Calculation of the load on a round pipe

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Notes: 1) Calculation of the pipe wall thickness is carried out according to the RD 10-249-98 method. 2) The values of the fields highlighted in color are filled in automatically from the internal database; if desired, you can enter your own values. 3) The values of the fields highlighted in color are filled in automatically based on the calculation results. 4) Allowable stresses are determined in accordance with RD 10-249-98. 5) For steel grades X10CrMoVNb9 and P265GH, the permissible stresses are taken according to EN data. The permissible stresses of X10CrMoVNb9 steel are determined at a temperature value of more than 500 * C 6) The minus tolerance for wall thickness is filled in automatically. Up to outer diameter 114 – 10% of the thickness, more – 5% (TU 14-3R-55). 7) The online program is working in test mode! Please leave your comments and suggestions in the reviews. IMPORTANT: By using this service you confirm that you are using the program at your own risk and solely for informational purposes. The resource administration is not responsible for the calculation results. The purpose of the program is preliminary calculations for subsequent independent calculations in accordance with the current Standards for strength calculations.

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One of the most popular products in construction is steel pipe. For example, VGP pipe VGP DN 15x2.8mm 6m can be used for communications, and square-section products are used as supports. In the latter case, during design it is necessary to correctly determine the load-bearing capacity of a metal square steel pipe.

What is the maximum load on a steel pipe support?

In many load-bearing structures, the pipe plays the role of an element, without which it is impossible to build a frame. In addition, the products are convenient to use when constructing various partitions. An important advantage of the product is that it is suitable for both temporary and permanent use. That is why pipes are often used as reliable supports for equipment and auxiliary equipment.

The operation of the pipe as a load-bearing element is explained by the fact that this product is different:

high compressive and tensile strength;
immunity to vibrations;
sufficient elasticity;
suitability for repeated use;
affordable price;
ease of installation.

To achieve such benefits from use, it is necessary to correctly determine the load-bearing capacity, that is, calculate the load that a steel pipe support for a canopy, overhead line, equipment, etc. can withstand.

Methods for deforming profile pipes

In order to give the greenhouse a characteristic semicircular shape at the top, the structural elements must not be straight, but curved with a certain radius.

It is no secret that it will not be possible to bend a rolled profile by forcefully bringing its two ends together, since the walls on the inside will wrinkle. However, there are many ways to correctly deform profiled metal.

Among the things that can be applied in a home workshop, I would like to note the following:

deformation using a pipe bender;
deformation using welded tacks;
deformation through cutting and subsequent welding.

Using a special tool

The instructions for bending a pipe using a pipe bender are similar, regardless of the modification of the tool.

Stages of working with hydraulic tools

Let's look at the stages listed in the diagram using the example of operating a homemade hydraulic pipe bender.

At the initial stage, we cut the pipes into pieces of the required length

Tool rollers in neutral position

The tool rollers are set to a neutral position, that is, no pressure is applied to the workpiece;

Adjusting the rollers to apply load to the workpiece

Then, using a jack, the rollers are moved so that the necessary pressure is applied to the workpiece;

Rolling the workpiece

Using a manual winch, the workpiece is rolled several times from side to side along the pressure rollers;
As the workpiece bends, the rollers are additionally pressed with a jack;
The workpiece is again rolled several times along the pressure rollers;

The required radius is almost achieved

The listed steps are repeated exactly until the workpiece takes on the required bend radius;
After the required configuration of the workpiece is obtained, the pressure rollers move away and the product is released.

Finished goods

A similar method is used when working with a manual pipe bender, where, unlike hydraulics, the rollers are pressed by tightening the screw.

Recommendations for bending profile pipes using a hydraulic pipe bender

Do not apply excessive pressure to the rollers at one time. As a result, you will not deform the workpiece and it will be easier to turn the gate.

Use rollers of a suitable configuration, that is, the width of the rollers should correspond to the cross-sectional width of the pipes. In this case, the bending will be more accurate, and the workpiece will not move from side to side when passing through the machine.

Before starting bending, I recommend preparing a radius template or measuring the distance that should be between the ends of a correctly bent pipe. Subsequently, knowing the distance or having a template, it will be easier to assess the readiness of the bend without removing the workpiece from the tool.

How to bend a profile pipe without a special machine

The price of a ready-made pipe bender is high, but this tool can be made with your own hands. On the other hand, this tool may simply not be at hand at the most necessary moment, so what should you do in such a situation?

I propose, as an example, to consider a unique technology for deforming rolled profiles for assembling a polycarbonate canopy.

Why a canopy? The fact is that the method I want to talk about has restrictions on the bend radius and it will not be possible to prepare components for the greenhouse, but bending the blanks for assembling the canopy trusses is easy.

The diagram shows how to do without a pipe bender

Let's look at the stages listed in the diagram in more detail.

Future farm foundation

At the initial stage, we prepare rolled profiles with a rectangular cross-section for the base of the truss;

Marking for jumpers

We measure the workpiece in length and, in accordance with the measurements, divide it into 6 equal fragments, as shown in the photo;
We prepare vertical supports;

Universal calculation of jumper heights

In the photo you can see the calculation and reduction factor for the length of the supports. This is a very important point, since cutting the supports in accordance with the above calculations allows you to bend any pipes without fear of crushing their walls.

