Welding Terms Part-8 (P)

This is a continuation of Part 7. Welding is a highly technical field that relies on specialized acronyms and abbreviations to ensure effective communication and execution of tasks. The following terms are commonly used in welding work.

Paralleling – Running multiple power generators to form a large capacity power source with redundancy. Often used for mission-critical operations such as oilfield and emergency backup power. 

Parent Metal – Also called "base metal", this is the metal or steel that you are actually welding on.

Pass – A single progression of a welding or surfacing operation along a joint, weld deposit, or substrate. The result of a pass is a weld bead, layer, or spray deposit.

Peel test – A destructive method of inspection that mechanically separates a lap joint by peeling.

Peening – The mechanical working of metals using impact blows.

Penetration – Is the fusion or depth into the parent metal from its surface, or the amount of fusion through an open-faced joint.

Penetrant Inspection – A non-destructive testing method that detects surface flaws using either fluorescent or dye penetrants. Fluorescent penetrants glow under black light, while dye penetrants produce bright red indications when drawn to the surface by a developer. The process involves cleaning the surface, applying the penetrant, waiting for it to be absorbed, removing excess penetrant, and applying the developer to reveal any defects.

Percussive Welding – A resistance welding process in which a discharge of electrical energy and the application of high pressure occur simultaneously, or with the electrical discharge occurring slightly before the application of pressure.

Perlite – Perlite is the lamellar aggregate of ferrite and iron carbide resulting from the direct transformation of austenite at the lower critical point.

Pilot Arc – A low-current continuous arc between the electrode and the constricting nozzle of a plasma torch that ionizes the gas and facilitates the start of the welding arc.

Pitch – Center-to-center spacing of welds.

Plasma – A gas that has been heated to at least partially ionized conditions, enabling it to conduct an electric current.

Plasma Arc Cutting (PAC) – An arc cutting process using a constricted arc to remove the molten metal with a high-velocity jet of ionized gas from the constricting orifice.

Plasma Arc Welding (PAW) – An arc welding process that uses a constricted arc between a non-consumable electrode and the weld pool (transferred arc) or between the electrode and the constricting nozzle (non-transferred arc). Shielding is obtained from the ionized gas issuing from the torch.

Plasma Spraying (PSP) – A thermal spraying process in which a non-transferred arc is used to create an arc plasma for melting and propelling the surfacing material to the substrate.

Plug Weld – A circular weld made through a hole in one member of a lap or T joint.

Poke Welding – A spot welding process in which pressure is applied manually to one electrode. The other electrode is clamped to any part of the metal in much the same manner that arc welding is grounded.

Polarity – When you turn on a welding machine, an electrical circuit is formed. The circuit has either a positive or negative pole, and this property is referred to as polarity. In straight polarity or normal polarity, the workpiece is positive and the tool is negative. When the workpiece is negative and the tool is positive, this type of polarity is commonly known as reversed polarity.

Porosity – A hole-like discontinuity formed by gas entrapment during solidification.

Ports – In a MIG gun, there are small orifices (holes) that allow the flow of shielding gas. The nozzle then directs the gas out over the weld puddle.

Positions of Welding – All welding is accomplished in one of four positions: flat, horizontal, overhead, and vertical. The limiting angles of the various positions depend somewhat on whether the weld is a fillet or groove weld.

Positioner (Rotating Table / Work center) – These are usually found in the bigger, more prestigious fab shops. They can turn, tilt, rotate, revolve, and that allows you to make most of the welds in the flat or horizontal welding positions.

Post-Heating – The application of heat to an assembly after welding, brazing, soldering, thermal spraying, or cutting operation.

Post-weld Heat Treatment (PWHT) – Any heat treatment after welding.

Post-weld Interval – In resistance welding, the heat time between the end of weld time, or weld interval, and the start of hold time. During this interval, the weld is subjected to mechanical and heat treatment.

Power Efficiency – How well an electrical machine uses the incoming electrical power.

Preform – The initial press of a powder metal that forms a compact.

Preheating – The application of heat to the base metal immediately before welding, brazing, soldering, thermal spraying, or cutting.

Preheat Temperature – The temperature of the base metal immediately before welding is started.

Pressure Controlled Welding – The making of many spot or projection welds in which several electrodes function progressively under the control of a pressure sequencing device.

Pressure Welding – a welding process where pressure is used to make a weld.

Pre-weld Interval – In spot, projection, and upset welding, the time between the end of squeeze time and the start of weld time or weld interval during which the material is preheated. In flash welding, it is the time during which the material is preheated.

Primary Power – Often referred to as the input line voltage and amperage available to the welding machine from the shop's main power line.

Procedure – The detailed elements (with prescribed values or ranges of values) of a process or method used to produce a specific result.

Procedure Qualification – Demonstration that a fabricating process, such as welding, made by a specific procedure can meet given standards.

Projection Welding – A resistance welding process between two or more surfaces or between the ends of one member and the surface of another. The welds are localized at predetermined points or projections.

Protective atmosphere – A gas envelope surrounding the part to be brazed, welded, or thermal sprayed, with the gas composition controlled with respect to chemical composition, dew point, pressure, flow rate, etc. Examples are inert gases, combusted fuel gases, hydrogen, and vacuum.

Puddle – The puddle is the same as the weld pool. It is the molten filler metal that is combining with the parent metal.

Pull Gun Technique – Same as backhand welding.

Pulse – A current of controlled duration through a welding circuit.

Pulsed Power Welding – Any arc welding method in which the power is cyclically programmed to pulse so that the effective but short-duration values of a parameter can be utilized. Such short-duration values are significantly different from the average value of the parameter. Equivalent terms are pulsed voltage or pulsed current welding.

Pulsed Spray Welding – An arc welding process variation in which the current is pulsed to achieve spray metal transfer at average currents equal to or less than the globular to spray transition current.

Pulsing – Sequencing and controlling the amount of current, the frequency, and the duration of the welding arc.

Push Angle – The travel angle at which the electrode is pointing in the direction of travel.

Push Welding – A technique in welding where the welding gun is pushed forward in the direction of the weld, resulting in better visibility and control over the weld. This technique is commonly used in Gas Metal Arc Welding (GMAW) and is preferred for creating clean, spatter-free welds.