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Registration/User Management

 Registration Steps

  1. Click HERE to open HUBPL portal.

  2. Click ‘Sign up’ on bottom of sign-in widget and fill out all information.

  3. Click blue ‘Sign Up’ button.

  4. On ‘Setup security methods’, click ‘Email’ > ‘Setup’.

  5. An automated email after registration from technicaltoolboxes.okta.com will be sent to you.

    1. Ex.:

  6. Input the code sent to your email (see outline in 4a. above).

    1. Note: If you haven’t received an email, you can press the Send again button to try again.

    2. If this doesn’t work, consult with support@technicaltoolboxes.com.

  7. Click ‘Verify’ button.

  8. On ‘Setup security methods’, click ‘Password’ > ‘Setup’.

  9. Click ‘Next’.

  10. If you encounter a screen for ‘Setup security methods’ that says ‘Setup optional’, click ‘Set up later’.

  11. You should be logged into HUBPL after this.

  12. Once inside HUBPL, you will see a screen inside the canvas that looks like this:

  13. Contact support@technicaltoolboxes.com to license your user.

 Registration Steps - Single Sign-On
  1. Click HERE to open HUBPL portal

  2. Click ‘Sign up’ on bottom of sign-in widget and fill in your email.

  3. Click the blue ‘Next’ button

  4. You should be directed to your corporate directory’s sign-on page:

    1. Ex.: Technical Toolboxes directory

  5. Complete the authentication steps in your directory:

    1. Ex.: Technical Toolboxes directory

  6. You should be immediately logged into HUBPL:

    1. Note: If you receive a screenshot like the below, this is due to Okta needing the following information and being unable to get everything from your corporate directory:

      1. Technical Toolboxes support will need to be consulted with your IT department to close the gap so future users can have an automatic registration.

      2. Report the finding to: support@technicaltoolboxes.com.

  7. You should be logged into HUBPL after completing this step.

  8. Once inside HUBPL, you will see a screen inside the canvas that looks like this:

  9. Contact support@technicaltoolboxes.com to license your user.

 Change Password & Okta User Dashboard

  1. Click HERE to open HUBPL portal.

  2. Login.

  3. In HUBPL, go to your username > Change Password.

  4. You will be taken to your Okta User Dashboard.

  5. All personal information here is managed by Technical Toolboxes Support.

    1. If information here is incorrect, email support@technialtoolboxes.com or put in a support ticket at TT Support Desk.

  6. Click Edit Profile and authenticate through Okta if prompted.

  7. To change your password, follow the text boxes and click Change Password.

 How do I correct my user info?

HUBPL users are managed in Technical Toolboxes’s Okta user management instance at: https://technicaltoolboxes.okta.com/

All users have the following information stored in their Okta user profile there that shows up in the HUBPL application in various areas shown below:

  • First Name

  • Last Name

  • Email Address

  • Title

  • Company

In HUBPL, a user’s info is visible in the following places:

  • User menu:

  • Preferences menu:

  • Change Password (redirect to Okta User Dashboard):

What do I do if my info is incorrect in these places?

Send an email to support@technicaltoolboxes.com or send in a support ticket in Jira at: Technical Toolboxes Jira Support

 How do I reset my password?

If you have forgotten your password like the below,

Follow the steps below:

  1. Click ‘Forgot password?’

  2. Click ‘Send me an email’.

  3. Click the verification link sent in the email or click ‘Enter a code from the email instead.

    1. Note: If a code was not send, click ‘Send again’

  4. Click ‘Verify’.

  5. Change your password per the password controls enforced on your user.

  6. After completion, you should be logged into HUBPL.

 Why do I get a message that says 'Reset password is not allowed at this time. Please contact support for assistance'?
Unable to render {include} The included page could not be found.

General Troubleshooting

 Where can i find the latest HUB release notes?
 Performance: HUB loading is slow
 What is TTI's security posture information?
 Can't generate reports?
 Case header Overview

Case-Header

The case header directive is used in all widgets that have the ability to save the inputs, and results, of analyses in the HUBPL (excludes Map, Database Import, Ad-Hoc Analysis, etc .).

