Custom Weld Neck Flange

If your application is a special flange such as used on a pressure vessel or heat exchanger, and you have all the material and dimensional details, this option will calculate a minimum bolt load for you. You may then enter your own additional bolt load or stress. As a further option, subject to data you have entered, Hydratight will recommend a bolt load for your application.

The following information needs to be entered on this screen. As each dimension is entered it will appear on the outline drawing on the right hand side of the screen. You need to be able to include a value for each entry for the Calculator to fully work.

First, confirm the Units you wish to use either mm or inches.

Confirm the geometry of flange by entering values for :

Flange OD (OD = Outside Diameter)

PCD (bolt pitch circle diameter)

Hub Diameter

Pipe OD

Gasket OD. This needs to be the outside diameter of the sealing area of the gasket.

Gasket ID. This needs to be the inside diameter of the sealing area of the gasket.

Flange Height. This is the length between the underside of the flange face to the weld joint with the pipe.

Flange Thickness.

Bolt Size. Click on units and then select your bolt diameter from the drop down box adjacent to the unit selection box.

Bolt Qty. This is the number of bolts in the flange joint.

Bolt Material. You may select from the listed bolting materials that appear from the drop down menu. The program will take account of stress relaxation factors due to temperature (when appropriate) as well as strength limitations due to bolt size.

Hub Radius. This is the radius at the intersection of the hub and flange face.

Gasket Details. Select the gasket type and the material from the adjacent drop down menus. For more information on gasket selection please refer to Appendix 4.0.

Grip Length. This is the distance between the two flange faces being bolted together. The length should include any spacers fitted between the flange faces such as tubesheets, blinds, etc. This value is used for calculating the load relaxation allowance if tensioners are to be used to tighten the joint.

Design and Test pressures. Enter the design or operating pressure in either Bar or p.s.i. as appropriate. At the same time the test pressure will be calculated based on a factor of 1.5 times the entered pressure. This can be altered if required to suit the particular test conditions.

Design Temperature. Enter temperature the bolting will experience under service conditions in either degrees Centigrade or degrees Fahrenheit.

NOTE! For all bolt materials other than A193 Grade B7 and B16 materials, the software will not permit selection of temperatures above 50ºC / 122º F. For Grade B7 the software will permit temperatures up to 400ºC / 750º F, and for Grade B16 the software will permit temperatures up to 500ºC / 930º F.

The data entered on this page, together with the database and calculation programs running in the background, will be used to calculate the required bolt load to seal your chosen flange under the entered operating and test conditions. The calculations are performed in accordance with ASME 8.

Once you have entered the data you need to click on the "Calculate" button. The Calculator will now calculate the minimum load per bolt to seal the application.

You can also click between Inputs and Calculations. Inputs will display the key factors used from the information given to calculate ASME 8 load to seal.

Calculations displays the outputs from the calculation. The values displayed include the total calculated bolt loads in accordance with ASME 8. Values are displayed for the Wm1 and Wm2 conditions as well as the minimum load per bolt for the worst condition to seal. This is the value that will be used in the tightening calculations, whether torque or tension tools are to be used. The key output is the bottom value labelled "Minimum bolt load to seal based on the ASME 8 Code." This is a minimum value to be applied to each bolt to achieve a seal. Hydratight recommend this value is always exceeded to be sure of a seal.

The only further information you need enter is to choose between tensioning or torquing up this flange. If you choose tension the calculator will continue and provide you with bolting pressures for use with your selected bolt tensioners.If you choose torque the calculator will give you the hydraulic pressure for use with the torque tool, based on your chosen lubricant.

You should now choose either "Torque" or "Tension" depending on the method of tightening you will be using for this application.

Clicking "Next" will take you to the next screen.