Forged fittings Carbon steel Stainelss steel

Plugs and Bushings are not identified.
They may be used up through Class 6000 NPS

Advantages and Disadvantages of Socket Weld fittings

ADVANTAGES

• The pipe need not be beveled for weld preparation.
• Temporary tack welding is no needed for alignment, because in principle the fitting ensures proper alignment.
• The weld metal can not penetrate into the bore of the pipe.
• They can be used in place of threaded fittings, so the risk of leakage is much smaller.
• Radiography is not practical on the fillet weld; therefore correct fitting and welding is crucial. The fillet weld may be inspected by surface examination, magnetic particle (MP), or liquid penetrant (PT) examination methods.
• Construction costs are lower than with butt-welded joints due to the lack of exacting fit-up requirements and elimination of special machining for butt weld end preparation.

TYPES OF THREADED FITTINGS BY CLASS AND SIZE

Plugs and Bushings are not identified. They may be used up through Class 6000

Advantages and Disadvantages of Threaded Fittings

ADVANTAGES

• Installation productivity is moderately high, and specialized installation skill requirements are not extensive.
• Leakage integrity is good for low-pressure, low-temperature installations where vibration is not encountered.

DISADVANTAGES

• Rapid temperature changes may lead to leaks due to differential thermal expansion between the pipe and fittings.
• Vibration can result in fatigue failures of screwed pipe joints due to the high stress intensification effects caused by the sharp notches at the base of the threads.
• In hazardous piping systems threaded connections should be avoided, if possible. Their vulnerability to fatigue damage is significant, especially where exposed threads are subject to corrosion.