Pipe Hanger

Did you ever consider another line of work?

One in which your complete lack of knowledge would not be such an impediment?

Did you ever consider consulting asking local agencies???

Did you ever consider that the contractor probably knows much more than you do?

Hangers - Support Spacing and Rod Size for Horizontal Pipes

pipe hanger spacing & weight chart - Guenther Supply, Inc.

At least he's not messing about with electricity now.

Although he would be better suited to

Sure I know what I am questioning here. I am not here to ask stupid question as Lyn always thought. Actually I more keen to know whether any defect will happen on the pipe in long run. The pipe support rods are suitable from not causing it to drop.

I'm glad you know what you are questioning, I don't. That is a failure to communicate.

It seems that your worries are not about things falling. That eliminates part 1. Your defect concerns do not address if the pipe defect will expose the contents. You're ignoring part 2.

I'm again reminded of a quote from the satirist, Tom Lehrer. "I feel that if a person can't communicate, the very least he can do is to shut up."

(the grey realm of being right and wrong)

Yes, right, about the OP. You can lead a horse to water, but you can't change his spots. His problem can't be fixed with duct tape.

Wrong for offering any help, at all.

I pity poor GW, who offered exactly what the OP had already described as an unacceptable mounting design to him. No good dead goes unpunished.

I'm left wondering how people such as the OP seem to always run into the simple problems they face and yet can never solve them. Never mind how they stay employed.

Apparently, close together and too far apart are good enough for some employers.

Don't pity me - I figured the OP hadn't googled anything, was not familiar with the scope of what was currently offered as standard hanging devices, and had not been around the block too often. All I was trying to do was point out "see, there is what they are doing - it is off the shelf mounting".

The OP kind of reminds me when we got a new CSA inspector literally fresh out of school. She (trying to not sound prejudicial) did the factory tour and immediately pulled our tickets because our hydraulic crimpers for 0000 TEW wire did not have a sticker saying they were approved for the lugs and cable we were crimping (it was at a transition time between when crimping tools originally were not "certified" for a particular crimp barrel and wire). We had pull-out test records, polished cross sections etc, etc. She would not bend. I was livid - I had her sit down and I called her boss - He talked with her in private, the phone was returned to me and he explained she was inexperienced and our facility was setting the industrial standards. Red faced she handed the tickets back to us and we never saw her again.

I try not to rise to the bait so fast anymore - it just labels me as a crotchety old man now.

I accept the label.

Don't get me started on calibration and government inspectors.

We used a lot of certified two part epoxies in a past life of mine. Military/NSA satellites and all. It took my boss and me two years to get mixing, repackaging and freezing these materials accepted as Ok for flight use. Never mind that freezing effectively slowed the chemical reactions of the materials. Now companies sell these materials pre-"everythinged".

Then there's calibration of triple beam balances. Never mind that the guys using them were not certified.

..not an unsubstantiated opinion. I've enjoyed running a licenced electrical contracting business in chicago where things of this nature are done by the book.. Which i have read.

It's a common sense question that deserves a common sense answer.

You did so well by providing the link.

It's interesting how you pick and choose when and who will be given your unbiased support, but not that interesting.

Did the contract specifications say anything about this beforehand?

No. Even the consultant also have no comments on it. But in my opinion, the bottom of pipe would face a concentrade force due to the weight of the pipe + water. I just wonder whether the pipe would deflect or last long in this condition. However, the pipe are hang in 2m apart. May be this would help.

In that case it cannot be "wrong" from the perspective of paying the contractor who is installing it. The cock-up lies further upstream through the organisation (is that word accurate? - rhetorical question - NNTR) not having any standards against which a contractor can lay pipe and a judgement can be made.

Do you mean like this?

http://www.gshangers.com/pipesupportdetails.php?supid=26

Most "googled" hangers appear to wrap the bottom of the pipe, but some don't.

Your described arrangement also appears to be an accepted method - but beware - I'm an EE, not mechanical.

