' span it has never sagged. But then I have never loaded it by hanging off of it.


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## HotRodx10 (Aug 24, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



Colbyt said:


> Just keep in mind that a ladder is not concentrating all the weight at the exact center point of the pipe. The load is spread over 16-18". I know that factors in I just don't know the math.


For 2 point loads, 16" apart on a 48" span, the math says the bending stress on the pipe would be reduced by 1/3, from what it would be for a single point load in the center. So if the ladder rails are 16" apart, the effect of 450 lbs would be about the same as the effect of a single 300 lb load at the center.

I didn't know how the ladders might be oriented in the rack. With the number of ladders mentioned, I assumed they might be set on edge.


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## SeniorSitizen (Sep 10, 2012)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



HotRodx10 said:


> The tensile strength of A53, Grade A (which is what Home Depot shows for their black pipe), has a min tensile strength of 48,000psi, and yield strength of 30,000psi.


Describe a " *Yield Strength Test *"
I have no knowledge of that test.


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## HotRodx10 (Aug 24, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



SeniorSitizen said:


> Describe a " *Yield Strength Test *"
> I have no knowledge of that test.


I don't know what's involved in the test either. All I know is that the tests are performed, with a "5% exclusion" criteria, which means at least 95% of the specimens tested have to yield at a value at or above the specified minimum (in this case 30,000psi).

If I've heard correctly, most of what's available as Grade A, are production lots that failed to meet the higher Grade B test criteria. So chances are good that any random piece you pick up at HD is quite a bit stronger than the specified minimum, but it might not be. 

In engineering, we account for the consequences of failure in setting the factors of safety. One of the questions to ask, then, is what happens if the random piece of pipe you choose is one of the ones that are at or below the minimum? Is it catastrophic? From what the OP describes, it doesn't seem so; it would just mean replacing the piece of pipe that's developed a 1" sag in the middle. If it's overstressed, it's going to bend, not break, so there will be warning if the yield has been exceeded. I'm not advocating a trial-and-error approach to the design, just trying to inform.


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## JLawrence08648 (Mar 1, 2019)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*

Get some eyebolts, open eyebolts, Rustoleum primer, and Rustoleum paint.


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## joe-nwt (Jul 15, 2020)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*

You will never deflect 1" pipe with ladders. Unless you flip the truck upside down in the ditch.


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## HotRodx10 (Aug 24, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



JLawrence08648 said:


> Get some eyebolts, open eyebolts, Rustoleum primer, and Rustoleum paint.


Looks like this may have be a response to a different thread?


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## That Guy (Aug 19, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



HotRodx10 said:


> For 2 point loads, 16" apart on a 48" span, the math says the bending stress on the pipe would be reduced by 1/3, from what it would be for a single point load in the center. So if the ladder rails are 16" apart, the effect of 450 lbs would be about the same as the effect of a single 300 lb load at the center.
> 
> I didn't know how the ladders might be oriented in the rack. With the number of ladders mentioned, I assumed they might be set on edge.













But mine is a box truck


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## SeniorSitizen (Sep 10, 2012)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*

Build it of 1-1/4" sch 80 pvc. I built a 1" pvc sch 40 folding / floating boat ladder with 12" wide steps that took the stress test of 200 + pound people.


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## That Guy (Aug 19, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



SeniorSitizen said:


> Build it of 1-1/4" sch 80 pvc. I built a 1" pvc sch 40 folding / floating boat ladder with 12" wide steps that took the stress test of 200 + pound people.


PVC is nice and all, but I dont want to be that guinea pig


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## HotRodx10 (Aug 24, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*



SeniorSitizen said:


> Build it of 1-1/4" sch 80 pvc. I built a 1" pvc sch 40 folding / floating boat ladder with 12" wide steps that took the stress test of 200 + pound people.


The bending stress of 200 lb on a 4' wide span is 4 times as much as the same 200 lbs on a 1' wide span. If his ladder rack was only a foot wide, your idea would probably work. On a 4' wide rack, not so much.