Jumpers are welded

We weld the vertical supports to the base of the truss according to the previously marked marks;

We try on the profile from the end with an overlap of at least 10 cm

We prepare a section of profile pipe that is to be bent;

Bend to one of the ends of the base

We apply the workpiece to the vertical supports at both ends of the base of the truss;

We weld the end by welding

We weld the pipe to the first support;

We weld the second end

Then we weld the pipe to the last support, gradually bending it, leaning on it with body weight.

Recommendations for bending:

The beam to which the arc will be tacked must be securely fastened, since working on a moving beam will not ensure bending accuracy;
The beam on which the supports will be welded must be made of a profile pipe with a cross-section of at least 50 by 50 mm, taking into account the bending of a pipe with a cross-section of 20 by 20 mm;

For ease of operation, the pipe can be temporarily tied

If you work alone, tie one of the ends of the bent workpiece with a rope while we direct it to the next support;
We weld the vertical posts to the beam at an angle of 90°;
The coefficients used to calculate the length of the vertical posts are relevant, regardless of the size of the finished structure;

The jumpers have been removed, but the deformation radius is still the same

The assembled structure is so strong that it can subsequently work without vertical posts only due to end tacks.

Deformation of a profile pipe by cutting with a grinder

Finally, I suggest you familiarize yourself with a simple method of deformation, which is relevant when working with large-section profiles.

To work, we will need an angle grinder (grinder) or a miter saw, a welding machine and a measuring tool.

The instructions for working with the profile pipe are as follows:

We mark the location of the cuts on one of the walls of the pipe (after bending, this wall will be external);

Marking for cutting

From the marks made, we draw triangles with an angle so that when folded at the cut sites, the product takes the desired shape and the desired radius of curvature is obtained;

Cutting made according to markings

Using the marks made, we saw the workpiece and remove unnecessary pieces of metal;

Deformation with the desired radius

The workpiece is bent so that the edges of the cuts meet;

Welding joints

The edges of the cuts are welded.

The method is good in its simplicity, but you need to take into account that the bend line will be broken. Therefore, this solution is not suitable for the manufacture of canopies, where the sheathing is pricked with a solid sheet of polycarbonate.

Properties of bendable metal

Metal has its own point of resistance, both maximum and minimum.

Maximum load on the structure leads to deformations, unnecessary bends and even breaks. When making calculations, we pay attention to the type of pipe, cross-section, dimensions, density, and general characteristics. Thanks to this data, it is known how the material will behave under the influence of environmental factors.

We take into account that when pressure is applied to the transverse part of the pipe, stress arises even at points distant from the neutral axis. The zone of most shear stress will be the one located near the neutral axis.

During bending, the inner layers in the bent corners are compressed and reduced in size, and the outer layers are stretched and lengthened, but the middle layers retain their original dimensions after the end of the process.

Allowable bend radii based on material strength

The bending radius of the profile depends on the external section DN, the thickness of the material, its density and flexibility.

State standards establish minimum bending radii for profiled pipes. Their permissible size is largely determined by the way the part is bent.

If the bend is made by heating the workpiece, or by filling it with sand, the bend radius must be at least 3.5 DN.
Bending on bending equipment without heating is possible with a minimum radius of 4 DN.
If the process uses furnace heating, a value of 2.5 DN is allowed.
An important condition for bending is the thinning of the walls of the product in the area of operation by no more than 15%.

How to make the right calculations

Calculation of a profile pipe for deflection is the determination of the degree of maximum stress at a specific point on the pipe.

Each material has normal stress indicators. They do not affect the product itself. To make the calculations correctly, you must apply a special formula. It is necessary to ensure that the indicators do not exceed the maximum permissible values. According to Hooke's law, the resulting elastic force is directly proportional to the deformation.

When calculating bending, it is also necessary to use the stress formula, which looks like M/W, where M is the bending indicator along the axis on which the force falls, but W is the bending resistance indicator along the same axis.

Why is this necessary?

Why know the mass of a linear meter of a profile product?

When constructing metal structures, some elements press on others with their own weight along with the payload . For example, the frame of a partition in an industrial building creates a load on the beams, a bridge truss on the columns, and so on. This load must be taken into account when calculating the strength of structures.
In addition, rolled products at metal depots are sold not by the meter, but by weight, and its price is indicated per ton . To convert the moldings calculated when creating the project into the treasured tons, you need to know how much a meter weighs for a particular section and wall thickness.

Let us clarify: the exact weight also, of course, depends on the steel grade; however, the difference between different brands is so small that the current GOSTs neglect it. The steel density is taken to be 7.85 t/m3.

When is deflection calculation needed? Let's try to explain with an example.

Imagine that you want to build a balcony with a frame made of corrugated pipe in your cottage. You know the reach of the balcony, and so does the expected load. In order to select the optimal section of the corrugated pipe for the role of load-bearing beams, you need to know the method for calculating the bending strength.