The Necessity of Bolted Flange Connection Training
There are numerous considerations for ensuring that a bolted flange connection (BFC) does not leak. They include damaged bolts and nuts, as well as flanges that are too far apart, misaligned or bent. Other issues involve sealing surface damage, improper lubrication, excessive piping loads, and excessive or insufficient bolt loads.
Additional considerations include debris on sealing surfaces, damaged gaskets, correct calibration and hookup of torque-limiting equipment, and proper tightening procedures.
Of these factors, nothing is as vital as the expertise of mechanics. No one is closer to the job or has a better opportunity to call out questionable conditions that can prevent a gasket from acquiring a successful sealing load.
Training ranges from on-site programs set up by company engineers to trial-and-error knowledge passed down from mechanic to mechanic. These educational avenues are valuable, but a complete training program that thoroughly covers the important topics related to successful installation of a gasket is rare.
Companies rarely can afford to commit the necessary resources to create and maintain an expert on this broad and detailed subject.
Given the numerous combinations of conditions, including the bolt-up procedure if one is used, that can prevent a perfectly good gasket from reliably sealing, how can someone know if a condition is acceptable? The connection must be tight enough to develop and retain a certain value of gasket stress but not so tight that damage results to any of the three primary flange components: gasket, flange and bolts. Installers need a complete understanding of the role and limits of the components so they can take suitable actions. A training program is available that provides all of this information.
The American Society of Mechanical Engineers (ASME) PCC-1-2013 document, Guidelines for Pressure Boundary Bolted Flange Joint Assembly, provides guidance on what conditions to look for and what actions to take as well as several time-tested tightening procedures. Unfortunately, it would be rare for a mechanic to have access to this information. Although this guidance is primarily intended for engineering resources, the first of several appendices are entirely dedicated to the training needs of mechanics, and many engineers would benefit greatly from such training. Additionally, it includes specific guidance on how to set up a training package and what should be included in it.
It was not until recently that a formal training program was developed that provides this information and results in an ASME Certificate of Completion that validates the training. In February 2016, ASME formally announced the launch of its Bolting Specialist Qualification Training Program.
Components of the Training Program
The training was the result of collaboration between members of an advisory group that collectively has more than 190 years of concentrated experience in preventing BFC leaks. These include mechanical engineers thoroughly grounded in the science of flanges, bolts and gaskets, as well as professional training resources.
The entire effort was managed by the oversight of ASME Training and Development. Its goal was to develop a comprehensive training program that would draw attention to the real-world practices and observations important to preventing leaks, as well as provide a clear understanding of why they are so important.
Forms of the Training Program
The training is provided in two forms: an online package and a one-day, hands-on session conducted by an ASME-approved technical professional. The online session is divided into four parts, which provide the majority of the training information. This form allows trainees to remain at their respective places of employment and proceed at their own pace. Graphics are extensively used to clarify concepts. At the end of each section, trainees can answer a series of true-or-false or multiple choice questions crafted to test a thorough understanding of the concepts. A passing score is required before moving on to the next part.
Part 1. Principles of Bolted Flange Joints & ASME PCC-1
This module provides a general introduction to the subject, focuses on the wide range of features important to the successful sealing and maintenance of bolted flange connections, and stresses the value of leak-free operation.
Part 2. Flanges, Fasteners & Gaskets
This section draws attention to the importance of understanding the role and limits of the three primary bolted connection components and how to identify mechanical flaws that can compromise the sealing of a connection. Central to this section is understanding how and why each of the three components interact with one another.
Part 3. Putting it Together/Taking it Apart
Critical to the successful tightening of a bolted flange connection is following an approved tightening procedure. As the temperature and pressure of a connection rise, the range of successful bolt loads can become very narrow. This section focuses on how to get it right the first time. Most important, this portion explains how and why a tightening procedure works.
Part 4. Bolting Safety & Tool Handling
Large forces are always involved in the tightening of a BFC. Safety is always the top concern, and the proper handling and use of high-torque equipment is especially important.
