Important Definitions & Considerations in Piping

Creep: Time dependent deformation of material that occurs under load at Elevated temperatures. 

• Creep range for Low Carbonsteel Material =0.05 to 0.25 
• Creep range for Medium Carbonsteel Material = 0.25 to 0.5
• Creep range for High Carbonsteel Material = >0.5

Jacking oil: In order to prevent the metal to metal contact b/w the journal & bearing shell during startup & shut down, which is damaging in the long term, an oil pocket is machined in to the bottom shell of the journal bearing is supplied with oil under high pressure.

Gland Steam Piping: While steam is passing through pipes there is a chance of leakage of air in to valves which causes a serious damage. In order to prevent this damage. Gland steam is supplied which pressure is slightly higher than the vacuum pressure.

Extended Gland Packing: It seals without aid of gland steam.

Control Valves: Mainly Control valves are 4 types.

1. Pressure Control Valve (PCV)
2. Temperature Control Valve (TCV)
3. Flow Control Valve ( FCV)
4. Level Control Valve(LCV)

• In L.O.Inlet lines PCV & TCV are used.
• In Seal Oil over Head Tank & Seal Oil Traps LCVS are used.
• Allowable Pressure Drop 1% in 100 mm length. 
• Allowable Slope 25 mm in 1m.Length.
• Pipe size 1 ½” and below we use Socket Weld 800 rating flanges.
• For 1 ½” Pipe line we use Piston Lift Non Return Valve generally.
• For 2” Pipeline we use Swing Check Non Return Valve.
• Bending Radius for 1” pipe = 100mm
• Bending Radius for ¾” pipe = 75mm
• Upto 1 ½” we use generally pipe bends.
• 1 ½” and above we use elbows.
• Connection blocks are used for take connections on casings. Along Connection Block Metallic Gaskets are used.
• Expansion Bellows are generally used in Turbine Inlet & Drain lines.
• Velocity of liquid less than that of Gases because liquids adhere to walls of pipe, then friction is more. Hence velocity is less. 

Flanges Withstanding Rating Capacity For Gas Lines:

150RF ------------ Up to 10.5 Ata.

300RF------------ 21 Ata.

600RF------------ 42 Ata.

1500RF------------ 105 Ata.

2500RF------------ 175 Ata.

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