Page 191 - Machinery Component Maintenance

Machinery Alignment 173

benefits or prevent the attainment and retention of good alignment. Here
is a list of such items and questions to ask oneself:

Foundation Adequate size and good condition? A rule of thumb calls
for concrete weight equal to three times machine weight
for rotating machines, and five times for reciprocating ma-
chines.

Grout Suitable material, good condition, with no voids remaining
beneath baseplate? Tapping with a small hammer can de-
tect hollow spots, which can then be filled by epoxy injec-
tion or other means. This is a lot of trouble, though, and
often is not necessary if the lack of grout is not causing
vibration or alignment drift.

Baseplate Designed for adequate rigidity? Machine mounting pads
level, flat, parallel, coplanar, clean? Check with straight-
edge and feeler gauge. Do this upon receipt of new pumps,
to make shop correction possible-and maybe collect the
cost from the pump manufacturer. Shims clean, of ade-
quate thickness, and of corrosion- and crush-resistant ma-
terial? If commercial pre-cut shims are used, check for ac-
tual versus marked thicknesses to avoid a soft foot
condition. Machine hold-down bolts of adequate size, with
clearance to permit alignment corrective movement‘? Pad
height leaving at least 2 in. jacking clearance beneath cen-
ter at each end of machine element to be adjusted for align-
ment? If jackscrews are required, are they mounted with
legs sufficiently rigid to avoid deflection? Are they made
of type 3 16 stainless steel, or other suitable material, to re-
sist field corrosion? Water or oil cooled or heated pedestals
are usually unnecessary, but can in some cases be used for
onstream alignment thermal compensation.

Piping Is connecting piping well fitted and supported, and suffi-
ciently flexible, so that no more than 0.003 in. vertical and
horizontal (measured separately -not total) movement oc-
curs at the flexible coupling when the last pipe flanges are
tightened? Selective flange bolt tightening may be re-
quired, while watching indicators at the coupling. If pipe
flange angular misalignment exists, a “dutchman” or ta-
pered filler piece may be necessary. To determine filler