The case header directive governs the portion of the widget where a user can:

  • Name/rename cases

  • Save/delete cases

  • Create new case

  • Toggle unit preference (between metric & US Field)

    • For this widget, this session only, or

    • For this widget, save new default units

      • Note that unit preferences can be adjusted for the entire platform in the User Preferences interface

  • Share a case or keep it private

  • See who created a case

  • See who modified a case, and when

  • Download data to excel

  • Execute the calculation

  • Generate reports

  • Assign a case to a project Case Header

  • Create a new project

 

  • Upload images and/or PDF’s for inclusion in reports

    • Part of Report Builder

  • Add geolocation data

    • Manually by typing latitude and longitude inputs, or

    • By selecting a point on the Map

  • Associate the calculation to an entity in the asset database

    • By selecting an entity in the Navigator

    • By selecting an entity in the Map

  • Add other notes and other contextual information, like location description and date

  • Record time spent working in the widget

    • Part of Encroachment Manager

  • View metal loss profiles loaded from ILI, RSTRENG, or Investigative Dig PowerTool

    • Part of Encroachment Manager

The case header directive can be expanded, or collapsed, per the user’s preference. In previous versions of Pipeline Toolbox, the free-text inputs in this section were the primary method for keeping track of the reason for the analysis, as well as for being able to find the case again.

 How to move HUB Database from one physical computer to another?

Create a backup (BACKPAC file) on the old computer using SQL Server management Studio (SSMS)

Step 1:

Download SQL Server management Studio (SSMS) Download SSMS

Step 2:

  1. Open SSMS

2. The window below will open

3. Connect to the desired SQL Server instance. In the ‘Object Explorer’ pane, right-click on the name of the desired database

 

4. Click on connect icon then “Connect to server” window will launch

 5. Fill the details and click connect

a.     Server Name :  .\HUBSERVER

b.     Authentication: SQL Server Authentication

c.      Login : sa

d.     Password :HUB@2018

 

6. Expand database node and right click on “UPDM_Test_1”

7. In the context menu, we select ‘Tasks’ and then ‘Export Data-tier Application’.

 

 

This launches an introduction page. This introduction page defines the summary and steps for this wizard. :

 

8. Click on Next button and then “Export settings” window will show then provide a location to store the backup file then click next

 

9. Click Finish on the summary window

10.  The Progress window below will be displayed

11.  It will take some time to complete the operation.

12.  Backup is done, click the close button

 

 

Step 2 Import database backup file

  1. Open installation path on new computer/laptop where you want to move the data to which is shown below 

C:\TechnicalToolBoxes\HUB\HubService\App_Data

 

2. Rename the old database file (HUB.bacpac) with a different name like :

 OLD_ HUB.bacpac

 

3. Then paste here the HUB.bacpac file form old computer to opened folder

C:\TechnicalToolBoxes\HUB\HubService\App_Data

 

4. Delete the new database that has created on new machine

 

5. Open command prompt and run the following commands

 

a.      sqlcmd -S .\HUBSERVER -U sa -P HUB@2018

b.     GO

c.      USE master;

d.     GOdrop database UPDM_TEST_1

e.      GO 

6. Now open the folder 

C:\TechnicalToolBoxes\HUB

And run the HUB.bat file as an administrator

 

 How do I import my old PLTB Desktop cases?

If you have old PLTB desktop data, please follow these steps below to import this into the cloud product.

 

To do this, please do the following on your local machine with PLTB-E desktop installed,:

 

  1. Go to an Explorer window and type in %appdata%

  2. Go into a folder below where there is something like Technical Toolboxes\APPLICATION

    1. Your file might also be located on your computer in a location like this: C:\Program Files (x86)\Technical Toolboxes\Pipeline Toolbox 2018 E

  3. There should be an .mdb file in this location.

 

In HUB cloud, please follow the steps:

  1. Go to Data Tools > db Import.

    1. Note: Per discussions with Sales, I’ve included this functionality on your license until the end of the month since you’re a legacy desktop user of PLTB coming to cloud.

