Contents

Asme pcc-1 2019 calculation engine

Eemua 234 solid weld neck flanges

How to change the units of a calculation

Create a bolt-load calculation

Blind flanges

Select a bolt-load calculation for a special flange

Select a bolt-load calculation for a heat exchanger

Select a partition gasket

How to change the target assembly stress

Lubricant values

Calculation output

Joint integrity review

Integrity review tabs

Joint integrity review colours explained

Select a tightening tool

Tightening pattern

Bolt relaxation

Saving a joint

Generating reports

Upgrading a joint to asme pcc-1 2019

ASME PCC-1 2019 Calculation Engine

New features

Our new ASME PCC-1 2019 calculation engine introduces the option to select pipe schedule within the joint specification and default to the wall thickness specified in ASME PCC-1 Appendix O, however users can override this.

Calculations have been improved and allows for calculating flange and bolt stresses at the user’s specified temperature. Increasing the temperature will not only cause the operating yield point to reduce, but also cause a higher amount of relaxation on the joint.

Updated Calculation Methodology Changes

Operating conditions

Operating and test pressures have been reconfigured and have a larger impact on calculations. Operating pressures default to match the maximum ceiling pressures (as per ASME B16.5 Table A.1). This will give the largest pressure offload, and the software will compensate for the high-pressure offload within the calculation.

Test pressure will now default to 1.1x the maximum ceiling pressure. Users will be able to manually increase or decrease this dependent upon the test pressure they are using. This will have an impact on the analysis. This is due to the possibility of a high-pressure offload, therefore there is the need for a higher target assembly bolt stress to compensate.

Manually reducing the operating or test pressure may reduce the target assembly bolt stress (dependent on the gasket and bolt parameters). This is because there is less need for a higher gasket stress if the pressure offload is reduced whilst still maintaining integrity.

Other

Target assembly bolt stress values have now been rounded to the nearest 250 psi increments with the Joint Integrity Review analysis based on this figure, ensuring the flange, bolt and gasket maximum allowable stresses have not been exceeded.

Flange Stress

Flange stress analysis has now been updated to include the user’s specified pipe wall thickness, providing more accurate flange stress calculations. This will allow the user to either increase the bolt stress (to allow for a higher gasket assembly stress) or reduce the bolt stress (to reduce risk of damage to the flange).

The optimum load during the applied phase when tensioning a joint will be calculated, reducing the risk of damage to the flanges, preventing the need for re-machining or replacement.

If a user has selected tensioning, they will also have to select the tool cover percentage from the following list:

• 100% cover
• 50% cover
• 33% cover
• 25% cover
• 50% multi pass procedure

The worst-case scenario on a flange will be when using 100% tensioning. This assumes that all bolts are tensioned above the target assembly bolt stress to account for the tool load loss factor. Therefore, there will be a higher load on the flanges.

The best-case scenario on a flange will be when the user has selected 25% cover. This assumes that 3/4 of the bolts will have been tightened to the assembly bolt stress, but only 1/4 will tensioned to the applied load. Therefore, it will have a lower impact on the flange stress compared to a 100% cover.

Analysis is conducted based upon the users’ specified temperature, allowing the software to calculate the flange stress during operation. This may cause the target assembly bolt stress to reduce, ensuring the flange does not yield during operation.

Depending on the bolt and gasket stress required to maintain a leak free joint, the software will attempt to apply a safety buffer on the flange. This will help reduce the likelihood of damage or risk to the flange over rotating. This will help to preserve the longevity of the flange and reduce the need for re-machining or maintenance work.

There is a new visual indicator on the Joint Integrity Review for when flange rotation is the limiting factor, this will be shown on the flange stress bar.

Gasket Stress

Gasket stress analysis calculations allow for more precision when calculating during the applied loading, assembly load, operational, and test phases.

The target assembly gasket stress values have been re-evaluated, and some joints may vary in target assembly bolt stress due to the streamlining of values.

The overall aim of the improved methodology is to attempt to achieve a minimum of a 50% margin over the minimum seating gasket stress, whilst maintaining a 50% margin over the operating and test gasket stress values.

