how to calculate PSI to Nm for torque

You can't without more info - (specifically an area that the pressure is acting on)

What exactly is your scenario? Trying to convert hydraulic pressure in a wrench to torque? Submerged lever/gate under water? ..........?

Guest Are you sure you have posted your question correctly? Are you maybe asking inch pounds to Newton meters for use in torqueing fasteners? J. Conway

1Newton = 225 pounds force.

1m = 1000mm = 1000/25.4 = 39.4 inches

1Nm = 225# * 39.4" = 8865#"

1#" = 1/8865 = 0.000113Nm

PSI is a unit of pressure and cannot be converted to Nm (a torque), but it could be converted to N/m² which is a pressure.

1 pound per square inch = 1/225 * (39.4)² = 6.9 N/m².

You can convert just about anything to anything else at this site.

......it could be converted to N/m² which is a pressure.

Why use Pa (N/m²)...............Pascals are too small a unit to use in any calculations.

much better off using:-

kPa(N/cm²), (kN/m²).............or................MPa (N/mm²), (MN/m²)

Guest you should consider signing up and become a member. Here's the conversions you are looking for. 1 Newton meter equals the following. 0.7375622 pounds-force foot. 8.850746 ounce-force inch. For other conversions please check Convert-me.com/en J.Conway -

You are converting Pressure to Torque.

Pressure is force acting on unit area and torque is force acting at unit distance. You can not convert these in anyway.

What psi is required to to do the same work as 1 ftpd of torque

It seems like nobody here understands bolting. The question is perfectly sensible: The gentleman has been given a bolt stress specification in psi likely based on a required gasket seating stress. He wants to tighten the bolt to this spec. First thing to do is to determnine what the equivalent force is: F = stess x effective cross sectional area of the bolt. Then, determine a torque by multiplying this force by the nominal diameter of the bolt. This value must then be multiplied by the K factor. As in any torque calculation, the engineer must take a wild-a** guess at what the K factor might be. Good luck! Next, convert the imperial torque value to a metric value. A much more sensible way of doing things is to also calculate what the elongation of the bolt will be at the specified bolt stress. Then, regardless of how incorrect the torque is, proper bolt stress can be verified by measuring the stretch after the bolt has been tightened. You might have to increase or decerease the torque to get achieve the proper stress.

If I knew how to upload a file to this forum I'd be happy to provide you with a useful (and free!) Excel spreadsheet that'll help with calculations. Alas, I don't know how :-(

The question is perfectly sensible

IF GUEST creating thread specifies that it is for bolting. You can not expect others to read his mind.

No need to read minds. Bolt loads are often specified in psi or MPa. Those who are remotely versed in this field would have picked up on the nature of the Guest's question right away

Boltintegrity check answer number 2

True enough and point made: The other scenario is that the first Guest has been given a torque value which he's trying to achieve with either a hydraulic or pneumatic torque wrench. If this is the case, he's likely lost the pressure gauge overlay or torque chart for that particular wrench model and size (each wrench has a different chart/overlay). Best thing to do is to call up the manufacturer of the wrench, inform them of the tool model and and ask for the appropriate chart. Unfortunately, it's very doubtful that this would result in the proper preload: "Torque" has limited, or dubious at best, relationship to actual residual bolt load. Owing to myriad unknown friction factors and subsequent load transfers as adjacent bolts are tightened, a "properly torqued" (sic) bolt may in fact, either be too loose or too tight. Consequently, the integrity and reliability of the joint would be at risk. As pointed out in the earlier comment: The only way to ensure that you've got the required bolt load is to measure how much the bolt has stretched after being tightened and then, adjust accordingly. Many people are surprised at the variation in torque required to achieve consistent preload and distribution.

This is really being over engineerd. I have done what's being asked many times during my 36 year career in the Tobacco Industry. Most all of our machinery were metric and most torque specs where in Newton Meters. The only torque wrenches we had read in Inch Pounds and Foot Pounds. The solution was to convert the Newton Meters to what we had to work with that being Inch Pounds or Foot Pounds. If you will look at a conversion chart you will find many things measured in Newtons just as you will find many things measured in Inches and Feet. Open your minds, what does the metric world use to torque fasteners? J.Conway

Mostly the metric world uses wrenches to torque fasteners.

Sorry. I couldn't resist. :)

Actually, if we're talking about "tightening" fasteners...

