How are Bolt Lengths Calculated in OpenPlant Modeler


Applies To 
Product(s):OpenPlant Modeler
Version(s):08.11.09.XXX (SS5) | 08.11.11.XXX (SS6)
Environment: Windows 7/8.1/10 (64 bit)
Area: Component
Subarea: Data
Original Author:Rahul Kumar, Bentley Product Advantage Group

 

Bolt Lengths Calculation in OpenPlant Modeler has been described below with Various cases.

Background

Bolts:

The Bolt selection mechanism does not select an individual bolt by the size (diameter) of bolt required but rather it will select the predefined “set” sized for a standard bolting of each facing, rating and size. In OpenPlant Modeler, two basic types of bolt has been classified, such as Machine Bolts and Stud Bolts which further has been categorized under BOLT/STUD BOLT class and significantly using its properties like BOLT_LEN, NUT_LENGTH, BOLT_INC, BOLT_XCESS etc. This set is read from the spec and all properties including bolt diameter and number required are read from the spec unaltered.  The length of the bolts in Open Plant Modeler is typically calculated as described below.

Controlling Through Variable
A configuration variable (set for each workspace) will toggle if the calculated length is included in the query. This variable is OPM_QUERY_BOLTS_WITH_IGNORE_LENGTH = (0 or 1)

The default value is “0” meaning all bolt spec queries will first try to find the correct value for bolt length in the BOLT_LENGTH column of the spec. If no records are found then the length is removed and the first record found is used. 

Setting this variable to “1” will prevent OpenPlant from querying on length. E.g. if we set the variable to ‘1’ here, it takes BOLT_LEN= 88.9 MM only. See explanations in the sample calculation provided below.

 

Bolt Length Calculation:

Length calculated by OPM is dependent on type of bolts and connection. These can be divided in to three main groups:

Wafer Connection:


Machine Bolt has a hexagon head and one threaded end with nut and excess.  The Head is not part of the length of a Machine bolt.

For these bolts we have the code logic, so a general formula for machined bolt’s length:

Machine Bolt_Length = COMP_LEN + [(Gasket_Thickness) x 2] + [(Flange_Thickness) x 2] + Nut_length + BOLT_XCESS


Stud Bolt has threads both ends, nuts both ends and excess both ends. So a general formula for stud bolt’s length:

Stud Bolt_Length = COMP_LEN + [(Gasket_Thickness) x 2] + [(Flange_Thickness) x 2] + [(Nut_length) x 2] + [(BOLT_XCESS) x 2] 

COMP_LEN here is the length of wafer assembly. See image above for clarification:

Lap Joint Stub End Flange Connection:

Machine Bolt has a hexagon head and one threaded end with nut and excess.  The Head is not part of the length of a Machine bolt.

So a general formula for machined bolt’s length:

Machine Bolt_Length = (Gasket_Thickness) + [(Flange_Thickness) x 2] + [(STUB_THK) x 2] + Nut_length + BOLT_XCESS

 

Stud Bolt has threads both ends, nuts both ends and excess both ends. So a general formula for stud bolt’s length:

Stud Bolt_Length = (Gasket_Thickness) + [(Flange_Thickness) x 2] + [(STUB_THK) x 2] + [(Nut_length) x 2] + [(BOLT_XCESS) x 2]

General Flange Connection:

Machine Bolt has a hexagon head and one threaded end with nut and excess.  The Head is not part of the length of a Machine bolt.

So a general formula for machined bolt’s length:

Machine Bolt_Length = (Gasket_Thickness) + [(Flange_Thickness) x 2] + Nut_length + BOLT_XCESS

 

Stud Bolt has threads both ends, nuts both ends and excess both ends. So a general formula for stud bolt’s length:

Stud Bolt_Length = (Gasket_Thickness) + [(Flange_Thickness) x 2] + [(Nut_length) x 2] + [(BOLT_XCESS) x 2]

Let's Take an Exercise For Each Case Mentioned Above

For Wafer Type Connection:

For Machine Bolt length Calculation:

Pipe Size = DN 100

Spec = mA1-OPM

Flange THK = 23.9 MM

Gasket- 3.2 MM

Nutlength/NUT_LEN = 14.3 MM

COMP_LEN = 55.6 MM

Bolt_EXCESS/ Bolt extension length = 7.1 MM

BOLT_LEN= 76.2 MM (As you can see Bolt_D_X_L = 3“length)

Using equation, Machine Bolt_Length   = COMP_LEN + [(Gasket_Thickness) x 2] + [(Flange_Thickness) x 2] + Nut_length + BOLT_XCESS

                                                         = 55.6+ (3.2 X2) + (23.9x2) +14.3 + 7.1

                                                         = 131.2 MM

Manual calculated length = 131.2 MM, as in OpenPlant Modeler dimension.


Role of BOLT_INC

As described above, it should get added to BOLT_LEN 9 times to surpass the above calculated value 131.2 MM.

Here it should be BOLT_LEN+ BOLT_INC = 76.2 + (6.4x9) = 133.8 MM.