If the calculation is unable to achieve a 50% margin over the minimum seating or operating gasket stress, the software will find the highest possible gasket stress while applying a safety buffer on the flange and bolt. This ensures that neither are damaged nor are a risk to integrity.

Bolt Stress

To ensure bolts are not over or under stressed, we have added additional bolt stress limits, this is to either limit the risk of damage or reduce the risk of loosening due to relaxation or vibration.

The minimum allowable bolt stress for any bolt material will be set to 20,000 psi / 137.6 MPa (as per ASME PCC-1 Appendix O).

These new limits for recommended minimum allowable bolt stress and minimum desired bolt stress allow the software to attempt to increase the bolt stress dependent on what the limiting factors for either the flange or gasket. This will help reduce the risk of leakage due to relaxation and vibration.

Dimension Updates

We have updated flange dimensions (in accordance with the latest revision of ASME B16.5 and ASME B16.47) which may have a minor impact on previously calculated flange stresses. The latest revisions of the standards brought the metric and imperial values closer together with regards to rounding of value.

With the addition of the selectable pipe wall schedule, the ASME B16.47 Series B 300 class flanges have had the length through hub extended to taper down to match the pipe outside diameter (as per ASME B36.10). This is due to the difference in the Hub Diameter Top A and the standard pipe outside diameter.

Materials

We have streamlined flange and bolt material names to include the following information:

• Standard
• Type / grade
• Class / condition
• UNS number
• Specific manufacturer naming

This has allowed for the removal of duplicates and to follow the conventional naming protocol for all materials, helping improve the search function for users when looking for a material.

Manufacturer’s gaskets can be added more easily (assuming we can acquire the appropriate data).

On the upper end of the scale, users will not be able to create joint tightening reports if the applied or assembly bolt stress exceeds 95% of the bolt material yield, which could risk the integrity of the joint and could cause long term damage. However, the software will not recommend bolt stresses this high. Typically, it will only advise a maximum assembly bolt stress of 70% of yield. There are however some bolt materials that do exceed this due to their low yield point.

When tensioning a joint, the tool load loss calculation will also be taken into consideration, the software will now recommend a maximum of 85% of yield during the applied load, which will limit the risk of permanent damage to the bolts due to scatter.

EEMUA 234 Solid Weld Neck Flanges

Introduction

CuNi 90/10 solid weld neck flanges designed to publication EEMUA 234 can be calculated in the ASME PCC-1 2019 connection type. Flange stress is calculated for each joint based on ASME BPVC Section VIII Division 1 Mandatory Appendix 2, ASME BPVC Section VIII Division 2 4.16 Design Rules for Flanged Joints, WRC 538, and ASME PCC-1 2019 Appendix O is used to determine the target assembly bolt stress.

The flanges have been added to meet EEMUA 234 requirements, thus some user selections are limited to meet the publication’s specification.

Flange materials

Only EEMUA 234-CuNi 90/10-UNS 7060X flange material is available.

Flange facing

Only flat face facing is available, as per EEMUA 234 flange dimensions tables.

Flange bore has been calculated based on the flange dimensions presented in EEMUA 234. N.B. The calculated flange bore is slightly different then EEMUA 234 specified pipe wall thicknesses. This can be verified in EEMUA 234.

Gasket materials

Only flat ring and full face Non-Asbestos Fibre, PTFE, PTFE/Neoprene, and PTFE/Neoprene with binder gasket types are available (soft type gaskets).

Gasket materials that have graphite in their composition have not been added.

Bolt materials

Bolt materials that have comparable mechanical and corrosions properties to ASTM B150 UNC C63000 have been added. One exception is bolt material, ASTM A3230-L7, which was added after reviewing previous calculation requests that used this bolt material.

How to Change the Units of a Calculation

You can change the units used in a calculation by updating your preferences:

1. From the Calculate landing page, click the Settings icon (2 cogs) in the navigation ribbon to the left.
2. Click the Units tab. This will load a list of the units used in Calculate.
3. Using the pull-down menus, choose the units you wish to use. Tip: if you make a change, you do not want, click the Use Default button to change back.
4. When you have finished, click the Save Preferences button. Tip: if you decide not to change units, click the Discard Changes button.

