Correct installation of a suction barrel is critical to proper and trouble-free operation of a vertical turbine pump. The barrel must be plumbed (vertical) so the pump and column are centered in the barrel. More critical is the level of the barrel’s top flange. An unlevel barrel top flange can lead to excessive vibration resulting in reduced life of the bearings and an early failure of the pump.
The barrel must be plumb within 0.015 inches / foot of barrel length along the entire length of the barrel. Once positioned plumb, the barrel must be secured and held plumb throughout the back-filling operation.
For barrels with top flanges which are seal welded to the barrel, the top flange must be held level at the same time and throughout the back-filling process.
A typical method for plumbing a suction barrel is through use of a plumb bob suspended from the top of the barrel. When barrels become significantly larger the use of a lift or vertical scaffolding is necessary. If safety and convenience become a concern, there is an alternate solution to check barrel plumb.
A theodolite is a precision optical instrument used for measuring angles between designated visible points in both the horizontal and vertical planes. You may be familiar with theodolite, often seen in construction and land surveying. Some advantages of plumbing a barrel with a theodolite, in addition to not having to perform the leveling while at the top of the barrel, is that it can be significantly less expensive when taking account of setting up scaffolding or renting a lift. The theodolite does not have the same restriction of using a plumb bob when it comes to weather as wind and rain do not impact the readings of the device, if proper cover is set up to protect the electronics.
The below images demonstrate the use of a theodolite at our shop. Targets are located on the barrel to assist with the process in the field.