  2. Select PLTB Desktop Database from your Select Data Type drop-down:

    1. Click Upload File (MDB)

  3. Select your file. 

  4. All your PLTB desktop cases should be loaded into the PLTB-G & PLTB-L modules on your cloud account of HUB.

PLTB Pipeline Crossing

 What are the best practice for Surface Load Mitigation measures?

METHOD

ADVANTAGES

DISADVANTAGES

Reduce the operating pressure of the pipeline.

Provides a direct reduction of the hoop stress due to internal pressure. This reduction allows for additional circumferential stress due to equipment loads

  • Reduces the beneficial effect of internal pressure on the pipe circumferential bending stresses due to fill and traffic loads.

  • Could reduce the overall capacity of the pipeline and therefore should not be considered as a long term fix.

Limit surface pressures under vehicles (e.g., using floatation tires or caterpillar tracks)

Spreads the surface load over a larger area and reduces the overall load to the pipe.

Depends on equipment. May not be possible or too costly to implement

Consider the beneficial effect of lateral soil restraint on circumferential stress

Has effect similar to pressure stiffening

Requires estimates of soil stiffness parameter, E’

Provide additional soil fill over the pipeline in the vicinity of the crossing

Reduces circumferential stresses due to traffic loads.

Increases circumferential stresses due to fill loads.

Deploy steel plates over the crossing

Easy to install.

Flexibility of steel plates can result in bending of the plate with a corresponding reduction in loaded footprint. Need to consider required thickness.

Deploy timber mats over the crossing area

Provides large loading footprint. Relatively easy to deploy.

Flexibility of timber mats can result in bending of the mats with a corresponding reduction in loaded footprint.

Construct a concrete slab with steel reinforcement over the crossing area

Provides large loading footprint. Slab can provide high bending stiffness

  • Relatively expensive.

  • Usually reserved for permanent crossings.

  • Slab limits access to pipeline for inspections and repairs.

Construct a short bridge crossing over the pipeline

Completely uncouples the traffic loading from the buried pipeline.

  • Requires construction of foundation structures.

  • Expensive to construct. Usually reserved for permanent crossings.

  • Bridge structure may limit access to pipeline for inspections and repairs.

Relocate the pipeline

Removes pipeline from loaded area.

  • Expensive to construct.

  • Usually considered only as a last resort.

Lower pipeline

Reduces circumferential stresses due to traffic loads.

  • Expensive to perform.

  • Usually considered only as a last resort.

 Validation checks in place for API 1102 - Pipeline Crossing Highway

Below are the list of validation checks we have incorporated in API 1102 - Pipeline Crossing Highway (Gas and Liquid)

Parameter 

Validation check

Operating Pressure

"Numerical value for operating pressure should be between 0 - 5000 [psi]."

Pipe Depth

"Numerical value for pipe depth should be between 3 - 10 [ft]."

Bored Diameter

"Numerical value for bored diameter should be between D and D + 6 [in] .  "

Operating Temperature

"Numerical value for operating temperature should be between -20 and 450 [deg F] . "

SMYS

"Numerical value for SMYS should be between 24,000 - 80,000 [psi]."

Outside Diameter

Numerical value for outside pipe diameter should be between 2 - 42 [in]. 

Wall Thickness

Numerical value for pipe wall thickness/outside pipe diameter ratio (tw/D) should be between 0.01 and 0.08!

Wall Thickness

Pipe wall thickness can not be less then 2.03 [mm] for pipes with outside diameter less or equal 185.75 [mm] ", 

Wall Thickness

Maximum pipe wall thickness can not be greater than 39.7 [mm] for pipes with outside diameter equal or greater then 355.6 [mm]. 

Wall Thickness

Insufficent pipe wall thickness for given operating conditions. In accordance with CFR 192 minimum required wall thickness should be XX inch and currently wall thickness is ** inch 

Installation Temperature

Numerical value for Installation temperature should be between -20 and 450 [deg F] .

 

 

 Validation checks in place for API 1102 - Pipeline Crossing Railroad

Below are the list of validation checks we have incorporated in API 1102 - Pipeline Crossing Highway (Gas and Liquid)

Parameter 

Validation check

Operating Pressure

"Numerical value for operating pressure should be between 0 - 5000 [psi]."