Create a Bolt-Load Calculation

To create a calculation:

1. From the Calculate landing page, click the Calculation engine icon.
2. Click the Joint Type and select from the list.
3. Expand the Flange, Gasket, and Fastener panels. Select the relevant details from the dropdown lists in each panel. A tick in the blue circle indicates you have completed each section.
4. Expand the Operating Conditions panel and update any fields required.
5. In the Tightening panel and choose between torque and tension.
6. Click the Calculate button.
7. The bolt-load calculation results are generated in line with the parameters selected.

Blind Flanges

Flat Covers/Blind Flanges

Flat covers/blind flanges designed as per ASME BPVC Sec. VIII Div. 1 UG-34 types J and K can be calculated in the Heat Exchanger and Special Flange connection types. The calculation methodology has been modified to base the analyses on material yield strength at ambient temperature rather than the maximum allowable stresses.

An example of populating the inputs required for a channel cover calculation is presented below. The example is based on a flat cover with a raised face and a step, but a similar process can be followed for all the other flange facings or for Special Flange calculations.

The example is based on data extracted from heat exchanger drawings. Heat exchanger drawings that provide the same level of details are required for conducting calculations.

Flange Dimensions

Figure 1 presents the user inputs based on the information extracted from Figure 2 (dimensions) and Figure 3 (corrosion allowance).

 

 

 

Joint Efficiency – Ej

As a default, Ej is loaded as 0.6 which is considered to be the worst-case scenario. As this value will have an impact on the blind flange stress calculation, the user should change the value to match the design of the heat exchanger to be analysed. Guidance on how to determine Ej is provide in Calculate next to the Ej input in the form this blue info box. Some heat exchanger drawings will provide the joint efficiency value, and this value shall be used for the calculation.

As it can be seen in Figure 1, for Joint Efficiency – Ej a value of 0.6 was used. Although 10% radiography is specified in Figure 5, weld type no. 3 was used as per Figure 5 as the weld details presented in Figure 4 do not provide any information on the use of backing strips. If information is available on the extent of radiographic or ultrasonic examinations and the use of backing strips, then weld types of no. 1 or 2 can be considered.

 

 

Gasket Dimensions

Figure 6 presents the gasket user inputs based on the information extracted form Figure 7 (gasket dimensions) and Figure 8 (partition groove depth).

The information was extracted from the same heat exchanger drawings used for the flange dimensions.

The gasket dimensions detail does not provide a gasket partition radius and it was assumed that the radius is equal to the partition thickness as this will affect the gasket sealing area.

 

 

 

Limitation

Calculations can only be performed for flat covers/blind flanges designed to ASME BPVC Sec. VIII Div. 1 UG-34 types J and K. Calculations carried for flat covers/blind flanges designed to other standards would or could provide inaccurate results and asset55 does not assume responsibility to any component damage or leakage resulted from using results for such a calculation.

Currently, flat covers/blind flanges stress analyses are only performed based on flange material yield values at ambient temperature.

For flat covers/blind flanges with flat face or recess face, the user will not be able to select gaskets with partitions. This is due to the reduction of flange thickness under the partition grove for these flange facings.

For flat covers/blind flanges with flat face and full-face gasket connected to a second flange that also has a flat face; where the gasket sealing outside diameter is bigger than the bolt circle diameter, the flat cover/blind flange stress is not calculated. This due to ASME BPVC Sec. VIII Div.1 UG-34 not covering bolt load calculations for this particular case.

Select a Bolt-Load Calculation for a Special Flange

1. From the Calculate landing page, click the Calculation engine icon.
2. Click the Joint Type dropdown.
3. From the dropdown list, select Special Flange.
4. Click to leave the page.
5. Once loaded you can then enter details for the special flange.

Select a Bolt-Load Calculation for a Heat Exchanger

1. From the Calculate landing page, click the Calculation engine icon.
2. Click the Joint Type dropdown.
3. From the dropdown list, select Heat Exchanger.
4. Click to leave the page.
5. Once loaded you can then enter details for the heat exchanger.