Likely because they were developed over there, it's interesting to note that the metric world more readily uses bolt tensioners rather than wrenches for large critical fasteners (this eliminates the inaccuracies of the torquing process and ensures even gasket compression in gasketed joints).

My dear, if the originator of the thread means the conversion of bolt torque to system pressure, he would have (or should have) used units from same dimensional system... either MKS or FPS.

For pressure he is using PSI (fps) and for torque Nm (MKS).

I am also very much related with many engineering fields including piping, but I could not read what he means (his mind).

Still good, you understood, what he needs (I hope he needed same thing).

You're speculating a little bit. He could also be interested in how much torque in a transmission as a function of the transmission oil pressure. Certain (maybe all) Bell (and probably other mfg's) helicopters have a torque gauge that is marked in psi because it is really a transmission oil pressure gauge. The pilot needs to keep one of his eyes on this gauge to make sure the needle doesn't go past the red mark or he'll have overtorqued and either prematurely ended his mission or caused unscheduled maintenance depending on the severity of the overtorquing.

that is a good example, one should not assume anything. not matter how sure one thinks he is, esspecially when dealing with very limited information

Oops. It appears that I can't see the forest for the trees (or, rather: Bolts!) Thanks for pointing out that there is a much bigger world outside of my box ;-)

Knowing now that there are so many possibilities, it would be very interesting to see exactly what it is that "Guest" was referring to

Now, you came to a point.

Till now the originator has not opened up, what he wanted. You were just pleading on his behalf, as you are from the field of fasteners.

Our challenge questions are fairly often be pretty ambiguous too. Also, guests who never return to clear up ambiguities are frequent. My immediate assumption was that he wanted to know the relationship between pressure and torque in a hydraulic motor (and was not bothering to supply enough details to be able to do the calculation, and was also a little loose with his units).

We may never know.

dear all, here is the situation im talking about. i have an actuator that its shaft is connected to a valve through a mounting brackett with a dimension of radius inner= 144mm radius outer = 168mm, height or lenght = 195mm, material=ss316L, What i have is that the actuator can produce a max output torque of 30000Nm. i wanted to know since i can calculate the shear stress, having ultimate tensile strenght of ss316L how can i justify my cylinder wall thickness of 12 mm? i figure out that stress Mpa (Nm^-2)if divided by the hollow cylinder volume (m^3) will get me Nm which is the torque. Please note that the hollow cylinder is used to connect the actuators shaft for open/closing of the valve purpose.

the explanation above is just my assumption so if you guys have any other ways of calculating please let me know as im out of idea on how to relate torque, dimensions that i have( above stated) and stress or pressure ( since its the same unit ) to justify the thickness of 12mm with maybe safety factor of 2 son that the desired calculation will be around 6mm. to add the actuator's weight is 220kg and all this while the mounting bracket used have never brake or suffer any kind of deformation. please help.

Very funny situation.

OP asked something very vaguely, and we guesses and guessed and faught between us about what OP wanted. Many replied to the guess they did.

Now OP reappeared after long, explaining what he wants, and everybody is silent.

hehehehehehehe

Hi,

I am also trying to find the torque equivalent of pressure . I found the below links for calculating the torque. The results are different from different even though they are using same formula.

https://www.engineersedge.com/calculators/torque_calc.htm

https://www.omnicalculator.com/construction/bolt-torque

I am trying to understand the source of discrepancy and which one is correct. Any suggestion is highly appreciated.

Thanks

Maybe it's because one is pushing, and the other one is pulling....

Try this...

http://joshmadison.com/article/download-convert-for-windows/

The Newton per square meter(N/m^2) is = to the Pascal(Pa) and 1 lb/in^2= 6895 Pa so therefore 1 lb/in^2=6895 N/m^2

J.Conway

One does not usually use the Pa or N/m² ...............in the majority of engineering calcs the MPa or N/mm² is used............or if you so desire MN/m².

The kPa or N/cm² can be ued..........kN/m² ..............however the preferred unit is the MPa............all dimensions on engineering drawings are mm........because they are the preferred unit, so it follows with calculations.

If you think education is expensive,try ignorance! Please clarify your particular application, so the use of crystal balls,tea leaves,bones, and examination of entrails will not be required to ascertain the information you desire.It will also eliminate SWAGs. ----------------------------------------------------------------------------------GUEST

I think, this is what you want. Just mind the units.