Pipe Depth

"Numerical value for pipe depth should be between 6 - 14 [ft]."

Bored Diameter

"Numerical value for bored diameter should be between D and D + 6 [in] .  "

Operating Temperature

"Numerical value for operating temperature should be between -20 and 450 [deg F] . "

SMYS

"Numerical value for SMYS should be between 24,000 - 80,000 [psi]."

Outside Diameter

Numerical value for outside pipe diameter should be between 2 - 42 [in]. 

Wall Thickness

Numerical value for pipe wall thickness/outside pipe diameter ratio (tw/D) should be between 0.01 and 0.08!

Wall Thickness

Pipe wall thickness can not be less then 2.03 [mm] for pipes with outside diameter less or equal 185.75 [mm] ", 

Wall Thickness

Maximum pipe wall thickness can not be greater than 39.7 [mm] for pipes with outside diameter equal or greater then 355.6 [mm]. 

Wall Thickness

Insufficent pipe wall thickness for given operating conditions. In accordance with CFR 192 minimum required wall thickness should be XX inch and currently wall thickness is ** inch 

Installation Temperature

Numerical value for Installation temperature should be between -20 and 450 [deg F] .

 

 

 Crossings with Casings

Today, casings are used primarily on railroads and specific highways such as toll roads.  The casing like the carrier pipe must be designed to withstand concentrated loads, loading, stresses, and must comply with minimum Federal Safety Standards.  Therefore, a cased crossing must be able take the superimposed loads, not the carrier pipe.  A casing is designed to protect the carrier pipe against strain and external loading.

Example, this is one of the reasons why a casing needs to be at least 6” greater in diameter than the carrier pipe.  Otherwise, the pipeline and casing can metallically short  in the middle or ends.  Using a 4” diameter difference can result in metal-to-metal contact of the carrier pipe and casing touching each other permanently or intermittently based on the loads.  Electrical and mechanical isolation between the carrier pipe and casing must be taken to minimize the likelihood to reduce the risk of corrosion and stress issues.

There are other issues with casings such a thinner wall thickness than the carrier pipe, spacers, end seals, etc.

  • Carrier pipe should conform to ASME B31.8

  • Casing pipe should be a minimum of two nominal pipe sizes than the carrier pipe whereas this can be a problem when casing is greater than 50 feet.

  • Consideration should be given for 3 pipe diameters or 6 inches  to avoid installation issues such as:

    • Spacers

    • End Seals

    • Thickness of Coating Layers

    • Insertion of Carrier Pipe through Casing Pipe

    • Heavy Wall Thickness to reduce the Internal Diameter of the Casing Pipe

 

Below is a typical schematic of Cased Crossing with a Carrier Pipe:

 Trench/Ditch Width for Wheel Load Analysis

A newly constructed pipeline trench width is typically excavated to a minimum width of 305 mm (12 inches) greater than the outside diameter of the pipe.

Trench Width is based on many factors:

  • Compaction of the soil

  • Type of Soil

  • Moisture Content of Soil

  • Uniform Support Underneath Pipeline i.e., Bedding

  • Depth of Cover (DOC)

  • Years pipeline has been in service

  • Overbends and Sags

  • Horizontal Bends – Point of Intersections (PIs)

Note: There are rules of thumb that most US pipeline operators use for determining trench width regarding Wheel Load Analysis and other Crossing applications.

  • Newly installed pipe trench less than 5 years - original trench width at bottom

  • 305 mm (12 inches) each side of the outside diameter of the pipeline

  • Compacted backfill after 5 years - diameter plus 100 mm (4 inches)

  • Bored pipelines - diameter plus 50 mm (2 inches)

 Difference between “Operating Weight” in Track Load Analysis and “concentrated surface load” in Wheel Load?
 Option to add "Steel Plates" in Top Layers/Pavement Type & Material is missing

Technical Toolboxes does not show a factor for steel plating for the following concerns.

  • Steel plates are flexible and can slide around when construction equipment is driven over them.

