Common Covered Task 408OP Inspect Cathodic Protection Rectifier

Transcription

1 Common Covered Task 408OP Inspect Cathodic Protection Rectifier Directions This training guide is to be used by a Veriforce Authorized Evaluator/Trainer and Trainee during on-thejob training (OJT) or prior to an evaluation as a resource. (S) Indicates a demonstration or skill task; (K) indicates a knowledge task. OJT Reminder OJT is an active hands-on process. Practice should be as similar to the actual job task as possible. However, if the training is being provided on an actual job site while a covered task is actually being performed, the Evaluator either needs to be qualified on that covered task or be assisted by someone who is qualified on the covered task. The Evaluator should closely monitor the Trainee's practices to ensure safe and correct task performance. At no time should a non-qualified individual perform, or train for, a covered task unless directed and observed by a qualified individual. However, if the span of control for that particular covered task is 1:0 (requiring only qualified individuals to perform the covered task), the training must be simulated. Training is simulated by "walking through" the task and simulating all actual manipulations (valves, switches, tools, etc.) an individual would use during the performance of a covered task. Simulating includes the use of safety and administrative requirements as if the task were being performed live. Refer to the Veriforce Evaluator Training Program for more on how to conduct formal OJT. Disclaimer This training resource is offered in good faith. Anyone choosing to utilize or rely on this training resource is doing so at their own discretion, risk and choice. Although every attempt has been made by Veriforce, LLC (the Company ) to ensure the correctness and suitability of this document and to correct any errors brought to the attention of the Company, the Company makes no representation or warranty regarding correctness or suitability (either directly or indirectly) of information referenced or implied within this training resource. In no event shall the Company be liable for any damages (including, but not limited to, special, incidental or consequential damages) whatsoever (including, but not limited to, death, personal injury, damage to person or property, loss of use, and/or loss of revenues), whether in an action of contract, negligence, or other action, arising out of or in any way associated with the use or misuse of this document. All critical information should be independently verified by the user and the user shall not rely on the contents provided herein without such independent verification. The subject matter included in this training has been compiled from a variety of sources and is subject to change without notice. The Company reserves the right to add, remove and alter information contained in this document without notice. The Company may provide links to other sites for your convenience; however, the Company takes no responsibility and makes no representation or warranty regarding the accuracy or currency of information contained within such sites. The Company does not endorse any information, goods, or services referred to within such sites, and the provision of links by the Company shall not be interpreted to be an endorsement of such information, goods or services. The content of this training resource is provided for personal use only, and all other use, copying or reproduction of this training or website or any part of it is prohibited. Page 1 of 7 Copyright 2019 Veriforce, LLC. All rights reserved. Rev. # 6 03/06/2019

2 Common Covered Task 408OP Inspect Cathodic Protection Rectifier Recommended Student Training or Resources: (b) (c) Introduction Rectifiers are the most frequently used power source for impressed current cathodic protection systems. Impressed current cathodic protection systems use the following components: A reliable power source A rectifier An anode This is the sacrificial element of an electrochemical cell consumed in the corrosion process. A cathode This is a metal surface, such as the pipeline. A metallic path between the anode & the cathode An electrolytic path This could be soil or water in this example. Rectifiers change alternating current (AC) power to the proper direct current (DC) power level. Providing the correct amount of DC power is an important part of ensuring appropriate cathodic protection. A rectifier that is providing too much DC power could cause coating damage, while a rectifier that is providing too little DC power may not provide adequate cathodic protection for the system. Therefore, it is crucial to inspect rectifiers to ensure they are operating as intended. According to 49 CFR (b) and 49 CFR (c), Each cathodic protection rectifier or other impressed current power source must be inspected six times each calendar year, but with intervals not exceeding months, to ensure that it is operating. Knowledge: Explain what is required prior to performing this task. Prior to performing this task, you will need to have the pipeline operator-approved procedures as well as the appropriate equipment and materials. The procedures will outline requirements for performing this task that are specific to the pipeline operator. Operators may also have specific requirements regarding the type of equipment that can be used to perform this task. Therefore, it s important to follow the specific requirements of the procedures and only use operatorapproved equipment. Doing so can ensure the task is performed correctly and according to the pipeline operator s standards. Page 2 of 7 Copyright 2019 Veriforce, LLC. All rights reserved. Rev. # 6 03/06/2019

