Speed Reducer

See Final DriveThe final reduction unit in the drive line..

Spelter

Zinc or galvanized coating on steel products.

SPG

StructuralPhysical adequacy to support imposed loads. Performance GradeThe elevations shown on plans and/or survey grade stakes for the installation of the carrier pipe. It is occasionally to give elevations for casing. In most cases, it is given to the flow line but can also be given to the top of the pipe or casing.; used to generate a final structural condition classification for sewer lengths. Recognizes the impact of external factors: surrounding soil conditions; frequency of surcharging, for example, and relates these to the Internal Condition Grade (ICGInternal Condition Grade; numeric criteria applied to visual images of sewers to develop a priority rating based on defects observed.).

Spillway

A low-level passage serving a dam or reservoir through which surplus water may be discharged; usually an open ditch around the end of a dam, a gateway, or a pipe in a dam. – An outlet pipe, flume or channel serving to discharge water from a ditch, ditch check, gutter or embankment protector.

Spiral Lining

A technique in which a ribbed plastic strip is spirally wound by a winding machine to form a liner which is inserted into a defective pipeline. The annular space may be grouted or the spiral liner expanded to reduce the annulus and form a Close-Fit liner.