  • Ends of steel plates can turn up from equipment.

  • There is no independent testing organization that has validated them to date.

  • ASME, API, PRCI does not have any specific information on them.

PLTB - Pipeline Testing

 Differences between the semiempirical blowdown calculation and the AGA blowdown calculation. When to use one over the other?

Due to the complexities and geometries of each blowdown piping system, recommending which method is better is difficult. These calculations can require dynamic calculations which are not provided in this AGA paper. It is impossible to generalize these conditions.

The document below provides more detail on the subject.

PLTB Pipeline Facilities

 What are the validation checks for Reinforcement of Welded Branch Connection - ASME B31.8 ?

Below table highlights the list of validation checks that are in effect in the PLTB Gas > Pipeline Facilities> Reinforcement of Welded Branch Connection - ASME B31.8 calculation.

Validation Check

Parameter

Message

Condition check

t - Required Wall Thickness Header

Inadequate Wall Thickness or Provided area is smaller than required area, reinforcement is not acceptable.

Nominal Wall thickness of the Header < Required Wall Thickness of the Header 

(H - t) - Excess Thickness in the Header Wall

Provided area is smaller than required area, reinforcement is not acceptable.

Excess Thickness in the Header Wall  < 0

AR - Reinforcement Required

Provided area is smaller than required area, reinforcement is not acceptable.

Reinforcement Required < 0

A1 - Reinforcement Provided

Provided area is smaller than required area, reinforcement is not acceptable.

Reinforcement Provided < 0

A2 - Effective Area in Branch/Outlet

Provided area is smaller than required area, reinforcement is not acceptable.

Effective Area in Branch/Outlet < 0

A3 - REQUIRED AREA

Provided area is smaller than required area, reinforcement is not acceptable.

 REQUIRED AREA < 0

AP - PROVIDED AREA

Provided area is smaller than required area, reinforcement is not acceptable.

PROVIDED AREA < 0

Disclaimer: All validation checks are placed in accordance with ASME B 31.8

PLTB – PipeBlast

 Estimating Equivalent Release Values – PipeBlast

Most chemical explosives have close to the same energy release per unit weight (We). If the explosive being used in a blasting situation is not known, the prediction equations can be used substituting a “typical” value for (We).

 Average energy release values for several commercial explosives are shown in the table 1 below.

Table 1 – Weight (We)

The quantity n is a measure of the relative energy ratio among the explosives. Using the energy release of ANFO (94/6) as the base, all explosive energies are normalized to determine the value of n.

 

N = 1.0 for ANFO

 Thus, ‘for ANFO (94/6), n equals 1.00. Those explosives more energetic have a value of n greater than 1.00 and those less energetic have a value of n less than 1.00. 

A list of equivalent energy release ratios is shown in table 2 below. It should be noted that Dyno Nobel is the primary manufacturer of most explosives in the Western World countries including older names brands that still may exist today.  The Chinese make up the remainder for Eastern World countries.

 

  Table 2 Equivalent Release Ratio (n)

 

                         Explosive                                                 n

Using a Dyno Nobel  Unimax Specification Sheet as shown below, the following Relative Weight Strength can be used to simulate (n) where the above values are not shown.

 

PRCI OBS

 Does PRCI OBS software have a water depth limitation?

In the PRCI OBS V3.0, the software could not receive water depths less than 6m.

In the PRCI OBS V4.0, this restriction has been removed and users can input any water depth. However, the applied theory has not been revised is still based on linear wave theory.

Therefore, it is the users' responsibility to ensure that ratio between the inputted wave data at the given water depth does not exhibit very nonlinear / breaking wave scenario.

The software performs a cursory check for the wave breaking limit and if the input wave is breaking, it returns an error, and the user should change the wave height and period in order to exit from the wave breaking zone.

The shallow water theory in being implemented in the software and would be included in the future releases of the software.

 Can OBS be used for HDPE pipe?

Except for the Level 3, the software can be used for stability assessment of HDPE pipes.

The level 3 uses a beam-element type of finite element approach that takes the stiffness of the pipe into account. However, the software has only been applied to steel pipes and no validation has been conducted on using Level 3 for analysis of flexible pipes.