As some others have alluded to, your information is insufficient to give you a reasonable answer. What size angle is being used (width of each side, thickness of the sides), the span of the piece of angle, size of rod that it is hung with (rod that is too small in diameter will fail before the angle) the spacing of each pipe to the adjacent pipes, is there going to be expansion of any of the pipes, length of the angle, the height of the ceiling and the height of the angle, etc.? Another thing is what does code say? Are there any other codes that might also apply to this?

Why is the contractor using angle instead of Uni-strut (sp?) channel? Although more expensive it's use is much quicker in time and choice of configurations for mounting the pipe. Who said that the angle was "not a proper installation"? The Unistrut (also called Kindorf (sp?) and several other names) channel has numerous pipe mounting types, some of which will support the pipe for the complete bottom half of the pipe. Is that what your concern is? If so why wasn't that specified in the original RFP?

Good Luck, Old Salt

Yes. My concern is mostly pipe hanger manual use hanger which covers most of the part of pipe for firm holder and load discipation. There must be reason why pipe not mounted on a flat surface. My question seems simple but in term of engineering, there must be a more convincing explaination.

Those pipes could be buried in the ground a flat surface. All the weight would be on the bottom. Plus any weight that would inserted on the pipe from the soil above. No one questions this practice.

I have seen pipes run in buildings like this many times with no problems. Either on perforated angle or unistrut bound with U bolts. With multiple runs it's usually faster and materials cost less.

When a single pipe is run hangers are used. Still most of those are just a saddle the weights still on the bottom.

A simple CALCULATED strap on the bottom of the pipe. Geee!

Not sure where you are located however the following apply:

Size of clamp/hanger, size of u-bolt, type of hanger & bolt assembly, and hanger/clamp spacing are dependent on:

1) Diameter of pipe.

2) Pipe wall thickness.

3) Weight of fluid being conveyed through the pipe.

4) Anticipated moments of inertia and resultant induced vibration/pipe movement.

5) Ambient environment conditions. (Temperature, humidity, caustic or acidic, etc.)

All pipe hanger manufacturers provide application tables and very acute information pertaining to installation of their systems.

It is in your best interest to determine the hanger/clamp assembly Original Equipment Manufacturer (OEM) and consult their applicable table(S) to discern whether the installation meets all requirements.

If you are unsure about any of the process variable values and/or mechanical loading variables and/or ambient conditions that could affect the stability and safety of the installation, I suggest you hire a competent mechanical engineering company to examine the process specifications and installation for the purpose of minimizing liability and risk factors.

To try to answer the original question, the concentration of weight over that short a length of pipe (2m) on the pipes described seems unlikely to produce any over stress in the pipe itself. With high pressure it might be different.

Many of the failures of rain water down pipes occur at the joints and not in the main pipe (except for external pipes which can receive blows from cars etc). I have seen failures on construction site rainwater pipes and this was due generally to too few hangers and especially not near the bends. There is a considerable horizontal and vertical force at these areas due to the change in direction of the water and the head of water. The obvious consequence is a flood.

As far as I am aware, the waste water pipes suffer from head pressures when blocked. A it more messy if that were to blow. I've not seen any of this as I am involved with the construction side.

One of the reasons for collars is also to prevent horizontal movement which would mean misalignment of the joints and the higher likelihood of a leak.

Run the calculation to identify the force required to either reach initial yield or change the diameter of the considered cross-section in a vice. If you don't have it, get yourself a copy of Roark's Formulas for Stress and Strain.

Then ask yourself, under worse-case operational conditions, will the pipe ever see that kind of loading?

Sheesh - you expect a calculation?

Here's one, based on what the OP knows.

2 meters of pipe weight + 2 meters of water weight ÷ support surface area.

The first two numbers are easy. It's that third one that's tough.

Maybe there's help:

I guess OP never tried to break/bend a piece of that pipe!

A Mech Eng once told me "make a conservative guess" - you're probably pretty close.

Funny - he was mostly right - if I thought it was close - it definitely required calculations.