3 Skill: Perform visual inspection of rectifier. In this objective, we ll discuss performing a visual inspection of the rectifier to check if there are any potential issues. Visual inspection is often the first sign that something could be wrong or potentially hazardous. Remember to always follow your pipeline operator-approved procedures while performing this task. You should check that the rectifier is properly mounted and level. Ensure that all connecting bolts are tight and secure. Check to make sure there isn t a rectifier support failure or that the support pole is damaged. Look for evidence of tampering such as a broken lock or scrapes along the edges where someone may have tried to pry the case open. Check the external wiring connections to ensure they are proper and tight. Make sure the AC input wiring isn t loose and that a proper ground connection is in place. Look for burn marks on the rectifier that may indicate damage from lightning or fire. You may also notice melted or charred marks. Inspect for insects, pests, varmints, or other creatures that may have taken up home or shelter in the rectifier cabinet. These can block airflow and also pose a potential hazard to you. Check that proper security is in place. Rectifiers should be locked in accordance with the pipeline operator approved procedures to protect against tampering or shock. Ensure that high voltage signage and markings are visible due to the high voltage present in rectifiers. If you notice something that fails visual inspection, consult your pipeline operator-approved procedures for information on the proper corrective measures. Knowledge: Explain techniques that may be used to determine if the rectifier case is energized with AC and DC voltage. Due to the electrical hazards present in rectifiers, it s important to ensure that the case isn t energized prior to performing work or testing the rectifier. If the case is energized, this indicates there is a problem. In this objective, we ll look at techniques that may be used to determine if the rectifier case is energized with AC or DC voltage. Remember to always follow your pipeline operator-approved procedures while performing this task. When using electronic testing devices, it s important to verify calibration and ensure that your device is in good working order. Checking the case with a faulty or non-calibrated device could lead to a false reading and potential electrical shock. Always follow the manufacturer s instructions for the device you are using. To check that the case is not hot, you can take an AC voltage-to-ground measurement with a portable meter (e.g. voltmeter or multimeter). For example, with a multimeter set to millivolts, connect the black lead to the ground and the red lead to the rectifier case and take a reading. Refer to your procedures to determine what voltage is appropriate. Page 3 of 7 Copyright 2019 Veriforce, LLC. All rights reserved. Rev. # 6 03/06/2019

4 There are various voltage testers that will alert you with flashing, beeping, and/or a general reading in the presence of an energized or hot connection. Some models have leads that you will need to connect in the same way as a voltmeter. Some of the newer models are contactless and allow you to hold the tip of the detector up to the case and press a button. If the tester flashes, beeps, or otherwise indicates voltage, exercise caution as this would indicate the cabinet is hot. Caution: Placing the back of your hand up to the rectifier case to determine if it is energized is usually not recommended. Grabbing an energized case with your fingers could cause your hand to clench from the current and not let go. Skill: Describe and demonstrate steps for testing/inspecting rectifier for proper operation. The task of inspecting a cathodic protection rectifier can be broken into three main steps. Verify the calibration of the meter or data logger. Check the rectifier cabinet for electrical shorts. Verify and interpret output of DC voltage and DC current using an appropriate instrument. Verify calibration of meter/data logger. To maintain the proper operation of the cathodic protection, the system s current and voltage need to be checked regularly. There are many different types of equipment that are used to take the current and voltage readings from the rectifier. The two most commonly used are: Digital voltmeters Data loggers Digital voltmeters are the most commonly used meters in comparison to data loggers. Digital voltmeters can handle AC voltage, DC voltage, and resistance measurements as well as many other functions. Data loggers are also used to take voltage and current readings, but unlike digital voltmeters, data loggers can gather GPS coordinates and store the collected data. All precision equipment needs to be calibrated and certified. For optimum accuracy, only use meters that have been calibrated and certified by the manufacturer. Meters should be recalibrated annually if damage occurs or if the meter reliability is in question. All meters should have a calibration sticker attached to them or documentation available stating the calibration specifics. Check rectifier cabinet for electrical shorts. Note: Any task that involves electricity is extremely dangerous and has a unique set of hazards associated with it. Therefore, you will need to utilize recognized industry safety best practices, proper personal protective equipment (PPE), and pipeline operator s policies and procedures to help ensure your safety. Before opening the rectifier cabinet, it needs to be checked for electrical shorts. Page 4 of 7 Copyright 2019 Veriforce, LLC. All rights reserved. Rev. # 6 03/06/2019