Select a Partition Gasket

1. From inside the Heat Exchanger or Special Flange calculation engine, complete flange data input, then open the gasket selection panel.
2. Open the Gasket Design dropdown and select a gasket partition configuration by clicking on the relevant image.
3. Select the relevant gasket type and material from the dropdown lists.
4. Using the simple illustration for guidance, input the relevant gasket dimensions.
5. Complete the full joint specification and click the Calculate button.

How to Change the Target Assembly Stress

1. From within the Calculate Calculation Engine, expand the Tightening panel.
2. Click in the Target Assembly Stress field and overwrite with a new value. Tip: if you want to revert to the default Calculate recommended target assembly stress, click the Reload Recommended button.
3. After entering your revised value, click on the Calculate button.

Lubricant Values

Overview

The lubricant values provided to users within Calculate are in accordance with the manufacturers’ latest published nut factors (K factor) and coefficient of friction (μ) data. This allows users the choice to choose either K or μ when conducting calculations in Calculate.

If a manufacturer does not provide both a K and μ, the assumption will be that the value of K in most applications at ambient temperature is generally considered to be approximately equal to the coefficient of friction μ plus 0.04.

ASME PCC-1 2019 appendix K nut factor calculation of target torque (K factor)

The nut factor or K factor is an experimentally determined dimensionless constant related to the coefficient of friction. It should be noted that the values within Calculate are taken directly from the manufacturers’ recommendation, but it should be noted that recent research has shown that there to be nut factor dependence on bolt material, bolt diameter, and assembly temperature.

The calculator provides the option to select the K factor, which has an impact on the torque calculation used as illustrated in the below formula:

Torque = nut factor x bolt diameter x target bolt load.

ASME PCC-1 Appendix J Calculation of Target Torque (µ value)

Determining the target torque for a given joint can be calculated using the mathematical model based around calculating the required torque to stretch the bolt, whilst overcoming both the friction within the pitch of the thread and the friction on the nut face.

This can be calculated based on the following calculation:

The following is a list of the individual calculations and components that derive the torque calculation:

De = effective bearing diameter of the nut face, mm (in.)

x = (do + di)/2

d2 = basic pitch diameter of the thread, mm (in.) (For metric threads, d2 = d − 0.6495p; for inch threads,

d2 = d − 0.6495/n.)

di = inner bearing diameter of the nut face, mm (in.)

do = outer bearing diameter of the nut face, mm (in.)

F = bolt preload, N (lb)

n = number of threads per inch, in.−1 (applies to inch threads)

p = pitch of the thread, mm (For inch threads, this is normally quoted as threads per inch, n; i.e., p = 1/n.)

T = total tightening torque, N·mm (in.-lb)

β = half included angle for the threads, deg (i.e., 30 deg for metric and unified threads)

μn = coefficient of friction for the nut face or bolt head

μt = coefficient of friction for the threads

Within the Calculate calculation engine, we use an average µ value of the friction of the nut face and friction of the threads to simplify the calculation; quite often manufacturers will only provide either the average of the two coefficients, or provide only the K value, which causes us to have to estimate the µ as 0.04 less than the K value.

Calculation Output

Once you have inputted your joint information and clicked calculate, your calculation outputs will appear on the right-hand side.

Calculate has now automatically calculated the optimum load based on the joint specification inputs in line with ASME PCC1.

You are provided with the target assembly bolt stress, bolt load and percentage of bolt yield.

The joint integrity review provides a very simple colour-coded indicator of the relevant stress, and therefore risk of that given load not only on the bolt but also the flange and the gasket, and we can therefore analyse the engineering interplay between all three components.

Users get this analysis of the joint not only at assembly stage, but also forward-looking into operations, which assesses the impact of both pressure offload and any bolt relaxation due to temperature.

This view is particularly helpful in reducing the necessity to retighten joints once the pipeline is in operation. The joint is also analysed under test conditions, which is as per the test pressure multiple selected in user preferences.

Joint Integrity Review

The Calculate Flange Management Joint Integrity Review provides a unique and powerful tool for quickly assessing the impact of any given bolt‐load upon the flange components. The simple, visual representation allows the user to instantly view the relevant stress levels on the gasket, flange, and bolt.

