Pin Brazing - by Glenn Symington
Pin brazing is basically 'Drawn-arc Silver Brazing', considered a Brazing process and not (as is sometimes incorrectly stated) 'Electric-arc Silver Soldering', as the working temperature or melting point of the filler material is below that of the base metal or substrate but above 426.6 Degrees Celsius (800 Degrees Farenheit). The filler metal, in the case of Pin Brazing is a Silver alloy consisting typically - Ag 55%, Cu 21%, Zn 22% and Sn 2%, which when molten flows directly into the closely fitted surfaces between the desired connection type and the substrate material by Capillary Action.
Using a specially designed Brazing Pin (the body of which is normally Brass or sometimes specialist Stainless Steel Threaded Studs can be produced, all of which are tipped with a specific portion of the above Silver alloy and a Flux material). An Automatic Pistol (similar in many ways to a Stud Welding Pistol, which acts as a means to complete a DC circuit via manual switch and provide "lift" via the use of a small electromagnet in order to facilitate generation of an Arc) and a Power supply, the Pin brazing process is renowned for being both Safe fast and reliable, requiring very little training.
As portability has been an essential factor in the development of Pin Brazing, power is supplied most commonly by a re-chargeable, portable battery pack. These vary in size and weight relative to the number of connections required. However in cases where a fixed power supply can be practically provided for example Welding Generators on-board a Pipe-laying Vessel, many continuous connections can be made in a Production environment. Timing is controlled either electronically (where an electronic device is fitted to a battery pack or generator) or via a fuse wire located on the Brazing Pin itself. Fuse wire controlled systems, which due to the nature of the process and the common locality of use, (that is remote locations and extreme environments) are proven to be more successful as they require less attention in the field and present the end user with easy to operate and maintain electromechanical equipment.
Attachment types vary between Threaded Stud Connectors and Direct Connections. Threaded Studs are popular when a temporary connection is required, mechanically secure and requiring the specified cable to be attached to a standard crimp lug and then secured to stud with a locking nut (Cable-Lug-Stud-Substrate), but are criticized due to their bulk and low electrical integrity. Direct Connections are more permanent fixtures, historically made via a Pin Brazing Compatible Cable Lug, wherein the required cable is crimped into the lug and then the lug is directly 'Pin Brazed' to the Substrate (Cable-Cable Lug-Substrate). However the electrical and mechanical integrity of these have been criticized more recently as the leading competitors for similar types of connection, involve a Thermite process and are able to make 'actual' direct connections (Cable-Substrate).
Pin Brazing solutions which produce Cable-Substrate attachments for Railroads have been available for some time, but in the Pipeline Industry are sometimes impractical, requiring pre-manufactured cables with 'integral lug' attachments, complex and expensive electronics or unsubstantial often flimsy Direct Pin Brazing systems which generate too much heat and could compromise the metallurgical integrity of the substrate. However two new Electrobraze systems now exist that allow Cable-Substrate connections which meet all of the criteria required of Cable-Substrate system products and improve on their shortcomings greatly. The first is a product named Integra-BondTM which combines the mechanical strength and versatility of a Cable lug attachment with Cable-Substrate electrical integrity and even reduced Heat Affected Zone (HAZ), the second is SABRETM which is actually a Shielded-Arc Electrode Brazing adaptation of the Integra-BondTM system, greatly reducing negative metallurgical effects within the HAZ.
Pin brazing is basically 'Drawn-arc Silver Brazing', considered a Brazing process and not (as is sometimes incorrectly stated) 'Electric-arc Silver Soldering', as the working temperature or melting point of the filler material is below that of the base metal or substrate but above 426.6 Degrees Celsius (800 Degrees Farenheit). The filler metal, in the case of Pin Brazing is a Silver alloy consisting typically - Ag 55%, Cu 21%, Zn 22% and Sn 2%, which when molten flows directly into the closely fitted surfaces between the desired connection type and the substrate material by Capillary Action.
Using a specially designed Brazing Pin (the body of which is normally Brass or sometimes specialist Stainless Steel Threaded Studs can be produced, all of which are tipped with a specific portion of the above Silver alloy and a Flux material). An Automatic Pistol (similar in many ways to a Stud Welding Pistol, which acts as a means to complete a DC circuit via manual switch and provide "lift" via the use of a small electromagnet in order to facilitate generation of an Arc) and a Power supply, the Pin brazing process is renowned for being both Safe fast and reliable, requiring very little training.
As portability has been an essential factor in the development of Pin Brazing, power is supplied most commonly by a re-chargeable, portable battery pack. These vary in size and weight relative to the number of connections required. However in cases where a fixed power supply can be practically provided for example Welding Generators on-board a Pipe-laying Vessel, many continuous connections can be made in a Production environment. Timing is controlled either electronically (where an electronic device is fitted to a battery pack or generator) or via a fuse wire located on the Brazing Pin itself. Fuse wire controlled systems, which due to the nature of the process and the common locality of use, (that is remote locations and extreme environments) are proven to be more successful as they require less attention in the field and present the end user with easy to operate and maintain electromechanical equipment.
Attachment types vary between Threaded Stud Connectors and Direct Connections. Threaded Studs are popular when a temporary connection is required, mechanically secure and requiring the specified cable to be attached to a standard crimp lug and then secured to stud with a locking nut (Cable-Lug-Stud-Substrate), but are criticized due to their bulk and low electrical integrity. Direct Connections are more permanent fixtures, historically made via a Pin Brazing Compatible Cable Lug, wherein the required cable is crimped into the lug and then the lug is directly 'Pin Brazed' to the Substrate (Cable-Cable Lug-Substrate). However the electrical and mechanical integrity of these have been criticized more recently as the leading competitors for similar types of connection, involve a Thermite process and are able to make 'actual' direct connections (Cable-Substrate).
Pin Brazing solutions which produce Cable-Substrate attachments for Railroads have been available for some time, but in the Pipeline Industry are sometimes impractical, requiring pre-manufactured cables with 'integral lug' attachments, complex and expensive electronics or unsubstantial often flimsy Direct Pin Brazing systems which generate too much heat and could compromise the metallurgical integrity of the substrate. However two new Electrobraze systems now exist that allow Cable-Substrate connections which meet all of the criteria required of Cable-Substrate system products and improve on their shortcomings greatly. The first is a product named Integra-BondTM which combines the mechanical strength and versatility of a Cable lug attachment with Cable-Substrate electrical integrity and even reduced Heat Affected Zone (HAZ), the second is SABRETM which is actually a Shielded-Arc Electrode Brazing adaptation of the Integra-BondTM system, greatly reducing negative metallurgical effects within the HAZ.