Therefore, it is not recommended to use Level 3 at this stage.

 What is the current velocity referenced to in Level 3?

The reference level for current input in Level 3 is the elevation of the top of the pipe, including any coatings, and assuming no embedment.

The theory used to convert specified currents to the elevation of the top of pipe is at the discretion of the user.

AC Mitigation

 AC Mitigation – Barnes Layers Soil Resistivity Practices

Barnes layer data are set up to represent the bulk soil multiple layers for the pipe/corrosive layer, deep/apparent layer (steady state and inductive fault), and conductive/surface layer (conductive fault).  Other considerations include:

  • Where soil resistivity are not deep and change i.e., from deep tower footing grounds compared to the shallower pipeline trench, faults may stress the coating.

    • Where these conditions exist, running multiple scenarios at the fault tower(s) are needed for to assess for various depths. 

  • Example, using the Barnes Layer in areas where there are deep HDD crossings.  Adjustment to the calculations may be needed to accommodate these depths for more accurate assessment of these layers.

  • In HDD crossings, it should be noted that drilling muds contain bentonite clays that have extremely low resistivity values in the range of 100 ohm-cm.  The soil resistivity equipment may, or in most cases may not detect this narrow layer of the drilling muds around the pipe.

    • If the backfill is typical soils, the drilling muds will migrate into the soil after several years.

    • If the backfill is in granite or similar rock, the muds may remain in place for many years.

  • Deep Layer (Apparent)

This layer is used to get the most accurate results with a minimum of a 100-foot depth or 30.5  meters.  This layer is used to assess Inductive Faults and Steady State inductive voltages. 

Note:  It has been reported that many practitioners use the common CP type soil resistivity meter readings with the calibrated 5’ intervals wiring that is limited to 20’ that matches the 20’ deep ground rods on towers.  These data may be useful where resistivity readings are low (<1000 ohm-cm) and there are slight changes in other layers.

  •  Pipe Layer (Barnes/Corrosive)

This layer should always be around the depth of the pipeline.  Typical depths run from 3 to 6 feet or 1 to 2 meters except for HDD crossings.  It is also used to calculate the current density of amps/m2.

  • Conductive Resistivity Layer (Surface)

This layer should always be the top surface layer.  Typical depths run from surface to 10 feet or 3 meters.  It used to calculate conductive faults, step/touch potentials and surface potentials or ground potential rise.

 

Note:  Barnes Layers - Below is a schematic of these three (3) major layers to consider bulk and specific layer resistivity.  Any of these layers can be varied in depth based on the geo layering and resistivity layers related to pipeline depth. 

NACE/AMPP - Excel Spreadsheet(s) are typically used to calculate these multiple layers. 

Schematic of Barnes Multi-Layers Soil Resistivity for AC Modeling and Mitigation

 AC Mitigation – Barnes Layers Soil Resistivity Practices

Barnes layer data are set up to represent the bulk soil multiple layers for the pipe/corrosive layer, deep/apparent layer (steady state and inductive fault), and conductive/surface layer (conductive fault).  Other considerations include:

  • Where soil resistivity are not deep and change i.e., from deep tower footing grounds compared to the shallower pipeline trench, faults may stress the coating.

    • Where these conditions exist, running multiple scenarios at the fault tower(s) are needed for to assess for various depths. 

  • Example, using the Barnes Layer in areas where there are deep HDD crossings.  Adjustment to the calculations may be needed to accommodate these depths for more accurate assessment of these layers.

  • In HDD crossings, it should be noted that drilling muds contain bentonite clays that have extremely low resistivity values in the range of 100 ohm-cm.  The soil resistivity equipment may, or in most cases may not detect this narrow layer of the drilling muds around the pipe.

    • If the backfill is typical soils, the drilling muds will migrate into the soil after several years.

    • If the backfill is in granite or similar rock, the muds may remain in place for many years.

  • Deep Layer (Apparent)

    • This layer is used to get the most accurate results with a minimum of a 100-foot depth or 30.5  meters.  This layer is used to assess Inductive Faults and Steady State inductive voltages. 