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## That Guy (Aug 19, 2017)

*Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*

PVC gets brittle in the sunlight, extreme cold.. Plus the constant vibration from driving, 

I dont want to be that poor guy that kills someone and takes out a bunch of cars on the freeway when his PVC ladder rack shatters LOL


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## pone (10 mo ago)

HotRodx10 said:


> *Re: How much weight will a 1" black pipe hold over a 4' span before it begins to defl*
> 
> If you get standard (Schedule 40) black steel pipe from Home Depot, it's A53, Grade A (30,000 psi yield strength), according to their website. At a 4' span, just over 300 lbs in the middle is what it would take to yield it (permanent deflection). It'll deflect about a 1/4" under 300 lbs. At about 350 lbs, it will bend, and just keep on bending.


What load will a 2 inch schedule 40 steel pipe handle? What is a good reference online that would let us see the weight that any arbitrary steel pipe can handle, given relevant entry variables?


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## JLawrence08648 (Mar 1, 2019)

I definitely wouldn't go PVC, black pipe requires painting with oil paint, galvanized would be better. 1" flexes too much. I'd go with 1 1/2" uprights and a 2" cross bar, consider welding gussets.


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## HotRodx10 (Aug 24, 2017)

pone said:


> What load will a 2 inch schedule 40 steel pipe handle? What is a good reference online that would let us see the weight that any arbitrary steel pipe can handle, given relevant entry variables?


Bending load (what us engineers call "moment") is the stress (in psi or ksi) multiplied by the section modulus (in the US it's typically labeled as "S", with units of in^3, i.e. inches cubed). If you only have the dimensions, S = .098175 * (OD^4 - ID^4) / OD .

For the 2" Sch. 40 you asked about, OD = 2.375" and ID = 2.067", so S = .561 in^3.

The stress that you would use to calculate what pipe can "handle", is based on what the performance limit is, e.g. if you want is to return to its original shape when the load is taken off (elastic deflection), for a steel pipe the stress will have to stay below the "yield stress". Beyond that, it will have a permanent bend, and it will continue to bend with very little additional load. 

The moment applied depends on what pattern of the of load is, e.g, applied at a single point or distributed (spread out), and the span. A point load "P" on a span "L" creates a moment "M" = P*L / 4. For a uniformly distributed load of magnitude "w" (in weight per unit length), M = w*L^2 / 8. 

*The units need to match between the moment and the moment capacity. *So for the pipe, with S in in^3, allowable stress in psi (lbs/in^2), the moment capacity is in units of lbs*in, so the load has to be in lbs, and the span in inches (and the uniform load in lbs / in)

Of course, for design, we always include a factor of safety, the magnitude of which is based on the consequences of failure.


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## pone (10 mo ago)

HotRodx10 said:


> For the 2" Sch. 40 you asked about, OD = 2.375" and ID = 2.067", so S = .561 in^3.
> 
> The stress that you would use to calculate what pipe can "handle", is based on what the performance limit is, e.g. if you want is to return to its original shape when the load is taken off (elastic deflection), for a steel pipe the stress will have to stay below the "yield stress". Beyond that, it will have a permanent bend, and it will continue to bend with very little additional load.
> 
> ...


What I took from that is that if you need to do these calculations once a year, better to find an engineer to review it.

Let's say you have a schedule 40 2 inch galvanized steel pipe that is either six or 10 feet long. You want to point load that pipe in the middle. What is the maximum weight that can be carried by the pipe without any deflection or long-term compromise of strength?

The actual application here is to carry a heavy concrete item over a narrow pathway that is not easily traversed by dolly. So the concrete item would be rigged with appropriate web strapping - following all the appropriate rules for safe rigging - and that rig would attached by a carabiner or anchor shackle to the mid-section of the pipe. Then two people on either end of the pipe would lift it on shoulder to carry the item a short distance. The total load is only about 500 pounds, and I am expecting a 2 inch pipe will be strong enough for that, but maybe at 10 feet it is close.


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## pone (10 mo ago)

When you see a 2 inch galvanized steel pipe that is not marked "schedule 40", how much can you rely on lower standards like "Complies with ANSI and ASTM A733, A53 standards"?








Southland 2 in. x 10 ft. Galvanized Steel Pipe 568-1200HC - The Home Depot


Pipes are a trusted method for transporting the needed materials to their final endpoint. Each pipe comes with plastic pipe caps to protect the threads from damage during transportation. General uses for this product are for transporting potable water, compressed air, drainage or to create your...



www.homedepot.com





Is it maybe more important to care about wall thickness than about internal pipe diameter?


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## HotRodx10 (Aug 24, 2017)

pone said:


> What I took from that is that if you need to do these calculations once a year, better to find an engineer to review it.