Tightening Torque, TfA, can be calculated using the equation below:

TfA=0.35k(1+1/Q) X σy X As X d

Where,

k - Torque Coefficient

d - Nominal Diameter of Bolt[cm]

Q - Tightening Coefficient

σy - Proof Stress(112kgf/mm2 when the strength class is 12.9)

As - Effective Sectional Area of the Bolt[mm2]

Although I've been rightfully humbled to realize that the fugacious guest may not have been writing of things bolted when he fleetingly came upon the site, I've been able to work it out so that the spreadsheet which I wrote of can now be available.

Here's the link: Bolt Load Calculator

Hi,

the link is asking for Username & Password.

Hmmm... Anybody else notice the request for a password and user name? When I "click" the link, a dialogue box appears asking what to do with the Excel file. Strange.

Now, what is that?

Drat: I don't know what that's about. I'll have to get my IT guru to have a look. Hopefully we can get it resolved. Sorry for the inconvenience :-(

Surprising PC

I could open and save the file without need of any user name and password

This thread makes me think of why California budget (and the whole economy for that matter) is so messed up. All these answers don't address a simple question. I like the ones about how psi and torque just don't convert. Mathematically, physically okay but I'll bet any wrench turner half their weight could answer this question pretty close but they don't generally create Excel tables to explain it and they don't look at egg-head websites like this.

Simple question: (I'll paraphrase) "I have a compressor that I can control the PSI to the hose. I have snazzy tool that plugs into the hose and lots of sockets that plug into the tool. I have a bolt under my lawn mower that I have to retighten because I just replaced my blades. I know that the bolt should be tightened to 50 ft. lbs. of torque per the manual. I DON'T have a torque wrench because I'm not really a mechanic, but I do have a compressor with a lot of snazzy tools. What should the psi be set so when I plug in my snazzy air powered socket and slap it on the bolt that will result in about 50 ft. lbs. of torque on the bolt?"

Answer: Spend the $20 on a torque wrench. Set your PSI to 10 and tighten you lawn mower bolt. Take it off with the torque wrench and see what the resulting ft. lbs of torque is. Repeat 9 times at 20, 30 psi etc.

Post newly created Excel spreadsheet here with the disclaimer "this is my chart based on a XYZ compressor and an ABC torque wrench. Your results may vary but I'll bet it's close. Not recommended for egghead types that are tightening bolts on the side of the space shuttle. NASA should spend $1,400 on a very precise torque wrench… manufactured in California.

"...egg-head websites like this..."

Quite an offensive statement to make for somebody who has just joined as a member, wouldn't you agree? It's precisely because of egg-heads that you've been given the technology to express your rude opinions such as you have in this medium. Were it not for egg-head discourses like this one, we'd all be left to convey our ideas, ignorant or enlightened, by scrawling them onto the walls and ceilings of our caves.

Most significantly, open-minded and wide-ranging technical discussions often prevent the type of catastrophes resulting from knuckle-dragging Luddite views such as the one that we've just read.

So… to make a statement I deem germane within this world requires tenure, how… elitist? By the way, thanks for all the technology; I'm sure we couldn't have done it without you.

Okay, Thok will take his charcoal writing apparatus and his antediluvian point of view to another cave. I'll find a magical subterrane where there is fire, people stay on topic, everyone knows how to use the technology you gave us, and feelings aren't as brittle.

Cheers,

Thok.

Dear Friend,

Torque provides a turning Moment and PSI is the Pressure Force in one Sq.Inch. Both are different elements or different nomenclature and cannot be converted.

DHAYANANDHAN.S

I don't get it. I'm trying to epoxy a steel bolt into an aluminum hole and have it fixed permenantly. Tthere's some threading on each but mostly unthreaded. Thebest epoxy I can find that's high heat is 4500 psi tensile strength. Granted I really should probably be looking for shear strength but can't find that number. The bolt is 8mm diameter and about 4cm long. How many ft/lbs of torque will the glued bolt be able to survive before releasing?

Well, most would obtain some context in which this question is asked first. Otherwise, all answers posted here would be based on guesswork, which is a complete waste of everyone's time.

Try adding a couple of paragraphs about the scenario in which the question has appeared, and see what happens.