Pin brazing is a metallurgically safe method of making

electrical connection Components of an electrical circuit are electrically connected if an electric current can run between them through an electrical conductor. An electrical connector is an electromechanical device used to create an electrical connection betwee ...

s to

steel Steel is an alloy of iron and carbon that demonstrates improved mechanical properties compared to the pure form of iron. Due to steel's high Young's modulus, elastic modulus, Yield (engineering), yield strength, Fracture, fracture strength a ...

and

ductile iron pipe Ductile iron pipe is pipe (material), pipe made of ductile iron, ductile cast iron commonly used for potable water transmission and distribution.Moser, A. P. and Folkman, Steven L. (2008) ''Buried Pipe Design'' (3rd edition) McGraw-Hill, New York ...

lines as well as other metallic structures, which are to be cathodically protected or electrically earthed. The pin brazing technique is based primarily upon Electric-arc silver soldering using a specially designed portable pin brazing unit, a hollow brazing pin containing

silver solder Solder (; NA: ) is a fusible metal alloy used to create a permanent bond between metal workpieces. Solder is melted in order to wet the parts of the joint, where it adheres to and connects the pieces after cooling. Metals or alloys suitable ...

and

flux Flux describes any effect that appears to pass or travel (whether it actually moves or not) through a surface or substance. Flux is a concept in applied mathematics and vector calculus which has many applications in physics. For transport phe ...

. The

brazing Brazing is a metal-joining process in which two or more metal items are joined by melting and flowing a filler metal into the joint, with the filler metal having a lower melting point than the adjoining metal. Brazing differs from welding in ...

process is initiated by depressing a trigger on the brazing gun. This, as with most forms of electrical

welding Welding is a fabrication (metal), fabrication process that joins materials, usually metals or thermoplastics, primarily by using high temperature to melting, melt the parts together and allow them to cool, causing Fusion welding, fusion. Co ...

, simply completes a circuit through which a DC current is passed. The pin tip is the point of highest resistance at which point an arc is drawn, melting the solder flux whilst simultaneously heating the lug material and the surface of the structure or pipeline to the required

soldering Soldering (; ) is a process of joining two metal surfaces together using a filler metal called solder. The soldering process involves heating the surfaces to be joined and melting the solder, which is then allowed to cool and solidify, creatin ...

temperature. After approximately 1.5 seconds the circuit is mechanically or electronically broken, the

solenoid upright=1.20, An illustration of a solenoid upright=1.20, Magnetic field created by a seven-loop solenoid (cross-sectional view) described using field lines A solenoid () is a type of electromagnet formed by a helix, helical coil of wire whos ...

is de-energised and the brazing pin is pushed forward into the molten pool of brazing

alloy An alloy is a mixture of chemical elements of which in most cases at least one is a metal, metallic element, although it is also sometimes used for mixtures of elements; herein only metallic alloys are described. Metallic alloys often have prop ...

. The pin tip, brazing alloy, flux and lug cool into a homogenous unit. The pin brazing process is well suited for joints between

insulated pipe Insulated pipes (called also preinsulated pipes or bonded pipe ) are widely used for district heating and hot water supply. They consist of a steel pipe called "service pipe", a thermal insulation layer and an outer casing. The insulation bonds t ...

sections, connection to measuring cables, installation of

sacrificial anode A galvanic anode, or sacrificial anode, is the main component of a galvanic cathodic protection system used to protect buried or submerged metal structures from corrosion. They are made from a metal alloy with a more "active" voltage (more n ...

s and bonding

zinc Zinc is a chemical element; it has symbol Zn and atomic number 30. It is a slightly brittle metal at room temperature and has a shiny-greyish appearance when oxidation is removed. It is the first element in group 12 (IIB) of the periodic tabl ...

bracelets to offshore pipelines, due to the ease and speed of installation, high

mechanical strength Mechanical may refer to: Machine * Machine (mechanical), a system of mechanisms that shape the actuator input to achieve a specific application of output forces and movement * Mechanical calculator, a device used to perform the basic operations of ...

and extremely low resistance. Within a cathodic protection system there are a multitude of connection requirements for anode cables, measuring posts etc., being extremely versatile, the pin brazing system is ideally suited to this. Attachments can be made vertically, horizontally or even overhead. If preferred, threaded pins with nuts can be attached or cable bonded directly onto the pipe by means of a special cable lug which can be crimped on site or supplied complete as a unique integrally crimped attachment. The pin brazing unit contains all the equipment and tools required to make safe cable connections. A welding generator may also be utilized as a power source wherever a battery unit may be impractical or a great many connections need to be made in such places as pipe-coating yards or lay-barges etc.

References

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