If failure could hurt or kill someone, I would say having an engineer review it is a necessity, regardless of how often you do the calculations.


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## pone (10 mo ago)

HotRodx10 said:


> If failure could hurt or kill someone, I would say having an engineer review it is a necessity, regardless of how often you do the calculations.


The way we have this rigged the item is four inches off the ground and if it collapses no one is in a position to get hurt. And in any case you are not responsible for how I use the pipe or tube. You are just describing how specifications apply and what kind of loads those usually imply with 95% confidence....


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## HotRodx10 (Aug 24, 2017)

pone said:


> Let's say you have a schedule 40 2 inch galvanized steel pipe that is either six or 10 feet long. You want to point load that pipe in the middle. What is the maximum weight that can be carried by the pipe without any deflection or long-term compromise of strength?


Two different questions:

How much weight with no deflection? Zero. It will deflect some under any load.
How much weight without permanent deformation? Depends on the yield strength of the pipe. 



pone said:


> ...attached by a carabiner or anchor shackle to the mid-section of the pipe. Then two people on either end of the pipe would lift it on shoulder to carry the item a short distance. The total load is only about 500 pounds, and I am expecting a 2 inch pipe will be strong enough for that, but maybe at 10 feet it is close.


P * L / 4 = M = 500 * 120 /4 = 15000 lbs*in
f * S = M ---> f = M / S = 15000 / .561 = 26,738 psi < 35,000 psi (A53, Grade A); seems like it would work.


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## HotRodx10 (Aug 24, 2017)

pone said:


> The way we have this rigged the item is four inches off the ground and if it collapses no one is in a position to get hurt. And in any case you are not responsible for how I use the pipe or tube. You are just describing how specifications apply and what kind of loads those usually imply with 95% confidence....


I was making a general cautionary statement about the uses of the information I provided. I'm not worried about liability; I just don't want anyone to get hurt by misusing it.


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## pone (10 mo ago)

HotRodx10 said:


> Two different questions:
> 
> How much weight with no deflection? Zero. It will deflect some under any load.
> How much weight without permanent deformation? Depends on the yield strength of the pipe.
> ...


In order to make the tube easier to store and transport, what if you had two 5 foot pipes joined in the middle by a screw thread female-to-female pipe connector? How much does that lower the capacity of the tube to absorb weight? I assume the load would be on either side of the female-to-female connector, not on the adapter directly.


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## HotRodx10 (Aug 24, 2017)

pone said:


> In order to make the tube easier to store and transport, what if you had two 5 foot pipes joined in the middle by a screw thread female-to-female pipe connector? How much does that lower the capacity of the tube to absorb weight? I assume the load would be on either side of the female-to-female connector, not on the adapter directly.


Alot depends on how far the pipes are threaded into the coupler. If the pipes are threaded nearly all the way in, the reduction would be fairly small. However, if they are only threaded halfway in, the reduction in capacity would be substantial. 

If you wanted to use shorter pieces without having a reduction in strength where the full strength is needed most, you'd need to build it in 3 pieces, so that the weaker points at the couplers were away from the location of the load, where the maximum bending stress is. With a 5' piece in the middle and 2.5' pieces on each end, the bending moment and stress in the pipe would be half as much at the couplers as in the middle.


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## pone (10 mo ago)

HotRodx10 said:


> Alot depends on how far the pipes are threaded into the coupler. If the pipes are threaded nearly all the way in, the reduction would be fairly small. However, if they are only threaded halfway in, the reduction in capacity would be substantial.
> 
> If you wanted to use shorter pieces without having a reduction in strength where the full strength is needed most, you'd need to build it in 3 pieces, so that the weaker points at the couplers were away from the location of the load, where the maximum bending stress is. With a 5' piece in the middle and 2.5' pieces on each end, the bending moment and stress in the pipe would be half as much at the couplers as in the middle.


Such great information, thank you.


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## partikalag (10 mo ago)

I didn't know how the ladders might be oriented in the rack. With the number of ladders mentioned, I assumed they might be set on edge.

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## HotRodx10 (Aug 24, 2017)

partikalag said:


> I didn't know how the ladders might be oriented in the rack. With the number of ladders mentioned, I assumed they might be set on edge.


I wrote this in Post #12. Did you mean to quote me and add a comment or question?


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