Automated orbital welding systems streamline in-process inspections
Passing in-process inspections for orbital welding projects is critical, as a failure can lead to costly rework, project delays, and system downtime.
John Glessman, Swagelok Company
Today’s orbital welding systems employ a variety of automated features, such as data collection, programming, and live weld progress, which help welders complete more accurate, high-quality welds, and increase their likelihood of passing in-process inspections.
Even more importantly, automation also provides efficiencies for welders and inspectors when conducting those inspections.
Today’s orbital welding power supplies automatically record the majority of required welding data for projects, removing the burden of manual documentation from welders. The systems capture this data electronically for simple, error-free transfer to quality control administrators and third-party inspectors. Automated electronic data collection ensures that searchable quality assurance data is available to welders and inspectors so each party can conduct in-process inspections in an efficient manner.
Welders are typically required to maintain comprehensive data about each weld in a project—a cumbersome process that can easily account for 30% of a project’s total construction labor hours when performed manually. The data includes multiple parameters associated with each weld as required by the project and code specifications, such as ASME B31.3 for process piping and ASME Section 8 for pressure vessels. Data may include the welder’s certifications, materials used, location of the weld according to a weld map, and numerous other details.
Automated data collection captures all of this data with minimal operator input, allowing welders to focus on their primary job, which is to complete accurate, high-quality welds. To ensure complete data collection, some orbital welding power supplies highlight required data fields and do not permit welding to start until operators fill in all open fields. In addition, welders can provide documentation data electronically to quality control administrators for input into spreadsheets, which virtually eliminates the potential for human error during data transfer. Proper data transfer yields a higher probability of passing in-process inspections.
Electronic documentation data made available to third-party inspectors expedites their in-process inspections. As part of quality control procedures, inspectors may review project data, including weld logs and documentation packages, to confirm that the welding company provided all of the required information, the examinations were performed appropriately, and the project is free of errors. In an electronic format, this data is sortable and searchable, providing inspectors with valuable efficiency during their reviews.
Electronic documentation records also help inspectors locate data faster during in-process inspections compared to leafing through hard copy weld logs. If an inspector spots an error on a specific weld during a visual examination or physical test, he can quickly find information about that weld, as well as any welds performed during the same time period or under similar parameters, in the database. This efficiency is especially helpful given the varying documentation and in-process inspection requirements set forth by industries, applications, and owner companies.
For example, welding projects in biopharmaceutical manufacturing plants typically require visual examination of every weld. Welders must visually check the outside diameter (OD) of welds and record this information—sometimes along with a video or image file. An inspector will use a borescope to examine the inside diameter (ID) of a specified percentage of welds in a system. With welds chosen randomly for examination, inspectors can quickly search electronic records to locate specific welds and their corresponding data.
Inspectors can also perform nondestructive tests on welds, including one or more of the following:
- Dye Penetrant Test (PT): A dye penetrant is applied to the OD of the weld bead, excess penetrant is removed, and a developer is applied. Any remaining dye penetrant is a visual indication of a surface flaw such as porosity or a crack.
- Radiographic Testing (RT): X-rays or gamma rays produce images on a film used to detect internal discontinuities of the weld. After the radiograph is taken, an inspector examines the film for signs of lack of fusion, voids, or cracks by looking for light or dark areas, or irregular shapes and variation.
- Ultrasonic Testing (UT): A probe transmits an ultrasonic signal into the weld surface, and the resulting reflection of that signal is displayed on a monitor. Operators watch the monitor to look for any imperfections within the weld, such as porosity, voids, or cracks.
Specifications often dictate what is or is not acceptable. If a weld fails a test, the inspector may search the electronic database to find all welds performed during the same period and review their parameters. Next, he may perform additional testing on those welds and potentially recommend rebuilding that portion of a system.
In some cases, welding jobs require intermediate in-process inspections at specific project milestones. In these cases, data automatically stored on the welding power supply may streamline the inspection and enable the welder to get back to welding sooner. For example, a particular code case for a nuclear project requires inspectors to examine the welding process every 4 hours.
Welders may be working on a section of tubing and literally have to stop when the 4-hour window expires. An inspector will then verify that the welds meet the inspection criteria and code requirements before the welder can resume working. Power supply data and alarm settings can assist with the isolation and troubleshooting of any weld in question.
In some industries and applications, in-process inspections may not focus on every weld. Instead, inspectors may check documentation data to confirm the consistent operation of the orbital welding power supply. Before completing actual project welds, welders will “coupon in” by performing a destructive test with a sample tubing section and examining it against specifications. This test becomes part of the searchable electronic weld log and serves as a baseline for subsequent welds.
These welds may also undergo tensile or bend testing as part of the qualification process. If the test weld meets quality standards, the welder can use the established weld schedule and process to continue welding the same materials before couponing out after a specified time limit or number of welds, or when an essential variable is changed. The interval between couponing in and out presents a verified time frame in which all welds should meet specifications, provided the last weld is as sound as the first.
By reducing manual requirements and instances of human error, even more automated features on today’s orbital welding power supplies improve the likelihood that welders will create successful, high-quality welds that will pass in-process inspections.
For example, newer orbital welding power supplies provide complete, automated control of both purge and shield gas. Purge gas controls help maintain proper ID pressure at the weld joint, while shield gas controls protect the weld bead from atmospheric contamination on the OD of the weld. Utilizing an integral mass flow controller, these systems adjust gas flow automatically based on the weld program. Rather than an operator manually controlling gas flow for each weld, which introduces variability, automatic controls adjust gas flow accurately throughout the welding process for consistent, high-quality welds.
In addition, some power supplies present detailed live weld progress data to help operators better evaluate welds. Graphics show the progression, performance levels, and stop/start for each level of a weld in real-time. If the weld deviates from the selected schedule, the graphic will indicate points where those variations occurred so the operator can evaluate the weld after completion. This feature enables welders to make efficient adjustments to improve weld quality.
Through in-process inspections, both welders and inspectors have their eyes on accuracy, quality, and completeness to minimize the potential of placing systems with flawed welds into service. By leveraging automated orbital welding power supply features, welders enhance their ability to create accurate, high-quality welds, while also improving their efficiency in collecting documentation data.
Ultimately, these automated features improve the likelihood of passing in-process inspections and creating leak-tight final systems.