The Joint Integrity Review is not just limited to the assembly of the joint, it also provides a full integrity picture during operations and under test conditions. Our bolt load calculator engine puts the power of specialised integrity engineering expertise into the hands of the user. This allows the user to make quick, safe, and traceable decisions in the field; this helps increase safety and reduce costs.

Integrity Review Tabs

Joint Integrity Review has four different headings: Assembly, Applied, Operating, and Test. Note the pointers provide an indication of the calculation outputs only and are not interactive.

Assembly

This shows the stress levels across the three major components of the bolted connection at assembly (no pressure in the line and at ambient temperature).

Applied

This shows the stress levels across the three major components of the bolted connection at applied, accounting for the additional load that would be applied to compensate for the tool load loss factor (no pressure in the line and at ambient temperature).

Note: When tensioning the joint ONLY

Operating

This shows the stress levels across the three major components of the bolted connection during operating conditions, accounting for operating temperature effects on the bolting (relaxation) and operating pressure effects on the gasket (pressure offloading).

Test

This shows the stress levels across the three major components of the bolted connection during testing conditions, accounting for operating pressure effects on the gasket (pressure offloading) at an increased level based on the test pressure factor defaulted within their user preferences or manually selected within the calculation.

Joint Integrity Review Colours Explained

The following diagrams provide a detailed explanation of the risk bandings and thresholds.

Gasket Stress at Assembly

Gasket Stress During Operation

Gasket Stress During Test

Flange Stress

Flange Stress at Assembly with Flange Rotation Limit

Calculate also considers flange rotation limit when recommending the target assembly stress when applicable to a calculation. This is shown as the end of the green bar presented in the Flange Stress section of the Joint Integrity Review. Flange rotation is calculated in degrees and compared against the rotation limit dictated by each individual gasket material.

The consequence of this is that the acceptable recommended target assembly bolt stress for the calculation may be limited to less than 100% of the maximum permissible bolt stress prior to flange damage due to the flange having reached the flange rotation limit. Exceeding the flange rotation limit may compromise the seal of the gasket and therefore the overall integrity of the joint.

Flange rotation calculations for Weld Neck Flanges are performed in line with the methodology given for calculating Rigidity Index in in BPVC VII-2023 Mandatory Appendix 2-14 ​and typical gasket rotation limits in ASME PCC-1 2022 Nonmandatory Appendix O.

Bolt Stress

Select a Tightening Tool

To select a tightening tool in Calculate for a calculation:

1. From within the Calculate Calculation Engine, click on Change in the Tool Selection panel.
2. Scroll down list to locate require tool. Details of each tool capacity % in relation to the load required is provided. Once a tool has been identified, click Select Tool.
3. The required pump pressure settings for the selected tool to achieve the given load are provided.

Tightening Pattern

To view the current tightening pattern and change the tightening pattern:

1. From within the Calculate Calculation Engine, click on Tightening Pattern in Joint Information.
2. To change the pattern expand the Tightening panel.
3. Change the Torque or Tension value from the dropdown list depending on if the calculation is set to torque or tension.
4. Click the Calculate button to recalculate the values.
5. Check the tightening pattern as step one.

Saving a Joint

To save a joint in Calculate:

1. From inside Calculate Calculation Engine, once all selections have been made and calculation completed, click on the Save button.
2. In the Add Joint popup, give the joint a unique ID and add any other identifying information. Once complete, click Create New. Your joint information will now be automatically stored in Joint Manager.

Generating Reports

1. From inside the Calculate Calculation Engine and from a saved joint, click on the Downloads button.
2. Click on the required report from the list.
3. Select the report format you require – PDF or Excel.
4. You will then receive a file in your downloads folder containing the report for the joint in the format you selected.

Upgrading a Joint to ASME PCC-1 2019

Introduction

With the release of Calculate v3 and our new ASME PCC-1 2019 calculation methodology you can create new joints in Calculate using this new calculation method, but we have not changed the joint or tightening specification of existing joints within the system.

