Another day we have passed again, but this faith still the same, there is no change at all. Oh God, please give me some miracle so I can continue this life with the new hope and new life. That's what I said inside this heart, but anything happen, I still try to give this Piping & Fabrication continuous post. And today we will Surf the deepest of Welding position, Pressure in the Pipe System.
Plastic.
A material which contains as an essential ingredient an organic substance of high to ultrahigh molecular weight, is solid in its finished state, and at some stage of its manufacture or processing can be shaped by flow. The two general types of plastic are thermoplastic and thermosetting.
Polarity.
A material which contains as an essential ingredient an organic substance of high to ultrahigh molecular weight, is solid in its finished state, and at some stage of its manufacture or processing can be shaped by flow. The two general types of plastic are thermoplastic and thermosetting.
Polarity.
 |
| Polarity |
The direction of flow of current with respect to the welding electrode and workpiece.
Porosity.
Presence of gas pockets or voids in metal.
Positioning Weld.
 |
| weld position |
A weld made in a joint which has been so placed as to facilitate the making of the weld.
Postheating.
The application of heat to a fabricated or welded section subsequent to a fabrication, welding, or cutting operation. Postheating may be done locally, as by induction heating; or the entire assembly may be postheated in a furnace.
Postweld Heat Treatment.
 |
| postweld heat treatment |
Any heat treatment subsequent to welding.
Preheating.
The application of heat to a base metal immediately prior to a welding or cutting operation.
Pressure.
 |
| pressure |
The force per unit that is acting on a real or imaginary surface within a fluid is the pressure or intensity of pressure. It is expressed in pounds per square inch:
 |
| pressure |
where p = absolute pressure at a point, psi (kg/cm2)
w = specific weight, lb/ft3 (kg/m3)
h = height of fluid column above the point, ft (m)
pa = atmospheric pressure, psi (kg/cm2)
The gauge pressure at a point is obtained by designating atmospheric pressure as zero:
where p = gauge pressure.
To obtain absolute pressure from gauge pressure, add the atmospheric pressure to the gauge pressure.
Pressure Head.
From the definition of pressure, the expression p/w is the pressure head. It can be defined as the height of the fluid above a point, and it is normally measured in feet.
Purging.
The displacement during welding, by an inert or neutral gas, of the air inside the piping underneath the weld area in order to avoid oxidation or contamination of the underside of the weld. Gases most commonly used are argon, helium, and nitrogen (the last is principally limited to austenitic stainless steel).
Purging can be done within a complete pipe section or by means of purging fixtures of a small area underneath the pipe weld.
w = specific weight, lb/ft3 (kg/m3)
h = height of fluid column above the point, ft (m)
pa = atmospheric pressure, psi (kg/cm2)
The gauge pressure at a point is obtained by designating atmospheric pressure as zero:
where p = gauge pressure.
To obtain absolute pressure from gauge pressure, add the atmospheric pressure to the gauge pressure.
Pressure Head.
From the definition of pressure, the expression p/w is the pressure head. It can be defined as the height of the fluid above a point, and it is normally measured in feet.
Purging.
The displacement during welding, by an inert or neutral gas, of the air inside the piping underneath the weld area in order to avoid oxidation or contamination of the underside of the weld. Gases most commonly used are argon, helium, and nitrogen (the last is principally limited to austenitic stainless steel).
Purging can be done within a complete pipe section or by means of purging fixtures of a small area underneath the pipe weld.
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