Multitech 1777.8/7-10 G3 Connecting the piping, Protection against foreign matter

5.4Connecting the piping

Suction lift lines shall be laid with a rising slope towards the pump and suction head lines with a downward slope towards the pump, to prevent the formation of air pockets.

With short pipelines, the nominal diameters should be at least equal to the nominal diameters of the pump nozzles. For long pipelines, the most economical nominal diameter has to be determined from case to case.

Adapters to larger diameters should have a diffuser angle of approx. 8￿ in order to avoid any pressure losses caused by the formation of air pockets or gas.

It is recommended to install check and shut-off elements in the system, depending on the type of plant and pump.

Caution	Never use the pump itself as an anchorage point
	for the piping. The piping-induced forces and

moments acting on the pump flanges (e.g. due to warped pipelines or thermal expansion) must not exceed the permissible forces and moments.

The pipelines shall be anchored in close proximity to the pump and connected without transmitting any stresses or strains. Their weight must not be carried by the pump.

Caution	If welding work must be performed on the piping
	when the pump is already installed, the electric

welding equipment must not be earthed on the pump or baseplate, to prevent current flowing through the rolling element bearings, which could cause their premature destruction (pitting effect).

Thermal expansions of the pipelines must be compensated by appropriate measures so as not to

impose any extra loads on the pump.

Expansion joints may have to be used. An excessive, impermissible increase in the pipeline forces may cause leaks on the pump where the fluid handled can escape into the atmosphere.

Danger to life when hot fluids are handled!

Fig. 9 Max. nozzle forces and moments

Direction of forces:

X= horizontal, parallel to the pump axis

Y= vertical to the pump axis

X= horizontal, at a right angle to the pump axis

Direction of moments:

X= around the horizontal axis, parallel to the pump axis MY = around the vertical nozzle axis

X= around the horizontal axis, at a right angle to the

pump axis

Suction and discharge nozzle are regarded separately.

Multitec

Max. permissible pipeline forces (material codes 10, 11, 12, 13)

Nom. nozzle diameter (DN)

32 50 65 80 100 125 150 200 250

Vertical nozzle, at a right angle to the shaft (N )

Fx	245	510	640	700	1015	1470	1780	2700	-
Fy	410	635	800	970	1270	1850	2220	3490	-
Fz	265	415	520	625	830	1220	1465	2220	-
Horizontal nozzle, at a right angle to the shaft (N )
Fx	245	510	640	800	1015	1470	1780	2700	-
Fy	265	415	520	625	830	1220	1465	2220	-
Fz	410	635	800	970	1270	1850	2220	3490	-
Axial nozzle, parallel to the shaft (N )
Fx	-	-	800	-	1270	1850	2220	3490	4760
Fy	-	-	520	-	830	1220	1465	2220	3180
Fz	-	-	640	-	1015	1470	1780	2700	3810
Moments for all nozzles (Nm )
Mx	260	330	460	680	950	1235	1640	2520	3580
My	160	250	350	520	715	930	1260	1840	2710
Mz	190	170	240	340	490	660	840	1260	1740

Example:

Multitec 50 with radial suction nozzle

-for the suction nozzle, the values given in table column DN80 apply

-for the discharge nozzle, the values given in table column DN50 apply

Max. permissible pipeline forces (material codes 20 to 30)

The values given for material codes 10, 11, 12,13 shall be multiplied by the factor 1.4.

Protection against foreign matter

Before commissioning new installations thoroughly clean, flush and blow through all vessels, pipelines and connections. Often welding beads, scale and other impurities only come off after a certain period of operation. Fit a strainer in the suction line to prevent them from entering the pump. The total cross-section of the holes in the strainer shall be three times the cross-section of the pipeline in order to avoid excessive pressure loss across the strainer due to clogging. Conical strainers with laid in wire mesh having a mesh width of 0.5 mm and a wire diameter of 0.25 mm, of corrosion-resistant material, shall be used.

1Strainer housing

2 Fine screen

3 Perforated plate

4 Pump suction nozzle

5 Differential pressure gauge

Fig. 10 Conical strainer for the suction line

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