Chemical Technology Oct 2015

Chemical Technology • October 2015

PUMPS & VALVES

place after 90 days of primer application, the baseplate

will need to be recoated with primer.

• F For modularised pumps, consideration should be given

to pregrouted baseplates.

Couplings and guards

Elastomeric and disk type spacer couplings are used for

connecting pump and driver shaft ends. Progressive cavity

pumps are driven by lubricated universal joint. While disk

spacer couplings are preferred for all applications, the

manufacturer’s standard coupling design for vertical in-line

pumps can be accepted. API 671, 4

Edition, based special

purpose couplings should be specified when continuous

operating speed is over 3 600 rpm.

The standard requirements for disk type spacer cou-

plings are:

Monitoring instrumentation guidelines

• API 670, 4th Edition based monitoring instrumentation

should be specified for pumps fitted with hydrodynamic

bearings and rated 1 118 KW (1 500 HP) and above.

This requirement also applies to pump drivers (steam

turbines, electric induction motors and gear units, if

furnished).

Radial bearings

• X-Y pair of non-contact proximity probes for each ra-

dial bearing Two-(2) Resistance Temperature Detectors

(RTDs) per bearing

• Thrust bearing

• Two-(2) axial position non-contact proximity probes

• Two-(2) Resistance Temperature Detectors (RTDs) per

side (active and inactive); total four-(4) RTD’s per bearing

Phase reference probe

• On motor and steam turbine shaft ends.

Winding temperature RTD’s

• Two-(2) per phase; total six-(6) RTDs

Casing accelerometers

• One accelerometer each on pinion and gear sides

• Casing accelerometer should be furnished for direct act-

ing reciprocating pumps above 150 KW.

Pumps fitted with hydrodynamic bearings and with rated

power between 746 KW and 1 118 KW should have provi-

sion for installing non-contact type radial vibration and axial

displacement probes. RTDs should be furnished for pump

and driver radial and thrust bearings.

Vibration, thrust position and bearing temperature-

related shutdowns are generally dictated by plant operating

and safeguarding philosophy and should be agreed to by

all parties involved in equipment selection, including the

equipment manufacturer.

This article first appeared in ‘Pump Engineer News’ published

by KCI Publishing.

www.pumpengineer.net

Minimum service factor:

(Standard SF=1.5 for

Disk/Diaphragm Couplings)

1.0 for constant torque applications

1.25 for pumps driven by motor + gearbox

1.5 for P.D Rotary pumps

2.0 for Reciprocating Pumps 125 mm (5’’ standard)

Minimum spacer length:

125 mm (5’’ standard)

Standard shaft end:

* Cylindrical with rectangular key, or

* Taper shaft end as dictated by API 610, 10th Edition, Para 6.2.8)

* Fits and tolerances on fits to be as per AGMA 9002-A86.

* Taper shaft end with hydraulic fit should be specified for centrifugal pumps when power rating exceeds 1500 KW.

Material

Corrosion resistant steel

Minimum Balance Grade

AGMA 9

Coupling Guard

In accordance with API 610, 10th Edition, Para 6.2.14 except that non-metallic guards as stated in 6.2.14 c) are not acceptable. Specify non-

sparking metallic guard