2.8.23 Water and Air Piping, Fitting and Accessories

2.8.23               Water and Air Piping, Fitting and Accessories:

 

                        All required water and air pipework including all instrument impulse piping and fitting for complete DAETP shall be provided as specified.

 

                        All piping system shall be capable of withstanding the maximum pressure (pump shut off) in the corresponding line at the relevant temperatures.

 

                        All piping system shall be properly designed to take care of water hammer/pressure surges which may arise during operation of the system. 

 

                        All piping shall be provided with vents at the highest points and drains at the lowest points alongwith vent valves and drain cocks. Vents shall not be less than 15mm in size. Drains shall not be less than 25 mm size.

 

                        Bends, loops, off sets, expansion or flexible joints shall be used as required in order to prevent over­stressing of the piping system due to thermal movements and to provide adequate flexibility.

 

                        The design, supply and installation of all pipe sup­ports and hangers including pipe clamps, turn buckles, hanger rods, auxiliary steel etc. shall be furnished.  All bolting materials companion flanges, nuts gaskets etc. as required in the piping system and at all terminal points shall be furnished.

 

                        All piping shall be routed so as to avoid interference with other pipes and their hangers and supports, elec­trical cable trays, ventilation ducting structural members, equipment etc.  Adequate clearance shall be ensured with respect to the above to accommodate pipe movement.

 

                        The piping shall be arranged to provide clearance for the removal of equipment requiring maintenance and for easy access to valves and other piping accessories required for operation and maintenance.

 

                        Piping shall generally be routed above ground but where specifically indicated/approved by the Engineer the pipes may be arranged in trenches or buried.  Bidder shall provide either coal tar and Bitumen tapes on conventional coat and wrap system for corrosion protec­tion of buried piping as per relevant codes and stand­ards.

 

                        Overhead piping shall have a normal minimum vertical clearance of 3 metres above walk ways and working areas and 6 metres above roadways.

 

The following line velocities shall be considered for estimating the line sizes of water pipes and Air Pipes:

 

 

                        ————————————————————————————————–

                        Service                             Velocity, M/Sec

                        ————————————————————————————————–

                                                                    Pipe size              Pipe size                Pipe size

                                                                    size below           of 50 to                  of 200 mm

                                                                    50 mm                150 mm                 and above

                        ————————————————————————————————–

                        a)   Water pump                    06-0.9                 1.2-1.5                   1.2-1.5

                              Suction

 

                        b)   Water Pump                    0.9-1.8                1.5-2.4                   1.8-2.8

                              Discharge

 

                        c)   Compressed                    15-20                  15-20                     20-30

                              air below

                              2 Kg/cm²(g)

 

                        d)   Compressed                    20-30                  20-25                     25-35

                              air, 2 Kg/cm² (g)

                              & above

                        ————————————————————————————————–

                        Note

 

                        1.         Pipe Size in pump suction side shall be at least one pipe size larger than the corresponding pump discharge connec­tion.

 

                        2.         The proposed sizes of the water and air pipes shall be submitted.

 

                        The pipe supports shall be spaced as follows.

 

                        Pipe size(NB)    25        50        100       150       200       300       400       500

                        Spacing in         2.1       3.0       4.3       5.2       5.8       7.8       8.2       9.8

                        metre   

                       

2.8.23.1                                         Water and Air Piping,

Fittings and Accessories

1.0	Type of Pipes	a) Upto & including150 NB		MS, ERW pipes to IS:1239 Heavy grade
		b) 200 NB to 450 NB		MS ERW to IS 3589.
				OR
		SAIL or equal make		ERW commercial quality pipes.
		c) 500 NB and above		Rolled and welded from MS plate to IS:226 Dimensional toler­ance as per IS:3589.
				OR
				SAIL OR Equal make
				spiral welded pipes.
				Dimensional toler­ance as per IS:3589.
2.0	Pipe SIzes	As required.
3.0	Thickness of Pipes	a) Pipe specs. as per IS:1239		Pipe thickness shall be of Heavy grade.
		b) Pipe spec. as per IS:3589(ERW)		Min 6.35mm thick for 200 NB to 400 NB size and Min. 7.14 mm thick for 450 NB size.
4.0	Type of Line joints.
		a) 50 NB and below		Socket welded to ANSI:B16.11.
		b) 65 NB and above.		Butt welded to ANSI:B16.25.
5.0	Quantity	As required
6.0	Fittings (Bends)
		a) For sizes upto& including65NB		3D radius bends and material same as that of parent pipe.
		b) For sizes 80 NB to 300 NB		SR & LR elbow and material same as that of parent pipe
		c) 350 NB & above.		Miter bends with Miter angle not exceeding 22.5°.  Material shall be same as that of parent pipe and dimensional toler­ance shall be as per BS : 534.
7.0	Flanges	Slip on flat face type with drilled and pressure rating as per valve and other specialities. Material of construction shall be IS:226 upto 20 MM thickness and IS:2062 for higher thickness.
8.0	Bolts	As per IS:1367 Cl.4.6 or ASTM-A-307-Gr.B.
9.0	Nuts	As per IS:1367 Cl.4.0 or ASTM A-307 Gr. B.
10.	Gaskets	Wire inserted Red rubber.  Thickness shall be 1.6 mm for sizes upto and including 250 NB and 3.2 mm for higher sizes.
II.  Air Pipes
1.0	Type of Pipe		a) ERW pipe as per IS:1239, heavy grade with galvanising as per IS:4736 for pipes  upto & including 150 NB. For pipes of sizes above 150 NB it shall be as per Cl. I (1.0, b) & Cl. No. I (3 b) above.
			b) For compressed air piping for instru­ment and control loops, bulk heads, the following standard shall be adopted
			i)                 For sizes25 NB and including 50 NB. ii)                For sizes below 25 NB	Seamless Red Brass ASTM B43 Sch.40.         Seamless Copper to ASTM  -75
2.0	Pipe Sizes		As required
3.0	Thickness of pipes		For pipe size upto & including 150 NB pipe thickness shall be of heavy grade as per IS:1239 and for pipes of higher sizes, the thickness shall be as per clause No. I (3.0) b & c on page-5 mentioned above for water pipes.
4.0	Type of Line joints		(a) 65 NB and below	Screwed
			(b) 80 NB and above	Sleeve welded . However valve etc. shall be IS:226 upto 20 mm thickness and is:2062 for higher thickness.
5.0	Quantity		As required.
6.0	Fittings/ (Elbows)		As per ASTM-A-234 Gr. WPB (GI)
7.0	Flanges		Raised face type G.I. screwed and pressure rating as per valve and other specialities.   Material of construction shall be IS:226 upto 20 mm thickness and IS:2062 for higher thickness.
8.0	Bolts, nuts & Gaskets.		Same as for water pipes

 

Advertisement