We have created a tool which will allow you to convert individual Legacy joints to the new v3 ASME PCC-1 2019 methodology. Materials in the Legacy calculation engine have been mapped to materials in the new calculation engine. In certain circumstances, there is no mapping, and you will have to select a new relevant material.

The tool will allow you to review the new joint specification, perform a new calculation, review the revised tightening specification, and save the upgraded joint or decide to leave it as is for now. You can still download reports and tightening certificates for joints which have not been converted.

Upgrade a Legacy Joint:

1. Open any Legacy joint as normal in the Calculation Engine. Press the orange “Convert to v3 joint” button.
2. A popup will be shown explaining the joint specification changes. Click “I understand” button to accept the changes and apply the new material names and upgrade to v3 a joint.
3. Review the changes to the joint specification. The calculation will retain (as close as possible) the previous Target Assembly Stress, you can press the “Reload Recommended” button to load in the new v3 ASME PCC-1 2019 methodology Target Assembly Stress. Press the “Calculate” button to recalculate the tightening specification for the joint.
4. Check the recommended tool is suitable and if you are happy, you can press “Save” to save the new joint and tightening specification.
5. If you do not want to save the changes, you can navigate away from the calculator page and not save the changes you have made.

Bolt Relaxation

This article highlights the importance of entering temperature limits in the ASME PCC-1 2019 Calculator and the Relaxation Factors which are applicable to calculations performed in Calculate for the Heat Exchanger and Special Flange connection types.

Bolt Relaxation for ASME PCC-1 (2019) Connection type

Bolt relaxation is an important variable that will affect any bolted connection for a variety of reasons.

Bolt relaxation will be calculated in the ASME PCC-1 2019 connection type based on the temperature parameters entered. It is important to accurately enter the temperature parameters so that the correct bolt relaxation factor can be automatically determined with respect to the application to be tightened. Bolt relaxation factors for common bolt grades are derived from BS 4882 : 1973 as shown in Figure 2.

If no temperature range is entered, as a safety factor, Calculate will allocate a default relaxation of 30% as per Figure 1. The 30% bolt relaxation is aligned with ASME PCC-1 2022 Nonmandatory Appendix O, section O-4.1 paragraph (i).

Figure 1

Relaxation Factors for Heat Exchanger/Special Flange Connection type

Relaxation factors are required for the Heat Exchanger and Special Flange connection types in Calculate, except in this connection type the relaxation factors need to be entered manually which can account for any intricacies in design. Relaxation factors may be available from manufacturers or designers and if obtainable should be incorporated into the calculation.

If there is no manufacturer guidance a relaxation factor can be determined based on bolt relaxation. It is first necessary to establish the temperature of the fasteners as follows:

• It is recommended to use the actual bolt temperature if this is known.
• If the bolt temperature is not known, then guidance can be taken from ASME PCC-1 2022 Appendix M, M-1.3 as per ASME B31.3, section 301, which states: o If the joint is insulated, then the temperature shall be equal the operating temperature. o If the joint is not insulated, then the bolt temperature can be considers as being 80% fluid temperature.

Once the applicable temperature has been discerned, the graph from Figure 9 of BS 4882 : 1973, which gives relaxation information for common bolt materials at temperature, as shown in figure 3, should be referenced and can be used to extrapolate the relaxation factor at a specific temperature.

The value plotted on the vertical axis against the temperature on the horizontal axis can be used to define the relaxation factors for the operating and design conditions.

Figure 2

Test relaxation is usually set between 5% and 10% to represent the load loss immediately after tightening from embedment etc. as specified by Bickford in ‘An Introduction to the Design and Behaviour of Bolted Joints’, based on research by the Southwestern Research Institute.

If relaxation factors are not known, 30% relaxation could be used as per ASME PCC-1 2022 recommendation from Nonmandatory Appendix O, section O-4.1 paragraph (i).

Once the relaxation factors have been decided, they need to be entered in the operating conditions need to be entered in the operating conditions as per Figure 3:

Figure 3

It is important to enter in relaxation factors when completing a Special Flange or Heat Exchanger calculation to allow the software to complete the requisite calculations for the Joint Integrity Review