5 When checking for voltage with a digital voltmeter, attach the black probe to the ground rod and connect the red probe to various locations on the enclosure that will be touched by hand. Read the meter for any voltage potentials. Some other ways to ensure there are no potential shorting issues with the rectifier include the following: Looking - Look for signs of hot spots on the rectifier and loose wires. Smelling - Stand downwind of the rectifier and try to detect any odors of burned insulation or other materials. Selenium and other semiconductors smell like rotten eggs when burned. Listening - Listen around the rectifier for sounds of arcing, static, or frying. If a short is suspected, determine the power source. If the power source is a distribution transformer bank, contact the appropriate personnel to shut off the power. Contractors not authorized and/or not qualified to work on distribution transformers should notify the pipeline operator representative immediately. Once you have verified that the rectifier does not have any electrical shorts, you can open the rectifier enclosure and inspect the inside for any abnormal conditions. Some of the items to look for include: Signs of overheating or arcing Damaged components and wires Blown transient devices Loose ground wires Verify/Interpret output DC voltage and DC output current. The DC output voltage should be evaluated to determine if the rectifier is running properly and efficiently. Utilize the following steps when measuring the DC output voltage of the rectifier: Measure the DC output voltage across each anode s positive terminal and the structure s negative terminal. Verify the measured voltage is approximately equal to the voltage indicated on the rectifier voltmeter. Just as the DC output voltage should be evaluated, so should the DC output current. To measure the DC output current, the meter is connected across a known precision resistor called a shunt. In order to verify the current reading indicated by the rectifier ammeter, a digital voltmeter is used to measure the millivolt potential across the shunt. The reading is then multiplied by the shunt factor to calculate the DC output current of the rectifier. The shunt factor is calculated by dividing the amp rating of the shunt by the millivolt rating of the shunt. To calculate the shunt factor, use the following formula: amp rating/millivolt rating = shunt factor. For example, if you have an amp rating of 50 and a millivolt rating of 50, your shunt factor will be 1. The DC output current is calculated by multiplying the shunt factor and the millivolt reading from the digital voltmeter. Calculate the DC output current by using this formula: shunt factor x digital voltmeter reading (millivolt reading) = DC output current (amps). For example, if you have a shunt factor rating of.5 and a digital voltmeter reading of 30 millivolt, your DC output current will be 15 amps. Page 5 of 7 Copyright 2019 Veriforce, LLC. All rights reserved. Rev. # 6 03/06/2019

6 Another common tool used to measure the DC output current is the clamp meter. The clamp meter is connected around a DC output current cable within the rectifier to gather accurate readings. The final step of the inspection is to compare the rectifier output readings with readings from previous inspections. If there are significant changes in the rectifier DC output current readings, contact a qualified specialist to report a possible change in the system and/or the system environment. Contractors should contact the pipeline operator representative to report a possible change in the system and/or system environment. Abnormal Operating Conditions (AOCs) Candidates are required to possess the ability to RECOGNIZE and REACT to the listed AOCs for each task. Be prepared to answer questions concerning additional AOCs that may be relevant. Evaluators may ask questions about AOCs throughout the evaluation. An AOC is defined in 49 CFR and as: A condition identified by the pipeline operator that may indicate a malfunction of a component or deviation from normal operations that may: Indicate a condition exceeding design limits; or Result in a hazard(s) to persons, property, or the environment. Recognize: Unintentional releases, vapors, or hazardous atmosphere could be signs that an abnormal operating condition has occurred. Examples could include, but are not limited to: Blowing gas Puddles Dead vegetation React/Respond: Proper reactions and/or responses to take in the event of an unintentional release, vapors, or hazardous atmosphere include the following: Eliminate potential ignition sources. Move to a safe location. Notify emergency response personnel, as appropriate. Limit access to the location, as necessary. Follow appropriate procedures for notification, documentation, and remedial action. Recognize: Material defects, anomalies, or physical damage of pipe or a component that have impaired or are likely to impair the serviceability of the pipeline are abnormal operating conditions. Examples include, but are not limited to: Shorted rectifier case Vandalism Page 6 of 7 Copyright 2019 Veriforce, LLC. All rights reserved. Rev. # 6 03/06/2019

7 React/Respond: Proper reactions/responses to take in the event of material defects, anomalies, or physical damage of pipe or a component that have impaired or are likely to impair the serviceability of the pipeline include the following: Determine the extent, cause, and potential hazard(s) of the defect, anomaly, and/or damage. Mark the location so it may be easily located, as appropriate. Follow appropriate procedures for notification, documentation, and remedial action. Recognize: Failure or malfunction of pipeline component(s) is an abnormal operating condition. Examples could include, but are not limited to: Rectifier shows signs of being hit by lightning Rectifier support failure or support pole damaged Damaged rectifier internals Engine generator down Solar panel damage React/Respond: Proper reactions/responses to take in the event of a failure or malfunction of pipeline component(s) include the following: Determine the extent, cause, and potential hazard(s) of the failure and/or malfunction. Follow appropriate procedures for notification, documentation, and remedial action. Page 7 of 7 Copyright 2019 Veriforce, LLC. All rights reserved. Rev. # 6 03/06/2019