    • Note:  It has been reported that many practitioners use the common CP type soil resistivity meter readings with the calibrated 5’ intervals wiring that is limited to 20’ that matches the 20’ deep ground rods on towers.  These data may be useful where resistivity readings are low (<1000 ohm-cm) and there are slight changes in other layers.

  •  Pipe Layer (Barnes/Corrosive)

    • This layer should always be around the depth of the pipeline.  Typical depths run from 3 to 6 feet or 1 to 2 meters except for HDD crossings.  It is also used to calculate the current density of amps/m2.

  • Conductive Resistivity Layer (Surface)

    • This layer should always be the top surface layer.  Typical depths run from surface to 10 feet or 3 meters.  It used to calculate conductive faults, step/touch potentials and surface potentials or ground potential rise.

 

Note:  Barnes Layers - Below is a schematic of these three (3) major layers to consider bulk and specific layer resistivity.  Any of these layers can be varied in depth based on the geo layering and resistivity layers related to pipeline depth. 

NACE/AMPP - Excel Spreadsheet(s) are typically used to calculate these multiple layers. 

Schematic of Barnes Multi-Layers Soil Resistivity for AC Modeling and Mitigation

 ACPT Fault - Why the differences in All versus the Closest Tower

When pipelines are in the proximity of a power line, it is subject to induced or conductive  effects depending upon the operational status of the power line. When a phase wire carries an electrical load, a magnetic field is produced around the wire which links the coated pipe. This mutual effect causes AC voltage and current to be induced into a parallel pipeline.

During a lightning strike or episodic upset, the AC power line will experience a short circuit condition i.e., fault. During the fault period which can last from micro to milliseconds to several seconds, the power system becomes unbalanced. One phase wire carries a much larger current than the others which may be up to 30 times or more than that carried in normal operation.  From this unbalance, the magnetic induction may increase from several hundred to a thousand times induced voltage levels.

During a fault, the current flows into the ground at the faulted and through the shield wires to the adjacent towers. This ground current flow adds an additional (conduction) component of voltage to that produced because of the magnetic field (induction). If the current is sufficiently large, a direct arc between the closest tower leg and the pipeline may be initiated which could lead to coating or pipeline puncture.

 ACPT Fault Voltage and Current program models both:

  • Inductive coupling

  • Conductive or resistive coupling including arching to the pipeline (Closest Distance)

Most faults are due to inductive coupling which produce peaks at pipeline locations where physical or electrical discontinuities occur.  This can occur at any tower along the right of way.  Since the magnitude of the induced voltage peak is location dependent, all faults at each tower must be analyzed at fault exposure.  High peak induced voltage levels may result in several locations.

The ACPT program allows the user to check the All box to get an initial picture of these locations for mitigation. Under the Pipeline Tab, Select Full Section determine the closest distance (Section Number)  to a tower and compare results.  Rerun again to determine the effects of these towers.  For more accurate results, it is recommended to run several towers to determine earth/ground average resistance in these identified areas of concern. 

The appropriate mitigation should be used for both induced steady state and fault conditions.

  • Voltage peaks – Discrete Anodes

  • Large voltage peak sections – Parallel wire such as copper grounding 

Complex collocated pipeline and powerline systems require an iterative process that engineering judgement and experience is required.  It usually takes one or two mitigation design changes to achieve the desired cost-effective results. 

 ACPT - SS: Discrete Ground Using Vertical/Horizontal Anodes, Casings, and Isolating Joints with De-Couplers

Pipeline grounding for mitigation typically uses discrete or deep anodes to reduce induced individual voltage peaks.  If induced voltage levels for steady state or fault conditions exceed industry acceptable levels, AC mitigation grounding implementation is required.