See Bolt Length shown below in element info,


In Spec: 76.2mm




For Stud Bolt length Calculation:

Similar procedure like explained above for Machine bolt, will be applicable for Stud Bolt using the formula,

Stud Bolt_Length = COMP_LEN + [(Gasket_Thickness) x 2] + [(Flange_Thickness) x 2] + [(Nut_length) x 2] + [(BOLT_XCESS) x 2] 

Using Stud bolt, calculated length in this case      = 55.6 + (3.2x2) + (23.9x2) + (14.3x2) + (7.1x2)

                                        = 152.6 MM


As per record shown above, the Length is 88.9 MM < 152.6MM. Hence BOLT_INC need to be added. 

Hence, 88.9 + (6.4 x 10) = 152.9 MM. See element info for reference.


 

Using Variable:

By Setting the variable OPM_QUERY_BOLTS_WITH_IGNORE_LENGTH = 1, It ignores the calculation shown above for Stud Bolts and consider the value as per record i.e. 88.9MM as a final one. See image below for same set of bolts.

 

For Lap Joint Stub End Flange Connection:

For Machine Bolt length Calculation:

Pipe Size = DN 100,

Spec = mEx-OPM,

Flange THK = 23.9 MM,

Gasket- 15.9 MM,

Nutlength/NUT_LEN = 14.3 MM,

STUB_THK = 6 MM,

Bolt_EXCESS/ Bolt extension length = 7.1 MM,

BOLT_LEN= 76.2 MM (As you can see Bolt_D_X_L = 3“length),

Using equation, Machine Bolt_Length   = (Gasket_Thickness) + [(Flange_Thickness) x 2] + [(STUB_THK) x 2] + Nut_length + BOLT_XCESS             

= 15.9+ (23.9x2) + (6x2) + 14.3 + 7.1

                                                                  =   97.1 MM

Manual calculated length,                     = 97.1 MM, as in OpenPlant Modeler dimension.

Role of BOLT_INC

As described above, it should get added to BOLT_LEN 4 times to surpass the above calculated value 97.1 MM.

Here it should be BOLT_LEN+ BOLT_INC = 76.2 + 6.4+6.4+6.4+6.4 = 101.8 MM, 

See Bolt Length shown below in element info,   = 101.8 MM


In Spec: 76.2 MM


For Stud Bolt length Calculation:

Similar procedure like explained above for Machine bolt, will be applicable for Stud Bolt using the formula,

Stud Bolt_Length = (Gasket_Thickness) + [(Flange_Thickness) x 2] + [(STUB_THK) x 2] + [(Nut_length) x 2] + [(BOLT_XCESS) x 2]

Using Stud bolt, calculated length in this case      = 15.9 + (23.9x2) + (6x2) + (14.3x2) + (7.1x2)

                                                                         = 118.5 MM


As per record shown above, the Length is 88.9 MM < 118.5MM. Hence BOLT_INC need to be added.

Hence, 88.9 + (6.4 x 5) = 120.9 MM. See element info for reference.


Using Variable:

By Setting the variable OPM_QUERY_BOLTS_WITH_IGNORE_LENGTH = 1, It ignores the calculation shown above for Machine Bolts and consider the value as per record i.e. 76.2 MM as a final one. See image below for same set of bolts.

 

For General Flange Connection:

For Machine Bolt length Calculation:

Pipe Size = DN 200,

Spec = mEx-OPM,

Flange THK = 28.4 mm,

Gasket- 15.9 MM,

Nutlength/NUT_LEN = 15.9 MM,

Bolt_EXCESS/ Bolt extension length = 7.9 MM,

BOLT_LEN= 88.9 MM (As you can see Bolt_D_X_L = 3 ½ “length),

Using equation, Machine Bolt_Length = (Gasket_Thickness) + [(Flange_Thickness) x 2] + Nut_length + BOLT_XCESS

              =   15.9+ (28.4X2) +15.9+7.9

              =   96.5 MM

        Manually calculated length                 = 96.5 MM, as in OpenPlant Modeler dimension.


Role of BOLT_INC


If no Bolt of current length is found after processing all the records, then we use the increment value (BOLT_INC) of the last record to calculate correct length.

Here it should be BOLT_LEN+ BOLT_INC = 88.9 + 6.4 = 95.3 MM, which is still less than the computed value 96.5 MM,
=> it again adds BOLT_INC value, i.e. 95.3+6.4 = 101.7 MM

Element Info Shows: 101.7 MM, see image below:


In Spec: 88.9 MM

For Stud Bolt length Calculation:

Similar procedure like explained above for Machine bolt, will be applicable for Stud Bolt using the formula,

Stud Bolt_Length = (Gasket_Thickness) + [(Flange_Thickness) x 2] + [(Nut_length) x 2] + [(BOLT_XCESS) x 2]

Using Stud bolt, calculated length in this case,    = 15.9 + (28.4x2) + (19.05x2) + (9.525x2)

                                                               = 129.85 MM


As per record the Length is 139.7 MM which is greater than the calculated value 129.85 mm. Hence no BOLT_INC required and final length would be 139.7 MM. See image below.


Using Variable:

By Setting the variable OPM_QUERY_BOLTS_WITH_IGNORE_LENGTH = 1, It ignores the calculation shown above for Machine Bolts and consider the value as per record i.e. 88.9 MM as a final one. See image below for same set of bolts.

To fix issue with bolts not being picked from spec

Sometimes bolt records exist in the spec but still they are not placed with gasket after joint is created. This could be related to the missing values for some key fields like BOLT_INC, BOLT_XCESS in BOLT table as shown below.

See Also

communities.bentley.com/.../15368.cannot-update-calculated-bolt-lengths-in-description-field

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