What Does Handhole Mean?
A handhole is a hole large enough only for insertion of a hand (as for lifting) or of a hand and arm (as for cleaning out otherwise inaccessible places or giving access to enclosed parts). In an underground electrical system, it is a shallow form of manhole giving access to a top row of ducts.
Handholes are used for the cleaning of closed systems through an easily accessible opening. It reduces chances of corrosion by allowing access to the deposits of corrosion products in an enclosed part.
Corrosionpedia Explains Handhole
A handhole is a type of small manhole, too small for access but useful for inspection and washing out the mechanism. In steam boilers, it is a small hole for the insertion of the hand in cleaning. It is an access opening usually not exceeding 17 cm in its longest dimension.
Handholes lessen chances of corrosion. For example, many commercial water heaters are used to produce incredibly high water temperatures, which in turn cause lime scale to settle on the bottom of the tank. Lime scale must be cleaned out by scraping and flushing. With the handhole clean-out opened, the level of lime scale can easily be observed and managed.
Handholes must be regularly checked for:
- Cracks and irregularities along weld
- Corrosion on the handhole
- Corrosion of welds around the handhole
- Missing handhole cover