Figures 1 and 2 display some key concepts to understand. Figure 1 introduces the force-distance relationship that develops a given value of torque.
Figure 2 explains the consequences of varying values of gasket stress, discusses the importance of understanding both lower and upper limits of tightening, and points out how a combination of high pressure and temperatures can narrow the range of safe sealing gasket stress.
The hands-on session, which becomes available upon the successful completion of all four parts, is conducted at a specialized training facility. A wide range of training equipment and power tools is available to demonstrate proper equipment setup and use.
The ASME Certificate of Completion signifies the trainee has demonstrated an understanding of the material. Maintenance personnel with the certificate will have a matured sense of expertise to bring to the field. Improvement is grounded in nderstanding, and this training is intended to provide it.
New dedicated automotive stud welding system provider created
A unique, dedicated supplier of stud welding systems to the global automotive sector has been created following the sale of the former Nelson Fastener Systems business by leading international component manufacturer Doncasters Group.
The automotive division of the business – now known as Nelson Automotive – has been retained by Doncasters as part of the Group´s focus and commitment to the global automotive sector. It will continue to supply the sector with the market-leading stud welding systems, service and consumables for which the Nelson name has become renowned worldwide.
Its global customer base already includes many of the leading OEMs and well as major Tier 1 suppliers, all of whom will continue to benefit from unparalleled levels of innovation and service.
Products will continue to be manufactured in Gevelsberg in Germany, where a dedicated team is focused on the development of the next generation of stud welding systems, pushing the boundaries of speed, performance and durability.
The company is at the forefront of innovation in the sector, with its SPEEDPORT feeding system enabling a single unit to weld more than 40,000 studs in a day. It also offers an extensive range of manual and automatic systems, as well as robotic weld heads for high production environments.
Nelson Automotive boasts global reach with a complete product portfolio backed up by outstanding local service. It enjoys strong synergies with other companies within Doncasters´ Speciality Automotive division.
A spokesman for the company commented: “Our systems are used by leading players in the automotive sector in Europe, Asia and the Americas, where our service-led approach and commitment to innovation sets us apart.
Remaining within Doncasters´ Specialty Automotive division give us access to extensive resources in the area of research & development, equipping us ideally to meet the challenges faced by automotive manufacturers seeking outstanding stud welding performance at best cost.
The future is very bright for the business and we look forward to extending existing partnerships as well as embarking on new ones, whether customers are seeking systems for new production facilities or as upgrades to existing plants.”
Routine maintenance is essential for the continued reliability of machinery, even when it is used infrequently. For a power station in Wales, the induced draft (ID) fan motors are scheduled for maintenance every ten years and sometimes the inspection can reveal some unexpected issues. Fortunately, Sulzer had delivered motor repairs in the past for this site and was able to provide a comprehensive repair and installation including realignment.
More and more coal-fired power stations in the UK are being taken off full-time operation and only used during periods of peak demand in a drive to reduce carbon emissions. As a result, the machinery and equipment is used less frequently but it must still be ready for operation when the demand for energy rises.
A program of routine maintenance minimizes the risk of breakdown by completing any repairs during planned outages that will not affect the ability of the power station to meet demand.
In this example of the importance of routine maintenance, a pair of ID fan motors was removed from service to check their overall condition. ID fans are used at the outlet of the boiler system to exhaust the flue gases, creating a negative pressure in the furnace; their reliable performance is essential to furnace efficiency.
As the leading independent provider of maintenance solutions for rotating equipment, Sulzer had already developed a working relationship with the power station and was contracted to complete the inspection and repair of one of the motors. The second motor was replaced with a spare unit and held for inspection at a later date.
Sulzer has a network of service centers throughout the UK and in this case the Avonmouth Service Center took the lead for the repair and sent a team of field service engineers to the site. Jamie Watt, Site Supervisor for Sulzer, explains: “These motors use a 3.3 KV supply and produce 1.4 MW of power to drive the fans.