AC mitigation analysis is used to determine induced voltage reduction for grounding systems that consist of an individual discrete grounding such as horizontal buried conductors or vertical deep anodes.  In addition, these grounding systems could consist of existing pipeline components such as:

Casings

  • Electrically isolated with individual decouplers

  • Electrically or mechanically shorted – Decouplers not required

Isolating flanges to stations with electrically grounded piping

  • Electrically isolated with individual decoupler

  • Electrically or mechanical shorted – Decouplers not required

Vertical or horizontal anodes

  • Deep vertical anode

  • Horizontal remote anode(s) 

It should be noted when casings and isolating flanges are mechanically and or electrically shorted to ground, the Discrete Ground box should be checked in the Mitigation Tab of the AC Mitigation program.  To determine resistance to ground of the casing or the station, use the AMPP/NACE remote ground techniques to measure this resistance to earth.

Note:  To reduce larger sections of induced voltages, distributed systems such as vertical or horizontal anode strings and parallel continuous horizontal copper cable or zinc can be used with properly spaced decouplers to the pipeline(s),

 Calibrate AC SS Induced AC Voltages Using Coating Resistance

Understanding Coating Resistance

Before calibrating the modeled induced AC voltages, an understanding of coating resistance quality is needed. The question comes up is are there a rule of thumb of values that can be used.  Yes and No, because the age, quality, or condition of the coating is one factor, whereas the soil resistivities are another to be considered.  When they are used together, then a more accurate assessment can be made.  How do initially assess coating quality:

·       Excellent (Typically Less than 2 years with no change in CP current demand)

·       Good (Typically greater than 2 years to 10 years and/or with minor change in CP current demand)

·       Fair (Typically where the CP current demand has a moderate change from original current requirement design)

·       Poor (Typically where the CP current demand has increased significantly with major coating deterioration and high CP demand).

Estimating Coating Resistance 

Four (4) parameters - pipe diameter, pipe depth, coating resistance, and coating thickness are required.. Coating resistance is the most subjective of all the parameters in that field measurements.  The resistance is a function of the coating quality, the average size of the coating holidays, the layer soil resistivity etc.  Guidelines for estimating average coating resistance are shown in the table below.

If more accurate coating resistance assessments are needed, it is recommended to run field tests for coating resistance or coating conductance.  These surveys are expensive and time consuming.  Also, see AMPP/NACE Conductance test methods “Measurement of Protective Coating Electrical Conductance on Underground Pipelines.”

Calibration of Coating Resistance 

Once the average coating resistance values have been established, calculate the induced steady state voltages, and compare them to several AC potential pipeline sites measured in the field.  It should be noted that the power loads (amps) on the AC power lines should be the same as in the ACPT calculations.  These values must be the same to adjust the coating resistance and to achieve comparable results in the field.  This is also a good check to align the data for more accurate results in modeling to the real world.

Design & Stress Analysis

 What is Maximum Span Length?

Regarding span factors with and without water are based on bending stress and deflection.  Larger diameter pipe spans require saddles for stability.   

Many standards that require pipes to be filled with water are based on bending and shear stresses not to exceed 1,500 psi and a deflection between supports not exceed 0.1 inches. 

Other factors to be considered are as follows:

  • Pipe is assumed to have standard W.T.

  • No concentrated loads i.e., valves

  • No changes of direction

  • Horizontal plane

  • Maximum deflection of span is limited 1 inch

  • Stress intensification factors of components not considered

The Pipeline Toolbox calculates the Hoop Stress, Maximum Allowable Bending Stress, Maximum Bending Moment, Maximum Span Length due to deflection with and without water using a factor of 10.  This statement was added to address the issues of deflection.

What value represents or what number to use

  • Deflection L/360 (Default) is the most conservative factor if related information is unknown.

  • Deflection L/270 is used when this information is known. Example residual stresses from construction activities are often present. These stresses are often difficult to evaluate accurately but can be disregarded in most cases. However, it is the engineer's responsibility to determine whether such stresses should be evaluated.

  • Deflection Other is used when other factors need to be applied.

  • Pipe Hydrotest will reduce the span length calculations due to the additional weight

  • Hydrostatic Deflection Factor is based on the pipe being exposed.

  • Hoop stress

  • Bending Moment

  • Length Bending

  • Length Deflection

  • Total Length of Span

Note:  Exposure to a failure of a buried pipe poses less consequence than from exposed piping.

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