“The motor and bedframe alone weigh 23 tonnes along with an additional 15 tonnes for the fan and the ductwork. The scale of the equipment required us to use a 100-tonne crane to assist with the removal process and allow the motor to be loaded for transport to the service center.”
Communication is key
The initial inspection of the motor found that electrically it was in good shape, passing all the insulation resistance tests for both stator and rotor. However, mechanically there were several issues that required attention, including a considerable amount of sheet-metal work that needed to be replaced.
Greg Sandy, Electrical Works Manager for Sulzer at the Avonmouth Service Center, comments: “From the outset, a continuous dialogue was established with the power station to advise on progress in the project and explain any changes to the original repair program. Sulzer uses critical path analysis to ensure that all the different aspects of the repair project are completed as efficiently as possible, minimizing the overall project timeframe.
Sharing the load
Inspection of the stator revealed that all the windings would need to be re-wedged, while the stator frame was very corroded and needed to be cleaned and repainted. The new wedges were manufactured in-house and the repair team worked around the clock to remove and replace the original coil wedges.
Meanwhile, the rotor bearing journals needed to be polished and the coupling journal was badly worn. This was machined before spiral weld was applied and then machined to nominal dimensions with a new key-way.
At the same time, the white metal bearings were re-surfaced and the bearing housings were refurbished. These were found to have been poorly repaired in the past and had different sized bolts holding them in place. The housings were machined, fitted with inserts and equipped with new retaining hardware.
Once the components had been fully refurbished, the motor was reassembled and the faulty auxiliary components, such as the tacho and some of the sensor wiring were replaced. In this case, the extended scope of repairs and manufacturing of new parts was completed in just two months.
The return of the motor to the power station was organized by the Avonmouth Service Center, which also provided the personnel to install and align it. The sheer scale of this equipment meant that the driveshaft could not be turned by hand, as required for a laser alignment process, so the installation was completed using more traditional tools.
The customer requested the alignment to be within 0.05 mm axially and 0.125 mm offset. In fact, the team managed to achieve an out-of-parallel figure of 0.02 mm using a series of hydraulic rams and feeler gauges. Jamie Watt concludes: “Fortunately, we still retain the skills to install larger equipment without some of the modern technology. The timing of the completion of this project coincided with the return of the transformers, which had also undergone extensive repairs, and the customer was very satisfied with the completed work.”
Digital display transmission with SDL4 B&R presents new generation of HMI panel interface
B&R recently introduced the fourth generation of its display transmission technology, Smart Display Link (SDL). SDL4 is based on HDBaseT 2.0 and can span up to 100 meters between the industrial PC and display device. This makes it easy to equip expansive machines and systems with multiple remote HMI panels.
Up to 100 m
SDL4 makes it possible to transmit display content and other data over much greater distances. It’s possible to span up to 100 meters between PC and display. An additional highlight of SDL4 is its use of standard Ethernet cables, which drastically reduces cable costs over longer distances. The thin cable and slim RJ45 connector are a perfect fit in tight situations such as feed-through openings and swing arm systems.
Up to 4 HMI panels per PC
An SDL4 converter allows up to three panels to be connected to one Automation PC. A fourth Automation Panel displaying different content can also be operated via an additional SDL4 interface. This is B&R’s response to the needs of modern manufacturing systems, which increasingly feature multiple locally-mounted operator panels.
Independent of operating system and software
The modular design of B&R’s PC and panel systems allows any Automation Panel to be equipped with an SDL4 interface. SDL4 transmission technology is independent of software and operating systems and integrates all communication channels – including USB, touch screen and function keys – in one single cable. SDL4 transmits all signals uncompressed and in high resolution for optimum image quality.
Smart Display Link 4 transmits all communication channels between PC and HMI panel via a standard Ethernet cable and is independent of operating system and software.
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